Raw Transaction Format

Dash 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.

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

Transactions prior to protocol version 70209 defaulted to version 1. Transaction version 2 was the default in protocol versions => 70209 and < 70213. Version 2 transactions have the same format, but the lock_time parameter was redefined by BIP68 to enable relative lock-times. (Note: transactions in the block chain are allowed to list a higher version number to permit soft forks, but they are treated as version 2 transactions by current software.)

Dash Core 0.13.0 (protocol version 70213) introduced transaction version 3 as part of the DIP2 - Special Transactions implementation. Details of the changes introduced by this feature and currently implemented special transactions can be found in the Special Transactions section below as well as in the DIP.

A raw transaction has the following top-level format:

BytesNameData TypeDescription
2versionuint16_tConverted from 4 bytes to 2 bytes by DIP2 in v0.13.0

Transaction version number; currently version 3. Programs creating transactions using newer consensus rules may use higher version numbers.
2typeuint16_tAdded by DIP2 in v0.13.0. Uses 2 bytes that were previously part of version

Transaction type number; 0 for classical transactions; Non-zero for DIP2 special transactions.
Variestx_in countcompactSize uintNumber of inputs in this transaction.
Variestx_intxInTransaction inputs. See description of txIn below.
Variestx_out countcompactSize uintNumber of outputs in this transaction.
Variestx_outtxOutTransaction outputs. See description of txOut below.
4lock_timeuint32_tA time (Unix epoch time) or block number. See the locktime parsing rules.
Variesextra_payload sizecompactSize uintAdded by DIP2 in v0.13.0

Variable number of bytes of extra payload for DIP2-based special transactions
Variesextra_payloadblobAdded by DIP2 in v0.13.0

Special transaction payload.

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.

JSON-RPC Responses

When retrieving transaction data via Dash Core RPCs (e.g. the getrawtransaction RPC), the transaction data is returned in the following format.

Version 1 and 2 Transaction Structure (prior to DIP2 activation in Dash Core v0.13.0):

{
  "txid": <string>,
  "size": <int>,
  "version": 2,
  "locktime": 0,
  "vin": [ ],
  "vout": [ ]
}

Version 3 Transaction Structure (Dash Core v0.13.0+ and activated DIP2):

{
  "txid": <string>,
  "size": <int>,
  "version": 3,
  "type": <int>,
  "locktime": 0,
  "vin": [ ],
  "vout": [ ],
  "extraPayloadSize": <variable int>,
  "extraPayload": …
}

For special transactions (those using the extraPayload fields), JSON-RPC responses contain a parsed JSON representation of the Transaction Payload.

The sample transaction below shows the response for a quorum commitment special transaction:

{
  "txid": "592a09d08348d970b4d9ba216246a23dac866717b460d3f369a86293b9839eea",
  "size": 342,
  "version": 3,
  "type": 6,
  "locktime": 0,
  "vin": [
  ],
  "vout": [
  ],
  "extraPayloadSize": 329,
  "extraPayload": "0100841b0000010001211cd3e4230b2bc47530e200447e998a38e960d4ed5f5251e26892130c000000320000000000000032000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000",
  "qcTx": {
    "version": 1,
    "height": 7044,
    "commitment": {
      "version": 1,
      "llmqType": 1,
      "quorumHash": "0000000c139268e251525fedd460e9388a997e4400e23075c42b0b23e4d31c21",
      "signersCount": 0,
      "validMembersCount": 0,
      "quorumPublicKey": "000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000"
    }
  },
  "instantlock": false
}

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.)

BytesNameData TypeDescription
36previous_outputoutpointThe previous outpoint being spent. See description of outpoint below.
Variesscript bytescompactSize uintThe number of bytes in the signature script. Maximum is 10,000 bytes.
Variessignature scriptchar[]A script-language script which satisfies the conditions placed in the outpoint's pubkey script. Should only contain data pushes; see the signature script modification warning.
4sequenceuint32_tSequence number. Default for Dash Core and almost all other programs is 0xffffffff.

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.

BytesNameData TypeDescription
32hashchar[32]The TXID of the transaction holding the output to spend. The TXID is a hash provided here in internal byte order.
4indexuint32_tThe output index number of the specific output to spend from the transaction. The first output is 0x00000000.

TxOut: A Transaction Output

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

BytesNameData TypeDescription
8valueint64_tNumber of duffs to spend. May be zero; the sum of all outputs may not exceed the sum of duffs previously spent to the outpoints provided in the input section. (Exception: coinbase transactions spend the block subsidy and collected transaction fees.)
1+pk_script bytescompactSize uintNumber of bytes in the pubkey script. Maximum is 10,000 bytes.
Variespk_scriptchar[]Defines the conditions which must be satisfied to spend this output.

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: 0
|
| 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 ......................... Duffs (49.99990000 Dash)
|
| 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.

BytesNameData TypeDescription
32hash (null)char[32]A 32-byte null, as a coinbase has no previous outpoint.
4index (UINT32_MAX)uint32_t0xffffffff, as a coinbase has no previous outpoint.
Variesscript bytescompactSize uintThe number of bytes in the coinbase script, up to a maximum of 100 bytes.
Varies (4)heightscriptThe block height of this block as required by BIP34. Uses script language: starts with a data-pushing opcode that indicates how many bytes to push to the stack followed by the block height as a little-endian unsigned integer. This script must be as short as possible, otherwise it may be rejected.

The data-pushing opcode will be 0x03 and the total size four bytes until block 16,777,216 about 300 years from now.
Variescoinbase scriptNoneThe coinbase field: Arbitrary data not exceeding 100 bytes minus the (4) height bytes. Miners commonly place an extra nonce in this field to update the block header merkle root during hashing.
4sequenceuint32_tSequence number.

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
|
| 18 .................................. Bytes in coinbase: 24
| |
| | 03 ................................ Bytes in height
| | | b8240b .......................... Height: 730296
| |
| | 03b8240b049d29aa59080400077efa95
| | 0000052f6d70682f .................. Arbitrary data
| 00000000 ............................ Sequence

02 .................................... Output count
| Transaction Output 1
| | f20cbe0a00000000 .................... Duffs (1.80227314 Dash)
| | 1976a9142cd46be3ceeacca983e0fea3
| | b88f26b08a26c29b88ac ................ P2PKH script
|
| Transaction Output 2
| | eb0cbe0a00000000 .................... Duffs (1.80227307 Dash)
| | 1976a914868180414905937a68fadeb0
| | f33e64d102c9591a88ac ................ P2PKH script
|
| 00000000 ............................ Locktime

Note: currently the normal coinbase has 2 outputs (1 for the miner and 1 for the selected masternode). Superblocks (superblock example) have multiple outputs depending on the number of proposals being funded.


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