Client and backend. This class is shared: the same code is compiled into your app and into your server, so everything on this page works in both.

public final class BitcoinTransaction

Object
BitcoinTransaction

A Bitcoin transaction: inputs spending previous outputs, new outputs, and the witness data SegWit inputs carry.

Mutable while it is built and signed; serialize writes the network form (with the witness when any input has one) and parse reads it back. The three signature hash algorithms are here – legacy (legacySighash), SegWit v0 BIP-143 (segwitV0Sighash) and Taproot BIP-341 (taprootSighash) – together with one-call signers for the common single-key inputs:

String prevTxid = "4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b";
byte[] privateKey = SecureRandom.bytes(32);
BitcoinTransaction tx = new BitcoinTransaction();
tx.addInput(prevTxid, 0);
tx.addOutput(50000, BitcoinAddress.parse("bc1q...", BitcoinNetwork.MAINNET).getScriptPubKey());
tx.signP2wpkh(0, privateKey, 60000);
String hex = tx.toHex();   // broadcast

Nested types

`class BitcoinTransaction.Input`	One input: the outpoint it spends, its unlocking script, sequence and witness.
`class BitcoinTransaction.Output`	One output: an amount in satoshis and the script that locks it.

Fields

`public static final int SIGHASH_ALL = 1`	Sign every input and output.
`public static final int SIGHASH_NONE = 2`	Sign every input and no output.
`public static final int SIGHASH_SINGLE = 3`	Sign every input and the output with the same index.
`public static final int SIGHASH_ANYONECANPAY = 128`	Combined with another type: sign only this input.
`public static final int SIGHASH_DEFAULT = 0`	Taproot’s default, which commits like `SIGHASH_ALL` and adds no byte to the signature.
`public static final long SEQUENCE_FINAL = 4294967295L`	The sequence that disables relative lock time and replace-by-fee signalling.
`public static final long SEQUENCE_RBF = 4294967293L`	The sequence an input signals BIP-125 replace-by-fee with.

Constructors

public BitcoinTransaction()

Methods

`public int addInput(String prevTxid, long index)`	Adds an input spending output `index` of the transaction `prevTxid` (display hex), with `SEQUENCE_RBF`.
`public int addInput(String prevTxid, long index, long sequence)`	Adds an input with an explicit sequence.
`public int addOutput(long value,` `Script scriptPubKey)`	Adds an output.
`public int addOutput(long value,` `BitcoinAddress address)`	Adds an output paying an address.
`public` `List<BitcoinTransaction.Input> getInputs()`	The inputs, live: changes to an `Input` change the transaction.
`public` `List<BitcoinTransaction.Output> getOutputs()`	The outputs.
`public long getVersion()`	The version, 2 by default.
`public void setVersion(long version)`	Sets the version.
`public long getLockTime()`	The lock time.
`public void setLockTime(long lockTime)`	Sets the lock time (a block height below 500000000, a Unix time above).
`public boolean hasWitness()`	Tells whether any input carries witness data.
`public byte[] serialize()`	The network serialization, with the witness when any input has one.
`public` `String toHex()`	`serialize` in hex, the form `sendrawtransaction` and every broadcast API take.
`public` `String getTxid()`	The transaction id in display hex: the reversed double SHA-256 of the form without witness.
`public` `String getWtxid()`	The witness transaction id in display hex.
`public long getVirtualSize()`	The virtual size in vbytes, which fees are priced in.
`public static` `BitcoinTransaction parse(byte[] raw)`	Reads a serialized transaction, with or without witness.
`public static` `BitcoinTransaction parse(byte[] raw, boolean allowWitness)`	Reads a serialized transaction.
`public static` `BitcoinTransaction fromHex(String hex)`	`parse` from hex.
`public byte[] legacySighash(int index,` `Script scriptCode, int sighashType)`	The legacy signature hash of input `index` against `scriptCode` (the spent output script, or the redeem script of P2SH).
`public byte[] segwitV0Sighash(int index,` `Script scriptCode, long amount, int sighashType)`	The BIP-143 signature hash of a SegWit v0 input.
`public byte[] taprootSighash(int index,` `List<BitcoinTransaction.Output> spent, int sighashType)`	The BIP-341 signature hash of a Taproot input, key path, no annex.
`public byte[] taprootSighash(int index,` `List<BitcoinTransaction.Output> spent, int sighashType, byte[] leafHash)`	The BIP-341 signature hash of a Taproot script-path spend of `leafHash` (BIP-342 extension, no annex, code separator position none); `null` for the key path.
`public void signP2pkh(int index, byte[] privateKey, boolean compressed)`	Signs a P2PKH input with `SIGHASH_ALL` and sets its `scriptSig`.
`public void signP2wpkh(int index, byte[] privateKey, long amount)`	Signs a P2WPKH input with `SIGHASH_ALL` and sets its witness.
`public void signP2shP2wpkh(int index, byte[] privateKey, long amount)`	Signs a BIP-49 P2SH-P2WPKH input with `SIGHASH_ALL`.
`public void signP2trKeyPath(int index, byte[] privateKey,` `List<BitcoinTransaction.Output> spent)`	Signs a BIP-86 Taproot key-path input with `SIGHASH_DEFAULT` and sets its witness.
`public void signP2trKeyPath(int index, byte[] privateKey, byte[] merkleRoot,` `List<BitcoinTransaction.Output> spent, int sighashType)`	Signs a Taproot key-path input, committing to a script tree’s Merkle root.
`public static byte[] ecdsa(byte[] sighash, byte[] privateKey, int sighashType)`	A DER ECDSA signature with the sighash byte appended, as legacy and SegWit v0 inputs carry it.

