Bitcoin Developer Reference

Block Chain

The following subsections briefly document core block details.

Block Headers

Block headers are serialized in the 80-byte format described below and then hashed as part of Bitcoin’s proof-of-work algorithm, making the serialized header format part of the consensus rules.

The hashes are in internal byte order; the other values are all in little-endian order.

An example header in hex:

02000000 ........................... Block version: 2

b6ff0b1b1680a2862a30ca44d346d9e8
910d334beb48ca0c0000000000000000 ... Hash of previous block's header
9d10aa52ee949386ca9385695f04ede2
70dda20810decd12bc9b048aaab31471 ... Merkle root

24d95a54 ........................... Unix time: 1415239972
30c31b18 ........................... Target: 0x1bc330 * 256**(0x18-3)
fe9f0864 ........................... Nonce

Block Versions

• Version 1 was introduced in the genesis block (January 2009).

• Version 2 was introduced in Bitcoin Core 0.7.0 (September 2012) as a soft fork. As described in BIP34, valid version 2 blocks require a block height parameter in the coinbase. Also described in BIP34 are rules for rejecting certain blocks; based on those rules, Bitcoin Core 0.7.0 and later versions began to reject version 2 blocks without the block height in coinbase at block height 224,412 (March 2013) and began to reject new version 1 blocks three weeks later at block height 227,930.

• Version 3 blocks were introduced in Bitcoin Core 0.10.0 (February 2015) as a soft fork. When the fork reached full enforcement (July 2015), it required strict DER encoding of all ECDSA signatures in new blocks as described in BIP66. Transactions that do not use strict DER encoding had previously been non-standard since Bitcoin Core 0.8.0 (February 2012).

• Version 4 blocks specified in BIP65 and introduced in Bitcoin Core 0.11.2 (November 2015) as a soft fork became active in December 2015. These blocks now support the new OP_CHECKLOCKTIMEVERIFY opcode described in that BIP.

The mechanism used for the version 2, 3, and 4 upgrades is commonly called IsSuperMajority() after the function added to Bitcoin Core to manage those soft forking changes. See BIP34 for a full description of this method.

As of this writing, a newer method called version bits is being designed to manage future soft forking changes, although it’s not known whether version 4 will be the last soft fork to use the IsSuperMajority() function. Draft BIP9 describes the version bits design as of this writing, although it is still being actively edited and may substantially change while in the draft state.

Merkle Trees

The merkle root is constructed using all the TXIDs of transactions in this block, but first the TXIDs are placed in order as required by the consensus rules:

• The coinbase transaction’s TXID is always placed first.

• Any input within this block can spend an output which also appears in this block (assuming the spend is otherwise valid). However, the TXID corresponding to the output must be placed at some point before the TXID corresponding to the input. This ensures that any program parsing block chain transactions linearly will encounter each output before it is used as an input.

If a block only has a coinbase transaction, the coinbase TXID is used as the merkle root hash.

If a block only has a coinbase transaction and one other transaction, the TXIDs of those two transactions are placed in order, concatenated as 64 raw bytes, and then SHA256(SHA256()) hashed together to form the merkle root.

If a block has three or more transactions, intermediate merkle tree rows are formed. The TXIDs are placed in order and paired, starting with the coinbase transaction’s TXID. Each pair is concatenated together as 64 raw bytes and SHA256(SHA256()) hashed to form a second row of hashes. If there are an odd (non-even) number of TXIDs, the last TXID is concatenated with a copy of itself and hashed. If there are more than two hashes in the second row, the process is repeated to create a third row (and, if necessary, repeated further to create additional rows). Once a row is obtained with only two hashes, those hashes are concatenated and hashed to produce the merkle root.

TXIDs and intermediate hashes are always in internal byte order when they’re concatenated, and the resulting merkle root is also in internal byte order when it’s placed in the block header.

Target nBits

The target threshold is a 256-bit unsigned integer which a header hash must be equal to or below in order for that header to be a valid part of the block chain. However, the header field nBits provides only 32 bits of space, so the target number uses a less precise format called “compact” which works like a base-256 version of scientific notation:

As a base-256 number, nBits can be quickly parsed as bytes the same way you might parse a decimal number in base-10 scientific notation:

Although the target threshold should be an unsigned integer, the original nBits implementation inherits properties from a signed data class, allowing the target threshold to be negative if the high bit of the significand is set. This is useless—the header hash is treated as an unsigned number, so it can never be equal to or lower than a negative target threshold. Bitcoin Core deals with this in two ways:

• When parsing nBits, Bitcoin Core converts a negative target threshold into a target of zero, which the header hash can equal (in theory, at least).

• When creating a value for nBits, Bitcoin Core checks to see if it will produce an nBits which will be interpreted as negative; if so, it divides the significand by 256 and increases the exponent by 1 to produce the same number with a different encoding.

Some examples taken from the Bitcoin Core test cases:

Difficulty 1, the minimum allowed difficulty, is represented on mainnet and the current testnet by the nBits value 0x1d00ffff. Regtest mode uses a different difficulty 1 value—0x207fffff, the highest possible value below uint32_max which can be encoded; this allows near-instant building of blocks in regtest mode.

Serialized Blocks

Under current consensus rules, a block is not valid unless its serialized size is less than or equal to 1 MB. All fields described below are counted towards the serialized size.

The first transaction in a block must be a coinbase transaction which should collect and spend any transaction fees paid by transactions included in this block.

All blocks with a block height less than 6,930,000 are entitled to receive a block subsidy of newly created bitcoin value, which also should be spent in the coinbase transaction. (The block subsidy started at 50 bitcoins and is being halved every 210,000 blocks—approximately once every four years. As of November 2017, it’s 12.5 bitcoins.)

Together, the transaction fees and block subsidy are called the block reward. A coinbase transaction is invalid if it tries to spend more value than is available from the block reward.

Transactions

The following subsections briefly document core transaction details.

OpCodes

The opcodes used in the pubkey scripts of standard transactions are:

• Various data pushing opcodes from 0x00 to 0x4e (1–78). These aren’t typically shown in examples, but they must be used to push signatures and public keys onto the stack. See the link below this list for a description.

• OP_TRUE/OP_1 (0x51) and OP_2 through OP_16 (0x52–0x60), which push the values 1 through 16 to the stack.

• OP_CHECKSIG consumes a signature and a full public key, and pushes true onto the stack if the transaction data specified by the SIGHASH flag was converted into the signature using the same ECDSA private key that generated the public key. Otherwise, it pushes false onto the stack.

• OP_DUP pushes a copy of the topmost stack item on to the stack.

• OP_HASH160 consumes the topmost item on the stack, computes the RIPEMD160(SHA256()) hash of that item, and pushes that hash onto the stack.

• OP_EQUAL consumes the top two items on the stack, compares them, and pushes true onto the stack if they are the same, false if not.

• OP_VERIFY consumes the topmost item on the stack. If that item is zero (false) it terminates the script in failure.

• OP_EQUALVERIFY runs OP_EQUAL and then OP_VERIFY in sequence.

• OP_CHECKMULTISIG consumes the value (n) at the top of the stack, consumes that many of the next stack levels (public keys), consumes the value (m) now at the top of the stack, and consumes that many of the next values (signatures) plus one extra value.

  The “one extra value” it consumes is the result of an off-by-one error in the Bitcoin Core implementation. This value is not used, so signature scripts prefix the list of secp256k1 signatures with a single OP_0 (0x00).

  OP_CHECKMULTISIG compares the first signature against each public key until it finds an ECDSA match. Starting with the subsequent public key, it compares the second signature against each remaining public key until it finds an ECDSA match. The process is repeated until all signatures have been checked or not enough public keys remain to produce a successful result.

  Because public keys are not checked again if they fail any signature comparison, signatures must be placed in the signature script using the same order as their corresponding public keys were placed in the pubkey script or redeem script. See the OP_CHECKMULTISIG warning below for more details.

• OP_RETURN terminates the script in failure when executed.

A complete list of opcodes can be found on the Bitcoin Wiki Script Page, with an authoritative list in the opcodetype enum of the Bitcoin Core script header file

Signature script modification warning: Signature scripts are not signed, so anyone can modify them. This means signature scripts should only contain data and data-pushing opcodes which can’t be modified without causing the pubkey script to fail. Placing non-data-pushing opcodes in the signature script currently makes a transaction non-standard, and future consensus rules may forbid such transactions altogether. (Non-data-pushing opcodes are already forbidden in signature scripts when spending a P2SH pubkey script.)

OP_CHECKMULTISIG warning: The multisig verification process described above requires that signatures in the signature script be provided in the same order as their corresponding public keys in the pubkey script or redeem script. For example, the following combined signature and pubkey script will produce the stack and comparisons shown:

OP_0 <A sig> <B sig> OP_2 <A pubkey> <B pubkey> <C pubkey> OP_3

Sig Stack       Pubkey Stack  (Actually a single stack)
---------       ------------
B sig           C pubkey
A sig           B pubkey
OP_0            A pubkey

1. B sig compared to C pubkey (no match)
2. B sig compared to B pubkey (match #1)
3. A sig compared to A pubkey (match #2)

Success: two matches found

But reversing the order of the signatures with everything else the same will fail, as shown below:

OP_0 <B sig> <A sig> OP_2 <A pubkey> <B pubkey> <C pubkey> OP_3

Sig Stack       Pubkey Stack  (Actually a single stack)
---------       ------------
A sig           C pubkey
B sig           B pubkey
OP_0            A pubkey

1. A sig compared to C pubkey (no match)
2. A sig compared to B pubkey (no match)

Failure, aborted: two signature matches required but none found so far, and there's only one pubkey remaining

Address Conversion

The hashes used in P2PKH and P2SH outputs are commonly encoded as Bitcoin addresses. This is the procedure to encode those hashes and decode the addresses.

First, get your hash. For P2PKH, you RIPEMD-160(SHA256()) hash a ECDSA public key derived from your 256-bit ECDSA private key (random data). For P2SH, you RIPEMD-160(SHA256()) hash a redeem script serialized in the format used in raw transactions (described in a following sub-section). Taking the resulting hash:

1. Add an address version byte in front of the hash. The version bytes commonly used by Bitcoin are:

   • 0x00 for P2PKH addresses on the main Bitcoin network (mainnet)

   • 0x6f for P2PKH addresses on the Bitcoin testing network (testnet)

   • 0x05 for P2SH addresses on mainnet

   • 0xc4 for P2SH addresses on testnet

2. Create a copy of the version and hash; then hash that twice with SHA256: SHA256(SHA256(version . hash))

3. Extract the first four bytes from the double-hashed copy. These are used as a checksum to ensure the base hash gets transmitted correctly.

4. Append the checksum to the version and hash, and encode it as a base58 string: BASE58(version . hash . checksum)

Bitcoin’s base58 encoding, called Base58Check may not match other implementations. Tier Nolan provided the following example encoding algorithm to the Bitcoin Wiki Base58Check encoding page under the Creative Commons Attribution 3.0 license:

code_string = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
x = convert_bytes_to_big_integer(hash_result)

output_string = ""

while(x > 0) 
   {
       (x, remainder) = divide(x, 58)
       output_string.append(code_string[remainder])
   }

repeat(number_of_leading_zero_bytes_in_hash)
   {
   output_string.append(code_string[0]);
   }

output_string.reverse();

Bitcoin’s own code can be traced using the base58 header file.

To convert addresses back into hashes, reverse the base58 encoding, extract the checksum, repeat the steps to create the checksum and compare it against the extracted checksum, and then remove the version byte.

Raw Transaction Format

Bitcoin transactions are broadcast between peers in a serialized byte format, called raw format. It is this form of a transaction which is SHA256(SHA256()) hashed to create the TXID and, ultimately, the merkle root of a block containing the transaction—making the transaction format part of the consensus rules.

Bitcoin Core and many other tools print and accept raw transactions encoded as hex.

As of Bitcoin Core 0.9.3 (October 2014), all transactions use the version 1 format described below. (Note: transactions in the block chain are allowed to list a higher version number to permit soft forks, but they are treated as version 1 transactions by current software.)

A raw transaction has the following top-level format:

A transaction may have multiple inputs and outputs, so the txIn and txOut structures may recur within a transaction. CompactSize unsigned integers are a form of variable-length integers; they are described in the CompactSize section.

TxIn: A Transaction Input (Non-Coinbase)

Each non-coinbase input spends an outpoint from a previous transaction. (Coinbase inputs are described separately after the example section below.)

Outpoint: The Specific Part Of A Specific Output

Because a single transaction can include multiple outputs, the outpoint structure includes both a TXID and an output index number to refer to specific output.

TxOut: A Transaction Output

Each output spends a certain number of satoshis, placing them under control of anyone who can satisfy the provided pubkey script.

Example

The sample raw transaction itemized below is the one created in the Simple Raw Transaction section of the Developer Examples. It spends a previous pay-to-pubkey output by paying to a new pay-to-pubkey-hash (P2PKH) output.

