Block diagram
This page hosts a formal specification of Bitcoin Transaction using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
meta:
id: bitcoin_transaction
title: Bitcoin Transaction
license: MIT
endian: le
doc-ref: |
https://bitcoin.org/en/developer-guide#transactions
https://en.bitcoin.it/wiki/Transaction
seq:
- id: version
type: u4
doc: |
Version number.
- id: num_vins
type: u1
doc: |
Number of input transactions.
- id: vins
type: vin
repeat: expr
repeat-expr: num_vins
doc: |
Input transactions.
An input refers to an output from a previous transaction.
- id: num_vouts
type: u1
doc: |
Number of output transactions.
- id: vouts
type: vout
repeat: expr
repeat-expr: num_vouts
doc: |
Output transactions.
- id: locktime
type: u4
types:
vin:
seq:
- id: txid
size: 32
doc: |
Previous transaction hash.
- id: output_id
type: u4
doc: |
ID indexing an ouput of the transaction refered by txid.
This output will be used as an input in the present transaction.
- id: len_script
type: u1
doc: |
ScriptSig's length.
- id: script_sig
size: len_script
type: script_signature
doc: |
ScriptSig.
doc-ref: |
https://en.bitcoin.it/wiki/Transaction#Input
https://en.bitcoin.it/wiki/Script
- id: end_of_vin
contents: [0xff, 0xff, 0xff, 0xff]
doc: |
Magic number indicating the end of the current input.
types:
script_signature:
seq:
- id: len_sig_stack
type: u1
- id: der_sig
type: der_signature
doc: |
DER-encoded ECDSA signature.
doc-ref: |
https://en.wikipedia.org/wiki/X.690#DER_encoding
https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm
- id: sig_type
type: u1
enum: sighash_type
doc: |
Type of signature.
- id: len_pubkey_stack
type: u1
- id: pubkey
type: public_key
doc: |
Public key (bitcoin address of the recipient).
types:
der_signature:
seq:
- id: sequence
contents: [0x30]
- id: len_sig
type: u1
- id: sep_1
contents: [0x02]
- id: len_sig_r
type: u1
doc: |
'r' value's length.
- id: sig_r
size: len_sig_r
doc: |
'r' value of the ECDSA signature.
doc-ref: 'https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm'
- id: sep_2
contents: [0x02]
- id: len_sig_s
type: u1
doc: |
's' value's length.
- id: sig_s
size: len_sig_s
doc: |
's' value of the ECDSA signature.
doc-ref: 'https://en.wikipedia.org/wiki/Elliptic_Curve_Digital_Signature_Algorithm'
public_key:
seq:
- id: type
type: u1
- id: x
size: 32
doc: |
'x' coordinate of the public key on the elliptic curve.
- id: y
size: 32
doc: |
'y' coordinate of the public key on the elliptic curve.
enums:
sighash_type:
1: sighash_all
2: sighash_none
3: sighash_single
80: sighash_anyonecanpay
vout:
seq:
- id: amount
type: u8
doc: |
Number of Satoshis to be transfered.
- id: len_script
type: u1
doc: |
ScriptPubKey's length.
- id: script_pub_key
size: len_script
doc: |
ScriptPubKey.
doc-ref: |
https://en.bitcoin.it/wiki/Transaction#Output
https://en.bitcoin.it/wiki/Script