BIP: 174 Layer: Applications Title: Partially Signed Bitcoin Transaction Format Author: Andrew Chow <[email protected]> Comments-Summary: No comments yet. Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0174 Status: Draft Type: Standards Track Created: 2017-07-12 License: BSD-2-Clause
This document proposes a binary transaction format which contains the information necessary for a signer to produce signatures for the transaction and holds the signatures for an input while the input does not have a complete set of signatures. The signer can be offline as all necessary information will be provided in the transaction.
This BIP is licensed under the 2-clause BSD license.
Creating unsigned or partially signed transactions to be passed around to multiple signers is currently implementation dependent, making it hard for people who use different wallet software from being able to easily do so. One of the goals of this document is to create a standard and extensible format that can be used between clients to allow people to pass around the same transaction to sign and combine their signatures. The format is also designed to be easily extended for future use which is harder to do with existing transaction formats.
Signing transactions also requires users to have access to the UTXOs being spent. This transaction format will allow offline signers such as air-gapped wallets and hardware wallets to be able to sign transactions without needing direct access to the UTXO set and without risk of being defrauded.
The Partially Signed Bitcoin Transaction (PSBT) format consists of key-value maps. Each key-value pair must be unique within its scope; duplicates are not allowed. Each map consists of a sequence of records, terminated by a 0x00 byte [1]. The format of a record is as follows:
Note: <..> indicates that the data is prefixed by a compact size unsigned integer representing the length of that data. {..} indicates the raw data itself.
<key>|<value>
| Name | Type | Description |
|---|---|---|
| Key Length | Compact Size Unsigned Integer | Specify how long the key is |
| Key | byte[] | The key itself with the first byte being the type of the key-value pair |
| Value Length | Compact Size Unsigned Integer | Specify how long the value is |
| Value | byte[] | The Value itself |
The format of each key-value map is as follows:
{key-value pair}|{key-value pair}|...|{0x00}
| Field Size | Name | Type | Value | Description |
|---|---|---|---|---|
| 1+ | Key-value pairs | Array of key-value pairs | varies | The key-value pairs. |
| 1 | separator | char | 0x00 | Must be 0x00. |
The first byte of each key specifies the type of the key-value pair. Some types are for global fields and other fields are for each input. The only required type in a PSBT is the transaction type, as defined below. The currently defined global types are as follows:
| Number | Name | Key Data | Value Data | Format Example |
|---|---|---|---|---|
| 0x00 | Transaction | None. The key must only contain the 1 byte type. | The transaction in network serialization. The scriptSigs and witnesses for each input must be empty unless the input is complete. The transaction must be in the witness serialization format as defined in BIP 144. A PSBT must have a transaction, otherwise it is invalid. |
Key:
{0x00}
Value:
{transaction}
|
| 0x01 | Redeem Script[2] | The hash160 of the redeem script | A redeem script that will be needed to sign a Pay-To-Script-Hash input or is spent to by an output.[3] |
Key:
{0x01}|{hash160}
Value:
{redeem script}
|
| 0x02 | Witness Script | The sha256 hash of the witness script | A witness script that will be needed to sign a Pay-To-Witness-Script-Hash input or is spent to by an output. |
Key:
{0x02}|{sha256}
Value:
{witness script}
|
| 0x03 | BIP 32 Derivation path, public key, and Master Key fingerprint | The public key | The master key fingerprint concatenated with the derivation path of the public key. The derivation path is represented as 32 bit unsigned integer indexes concatenated with each other. This must omit the index of the master key. |
Key:
{0x03}|{public key}
Value:
{master key fingerprint}|{32-bit int}|...|{32-bit int}
|
| 0x04 | Number of inputs provided in the PSBT | None. The key must only contain the 1 byte type. | A compact size unsigned integer representing the number of inputs that this PSBT has |
Key:
{0x04}
Value:
{number of inputs}
|
The currently defined per-input types are defined as follows:
| Number | Name | Key Data | Value Data | Format Example |
|---|---|---|---|---|
| 0x00 | Non-Witness UTXO | None. The key must only contain the 1 byte type. | The transaction in network serialization format the current input spends from. |
Key:
{0x00}
Value:
{transaction}
|
| 0x01 | Witness UTXO | None. The key must only contain the 1 byte type. | The entire transaction output in network serialization which the current input spends from. |