01000000 ................................... Version

01 ......................................... Number of inputs
|
| 7b1eabe0209b1fe794124575ef807057
| c77ada2138ae4fa8d6c4de0398a14f3f ......... Outpoint TXID
| 00000000 ................................. Outpoint index number
|
| 49 ....................................... Bytes in sig. script: 73
| | 48 ..................................... Push 72 bytes as data
| | | 30450221008949f0cb400094ad2b5eb3
| | | 99d59d01c14d73d8fe6e96df1a7150de
| | | b388ab8935022079656090d7f6bac4c9
| | | a94e0aad311a4268e082a725f8aeae05
| | | 73fb12ff866a5f01 ..................... Secp256k1 signature
|
| ffffffff ................................. Sequence number: UINT32_MAX

01 ......................................... Number of outputs
| f0ca052a01000000 ......................... Satoshis (49.99990000 BTC)
|
| 19 ....................................... Bytes in pubkey script: 25
| | 76 ..................................... OP_DUP
| | a9 ..................................... OP_HASH160
| | 14 ..................................... Push 20 bytes as data
| | | cbc20a7664f2f69e5355aa427045bc15
| | | e7c6c772 ............................. PubKey hash
| | 88 ..................................... OP_EQUALVERIFY
| | ac ..................................... OP_CHECKSIG

00000000 ................................... locktime: 0 (a block height)

Coinbase Input: The Input Of The First Transaction In A Block

The first transaction in a block, called the coinbase transaction, must have exactly one input, called a coinbase. The coinbase input currently has the following format.

Most (but not all) blocks prior to block height 227,836 used block version 1 which did not require the height parameter to be prefixed to the coinbase script. The block height parameter is now required.

Although the coinbase script is arbitrary data, if it includes the bytes used by any signature-checking operations such as OP_CHECKSIG, those signature checks will be counted as signature operations (sigops) towards the block’s sigop limit. To avoid this, you can prefix all data with the appropriate push operation.

An itemized coinbase transaction:

01000000 .............................. Version

01 .................................... Number of inputs
| 00000000000000000000000000000000
| 00000000000000000000000000000000 ...  Previous outpoint TXID
| ffffffff ............................ Previous outpoint index
|
| 29 .................................. Bytes in coinbase
| |
| | 03 ................................ Bytes in height
| | | 4e0105 .......................... Height: 328014
| |
| | 062f503253482f0472d35454085fffed
| | f2400000f90f54696d65202620486561
| | 6c74682021 ........................ Arbitrary data
| 00000000 ............................ Sequence

01 .................................... Output count
| 2c37449500000000 .................... Satoshis (25.04275756 BTC)
| 1976a914a09be8040cbf399926aeb1f4
| 70c37d1341f3b46588ac ................ P2PKH script
| 00000000 ............................ Locktime

CompactSize Unsigned Integers

The raw transaction format and several peer-to-peer network messages use a type of variable-length integer to indicate the number of bytes in a following piece of data.

Bitcoin Core code and this document refers to these variable length integers as compactSize. Many other documents refer to them as var_int or varInt, but this risks conflation with other variable-length integer encodings—such as the CVarInt class used in Bitcoin Core for serializing data to disk. Because it’s used in the transaction format, the format of compactSize unsigned integers is part of the consensus rules.

For numbers from 0 to 252, compactSize unsigned integers look like regular unsigned integers. For other numbers up to 0xffffffffffffffff, a byte is prefixed to the number to indicate its length—but otherwise the numbers look like regular unsigned integers in little-endian order.

For example, the number 515 is encoded as 0xfd0302.

Wallets

Deterministic Wallet Formats

Type 1: Single Chain Wallets

Type 1 deterministic wallets are the simpler of the two, which can create a single series of keys from a single seed. A primary weakness is that if the seed is leaked, all funds are compromised, and wallet sharing is extremely limited.

Type 2: Hierarchical Deterministic (HD) Wallets

For an overview of HD wallets, please see the developer guide section. For details, please see BIP32.

P2P Network

This section describes the Bitcoin P2P network protocol (but it is not a specification). It does not describe the discontinued direct IP-to-IP payment protocol, the deprecated BIP70 payment protocol, the GetBlockTemplate mining protocol, or any network protocol never implemented in an official version of Bitcoin Core.

All peer-to-peer communication occurs entirely over TCP.

Note: unless their description says otherwise, all multi-byte integers mentioned in this section are transmitted in little-endian order.

Constants And Defaults

The following constants and defaults are taken from Bitcoin Core’s chainparams.cpp source code file.

Note: the testnet start string and nBits above are for testnet3; the original testnet used a different string and higher (less difficult) nBits.

Command line parameters can change what port a node listens on (see -help). Start strings are hardcoded constants that appear at the start of all messages sent on the Bitcoin network; they may also appear in data files such as Bitcoin Core’s block database. The nBits displayed above are in big-endian order; they’re sent over the network in little-endian order.

Bitcoin Core’s chainparams.cpp also includes other constants useful to programs, such as the hash of the genesis blocks for the different networks.

Protocol Versions

The table below lists some notable versions of the P2P network protocol, with the most recent versions listed first. (If you know of a protocol version that implemented a major change but which is not listed here, please open an issue.)

As of Bitcoin Core 0.18.0, the most recent protocol version is 70015.

Message Headers

All messages in the network protocol use the same container format, which provides a required multi-field message header and an optional payload. The message header format is:

The following example is an annotated hex dump of a mainnet message header from a verack message which has no payload.

f9beb4d9 ................... Start string: Mainnet
76657261636b000000000000 ... Command name: verack + null padding
00000000 ................... Byte count: 0
5df6e0e2 ................... Checksum: SHA256(SHA256(<empty>))

Data Messages

The following network messages all request or provide data related to transactions and blocks.

Many of the data messages use inventories as unique identifiers for transactions and blocks. Inventories have a simple 36-byte structure:

The currently-available type identifiers are:

† These are the same as their respective type identifier but with their 30th bit set to indicate witness. For example MSG_WITNESS_TX = 0x01000040.

Type identifier zero and type identifiers greater than seven are reserved for future implementations. Bitcoin Core ignores all inventories with one of these unknown types.

Block

The block message transmits a single serialized block in the format described in the serialized blocks section. See that section for an example hexdump. It can be sent for two different reasons:

1. GetData Response: Nodes will always send it in response to a getdata message that requests the block with an inventory type of MSG_BLOCK (provided the node has that block available for relay).

2. Unsolicited: Some miners will send unsolicited block messages broadcasting their newly-mined blocks to all of their peers. Many mining pools do the same thing, although some may be misconfigured to send the block from multiple nodes, possibly sending the same block to some peers more than once.

GetBlocks

The getblocks message requests an inv message that provides block header hashes starting from a particular point in the block chain. It allows a peer which has been disconnected or started for the first time to get the data it needs to request the blocks it hasn’t seen.

Peers which have been disconnected may have stale blocks in their locally-stored block chain, so the getblocks message allows the requesting peer to provide the receiving peer with multiple header hashes at various heights on their local chain. This allows the receiving peer to find, within that list, the last header hash they had in common and reply with all subsequent header hashes.

Note: the receiving peer itself may respond with an inv message containing header hashes of stale blocks. It is up to the requesting peer to poll all of its peers to find the best block chain.

If the receiving peer does not find a common header hash within the list, it will assume the last common block was the genesis block (block zero), so it will reply with in inv message containing header hashes starting with block one (the first block after the genesis block).

The following annotated hexdump shows a getblocks message. (The message header has been omitted.)

71110100 ........................... Protocol version: 70001
02 ................................. Hash count: 2

d39f608a7775b537729884d4e6633bb2
105e55a16a14d31b0000000000000000 ... Hash #1

5c3e6403d40837110a2e8afb602b1c01
714bda7ce23bea0a0000000000000000 ... Hash #2

00000000000000000000000000000000
00000000000000000000000000000000 ... Stop hash

GetData

The getdata message requests one or more data objects from another node. The objects are requested by an inventory, which the requesting node typically received previously by way of an inv message.

The response to a getdata message can be a tx message, block message, merkleblock message, cmpctblock message, or notfound message.

This message cannot be used to request arbitrary data, such as historic transactions no longer in the memory pool or relay set. Full nodes may not even be able to provide older blocks if they’ve pruned old transactions from their block database. For this reason, the getdata message should usually only be used to request data from a node which previously advertised it had that data by sending an inv message.

The format and maximum size limitations of the getdata message are identical to the inv message; only the message header differs.

GetHeaders

Added in protocol version 31800.

The getheaders message requests a headers message that provides block headers starting from a particular point in the block chain. It allows a peer which has been disconnected or started for the first time to get the headers it hasn’t seen yet.

The getheaders message is nearly identical to the getblocks message, with one minor difference: the inv reply to the getblocks message will include no more than 500 block header hashes; the headers reply to the getheaders message will include as many as 2,000 block headers.

Headers

Added in protocol version 31800.

The headers message sends block headers to a node which previously requested certain headers with a getheaders message. A headers message can be empty.

The following annotated hexdump shows a headers message. (The message header has been omitted.)

01 ................................. Header count: 1

02000000 ........................... Block version: 2
b6ff0b1b1680a2862a30ca44d346d9e8
910d334beb48ca0c0000000000000000 ... Hash of previous block's header
9d10aa52ee949386ca9385695f04ede2
70dda20810decd12bc9b048aaab31471 ... Merkle root
24d95a54 ........................... Unix time: 1415239972
30c31b18 ........................... Target (bits)
fe9f0864 ........................... Nonce

00 ................................. Transaction count (0x00)

Inv

The inv message (inventory message) transmits one or more inventories of objects known to the transmitting peer. It can be sent unsolicited to announce new transactions or blocks, or it can be sent in reply to a getblocks message or mempool message.

The receiving peer can compare the inventories from an inv message against the inventories it has already seen, and then use a follow-up message to request unseen objects.

The following annotated hexdump shows an inv message with two inventory entries. (The message header has been omitted.)

02 ................................. Count: 2

01000000 ........................... Type: MSG_TX
de55ffd709ac1f5dc509a0925d0b1fc4
42ca034f224732e429081da1b621f55a ... Hash (TXID)

01000000 ........................... Type: MSG_TX
91d36d997037e08018262978766f24b8
a055aaf1d872e94ae85e9817b2c68dc7 ... Hash (TXID)

MemPool

Added in protocol version 60002.

The mempool message requests the TXIDs of transactions that the receiving node has verified as valid but which have not yet appeared in a block. That is, transactions which are in the receiving node’s memory pool. The response to the mempool message is one or more inv messages containing the TXIDs in the usual inventory format.

Sending the mempool message is mostly useful when a program first connects to the network. Full nodes can use it to quickly gather most or all of the unconfirmed transactions available on the network; this is especially useful for miners trying to gather transactions for their transaction fees. SPV clients can set a filter before sending a mempool to only receive transactions that match that filter; this allows a recently-started client to get most or all unconfirmed transactions related to its wallet.

The inv response to the mempool message is, at best, one node’s view of the network—not a complete list of unconfirmed transactions on the network. Here are some additional reasons the list might not be complete:

• Before Bitcoin Core 0.9.0, the response to the mempool message was only one inv message. An inv message is limited to 50,000 inventories, so a node with a memory pool larger than 50,000 entries would not send everything. Later versions of Bitcoin Core send as many inv messages as needed to reference its complete memory pool.

• The mempool message is not currently fully compatible with the filterload message’s BLOOM_UPDATE_ALL and BLOOM_UPDATE_P2PUBKEY_ONLY flags. Mempool transactions are not sorted like in-block transactions, so a transaction (tx2) spending an output can appear before the transaction (tx1) containing that output, which means the automatic filter update mechanism won’t operate until the second-appearing transaction (tx1) is seen—missing the first-appearing transaction (tx2). It has been proposed in Bitcoin Core issue #2381 that the transactions should be sorted before being processed by the filter.

There is no payload in a mempool message. See the message header section for an example of a message without a payload.

MerkleBlock

Added in protocol version 70001 as described by BIP37.

The merkleblock message is a reply to a getdata message which requested a block using the inventory type MSG_MERKLEBLOCK. It is only part of the reply: if any matching transactions are found, they will be sent separately as tx messages.

If a filter has been previously set with the filterload message, the merkleblock message will contain the TXIDs of any transactions in the requested block that matched the filter, as well as any parts of the block’s merkle tree necessary to connect those transactions to the block header’s merkle root. The message also contains a complete copy of the block header to allow the client to hash it and confirm its proof of work.

The annotated hexdump below shows a merkleblock message which corresponds to the examples below. (The message header has been omitted.)