Inherited methods

From Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait, clone, finalize

Field details

SIGHASH_ALL

public static final int SIGHASH_ALL = 1

Sign every input and output.

SIGHASH_NONE

public static final int SIGHASH_NONE = 2

Sign every input and no output.

SIGHASH_SINGLE

public static final int SIGHASH_SINGLE = 3

Sign every input and the output with the same index.

SIGHASH_ANYONECANPAY

public static final int SIGHASH_ANYONECANPAY = 128

Combined with another type: sign only this input.

SIGHASH_DEFAULT

public static final int SIGHASH_DEFAULT = 0

Taproot’s default, which commits like SIGHASH_ALL and adds no byte to the signature.

SEQUENCE_FINAL

public static final long SEQUENCE_FINAL = 4294967295L

The sequence that disables relative lock time and replace-by-fee signalling.

SEQUENCE_RBF

public static final long SEQUENCE_RBF = 4294967293L

The sequence an input signals BIP-125 replace-by-fee with.

Constructor details

BitcoinTransaction

public BitcoinTransaction()

Method details

addInput

public int addInput(String prevTxid, long index)

Adds an input spending output index of the transaction prevTxid (display hex), with SEQUENCE_RBF. Returns its index.

addInput

public int addInput(String prevTxid, long index, long sequence)

Adds an input with an explicit sequence. Returns its index.

addOutput

public int addOutput(long value, Script scriptPubKey)

Adds an output. Returns its index.

addOutput

public int addOutput(long value, BitcoinAddress address)

Adds an output paying an address. Returns its index.

getInputs

public List<BitcoinTransaction.Input> getInputs()

The inputs, live: changes to an Input change the transaction.

getOutputs

public List<BitcoinTransaction.Output> getOutputs()

The outputs.

getVersion

public long getVersion()

The version, 2 by default.

setVersion

public void setVersion(long version)

Sets the version.

getLockTime

public long getLockTime()

The lock time.

setLockTime

public void setLockTime(long lockTime)

Sets the lock time (a block height below 500000000, a Unix time above).

hasWitness

public boolean hasWitness()

Tells whether any input carries witness data.

serialize

public byte[] serialize()

The network serialization, with the witness when any input has one.

toHex

public String toHex()

serialize in hex, the form sendrawtransaction and every broadcast API take.

getTxid

public String getTxid()

The transaction id in display hex: the reversed double SHA-256 of the form without witness.

getWtxid

public String getWtxid()

The witness transaction id in display hex.

getVirtualSize

public long getVirtualSize()

The virtual size in vbytes, which fees are priced in.

parse

public static BitcoinTransaction parse(byte[] raw)

Reads a serialized transaction, with or without witness.

Throws

IllegalArgumentException: for truncated or trailing data

parse

public static BitcoinTransaction parse(byte[] raw, boolean allowWitness)

Reads a serialized transaction. With allowWitness false the SegWit marker is not recognized, which is how a PSBT’s unsigned transaction is read: a transaction with no inputs would otherwise begin with the marker byte.

Throws

: : for truncated or trailing data

fromHex

public static BitcoinTransaction fromHex(String hex)

parse from hex.

legacySighash

public byte[] legacySighash(int index, Script scriptCode, int sighashType)

The legacy signature hash of input index against scriptCode (the spent output script, or the redeem script of P2SH).

segwitV0Sighash

public byte[] segwitV0Sighash(int index, Script scriptCode, long amount, int sighashType)

The BIP-143 signature hash of a SegWit v0 input.

Parameters

index int: Not documented.
scriptCode Script: for P2WPKH the P2PKH script of the key hash; for P2WSH the witness script
amount long: the value of the spent output in satoshis, which the signature commits to
sighashType int: Not documented.

taprootSighash

public byte[] taprootSighash(int index, List<BitcoinTransaction.Output> spent, int sighashType)

The BIP-341 signature hash of a Taproot input, key path, no annex.

Parameters

index int: Not documented.
spent List<BitcoinTransaction.Output>: the output every input spends, in input order – Taproot signatures commit to all their amounts and scripts
sighashType int: Not documented.

taprootSighash

public byte[] taprootSighash(int index, List<BitcoinTransaction.Output> spent, int sighashType, byte[] leafHash)

The BIP-341 signature hash of a Taproot script-path spend of leafHash (BIP-342 extension, no annex, code separator position none); null for the key path.

signP2pkh

public void signP2pkh(int index, byte[] privateKey, boolean compressed)

Signs a P2PKH input with SIGHASH_ALL and sets its scriptSig.

signP2wpkh

public void signP2wpkh(int index, byte[] privateKey, long amount)

Signs a P2WPKH input with SIGHASH_ALL and sets its witness.

signP2shP2wpkh

public void signP2shP2wpkh(int index, byte[] privateKey, long amount)

Signs a BIP-49 P2SH-P2WPKH input with SIGHASH_ALL.

signP2trKeyPath

public void signP2trKeyPath(int index, byte[] privateKey, List<BitcoinTransaction.Output> spent)

Signs a BIP-86 Taproot key-path input with SIGHASH_DEFAULT and sets its witness.

Parameters

index int: Not documented.
privateKey byte[]: the untweaked internal private key
spent List<BitcoinTransaction.Output>: the output every input spends, in input order

signP2trKeyPath

public void signP2trKeyPath(int index, byte[] privateKey, byte[] merkleRoot, List<BitcoinTransaction.Output> spent, int sighashType)

Signs a Taproot key-path input, committing to a script tree’s Merkle root.

ecdsa

public static byte[] ecdsa(byte[] sighash, byte[] privateKey, int sighashType)

A DER ECDSA signature with the sighash byte appended, as legacy and SegWit v0 inputs carry it.