Key:
{0x01}
Value:
{serialized transaction output({output value}|<scriptPubKey>)}
|
| 0x02 | Partial Signature | The public key which corresponds to this signature. | The signature as would be pushed to the stack from a scriptSig or witness. |
Key:
{0x02}|{public key}
Value:
{signature}
|
| 0x03 | Sighash Type | None. The key must only contain the 1 byte type. | The 32-bit unsigned integer recommending a sighash type to be used for this input. The sighash type is only a recommendation and the signer does not need to use the sighash type specified. |
Key:
{0x03}
Value:
{sighash type}
|
| 0x04 | Input index | None. The key must only contain the 1 byte type. | A compact size unsigned integer representing the 0-based index of this input. This field is optional to allow for completed inputs to be skipped without needing a separator byte. If one input has this type, then all inputs must have it. |
Key:
{0x04}
Value:
{input index}
|
The transaction format is specified as follows:
{0x70736274}|{0xff}|{global key-value map}|{input key-value map}|...|{input key-value map}
| Field Size | Name | Type | Value | Description |
|---|---|---|---|---|
| 4 | Magic Bytes | int32_t | 0x70736274 | Magic bytes which are ASCII for psbt. [4] This integer should be serialized in most significant byte order. |
| 1 | separator | char | 0xff | Must be 0xff [5] |
| 1+ | Global data | Key-value Map | varies | The key-value pairs for all global data. |
| 1+ | Inputs | Array of key-value maps | varies | The key-value pairs for each input as described below |
Each block of data between separators can be viewed as a scope, and all separators are required[6]. Types can be skipped when they are unnecessary. For example, if an input is a witness input, then it should not have a Non-Witness UTXO key-value pair.
If the signer encounters key-value pairs that it does not understand, it must pass those key-value pairs through when re-serializing the transaction.
Keys within each scope should never be duplicated; all keys in the format are unique. However implementors will still need to handle events where keys are duplicated, either duplicated in the transaction itself or when combining transactions with duplicated fields. If duplicated keys are encountered, the software may choose to use any of the values corresponding to that key.
Using the transaction format involves many different responsibilities. These responsibilities can be handled by a single entity, but each responsibility is specialized in what it should be capable of doing.
The Creator must be capable of accepting either a network serialized transaction, or a PSBT. The Creator can either produce a new PSBT, or update the provided PSBT. For any scriptSigs which are non-final, the Creator will provide an empty scriptSig and input fields with information from the scriptSig, if any. If possible, the Creator should also look for any required redeemScripts and witnesScripts and add those to the global data section of the PSBT. The Creator should also provide any related UTXOs that it knows about.
The Signer must only accept a PSBT. The Signer must only use the UTXOs provided in the PSBT to produce signatures for inputs. The Signer should not need require any additional data sources, as all necessary information is provided in the PSBT format. Any signatures created by the Signer must be added as a "Partial Signature" key-value pair for the respective input it relates to.
The Signer can additionally compute the addresses and values being sent, and the transaction fee, optionally showing this data to the user as a confirmation of intent and the consequences of signing the PSBT.
The Combiner can accept 1 or many PSBTs. The Combiner must merge them into one PSBT (if possible), or fail. The resulting PSBT must contains all of the key-value pairs from each of the PSBTs. The Combined must remove any duplicate key-value pairs, in accordance with the specification.
The Finalizer must only accept a PSBT. The Finalizer transforms a PSBT into a network serialized transaction.
For any inputs which are not complete, the Finalizer will emplace an empty scriptSig in the network serialized transaction. For any input which has a complete set of signatures, the Finalizer must attempt to build the complete scriptSig and encode it into the network serialized transaction.
The Partially Signed Transaction format can be extended in the future by adding new types for key-value pairs. Backwards compatibilty will still be maintained as those new types will be ignored and passed-through by signers which do not know about them.
Additional key-value maps with different types for the key-value pairs can be added on to the end of the format. The number of each map that follows must be specified in the globals section so that parsers will know when to use different definitions of the data types.