01000000 ........................... Block version: 1
82bb869cf3a793432a66e826e05a6fc3
7469f8efb7421dc88067010000000000 ... Hash of previous block's header
7f16c5962e8bd963659c793ce370d95f
093bc7e367117b3c30c1f8fdd0d97287 ... Merkle root
76381b4d ........................... Time: 1293629558
4c86041b ........................... nBits: 0x04864c * 256**(0x1b-3)
554b8529 ........................... Nonce

07000000 ........................... Transaction count: 7
04 ................................. Hash count: 4

3612262624047ee87660be1a707519a4
43b1c1ce3d248cbfc6c15870f6c5daa2 ... Hash #1
019f5b01d4195ecbc9398fbf3c3b1fa9
bb3183301d7a1fb3bd174fcfa40a2b65 ... Hash #2
41ed70551dd7e841883ab8f0b16bf041
76b7d1480e4f0af9f3d4c3595768d068 ... Hash #3
20d2a7bc994987302e5b1ac80fc425fe
25f8b63169ea78e68fbaaefa59379bbf ... Hash #4

01 ................................. Flag bytes: 1
1d ................................. Flags: 1 0 1 1 1 0 0 0

Note: when fully decoded, the above merkleblock message provided the TXID for a single transaction that matched the filter. In the network traffic dump this output was taken from, the full transaction belonging to that TXID was sent immediately after the merkleblock message as a tx message.

Parsing A MerkleBlock Message

As seen in the annotated hexdump above, the merkleblock message provides three special data types: a transaction count, a list of hashes, and a list of one-bit flags.

You can use the transaction count to construct an empty merkle tree. We’ll call each entry in the tree a node; on the bottom are TXID nodes—the hashes for these nodes are TXIDs; the remaining nodes (including the merkle root) are non-TXID nodes—they may actually have the same hash as a TXID, but we treat them differently.

Keep the hashes and flags in the order they appear in the merkleblock message. When we say “next flag” or “next hash”, we mean the next flag or hash on the list, even if it’s the first one we’ve used so far.

Start with the merkle root node and the first flag. The table below describes how to evaluate a flag based on whether the node being processed is a TXID node or a non-TXID node. Once you apply a flag to a node, never apply another flag to that same node or reuse that same flag again.

Any time you begin processing a node for the first time, evaluate the next flag. Never use a flag at any other time.

When processing a child node, you may need to process its children (the grandchildren of the original node) or further-descended nodes before returning to the parent node. This is expected—keep processing depth first until you reach a TXID node or a non-TXID node with a flag of 0.

After you process a TXID node or a non-TXID node with a flag of 0, stop processing flags and begin to ascend the tree. As you ascend, compute the hash of any nodes for which you now have both child hashes or for which you now have the sole child hash. See the merkle tree section for hashing instructions. If you reach a node where only the left hash is known, descend into its right child (if present) and further descendants as necessary.

However, if you find a node whose left and right children both have the same hash, fail. This is related to CVE-2012-2459.

Continue descending and ascending until you have enough information to obtain the hash of the merkle root node. If you run out of flags or hashes before that condition is reached, fail. Then perform the following checks (order doesn’t matter):

• Fail if there are unused hashes in the hashes list.

• Fail if there are unused flag bits—except for the minimum number of bits necessary to pad up to the next full byte.

• Fail if the hash of the merkle root node is not identical to the merkle root in the block header.

• Fail if the block header is invalid. Remember to ensure that the hash of the header is less than or equal to the target threshold encoded by the nBits header field. Your program should also, of course, attempt to ensure the header belongs to the best block chain and that the user knows how many confirmations this block has.

For a detailed example of parsing a merkleblock message, please see the corresponding merkle block examples section.

Creating A MerkleBlock Message

It’s easier to understand how to create a merkleblock message after you understand how to parse an already-created message, so we recommend you read the parsing section above first.

Create a complete merkle tree with TXIDs on the bottom row and all the other hashes calculated up to the merkle root on the top row. For each transaction that matches the filter, track its TXID node and all of its ancestor nodes.

Start processing the tree with the merkle root node. The table below describes how to process both TXID nodes and non-TXID nodes based on whether the node is a match, a match ancestor, or neither a match nor a match ancestor.

Any time you begin processing a node for the first time, a flag should be appended to the flag list. Never put a flag on the list at any other time, except when processing is complete to pad out the flag list to a byte boundary.

When processing a child node, you may need to process its children (the grandchildren of the original node) or further-descended nodes before returning to the parent node. This is expected—keep processing depth first until you reach a TXID node or a node which is neither a TXID nor a match ancestor.

After you process a TXID node or a node which is neither a TXID nor a match ancestor, stop processing and begin to ascend the tree until you find a node with a right child you haven’t processed yet. Descend into that right child and process it.

After you fully process the merkle root node according to the instructions in the table above, processing is complete. Pad your flag list to a byte boundary and construct the merkleblock message using the template near the beginning of this subsection.

CmpctBlock

Added in protocol version 70014 as described by BIP152.

Version 1 compact blocks are pre-segwit (txids) Version 2 compact blocks are post-segwit (wtxids)

The cmpctblock message is a reply to a getdata message which requested a block using the inventory type MSG_CMPCT_BLOCK. If the requested block was recently announced and is close to the tip of the best chain of the receiver and after having sent the requesting peer a sendcmpct message, nodes respond with a cmpctblock message containing data for the block.

If the requested block is too old, the node responds with a full non-compact block

Upon receipt of a cmpctblock message, after sending a sendcmpct message, nodes should calculate the short transaction ID for each unconfirmed transaction they have available (ie in their mempool) and compare each to each short transaction ID in the cmpctblock message. After finding already-available transactions, nodes which do not have all transactions available to reconstruct the full block should request the missing transactions using a getblocktxn message.

A node must not send a cmpctblock message unless they are able to respond to a getblocktxn message which requests every transaction in the block. A node must not send a cmpctblock message without having validated that the header properly commits to each transaction in the block, and properly builds on top of the existing, fully-validated chain with a valid proof-of-work either as a part of the current most-work valid chain, or building directly on top of it. A node may send a cmpctblock message before validating that each transaction in the block validly spends existing UTXO set entries.

The cmpctblock message contains a vector of PrefilledTransaction whose structure is defined below.

The cmpctblock message is compromised of a serialized HeaderAndShortIDs structure which is defined below. A HeaderAndShortIDs structure is used to relay a block header, the short transactions IDs used for matching already-available transactions, and a select few transactions which we expect a peer may be missing.

Important protocol version 70015 notes regarding Compact Blocks

New banning behavior was added to the compact block logic in protocol version 70015 to prevent node abuse, the new changes are outlined below as defined in BIP152.

Any undefined behavior in this spec may cause failure to transfer block to, peer disconnection by, or self-destruction by the receiving node. A node receiving non-minimally-encoded CompactSize encodings should make a best-effort to eat the sender’s cat.

As high-bandwidth mode permits relaying of cmpctblock messages prior to full validation (requiring only that the block header is valid before relay), nodes SHOULD NOT ban a peer for announcing a new block with a cmpctblock message that is invalid, but has a valid header.

For avoidance of doubt, nodes SHOULD bump their peer-to-peer protocol version to 70015 or higher to signal that they will not ban or punish a peer for announcing compact blocks prior to full validation, and nodes SHOULD NOT announce a cmpctblock message to a peer with a version number below 70015 before fully validating the block.

Version 2 compact blocks notes

Transactions inside cmpctblock messages (both those used as direct announcement and those in response to getdata) and in blocktxn messages should include witness data, using the same format as responses to getdata MSG_WITNESS_TX, specified in BIP144.

Upon receipt of a getdata message containing a request for a MSG_CMPCT_BLOCK object for which a cmpctblock message is not sent in response, the block message containing the requested block in non-compact form MUST be encoded with witnesses (as is sent in reply to a MSG_WITNESS_BLOCK) if the protocol version used to encode the cmpctblock message would have been 2, and encoded without witnesses (as is sent in response to a MSG_BLOCK) if the protocol version used to encode the cmpctblock message would have been 1.

Short Transaction ID calculation

Short transaction IDs are used to represent a transaction without sending a full 256-bit hash. They are calculated as follows,

• A single-SHA256 hashing the block header with the nonce appended (in little-endian)
• Running SipHash-2-4 with the input being the transaction ID (wtxid in version 2 of compact blocks) and the keys (k0/k1) set to the first two little-endian 64-bit integers from the above hash, respectively.
• Dropping the 2 most significant bytes from the SipHash output to make it 6 bytes.
• Two null-bytes appended so it can be read as an 8-byte integer.

SendCmpct

Added in protocol version 70014 as described by BIP152.

The sendcmpct message is defined as a message containing a 1-byte integer followed by a 8-byte integer. The first integer is interpreted as a boolean and should have a value of either 1 or 0. The second integer is be interpreted as a little-endian version number.

Upon receipt of a sendcmpct message with the first and second integers set to 1, the node should announce new blocks by sending a cmpctblock message.

Upon receipt of a sendcmpct message with the first integer set to 0, the node shouldn’t announce new blocks by sending a cmpctblock message, but instead announce new blocks by sending invs or headers, as defined by BIP130.

Upon receipt of a sendcmpct message with the second integer set to something other than 1, nodes should treat the peer as if they had not received the message (as it indicates the peer will provide an unexpected encoding in cmpctblock messages, and/or other, messages). This allows future versions to send duplicate sendcmpct messages with different versions as a part of a version handshake for future versions.

Nodes should check for a protocol version of >= 70014 before sending sendcmpct messages. Nodes shouldn’t send a request for a MSG_CMPCT_BLOCK object to a peer before having received a sendcmpct message from that peer. Nodes shouldn’t request a MSG_CMPCT_BLOCK object before having sent all sendcmpct messages to that peer which they intend to send, as the peer cannot know what version protocol to use in the response.

The structure of a sendcmpct message is defined below.

GetBlockTxn

Added in protocol version 70014 as described by BIP152.

The getblocktxn message is defined as a message containing a serialized BlockTransactionsRequest message. Upon receipt of a properly-formatted getblocktxn message, nodes which recently provided the sender of such a message a cmpctblock message for the block hash identified in this message must respond with either an appropriate blocktxn message, or a full block message.

A blocktxn message response must contain exactly and only each transaction which is present in the appropriate block at the index specified in the getblocktxn message indexes list, in the order requested.

The structure of BlockTransactionsRequest is defined below.

BlockTxn

Added in protocol version 70014 as described by BIP152.

The blocktxn message is defined as a message containing a serialized BlockTransactions message. Upon receipt of a properly-formatted requested blocktxn message, nodes should attempt to reconstruct the full block by taking the prefilledtxn transactions from the original cmpctblock message and placing them in the marked positions, then for each short transaction ID from the original cmpctblock message, in order, find the corresponding transaction either from the blocktxn message or from other sources and place it in the first available position in the block then once the block has been reconstructed, it shall be processed as normal, keeping in mind that short transaction IDs are expected to occasionally collide, and that nodes must not be penalized for such collisions, wherever they appear.

The structure of BlockTransactions is defined below.

NotFound

Added in protocol version 70001.

The notfound message is a reply to a getdata message which requested an object the receiving node does not have available for relay. (Nodes are not expected to relay historic transactions which are no longer in the memory pool or relay set. Nodes may also have pruned spent transactions from older blocks, making them unable to send those blocks.)

The format and maximum size limitations of the notfound message are identical to the inv message; only the message header differs.

Tx

The tx message transmits a single transaction in the raw transaction format. It can be sent in a variety of situations;

• Transaction Response: Bitcoin Core and BitcoinJ will send it in response to a getdata message that requests the transaction with an inventory type of MSG_TX.

• MerkleBlock Response: Bitcoin Core will send it in response to a getdata message that requests a merkle block with an inventory type of MSG_MERKLEBLOCK. (This is in addition to sending a merkleblock message.) Each tx message in this case provides a matched transaction from that block.

• Unsolicited: BitcoinJ will send a tx message unsolicited for transactions it originates.

For an example hexdump of the raw transaction format, see the raw transaction section.

Control Messages

The following network messages all help control the connection between two peers or allow them to advise each other about the rest of the network.

Note that almost none of the control messages are authenticated in any way, meaning they can contain incorrect or intentionally harmful information. In addition, this section does not yet cover P2P protocol operation over the Tor network; if you would like to contribute information about Tor, please open an issue.

Addr

The addr (IP address) message relays connection information for peers on the network. Each peer which wants to accept incoming connections creates an addr message providing its connection information and then sends that message to its peers unsolicited. Some of its peers send that information to their peers (also unsolicited), some of which further distribute it, allowing decentralized peer discovery for any program already on the network.

An addr message may also be sent in response to a getaddr message.

Each encapsulated network IP address currently uses the following structure:

The following annotated hexdump shows part of an addr message. (The message header has been omitted and the actual IP address has been replaced with a RFC5737 reserved IP address.)

fde803 ............................. Address count: 1000

d91f4854 ........................... Epoch time: 1414012889
0100000000000000 ................... Service bits: 01 (network node)
00000000000000000000ffffc0000233 ... IP Address: ::ffff:192.0.2.51
208d ............................... Port: 8333

[...] .............................. (999 more addresses omitted)

Alert

Added in protocol version 311. Removed in protocol version 70013 and released in Bitcoin Core 0.13.0

The legacy p2p network alert messaging system has been retired; however, internal alerts, partition detection warnings and the -alertnotify option features remain. See Alert System Retirement for details.

FeeFilter

Added in protocol version 70013 as described by BIP133.

The feefilter message is a request to the receiving peer to not relay any transaction inv messages to the sending peer where the fee rate for the transaction is below the fee rate specified in the feefilter message.

feefilter was introduced in Bitcoin Core 0.13.0 following the introduction of mempool limiting in Bitcoin Core 0.12.0. Mempool limiting provides protection against attacks and spam transactions that have low fee rates and are unlikely to be included in mined blocks. The feefilter messages allows a node to inform its peers that it will not accept transactions below a specified fee rate into its mempool, and therefore that the peers can skip relaying inv messages for transactions below that fee rate to that node.

The receiving peer may choose to ignore the message and not filter transaction inv messages.

The fee filter is additive with bloom filters. If an SPV client loads a bloom filter and sends a feefilter message, transactions should only be relayed if they pass both filters.

Note however that feefilter has no effect on block propagation or responses to getdata messages. For example, if a node requests a merkleblock from its peer by sending a getdata message with inv type MSG_FILTERED_BLOCK and it has previously sent a feefilter to that peer, the peer should respond with a merkleblock containing all the transactions matching the bloom filter, even if they are below the feefilter fee rate.

inv messages generated from a mempool message are subject to a fee filter if it exists.

The annotated hexdump below shows a feefilter message. (The message header has been omitted.)

7cbd000000000000 ... satoshis per kilobyte: 48,508

FilterAdd

Added in protocol version 70001 as described by BIP37.

The filteradd message tells the receiving peer to add a single element to a previously-set bloom filter, such as a new public key. The element is sent directly to the receiving peer; the peer then uses the parameters set in the filterload message to add the element to the bloom filter.

Because the element is sent directly to the receiving peer, there is no obfuscation of the element and none of the plausible-deniability privacy provided by the bloom filter. Clients that want to maintain greater privacy should recalculate the bloom filter themselves and send a new filterload message with the recalculated bloom filter.

Note: a filteradd message will not be accepted unless a filter was previously set with the filterload message.

The annotated hexdump below shows a filteradd message adding a TXID. (The message header has been omitted.) This TXID appears in the same block used for the example hexdump in the merkleblock message; if that merkleblock message is re-sent after sending this filteradd message, six hashes are returned instead of four.

20 ................................. Element bytes: 32
fdacf9b3eb077412e7a968d2e4f11b9a
9dee312d666187ed77ee7d26af16cb0b ... Element (A TXID)

FilterClear

Added in protocol version 70001 as described by BIP37.

The filterclear message tells the receiving peer to remove a previously-set bloom filter. This also undoes the effect of setting the relay field in the version message to 0, allowing unfiltered access to inv messages announcing new transactions.

Bitcoin Core does not require a filterclear message before a replacement filter is loaded with filterload. It also doesn’t require a filterload message before a filterclear message.

There is no payload in a filterclear message. See the message header section for an example of a message without a payload.

FilterLoad

Added in protocol version 70001 as described by BIP37.

The filterload message tells the receiving peer to filter all relayed transactions and requested merkle blocks through the provided filter. This allows clients to receive transactions relevant to their wallet plus a configurable rate of false positive transactions which can provide plausible-deniability privacy.

The annotated hexdump below shows a filterload message. (The message header has been omitted.) For an example of how this payload was created, see the filterload example.

02 ......... Filter bytes: 2
b50f ....... Filter: 1010 1101 1111 0000
0b000000 ... nHashFuncs: 11
00000000 ... nTweak: 0/none
00 ......... nFlags: BLOOM_UPDATE_NONE

Initializing A Bloom Filter

Filters have two core parameters: the size of the bit field and the number of hash functions to run against each data element. The following formulas from BIP37 will allow you to automatically select appropriate values based on the number of elements you plan to insert into the filter (n) and the false positive rate (p) you desire to maintain plausible deniability.

• Size of the bit field in bytes (nFilterBytes), up to a maximum of 36,000: (-1 / log(2)**2 * n * log(p)) / 8

• Hash functions to use (nHashFuncs), up to a maximum of 50: nFilterBytes * 8 / n * log(2)

Note that the filter matches parts of transactions (transaction elements), so the false positive rate is relative to the number of elements checked—not the number of transactions checked. Each normal transaction has a minimum of four matchable elements (described in the comparison subsection below), so a filter with a false-positive rate of 1 percent will match about 4 percent of all transactions at a minimum.

According to BIP37, the formulas and limits described above provide support for bloom filters containing 20,000 items with a false positive rate of less than 0.1 percent or 10,000 items with a false positive rate of less than 0.0001 percent.

Once the size of the bit field is known, the bit field should be initialized as all zeroes.

Populating A Bloom Filter

The bloom filter is populated using between 1 and 50 unique hash functions (the number specified per filter by the nHashFuncs field). Instead of using up to 50 different hash function implementations, a single implementation is used with a unique seed value for each function.

The seed is nHashNum * 0xfba4c795 + nTweak as a uint32_t, where the values are:

• nHashNum is the sequence number for this hash function, starting at 0 for the first hash iteration and increasing up to the value of the nHashFuncs field (minus one) for the last hash iteration.

• 0xfba4c795 is a constant optimized to create large differences in the seed for different values of nHashNum.

• nTweak is a per-filter constant set by the client to require the use of an arbitrary set of hash functions.

If the seed resulting from the formula above is larger than four bytes, it must be truncated to its four most significant bytes (for example, 0x8967452301 & 0xffffffff → 0x67452301).

The actual hash function implementation used is the 32-bit Murmur3 hash function.

Warning: the Murmur3 hash function has separate 32-bit and 64-bit versions that produce different results for the same input. Only the 32-bit Murmur3 version is used with Bitcoin bloom filters.

The data to be hashed can be any transaction element which the bloom filter can match. See the next subsection for the list of transaction elements checked against the filter. The largest element which can be matched is a script data push of 520 bytes, so the data should never exceed 520 bytes.

The example below from Bitcoin Core bloom.cpp combines all the steps above to create the hash function template. The seed is the first parameter; the data to be hashed is the second parameter. The result is a uint32_t modulo the size of the bit field in bits.

MurmurHash3(nHashNum * 0xFBA4C795 + nTweak, vDataToHash) % (vData.size() * 8)

Each data element to be added to the filter is hashed by nHashFuncs number of hash functions. Each time a hash function is run, the result will be the index number (nIndex) of a bit in the bit field. That bit must be set to 1. For example if the filter bit field was 00000000 and the result is 5, the revised filter bit field is 00000100 (the first bit is bit 0).

It is expected that sometimes the same index number will be returned more than once when populating the bit field; this does not affect the algorithm—after a bit is set to 1, it is never changed back to 0.

After all data elements have been added to the filter, each set of eight bits is converted into a little-endian byte. These bytes are the value of the filter field.

Comparing Transaction Elements To A Bloom Filter

To compare an arbitrary data element against the bloom filter, it is hashed using the same parameters used to create the bloom filter. Specifically, it is hashed nHashFuncs times, each time using the same nTweak provided in the filter, and the resulting output is modulo the size of the bit field provided in the filter field. After each hash is performed, the filter is checked to see if the bit at that indexed location is set. For example if the result of a hash is 5 and the filter is 01001110, the bit is considered set.

If the result of every hash points to a set bit, the filter matches. If any of the results points to an unset bit, the filter does not match.

The following transaction elements are compared against bloom filters. All elements will be hashed in the byte order used in blocks (for example, TXIDs will be in internal byte order).

• TXIDs: the transaction’s SHA256(SHA256()) hash.

• Outpoints: each 36-byte outpoint used this transaction’s input section is individually compared to the filter.

• Signature Script Data: each element pushed onto the stack by a data-pushing opcode in a signature script from this transaction is individually compared to the filter. This includes data elements present in P2SH redeem scripts when they are being spent.

• PubKey Script Data: each element pushed onto the the stack by a data-pushing opcode in any pubkey script from this transaction is individually compared to the filter. (If a pubkey script element matches the filter, the filter will be immediately updated if the BLOOM_UPDATE_ALL flag was set; if the pubkey script is in the P2PKH format and matches the filter, the filter will be immediately updated if the BLOOM_UPDATE_P2PUBKEY_ONLY flag was set. See the subsection below for details.)

The following annotated hexdump of a transaction is from the raw transaction format section; the elements which would be checked by the filter are emphasized in bold. Note that this transaction’s TXID (01000000017b1eab[...]) would also be checked, and that the outpoint TXID and index number below would be checked as a single 36-byte element.

01000000 ................................... Version

01 ......................................... Number of inputs
|
| 7b1eabe0209b1fe794124575ef807057
| c77ada2138ae4fa8d6c4de0398a14f3f ......... Outpoint TXID
| 00000000 ................................. Outpoint index number
|
| 49 ....................................... Bytes in sig. script: 73
| | 48 ..................................... Push 72 bytes as data
| | | 30450221008949f0cb400094ad2b5eb3
| | | 99d59d01c14d73d8fe6e96df1a7150de
| | | b388ab8935022079656090d7f6bac4c9
| | | a94e0aad311a4268e082a725f8aeae05
| | | 73fb12ff866a5f01 ..................... Secp256k1 signature
|
| ffffffff ................................. Sequence number: UINT32_MAX

01 ......................................... Number of outputs
| f0ca052a01000000 ......................... Satoshis (49.99990000 BTC)
|
| 19 ....................................... Bytes in pubkey script: 25
| | 76 ..................................... OP_DUP
| | a9 ..................................... OP_HASH160
| | 14 ..................................... Push 20 bytes as data
| | | cbc20a7664f2f69e5355aa427045bc15
| | | e7c6c772 ............................. PubKey hash
| | 88 ..................................... OP_EQUALVERIFY
| | ac ..................................... OP_CHECKSIG

00000000 ................................... locktime: 0 (a block height)

Updating A Bloom Filter

Clients will often want to track inputs that spend outputs (outpoints) relevant to their wallet, so the filterload field nFlags can be set to allow the filtering node to update the filter when a match is found. When the filtering node sees a pubkey script that pays a pubkey, address, or other data element matching the filter, the filtering node immediately updates the filter with the outpoint corresponding to that pubkey script.

If an input later spends that outpoint, the filter will match it, allowing the filtering node to tell the client that one of its transaction outputs has been spent.

The nFlags field has three allowed values:

In addition, because the filter size stays the same even though additional elements are being added to it, the false positive rate increases. Each false positive can result in another element being added to the filter, creating a feedback loop that can (after a certain point) make the filter useless. For this reason, clients using automatic filter updates need to monitor the actual false positive rate and send a new filter when the rate gets too high.

GetAddr

The getaddr message requests an addr message from the receiving node, preferably one with lots of IP addresses of other receiving nodes. The transmitting node can use those IP addresses to quickly update its database of available nodes rather than waiting for unsolicited addr messages to arrive over time.

There is no payload in a getaddr message. See the message header section for an example of a message without a payload.

Ping

The ping message helps confirm that the receiving peer is still connected. If a TCP/IP error is encountered when sending the ping message (such as a connection timeout), the transmitting node can assume that the receiving node is disconnected. The response to a ping message is the pong message.

Before protocol version 60000, the ping message had no payload. As of protocol version 60001 and all later versions, the message includes a single field, the nonce.

The annotated hexdump below shows a ping message. (The message header has been omitted.)

0094102111e2af4d ... Nonce

Pong

Added in protocol version 60001 as described by BIP31.

The pong message replies to a ping message, proving to the pinging node that the ponging node is still alive. Bitcoin Core will, by default, disconnect from any clients which have not responded to a ping message within 20 minutes.

To allow nodes to keep track of latency, the pong message sends back the same nonce received in the ping message it is replying to.

The format of the pong message is identical to the ping message; only the message header differs.

Reject

Added in protocol version 70002 as described by BIP61.

Deprecated in Bitcoin Core 0.18.0.

The reject message informs the receiving node that one of its previous messages has been rejected.

The following table lists message reject codes. Codes are tied to the type of message they reply to; for example there is a 0x10 reject code for transactions and a 0x10 reject code for blocks.

The annotated hexdump below shows a reject message. (The message header has been omitted.)

02 ................................. Number of bytes in message: 2
7478 ............................... Type of message rejected: tx
12 ................................. Reject code: 0x12 (duplicate)
15 ................................. Number of bytes in reason: 21
6261642d74786e732d696e707574732d
7370656e74 ......................... Reason: bad-txns-inputs-spent
394715fcab51093be7bfca5a31005972
947baf86a31017939575fb2354222821 ... TXID

SendHeaders

The sendheaders message tells the receiving peer to send new block announcements using a headers message rather than an inv message.

There is no payload in a sendheaders message. See the message header section for an example of a message without a payload.

VerAck

Added in protocol version 209.

The verack message acknowledges a previously-received version message, informing the connecting node that it can begin to send other messages. The verack message has no payload; for an example of a message with no payload, see the message headers section.

Version

The version message provides information about the transmitting node to the receiving node at the beginning of a connection. Until both peers have exchanged version messages, no other messages will be accepted.

If a version message is accepted, the receiving node should send a verack message—but no node should send a verack message before initializing its half of the connection by first sending a version message.

The following service identifiers have been assigned.

Note: Protocol version 70001 introduced the optional relay field, adding the possibility of an additional byte to the version message. This introduces an incompatibility with implementations of lower protocol versions which validate the version message size. When implementing support for protocol versions less than 70001 you may want to handle the case of a peer potentially sending an extra byte, treating it as invalid only in the case of a requested protocol version less than 70001.

The following annotated hexdump shows a version message. (The message header has been omitted and the actual IP addresses have been replaced with RFC5737 reserved IP addresses.)

72110100 ........................... Protocol version: 70002
0100000000000000 ................... Services: NODE_NETWORK
bc8f5e5400000000 ................... Epoch time: 1415483324

0100000000000000 ................... Receiving node's services
00000000000000000000ffffc61b6409 ... Receiving node's IPv6 address
208d ............................... Receiving node's port number

0100000000000000 ................... Transmitting node's services
00000000000000000000ffffcb0071c0 ... Transmitting node's IPv6 address
208d ............................... Transmitting node's port number

128035cbc97953f8 ................... Nonce

0f ................................. Bytes in user agent string: 15
2f5361746f7368693a302e392e332f ..... User agent: /Satoshi:0.9.3/

cf050500 ........................... Start height: 329167
01 ................................. Relay flag: true

Bitcoin Core APIs

Hash Byte Order

Bitcoin Core RPCs accept and return the byte-wise reverse of computed SHA-256 hash values. For example, the Unix sha256sum command displays the SHA256(SHA256()) hash of mainnet block 300,000’s header as:

> /bin/echo -n '020000007ef055e1674d2e6551dba41cd214debbee34aeb544c7ec670000000000000000d3998963f80c5bab43fe8c26228e98d030edf4dcbe48a666f5c39e2d7a885c9102c86d536c890019593a470d' | xxd -r -p | sha256sum -b | xxd -r -p | sha256sum -b
5472ac8b1187bfcf91d6d218bbda1eb2405d7c55f1f8cc820000000000000000

The result above is also how the hash appears in the previous-header-hash part of block 300,001’s header:

020000005472ac8b1187bfcf91d6d218bbda1eb2405d7c55f1f8cc82000\
0000000000000ab0aaa377ca3f49b1545e2ae6b0667a08f42e72d8c24ae\
237140e28f14f3bb7c6bcc6d536c890019edd83ccf

However, Bitcoin Core’s RPCs use the byte-wise reverse for hashes, so if you want to get information about block 300,000 using the getblock RPC, you need to reverse the requested hash:

> bitcoin-cli getblock \
  000000000000000082ccf8f1557c5d40b21edabb18d2d691cfbf87118bac7254

(Note: hex representation uses two characters to display each byte of data, which is why the reversed string looks somewhat mangled.)

The rationale for the reversal is unknown, but it likely stems from Bitcoin Core’s use of hashes (which are byte arrays in C++) as integers for the purpose of determining whether the hash is below the network target. Whatever the reason for reversing header hashes, the reversal also extends to other hashes used in RPCs, such as TXIDs and merkle roots.

As header hashes and TXIDs are widely used as global identifiers in other Bitcoin software, this reversal of hashes has become the standard way to refer to certain objects. The table below should make clear where each byte order is used.

Note: RPCs which return raw results, such as getrawtransaction or the raw mode of getblock, always display hashes as they appear in blocks (internal byte order).

The code below may help you check byte order by generating hashes from raw hex.

#!/usr/bin/env python

from sys import byteorder
from hashlib import sha256

## You can put in $data an 80-byte block header to get its header hash,
## or a raw transaction to get its txid
data = "00".decode("hex")
hash = sha256(sha256(data).digest()).digest()

print "Warning: this code only tested on a little-endian x86_64 arch"
print
print "System byte order:", byteorder
print "Internal-Byte-Order Hash: ", hash.encode('hex_codec')
print "RPC-Byte-Order Hash:      ", hash[::-1].encode('hex_codec')

Remote Procedure Calls (RPCs)

Bitcoin Core provides a remote procedure call (RPC) interface for various administrative tasks, wallet operations, and queries about network and block chain data.

If you start Bitcoin Core using bitcoin-qt, the RPC interface is disabled by default. To enable it, set server=1 in bitcoin.conf or supply the -server argument when invoking the program. If you start Bitcoin Core using bitcoind, the RPC interface is enabled by default.

The interface requires the user to provide a password for authenticating RPC requests. This password can be set either using the rpcpassword property in bitcoin.conf or by supplying the -rpcpassword program argument. Optionally a username can be set using the rpcuser configuration value. See the Examples Page for more information about setting Bitcoin Core configuration values.

Open-source client libraries for the RPC interface are readily available in most modern programming languages, so you probably don’t need to write your own from scratch. Bitcoin Core also ships with its own compiled C++ RPC client, bitcoin-cli, located in the bin directory alongside bitcoind and bitcoin-qt. The bitcoin-cli program can be used as a command-line interface (CLI) to Bitcoin Core or for making RPC calls from applications written in languages lacking a suitable native client. The remainder of this section describes the Bitcoin Core RPC protocol in detail.

The Bitcoin Core RPC service listens for HTTP POST requests on port 8332 in mainnet mode or 18332 in testnet or regtest mode. The port number can be changed by setting rpcport in bitcoin.conf. By default the RPC service binds to your server’s localhost loopback network interface so it’s not accessible from other servers. Authentication is implemented using HTTP basic authentication. RPC HTTP requests must include a Content-Type header set to text/plain and a Content-Length header set to the size of the request body.

The format of the request body and response data is based on version 1.0 of the JSON-RPC specification. Specifically, the HTTP POST data of a request must be a JSON object with the following format:

In the table above and in other tables describing RPC input and output, we use the following conventions

• “→” indicates an argument that is the child of a JSON array or JSON object. For example, “→ → Parameter” above means Parameter is the child of the params array which itself is a child of the Request object.

• Plain-text names like “Request” are unnamed in the actual JSON object

• Code-style names like params are literal strings that appear in the JSON object.

• “Type” is the JSON data type and the specific Bitcoin Core type.

• “Presence” indicates whether or not a field must be present within its containing array or object. Note that an optional object may still have required children.

The HTTP response data for a RPC request is a JSON object with the following format:

As an example, here is the JSON-RPC request object for the hash of the genesis block:

{
    "method": "getblockhash",
    "params": [0],
    "id": "foo"
}

The command to send this request using bitcoin-cli is:

bitcoin-cli getblockhash 0

Alternatively, we could POST this request using the cURL command-line program as follows:

curl --user ':my_secret_password' --data-binary '''
  {
      "method": "getblockhash",
      "params": [0],
      "id": "foo"
  }''' \
  --header 'Content-Type: text/plain;' localhost:8332

The HTTP response data for this request would be:

{
    "result": "000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f",
    "error": null,
    "id": "foo"
}

Note: In order to minimize its size, the raw JSON response from Bitcoin Core doesn’t include any extraneous whitespace characters. Here we’ve added whitespace to make the object more readable. Speaking of which, bitcoin-cli also transforms the raw response to make it more human-readable. It:

• Adds whitespace indentation to JSON objects
• Expands escaped newline characters (\n) into actual newlines
• Returns only the value of the result field if there’s no error
• Strips the outer double-quotes around results of type string
• Returns only the error field if there’s an error

Continuing with the example above, the output from the bitcoin-cli command would be simply:

000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f

If there’s an error processing a request, Bitcoin Core sets the result field to null and provides information about the error in the error field. For example, a request for the block hash at block height -1 would be met with the following response (again, whitespace added for clarity):

{
    "result": null,
    "error": {
        "code": -8,
        "message": "Block height out of range"
    },
    "id": "foo"
}

If bitcoin-cli encounters an error, it exits with a non-zero status code and outputs the error field as text to the process’s standard error stream:

error: {"code": -8, "message": "Block height out of range"}

Starting in Bitcoin Core version 0.7.0, the RPC interface supports request batching as described in version 2.0 of the JSON-RPC specification. To initiate multiple RPC requests within a single HTTP request, a client can POST a JSON array filled with Request objects. The HTTP response data is then a JSON array filled with the corresponding Response objects. Depending on your usage pattern, request batching may provide significant performance gains. The bitcoin-cli RPC client does not support batch requests.

To keep this documentation compact and readable, the examples for each of the available RPC calls will be given as bitcoin-cli commands:

bitcoin-cli [options] <method name> <param1> <param2> ...

This translates into an JSON-RPC Request object of the form:

{
    "method": "<method name>",
    "params": [ "<param1>", "<param2>", "..." ],
    "id": "foo"
}

[]proper money handling if you write programs using the JSON-RPC interface, you must ensure they handle high-precision real numbers correctly. See the Proper Money Handling Bitcoin Wiki article for details and example code.

Quick Reference

Blockchain RPCs

• GetBestBlockHash: returns the hash of the best (tip) block in the longest blockchain.
• GetBlock: gets a block with a particular header hash from the local block database either as a JSON object or as a serialized block.
• GetBlockChainInfo: returns an object containing various state info regarding blockchain processing.
• GetBlockCount: returns the number of blocks in the longest blockchain.
• GetBlockHash: returns hash of block in best-block-chain at height provided.
• GetBlockHeader: if verbose is false, returns a string that is serialized, hex-encoded data for blockheader ‘hash’.
• GetBlockStats: compute per block statistics for a given window.
• GetChainTips: return information about all known tips in the block tree, including the main chain as well as orphaned branches.
• GetChainTxStats: compute statistics about the total number and rate of transactions in the chain.
• GetDifficulty: returns the proof-of-work difficulty as a multiple of the minimum difficulty.
• GetMemPoolAncestors: if txid is in the mempool, returns all in-mempool ancestors.
• GetMemPoolDescendants: if txid is in the mempool, returns all in-mempool descendants.
• GetMemPoolEntry: returns mempool data for given transaction.
• GetMemPoolInfo: returns details on the active state of the TX memory pool.
• GetRawMemPool: returns all transaction ids in memory pool as a json array of string transaction ids.
• GetTxOut: returns details about an unspent transaction output.
• GetTxOutProof: returns a hex-encoded proof that
• GetTxOutSetInfo: returns statistics about the unspent transaction output set.
• PreciousBlock: treats a block as if it were received before others with the same work.
• PruneBlockChain: does PruneBlockChain.
• SaveMemPool: dumps the mempool to disk.
• ScanTxOutSet: eXPERIMENTAL warning: this call may be removed or changed in future releases.
• VerifyChain: verifies blockchain database.
• VerifyTxOutProof: verifies that a proof points to a transaction in a block, returning the transaction it commits to and throwing an RPC error if the block is not in our best chain.

Control RPCs

• GetMemoryInfo: returns an object containing information about memory usage.
• GetRpcInfo: returns details of the RPC server.
• Help: list all commands, or get help for a specified command.
• Logging: gets and sets the logging configuration.
• Stop: stop Bitcoin server.
• Uptime: returns the total uptime of the server.

Generating RPCs

• Generate: mine up to nblocks blocks immediately (before the RPC call returns) to an address in the wallet.
• GenerateToAddress: mine blocks immediately to a specified address (before the RPC call returns).

Mining RPCs

• GetBlockTemplate: if the request parameters include a ‘mode’ key, that is used to explicitly select between the default ‘template’ request or a ‘proposal’.
• GetMiningInfo: returns a json object containing mining-related information.
• GetNetworkHashPs: returns the estimated network hashes per second based on the last n blocks.
• PrioritiseTransaction: accepts the transaction into mined blocks at a higher (or lower) priority.
• SubmitBlock: attempts to submit new block to network.
• SubmitHeader: decode the given hexdata as a header and submit it as a candidate chain tip if valid.

Network RPCs

• AddNode: attempts to add or remove a node from the addnode list.
• ClearBanned: clear all banned IPs.
• DisconnectNode: immediately disconnects from the specified peer node.
• GetAddedNodeInfo: returns information about the given added node, or all added nodes (note that onetry addnodes are not listed here).
• GetConnectionCount: returns the number of connections to other nodes.
• GetNetTotals: returns information about network traffic, including bytes in, bytes out, and current time.
• GetNetworkInfo: returns an object containing various state info regarding P2P networking.
• GetNodeAddresses: return known addresses which can potentially be used to find new nodes in the network.
• GetPeerInfo: returns data about each connected network node as a json array of objects.
• ListBanned: list all banned IPs/Subnets.
• Ping: requests that a ping be sent to all other nodes, to measure ping time.
• SetBan: attempts to add or remove an IP/Subnet from the banned list.
• SetNetworkActive: disable/enable all p2p network activity.

Rawtransactions RPCs

• AnalyzePsbt: analyzes and provides information about the current status of a PSBT and its inputs.
• CombinePsbt: combine multiple partially signed Bitcoin transactions into one transaction.
• CombineRawTransaction: combine multiple partially signed transactions into one transaction.
• ConvertToPsbt: converts a network serialized transaction to a PSBT.
• CreatePsbt: creates a transaction in the Partially Signed Transaction format.
• CreateRawTransaction: create a transaction spending the given inputs and creating new outputs.
• DecodePsbt: return a JSON object representing the serialized, base64-encoded partially signed Bitcoin transaction.
• DecodeRawTransaction: return a JSON object representing the serialized, hex-encoded transaction.
• DecodeScript: decode a hex-encoded script.
• FinalizePsbt: finalize the inputs of a PSBT.
• FundRawTransaction: add inputs to a transaction until it has enough in value to meet its out value.
• GetRawTransaction: return the raw transaction data.
• JoinPsbts: joins multiple distinct PSBTs with different inputs and outputs into one PSBT with inputs and outputs from all of the PSBTs No input in any of the PSBTs can be in more than one of the PSBTs.
• SendRawTransaction: submits raw transaction (serialized, hex-encoded) to local node and network.
• SignRawTransactionWithKey: sign inputs for raw transaction (serialized, hex-encoded).
• TestmemPoolAccept: returns result of mempool acceptance tests indicating if raw transaction (serialized, hex-encoded) would be accepted by mempool.
• UtxoUpdatePsbt: updates a PSBT with witness UTXOs retrieved from the UTXO set or the mempool.

Util RPCs

• CreateMultiSig: creates a multi-signature address with n signature of m keys required.
• DeriveAddresses: derives one or more addresses corresponding to an output descriptor.
• EstimateSmartFee: estimates the approximate fee per kilobyte needed for a transaction to begin confirmation within conf_target blocks if possible and return the number of blocks for which the estimate is valid.
• GetDescriptorInfo: analyses a descriptor.
• SignMessageWithPrivKey: sign a message with the private key of an address.
• ValidateAddress: return information about the given bitcoin address.
• VerifyMessage: verify a signed message.

Wallet RPCs

Note: the wallet RPCs are only available if Bitcoin Core was built with wallet support, which is the default.

• AbandonTransaction: marks an in-wallet transaction and all its in-wallet descendants as abandoned. This allows their inputs to be respent.
• AbortRescan: Stops current wallet rescan
• AddMultiSigAddress: adds a P2SH multisig address to the wallet.
• BackupWallet: safely copies current wallet file to destination, which can be a directory or a path with filename.
• BumpFee: bumps the fee of an opt-in-RBF transaction T, replacing it with a new transaction B.
• CreateWallet: creates and loads a new wallet.
• DumpPrivKey: reveals the private key corresponding to ‘address’.
• DumpWallet: dumps all wallet keys in a human-readable format to a server-side file.
• EncryptWallet: encrypts the wallet with ‘passphrase’.
• GetAddressesByLabel: returns the list of addresses assigned the specified label.
• GetAddressInfo: return information about the given bitcoin address.
• GetBalance: returns the total available balance.
• GetNewAddress: returns a new Bitcoin address for receiving payments.
• GetRawChangeAddress: returns a new Bitcoin address, for receiving change.
• GetReceivedByAddress: returns the total amount received by the given address in transactions with at least minconf confirmations.
• GetReceivedByLabel: returns the total amount received by addresses with in transactions with at least [minconf] confirmations.
• GetTransaction: get detailed information about in-wallet transaction <txid>.
• GetUnconfirmedBalance: returns the server’s total unconfirmed balance.
• GetWalletInfo: returns an object containing various wallet state info.
• ImportAddress: adds an address or script (in hex) that can be watched as if it were in your wallet but cannot be used to spend.
• ImportMulti: import addresses/scripts (with private or public keys, redeem script (P2SH)), optionally rescanning the blockchain from the earliest creation time of the imported scripts.
• ImportPrivKey: adds a private key (as returned by dumpprivkey) to your wallet.
• ImportPrunedFunds: imports funds without rescan.
• ImportPubKey: adds a public key (in hex) that can be watched as if it were in your wallet but cannot be used to spend.
• ImportWallet: imports keys from a wallet dump file (see dumpwallet).
• KeyPoolRefill: fills the keypool.
• ListAddressGroupings: lists groups of addresses which have had their common ownership made public by common use as inputs or as the resulting change in past transactions.
• ListLabels: returns the list of all labels, or labels that are assigned to addresses with a specific purpose.
• ListLockUnspent: returns list of temporarily unspendable outputs.
• ListReceivedByAddress: list balances by receiving address.
• ListReceivedByLabel: list received transactions by label.
• ListSinceBlock: get all transactions in blocks since block [blockhash], or all transactions if omitted.
• ListTransactions: if a label name is provided, this will return only incoming transactions paying to addresses with the specified label.
• ListUnspent: returns array of unspent transaction outputs with between minconf and maxconf (inclusive) confirmations.
• ListWalletDir: returns a list of wallets in the wallet directory.
• ListWallets: returns a list of currently loaded wallets.
• LoadWallet: loads a wallet from a wallet file or directory.
• LockUnspent: updates list of temporarily unspendable outputs.
• RemovePrunedFunds: deletes the specified transaction from the wallet.
• RescanBlockChain: rescan the local blockchain for wallet related transactions.
• SendMany: send multiple times.
• SendToAddress: send an amount to a given address.
• SetHdSeed: set or generate a new HD wallet seed.
• SetLabel: sets the label associated with the given address.
• SetTxFee: set the transaction fee per kB for this wallet.
• SignMessage: sign a message with the private key of an address.
• SignRawTransactionWithWallet: sign inputs for raw transaction (serialized, hex-encoded).
• UnloadWallet: unloads the wallet referenced by the request endpoint otherwise unloads the wallet specified in the argument.
• WalletCreatefundedPsbt: creates and funds a transaction in the Partially Signed Transaction format.
• WalletLock: removes the wallet encryption key from memory, locking the wallet.
• WalletPassphrase: stores the wallet decryption key in memory for ‘timeout’ seconds.
• WalletPassphraseChange: changes the wallet passphrase from ‘oldpassphrase’ to ‘newpassphrase’.
• WalletProcessPsbt: update a PSBT with input information from our wallet and then sign inputs that we can sign for.

RPCs

the block chain and memory pool can include arbitrary data which several of the commands below will return in hex format. If you convert this data to another format in an executable context, it could be used in an exploit. For example, displaying a pubkey script as ASCII text in a webpage could add arbitrary Javascript to that page and create a cross-site scripting (XSS) exploit. To avoid problems, please treat block chain and memory pool data as an arbitrary input from an untrusted source.

AbandonTransaction

Added in Bitcoin Core 0.12.0

The abandontransaction RPC marks an in-wallet transaction and all its in-wallet descendants as abandoned. This allows their inputs to be respent.

Mark in-wallet transaction <txid> as abandoned This will mark this transaction and all its in-wallet descendants as abandoned which will allow for their inputs to be respent. It can be used to replace “stuck” or evicted transactions.

It only works on transactions which are not included in a block and are not currently in the mempool.

It has no effect on transactions which are already abandoned.

Parameter #1—txid

Result—null on success

Example

bitcoin-cli abandontransaction "1075db55d416d3ca199f55b6084e2115b9345e16c5cf302fc80e9d5fbf5d48d"

See also

• SendRawTransaction: submits raw transaction (serialized, hex-encoded) to local node and network.

AbortRescan

The abortrescan RPC Stops current wallet rescan

Stops current wallet rescan triggered by an RPC call, e.g. by an importprivkey call.

Parameters: none

Result—null on success

Example

Import a private key

bitcoin-cli importprivkey "mykey"

Abort the running wallet rescan

bitcoin-cli abortrescan

AddMultiSigAddress

Requires wallet support.

The addmultisigaddress RPC adds a P2SH multisig address to the wallet.

Add a nrequired-to-sign multisignature address to the wallet. Requires a new wallet backup.

Each key is a Bitcoin address or hex-encoded public key.

This functionality is only intended for use with non-watchonly addresses.

See importaddress for watchonly p2sh address support.

If ‘label’ is specified, assign address to that label.

Parameter #1—nrequired

Parameter #2—keys

[
  "key",      (string) bitcoin address or hex-encoded public key
  ...
]

Parameter #3—label

Parameter #4—address_type

Result

{
  "address":"multisigaddress",    (string) The value of the new multisig address.
  "redeemScript":"script"         (string) The string value of the hex-encoded redemption script.
}

Example

Add a multisig address from 2 addresses

bitcoin-cli addmultisigaddress 2 "[\"16sSauSf5pF2UkUwvKGq4qjNRzBZYqgEL5\",\"171sgjn4YtPu27adkKGrdDwzRTxnRkBfKV\"]"

See also

• CreateMultiSig: creates a multi-signature address with n signature of m keys required.
• DecodeScript: decode a hex-encoded script.
• Pay-To-Script-Hash (P2SH)

AddNode

The addnode RPC attempts to add or remove a node from the addnode list.

Or try a connection to a node once.

Nodes added using addnode (or -connect) are protected from DoS disconnection and are not required to be full nodes/support SegWit as other outbound peers are (though such peers will not be synced from).

Parameter #1—node

Parameter #2—command

Result—null on success

Example

bitcoin-cli addnode "192.168.0.6:8333" "onetry"

See also

• GetAddedNodeInfo: returns information about the given added node, or all added nodes (note that onetry addnodes are not listed here).

AnalyzePsbt

Added in Bitcoin Core 0.18.0

The analyzepsbt RPC analyzes and provides information about the current status of a PSBT and its inputs.

Parameter #1—psbt

Result

{
  "inputs" : [                      (array of json objects)
    {
      "has_utxo" : true|false     (boolean) Whether a UTXO is provided
      "is_final" : true|false     (boolean) Whether the input is finalized
      "missing" : {               (json object, optional) Things that are missing that are required to complete this input
        "pubkeys" : [             (array, optional)
          "keyid"                 (string) Public key ID, hash160 of the public key, of a public key whose BIP 32 derivation path is missing
        ]
        "signatures" : [          (array, optional)
          "keyid"                 (string) Public key ID, hash160 of the public key, of a public key whose signature is missing
        ]
        "redeemscript" : "hash"   (string, optional) Hash160 of the redeemScript that is missing
        "witnessscript" : "hash"  (string, optional) SHA256 of the witnessScript that is missing
      }
      "next" : "role"             (string, optional) Role of the next person that this input needs to go to
    }
    ,...
  ]
  "estimated_vsize" : vsize       (numeric, optional) Estimated vsize of the final signed transaction
  "estimated_feerate" : feerate   (numeric, optional) Estimated feerate of the final signed transaction in BTC/kB. Shown only if all UTXO slots in the PSBT have been filled.
  "fee" : fee                     (numeric, optional) The transaction fee paid. Shown only if all UTXO slots in the PSBT have been filled.
  "next" : "role"                 (string) Role of the next person that this psbt needs to go to
}

Example

bitcoin-cli analyzepsbt "psbt"

BackupWallet

Requires wallet support.

The backupwallet RPC safely copies current wallet file to destination, which can be a directory or a path with filename.

Parameter #1—destination

Result—null on success

Example

bitcoin-cli backupwallet "backup.dat"

See also

• DumpWallet: dumps all wallet keys in a human-readable format to a server-side file.
• ImportWallet: imports keys from a wallet dump file (see dumpwallet).

BumpFee

Added in Bitcoin Core 0.14.0

The bumpfee RPC bumps the fee of an opt-in-RBF transaction T, replacing it with a new transaction B.

An opt-in RBF transaction with the given txid must be in the wallet.

The command will pay the additional fee by decreasing (or perhaps removing) its change output.

If the change output is not big enough to cover the increased fee, the command will currently fail instead of adding new inputs to compensate. (A future implementation could improve this.) The command will fail if the wallet or mempool contains a transaction that spends one of T’s outputs.

By default, the new fee will be calculated automatically using estimatesmartfee.

The user can specify a confirmation target for estimatesmartfee.

Alternatively, the user can specify totalFee, or use RPC settxfee to set a higher fee rate.

At a minimum, the new fee rate must be high enough to pay an additional new relay fee (incrementalfee returned by getnetworkinfo) to enter the node’s mempool.

Parameter #1—txid

Parameter #2—options

{
  "confTarget": n,           (numeric, optional, default=fallback to wallet's default) Confirmation target (in blocks)
  "totalFee": n,             (numeric, optional, default=fallback to 'confTarget') Total fee (NOT feerate) to pay, in satoshis.
                             In rare cases, the actual fee paid might be slightly higher than the specified
                             totalFee if the tx change output has to be removed because it is too close to
                             the dust threshold.
  "replaceable": bool,       (boolean, optional, default=true) Whether the new transaction should still be
                             marked bip-125 replaceable. If true, the sequence numbers in the transaction will
                             be left unchanged from the original. If false, any input sequence numbers in the
                             original transaction that were less than 0xfffffffe will be increased to 0xfffffffe
                             so the new transaction will not be explicitly bip-125 replaceable (though it may
                             still be replaceable in practice, for example if it has unconfirmed ancestors which
                             are replaceable).
  "estimate_mode": "str",    (string, optional, default=UNSET) The fee estimate mode, must be one of:
                             "UNSET"
                             "ECONOMICAL"
                             "CONSERVATIVE"
}

Result

{
  "txid":    "value",   (string)  The id of the new transaction
  "origfee":  n,         (numeric) Fee of the replaced transaction
  "fee":      n,         (numeric) Fee of the new transaction
  "errors":  [ str... ] (json array of strings) Errors encountered during processing (may be empty)
}

Example

Bump the fee, get the new transaction’s txid

bitcoin-cli bumpfee <txid>

See also

• CreateRawTransaction: create a transaction spending the given inputs and creating new outputs.
• FundRawTransaction: add inputs to a transaction until it has enough in value to meet its out value.
• SendRawTransaction: submits raw transaction (serialized, hex-encoded) to local node and network.

ClearBanned

Added in Bitcoin Core 0.12.0

The clearbanned RPC clear all banned IPs.

Parameters: none

Result—null on success

Example

bitcoin-cli clearbanned

See also

• ListBanned: list all banned IPs/Subnets.
• SetBan: attempts to add or remove an IP/Subnet from the banned list.

CombinePsbt

The combinepsbt RPC combine multiple partially signed Bitcoin transactions into one transaction.

Implements the Combiner role.

Parameter #1—txs

[
  "psbt",    (string) A base64 string of a PSBT
  ...
]

Result—null on success

Example

bitcoin-cli combinepsbt ["mybase64_1", "mybase64_2", "mybase64_3"]

CombineRawTransaction

The combinerawtransaction RPC combine multiple partially signed transactions into one transaction.

The combined transaction may be another partially signed transaction or a fully signed transaction.

Parameter #1—txs

[
  "hexstring",    (string) A transaction hash
  ...
]

Result

Example

bitcoin-cli combinerawtransaction ["myhex1", "myhex2", "myhex3"]

ConvertToPsbt

The converttopsbt RPC converts a network serialized transaction to a PSBT.

This should be used only with createrawtransaction and fundrawtransaction createpsbt and walletcreatefundedpsbt should be used for new applications.

Parameter #1—hexstring

Parameter #2—permitsigdata

Parameter #3—iswitness

Result—null on success

Example

Create a transaction

bitcoin-cli createrawtransaction "[{\"txid\":\"myid\",\"vout\":0}]" "[{\"data\":\"00010203\"}]"

Convert the transaction to a PSBT

bitcoin-cli converttopsbt "rawtransaction"

CreateMultiSig

The createmultisig RPC creates a multi-signature address with n signature of m keys required.

It returns a json object with the address and redeemScript.

Parameter #1—nrequired

Parameter #2—keys

[
  "key",      (string) The hex-encoded public key
  ...
]

Parameter #3—address_type

Result

{
  "address":"multisigaddress",  (string) The value of the new multisig address.
  "redeemScript":"script"       (string) The string value of the hex-encoded redemption script.
}

Example

Create a multisig address from 2 public keys

bitcoin-cli createmultisig 2 "[\"03789ed0bb717d88f7d321a368d905e7430207ebbd82bd342cf11ae157a7ace5fd\",\"03dbc6764b8884a92e871274b87583e6d5c2a58819473e17e107ef3f6aa5a61626\"]"

See also

• AddMultiSigAddress: adds a P2SH multisig address to the wallet.
• DecodeScript: decode a hex-encoded script.

CreatePsbt

The createpsbt RPC creates a transaction in the Partially Signed Transaction format.

Implements the Creator role.

Parameter #1—inputs

[
  {                       (json object)
    "txid": "hex",        (string, required) The transaction id
    "vout": n,            (numeric, required) The output number
    "sequence": n,        (numeric, optional, default=depends on the value of the 'replaceable' and 'locktime' arguments) The sequence number
  },
  ...
]

Parameter #2—outputs

[
  {                       (json object)
    "address": amount,    (numeric or string, required) A key-value pair. The key (string) is the bitcoin address, the value (float or string) is the amount in BTC
  },
  {                       (json object)
    "data": "hex",        (string, required) A key-value pair. The key must be "data", the value is hex-encoded data
  },
  ...
]

Parameter #3—locktime

Parameter #4—replaceable

Result—null on success

Example

bitcoin-cli createpsbt "[{\"txid\":\"myid\",\"vout\":0}]" "[{\"data\":\"00010203\"}]"

CreateRawTransaction

The createrawtransaction RPC create a transaction spending the given inputs and creating new outputs.

Outputs can be addresses or data.

Returns hex-encoded raw transaction.

Note that the transaction’s inputs are not signed, and it is not stored in the wallet or transmitted to the network.

Parameter #1—inputs

[
  {                       (json object)
    "txid": "hex",        (string, required) The transaction id
    "vout": n,            (numeric, required) The output number
    "sequence": n,        (numeric, optional, default=depends on the value of the 'replaceable' and 'locktime' arguments) The sequence number
  },
  ...
]

Parameter #2—outputs

[
  {                       (json object)
    "address": amount,    (numeric or string, required) A key-value pair. The key (string) is the bitcoin address, the value (float or string) is the amount in BTC
  },
  {                       (json object)
    "data": "hex",        (string, required) A key-value pair. The key must be "data", the value is hex-encoded data
  },
  ...
]

Parameter #3—locktime

Parameter #4—replaceable

Result

Example

bitcoin-cli createrawtransaction "[{\"txid\":\"myid\",\"vout\":0}]" "[{\"address\":0.01}]"

bitcoin-cli createrawtransaction "[{\"txid\":\"myid\",\"vout\":0}]" "[{\"data\":\"00010203\"}]"

See also

• DecodeRawTransaction: return a JSON object representing the serialized, hex-encoded transaction.
• SendRawTransaction: submits raw transaction (serialized, hex-encoded) to local node and network.

CreateWallet

The createwallet RPC creates and loads a new wallet.

Parameter #1—wallet_name

Parameter #2—disable_private_keys

Parameter #3—blank

Result

{
  "name" :    <wallet_name>,        (string) The wallet name if created successfully. If the wallet was created using a full path, the wallet_name will be the full path.
  "warning" : <warning>,            (string) Warning message if wallet was not loaded cleanly.
}

Example

bitcoin-cli createwallet "testwallet"

DecodePsbt

The decodepsbt RPC return a JSON object representing the serialized, base64-encoded partially signed Bitcoin transaction.

Parameter #1—psbt

Result

{
  "tx" : {                   (json object) The decoded network-serialized unsigned transaction.
    ...                                      The layout is the same as the output of decoderawtransaction.
  },
  "unknown" : {                (json object) The unknown global fields
    "key" : "value"            (key-value pair) An unknown key-value pair
     ...
  },
  "inputs" : [                 (array of json objects)
    {
      "non_witness_utxo" : {   (json object, optional) Decoded network transaction for non-witness UTXOs
        ...
      },
      "witness_utxo" : {            (json object, optional) Transaction output for witness UTXOs
        "amount" : x.xxx,           (numeric) The value in BTC
        "scriptPubKey" : {          (json object)
          "asm" : "asm",            (string) The asm
          "hex" : "hex",            (string) The hex
          "type" : "pubkeyhash",    (string) The type, eg 'pubkeyhash'
          "address" : "address"     (string) Bitcoin address if there is one
        }
      },
      "partial_signatures" : {             (json object, optional)
        "pubkey" : "signature",           (string) The public key and signature that corresponds to it.
        ,...
      }
      "sighash" : "type",                  (string, optional) The sighash type to be used
      "redeem_script" : {       (json object, optional)
          "asm" : "asm",            (string) The asm
          "hex" : "hex",            (string) The hex
          "type" : "pubkeyhash",    (string) The type, eg 'pubkeyhash'
        }
      "witness_script" : {       (json object, optional)
          "asm" : "asm",            (string) The asm
          "hex" : "hex",            (string) The hex
          "type" : "pubkeyhash",    (string) The type, eg 'pubkeyhash'
        }
      "bip32_derivs" : {          (json object, optional)
        "pubkey" : {                     (json object, optional) The public key with the derivation path as the value.
          "master_fingerprint" : "fingerprint"     (string) The fingerprint of the master key
          "path" : "path",                         (string) The path
        }
        ,...
      }
      "final_scriptsig" : {       (json object, optional)
          "asm" : "asm",            (string) The asm
          "hex" : "hex",            (string) The hex
        }
       "final_scriptwitness": ["hex", ...] (array of string) hex-encoded witness data (if any)
      "unknown" : {                (json object) The unknown global fields
        "key" : "value"            (key-value pair) An unknown key-value pair
         ...
      },
    }
    ,...
  ]
  "outputs" : [                 (array of json objects)
    {
      "redeem_script" : {       (json object, optional)
          "asm" : "asm",            (string) The asm
          "hex" : "hex",            (string) The hex
          "type" : "pubkeyhash",    (string) The type, eg 'pubkeyhash'
        }
      "witness_script" : {       (json object, optional)
          "asm" : "asm",            (string) The asm
          "hex" : "hex",            (string) The hex
          "type" : "pubkeyhash",    (string) The type, eg 'pubkeyhash'
      }
      "bip32_derivs" : [          (array of json objects, optional)
        {
          "pubkey" : "pubkey",                     (string) The public key this path corresponds to
          "master_fingerprint" : "fingerprint"     (string) The fingerprint of the master key
          "path" : "path",                         (string) The path
          }
        }
        ,...
      ],
      "unknown" : {                (json object) The unknown global fields
        "key" : "value"            (key-value pair) An unknown key-value pair
         ...
      },
    }
    ,...
  ]
  "fee" : fee                      (numeric, optional) The transaction fee paid if all UTXOs slots in the PSBT have been filled.
}

Example

bitcoin-cli decodepsbt "psbt"

DecodeRawTransaction

The decoderawtransaction RPC return a JSON object representing the serialized, hex-encoded transaction.

Parameter #1—hexstring

Parameter #2—iswitness

Result

{
  "txid" : "id",        (string) The transaction id
  "hash" : "id",        (string) The transaction hash (differs from txid for witness transactions)
  "size" : n,             (numeric) The transaction size
  "vsize" : n,            (numeric) The virtual transaction size (differs from size for witness transactions)
  "weight" : n,           (numeric) The transaction's weight (between vsize*4 - 3 and vsize*4)
  "version" : n,          (numeric) The version
  "locktime" : ttt,       (numeric) The lock time
  "vin" : [               (array of json objects)
     {
       "txid": "id",    (string) The transaction id
       "vout": n,         (numeric) The output number
       "scriptSig": {     (json object) The script
         "asm": "asm",  (string) asm
         "hex": "hex"   (string) hex
       },
       "txinwitness": ["hex", ...] (array of string) hex-encoded witness data (if any)
       "sequence": n     (numeric) The script sequence number
     }
     ,...
  ],
  "vout" : [             (array of json objects)
     {
       "value" : x.xxx,            (numeric) The value in BTC
       "n" : n,                    (numeric) index
       "scriptPubKey" : {          (json object)
         "asm" : "asm",          (string) the asm
         "hex" : "hex",          (string) the hex
         "reqSigs" : n,            (numeric) The required sigs
         "type" : "pubkeyhash",  (string) The type, eg 'pubkeyhash'
         "addresses" : [           (json array of string)
           "12tvKAXCxZjSmdNbao16dKXC8tRWfcF5oc"   (string) bitcoin address
           ,...
         ]
       }
     }
     ,...
  ],
}

Example

bitcoin-cli decoderawtransaction "hexstring"

See also

• CreateRawTransaction: create a transaction spending the given inputs and creating new outputs.
• SendRawTransaction: submits raw transaction (serialized, hex-encoded) to local node and network.

DecodeScript

The decodescript RPC decode a hex-encoded script.

Parameter #1—hexstring

Result

{
  "asm":"asm",   (string) Script public key
  "hex":"hex",   (string) hex-encoded public key
  "type":"type", (string) The output type
  "reqSigs": n,    (numeric) The required signatures
  "addresses": [   (json array of string)
     "address"     (string) bitcoin address
     ,...
  ],
  "p2sh","address" (string) address of P2SH script wrapping this redeem script (not returned if the script is already a P2SH).
}

Example

bitcoin-cli decodescript "hexstring"

See also

• CreateMultiSig: creates a multi-signature address with n signature of m keys required.

DeriveAddresses

Added in Bitcoin Core 0.18.0

The deriveaddresses RPC derives one or more addresses corresponding to an output descriptor.

Examples of output descriptors are:

pkh(<pubkey>)                        P2PKH outputs for the given pubkey
wpkh(<pubkey>)                       Native segwit P2PKH outputs for the given pubkey
sh(multi(<n>,<pubkey>,<pubkey>,...)) P2SH-multisig outputs for the given threshold and pubkeys
raw(<hex script>)                    Outputs whose scriptPubKey equals the specified hex scripts

In the above, <pubkey> either refers to a fixed public key in hexadecimal notation, or to an xpub/xprv optionally followed by one or more path elements separated by “/”, where “h” represents a hardened child key.

For more information on output descriptors, see the documentation in the doc/descriptors.md file.

Parameter #1—descriptor

Parameter #2—range

Result

[ address ] (array) the derived addresses

Example

First three native segwit receive addresses

bitcoin-cli deriveaddresses "wpkh([d34db33f/84h/0h/0h]xpub6DJ2dNUysrn5Vt36jH2KLBT2i1auw1tTSSomg8PhqNiUtx8QX2SvC9nrHu81fT41fvDUnhMjEzQgXnQjKEu3oaqMSzhSrHMxyyoEAmUHQbY/0/*)#trd0mf0l" "[0,2]"

DisconnectNode

Added in Bitcoin Core 0.12.0

The disconnectnode RPC immediately disconnects from the specified peer node.

Strictly one out of ‘address’ and ‘nodeid’ can be provided to identify the node.

To disconnect by nodeid, either set ‘address’ to the empty string, or call using the named ‘nodeid’ argument only.

Parameter #1—address

Parameter #2—nodeid

Result—null on success

Example

bitcoin-cli disconnectnode "192.168.0.6:8333"

bitcoin-cli disconnectnode "" 1

See also

• AddNode: attempts to add or remove a node from the addnode list.
• GetAddedNodeInfo: returns information about the given added node, or all added nodes (note that onetry addnodes are not listed here).

DumpPrivKey

The dumpprivkey RPC reveals the private key corresponding to ‘address’.

Then the importprivkey can be used with this output

Parameter #1—address

Result

Example

bitcoin-cli dumpprivkey "myaddress"

bitcoin-cli importprivkey "mykey"

See also

• ImportPrivKey: adds a private key (as returned by dumpprivkey) to your wallet.
• DumpWallet: dumps all wallet keys in a human-readable format to a server-side file.

DumpWallet

The dumpwallet RPC dumps all wallet keys in a human-readable format to a server-side file.

This does not allow overwriting existing files.

Imported scripts are included in the dumpfile, but corresponding BIP173 addresses, etc. may not be added automatically by importwallet.

Note that if your wallet contains keys which are not derived from your HD seed (e.g. imported keys), these are not covered by only backing up the seed itself, and must be backed up too (e.g. ensure you back up the whole dumpfile).

Parameter #1—filename

Result

{                           (json object)
  "filename" : {        (string) The filename with full absolute path
}

Example

bitcoin-cli dumpwallet "test"

See also

• BackupWallet: safely copies current wallet file to destination, which can be a directory or a path with filename.
• ImportWallet: imports keys from a wallet dump file (see dumpwallet).

EncryptWallet

The encryptwallet RPC encrypts the wallet with ‘passphrase’.

This is for first time encryption.

After this, any calls that interact with private keys such as sending or signing will require the passphrase to be set prior the making these calls.

Use the walletpassphrase call for this, and then walletlock call.

If the wallet is already encrypted, use the walletpassphrasechange call.

Parameter #1—passphrase

Result—null on success

Example

Encrypt your wallet

bitcoin-cli encryptwallet "my pass phrase"

Now set the passphrase to use the wallet, such as for signing or sending bitcoin

bitcoin-cli walletpassphrase "my pass phrase"

Now we can do something like sign

bitcoin-cli signmessage "address" "test message"

Now lock the wallet again by removing the passphrase

bitcoin-cli walletlock

See also

• WalletPassphrase: stores the wallet decryption key in memory for ‘timeout’ seconds.
• WalletLock: removes the wallet encryption key from memory, locking the wallet.
• WalletPassphraseChange: changes the wallet passphrase from ‘oldpassphrase’ to ‘newpassphrase’.

EstimateSmartFee

The estimatesmartfee RPC estimates the approximate fee per kilobyte needed for a transaction to begin confirmation within conf_target blocks if possible and return the number of blocks for which the estimate is valid.

Uses virtual transaction size as defined in BIP 141 (witness data is discounted).

Parameter #1—conf_target

Parameter #2—estimate_mode

Result

{
  "feerate" : x.x,     (numeric, optional) estimate fee rate in BTC/kB
  "errors": [ str... ] (json array of strings, optional) Errors encountered during processing
  "blocks" : n         (numeric) block number where estimate was found
}

Example

bitcoin-cli estimatesmartfee 6

FinalizePsbt

The finalizepsbt RPC finalize the inputs of a PSBT.

If the transaction is fully signed, it will produce a network serialized transaction which can be broadcast with sendrawtransaction. Otherwise a PSBT will be created which has the final_scriptSig and final_scriptWitness fields filled for inputs that are complete.

Implements the Finalizer and Extractor roles.

Parameter #1—psbt

Parameter #2—extract

Result

{
  "psbt" : "value",          (string) The base64-encoded partially signed transaction if not extracted
  "hex" : "value",           (string) The hex-encoded network transaction if extracted
  "complete" : true|false,   (boolean) If the transaction has a complete set of signatures
  ]
}

Example

bitcoin-cli finalizepsbt "psbt"

FundRawTransaction

Added in Bitcoin Core 0.12.0

The fundrawtransaction RPC add inputs to a transaction until it has enough in value to meet its out value.

This will not modify existing inputs, and will add at most one change output to the outputs.

No existing outputs will be modified unless “subtractFeeFromOutputs” is specified.

Note that inputs which were signed may need to be resigned after completion since in/outputs have been added.

The inputs added will not be signed, use signrawtransactionwithkey or signrawtransactionwithwallet for that.

Note that all existing inputs must have their previous output transaction be in the wallet.

Note that all inputs selected must be of standard form and P2SH scripts must be in the wallet using importaddress or addmultisigaddress (to calculate fees).

You can see whether this is the case by checking the “solvable” field in the listunspent output.

Only pay-to-pubkey, multisig, and P2SH versions thereof are currently supported for watch-only

Parameter #1—hexstring

Parameter #2—options

{
  "changeAddress": "str",        (string, optional, default=pool address) The bitcoin address to receive the change
  "changePosition": n,           (numeric, optional, default=random) The index of the change output
  "change_type": "str",          (string, optional, default=set by -changetype) The output type to use. Only valid if changeAddress is not specified. Options are "legacy", "p2sh-segwit", and "bech32".
  "includeWatching": bool,       (boolean, optional, default=false) Also select inputs which are watch only
  "lockUnspents": bool,          (boolean, optional, default=false) Lock selected unspent outputs
  "feeRate": amount,             (numeric or string, optional, default=not set: makes wallet determine the fee) Set a specific fee rate in BTC/kB
  "subtractFeeFromOutputs": [    (json array, optional, default=empty array) A json array of integers.
                                 The fee will be equally deducted from the amount of each specified output.
                                 Those recipients will receive less bitcoins than you enter in their corresponding amount field.
                                 If no outputs are specified here, the sender pays the fee.
    vout_index,                  (numeric) The zero-based output index, before a change output is added.
    ...
  ],

Parameter #3—iswitness

Result

{
  "hex":       "value", (string)  The resulting raw transaction (hex-encoded string)
  "fee":       n,         (numeric) Fee in BTC the resulting transaction pays
  "changepos": n          (numeric) The position of the added change output, or -1
}

Example

Create a transaction with no inputs

bitcoin-cli createrawtransaction "[]" "{\"myaddress\":0.01}"

Add sufficient unsigned inputs to meet the output value

bitcoin-cli fundrawtransaction "rawtransactionhex"

Sign the transaction

bitcoin-cli signrawtransactionwithwallet "fundedtransactionhex"

Send the transaction

bitcoin-cli sendrawtransaction "signedtransactionhex"

See also

• CreateRawTransaction: create a transaction spending the given inputs and creating new outputs.
• DecodeRawTransaction: return a JSON object representing the serialized, hex-encoded transaction.
• SendRawTransaction: submits raw transaction (serialized, hex-encoded) to local node and network.

Generate

Added in Bitcoin Core 0.11.0

The generate RPC mine up to nblocks blocks immediately (before the RPC call returns) to an address in the wallet.

Parameter #1—nblocks

Parameter #2—maxtries

Result

[ blockhashes ]     (array) hashes of blocks generated

Example

Generate 11 blocks

bitcoin-cli generate 11

See also

• GenerateToAddress: mine blocks immediately to a specified address (before the RPC call returns).
• GetMiningInfo: returns a json object containing mining-related information.
• GetBlockTemplate: if the request parameters include a ‘mode’ key, that is used to explicitly select between the default ‘template’ request or a ‘proposal’.

GenerateToAddress

Added in Bitcoin Core 0.13.0

The generatetoaddress RPC mine blocks immediately to a specified address (before the RPC call returns).

Parameter #1—nblocks

Parameter #2—address

Parameter #3—maxtries

Result

[ blockhashes ]     (array) hashes of blocks generated

Example

Generate 11 blocks to myaddress

bitcoin-cli generatetoaddress 11 "myaddress"

If you are running the bitcoin core wallet, you can get a new address to send the newly generated bitcoin to with:

bitcoin-cli getnewaddress

See also

• Generate: mine up to nblocks blocks immediately (before the RPC call returns) to an address in the wallet.
• GetMiningInfo: returns a json object containing mining-related information.
• GetBlockTemplate: if the request parameters include a ‘mode’ key, that is used to explicitly select between the default ‘template’ request or a ‘proposal’.

GetAddedNodeInfo

The getaddednodeinfo RPC returns information about the given added node, or all added nodes (note that onetry addnodes are not listed here).

Parameter #1—node

Result

[
  {
    "addednode" : "192.168.0.201",   (string) The node IP address or name (as provided to addnode)
    "connected" : true|false,          (boolean) If connected
    "addresses" : [                    (list of objects) Only when connected = true
       {
         "address" : "192.168.0.201:8333",  (string) The bitcoin server IP and port we're connected to
         "connected" : "outbound"           (string) connection, inbound or outbound
       }
     ]
  }
  ,...
]

Example

bitcoin-cli getaddednodeinfo "192.168.0.201"

See also

• AddNode: attempts to add or remove a node from the addnode list.
• GetPeerInfo: returns data about each connected network node as a json array of objects.

GetAddressesByLabel

Added in Bitcoin Core 0.17.0

The getaddressesbylabel RPC returns the list of addresses assigned the specified label.

Parameter #1—label

Result

{ (json object with addresses as keys)
  "address": { (json object with information about address)
    "purpose": "string" (string)  Purpose of address ("send" for sending address, "receive" for receiving address)
  },...
}

Example

bitcoin-cli getaddressesbylabel "tabby"

GetAddressInfo

Added in Bitcoin Core 0.17.0

The getaddressinfo RPC return information about the given bitcoin address.

Some information requires the address to be in the wallet.

Parameter #1—address

Result

{
  "address" : "address",        (string) The bitcoin address validated
  "scriptPubKey" : "hex",       (string) The hex-encoded scriptPubKey generated by the address
  "ismine" : true|false,        (boolean) If the address is yours or not
  "iswatchonly" : true|false,   (boolean) If the address is watchonly
  "solvable" : true|false,      (boolean) Whether we know how to spend coins sent to this address, ignoring the possible lack of private keys
  "desc" : "desc",            (string, optional) A descriptor for spending coins sent to this address (only when solvable)
  "isscript" : true|false,      (boolean) If the key is a script
  "ischange" : true|false,      (boolean) If the address was used for change output
  "iswitness" : true|false,     (boolean) If the address is a witness address
  "witness_version" : version   (numeric, optional) The version number of the witness program
  "witness_program" : "hex"     (string, optional) The hex value of the witness program
  "script" : "type"             (string, optional) The output script type. Only if "isscript" is true and the redeemscript is known. Possible types: nonstandard, pubkey, pubkeyhash, scripthash, multisig, nulldata, witness_v0_keyhash, witness_v0_scripthash, witness_unknown
  "hex" : "hex",                (string, optional) The redeemscript for the p2sh address
  "pubkeys"                     (string, optional) Array of pubkeys associated with the known redeemscript (only if "script" is "multisig")
    [
      "pubkey"
      ,...
    ]
  "sigsrequired" : xxxxx        (numeric, optional) Number of signatures required to spend multisig output (only if "script" is "multisig")
  "pubkey" : "publickeyhex",    (string, optional) The hex value of the raw public key, for single-key addresses (possibly embedded in P2SH or P2WSH)
  "embedded" : {...},           (object, optional) Information about the address embedded in P2SH or P2WSH, if relevant and known. It includes all getaddressinfo output fields for the embedded address, excluding metadata ("timestamp", "hdkeypath", "hdseedid") and relation to the wallet ("ismine", "iswatchonly").
  "iscompressed" : true|false,  (boolean, optional) If the pubkey is compressed
  "label" :  "label"         (string) The label associated with the address, "" is the default label
  "timestamp" : timestamp,      (number, optional) The creation time of the key if available in seconds since epoch (Jan 1 1970 GMT)
  "hdkeypath" : "keypath"       (string, optional) The HD keypath if the key is HD and available
  "hdseedid" : "<hash160>"      (string, optional) The Hash160 of the HD seed
  "hdmasterfingerprint" : "<hash160>" (string, optional) The fingperint of the master key.
  "labels"                      (object) Array of labels associated with the address.
    [
      { (json object of label data)
        "name": "labelname" (string) The label
        "purpose": "string" (string) Purpose of address ("send" for sending address, "receive" for receiving address)
      },...
    ]
}

Example

bitcoin-cli getaddressinfo "1PSSGeFHDnKNxiEyFrD1wcEaHr9hrQDDWc"

GetBalance

The getbalance RPC returns the total available balance.

The available balance is what the wallet considers currently spendable, and is thus affected by options which limit spendability such as -spendzeroconfchange.

Parameter #1—dummy