This transaction format is designed so that it is unable to be properly unserialized by normal transaction unserializers. Likewise, a normal transaction will not be able to be unserialized by an unserializer for the PSBT format.
The following test vectors are done with keys derived from the following master private key. Keypaths and individual private keys will be specified when necessary
tprv8ZgxMBicQKsPdHrvvmuEXXZ7f5EheFqshqVmtPjeLLMjqwrWbSeuGDcgJU1icTHtLjYiGewa5zcMScbGSRR8AqB8A5wvB3XRdNYBDMhXpBS
The following are invalid PSBTs:
| Test Case | Explanation |
|---|---|
0200000001268171371edff285e937adeea4b37b78000c0566cbb3ad64641713ca42171bf6000000006a473044022070b2245123e6bf474d60c5b50c043d4c691a5d2435f09a34a7662a9dc251790a022001329ca9dacf280bdf30740ec0390422422c81cb45839457aeb76fc12edd95b3012102657d118d3357b8e0f4c2cd46db7b39f6d9c38d9a70abcb9b2de5dc8dbfe4ce31feffffff02d3dff505000000001976a914d0c59903c5bac2868760e90fd521a4665aa7652088ac00e1f5050000000017a9143545e6e33b832c47050f24d3eeb93c9c03948bc787b32e1300 | Network transaction, not PSBT format |
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 | PSBT missing null terminator |
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 | PSBT with one P2PKH input and one P2SH-P2WPKH input with only the first input signed, finalized, and skipped. Input index is specified but total input count is not given. |
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 | PSBT with one P2PKH input and one P2SH-P2WPKH input with only the first input signed, finalized, and skipped. Total input count is given but second input does not have its index. |
The following are valid PSBTs:
| Test Case | Explanation |
|---|---|
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 | PSBT with one P2PKH input which has a non-final scriptSig. |
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 | PSBT with one P2PKH input which has a non-final scriptSig and has a sighash type specified. |
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 | PSBT with one P2PKH input and one P2SH-P2WPKH input both with non-final scriptSigs. P2SH-P2WPKH input's redeemScript is available. |
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 | PSBT with one P2PKH input and one P2SH-P2WPKH input with only the first input signed and finalized. |
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 | PSBT with one P2PKH input and one P2SH-P2WPKH input with only the first input signed, finalized, and skipped. Input indexes are used. |
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 | PSBT with one P2SH-P2WSH input of a 2-of-2 multisig, redeemScript, witnessScript, and keypaths are available. Contains one signature. |
A creator with only the following:
- Redeem Scripts:
- 522103c8727ce35f1c93eb0be21406ee9a923c89219fe9c9e8504c8314a6a22d1295c02103c74dc710c407d7db6e041ee212d985cd2826d93f806ed44912b9a1da691c977352ae
- 0020a8f44467bf171d51499153e01c0bd6291109fc38bd21b3c3224c9dc6b57590df
- Witness Scripts:
- 522102e80dec31d167865c1685e9d7a9291e66a4ea22c65cfee324289a1667ccda3b87210258cbbc3cb295a8bebac233aadc7773978804993798be5390ab444f6dd4c5327e52ae
- UTXOs
- TXID: 0a4381c05136c0cb44886a5df7c26f1930bcc2c12e00ec60e027c4378d7d8c2e, Index: 1
- scriptPubKey: a914203736c3c06053896d7041ce8f5bae3df76cc49187
- value: 0.50000000
- TXID: 2c4df245d00b491bdf24965adbbccdaa7f62ccac933d3e9377f336c60c4ea096, Index: 0
- scriptPubKey: a914f3ba8a120d960ae07d1dbe6f0c37fb4c926d76d587
- value: 2.00000000
- TXID: 0a4381c05136c0cb44886a5df7c26f1930bcc2c12e00ec60e027c4378d7d8c2e, Index: 1
02000000022e8c7d8d37c427e060ec002ec1c2bc30196fc2f75d6a8844cbc03651c081430a0100000000ffffffff96a04e0cc636f377933e3d93accc627faacdbcdb5a9624df1b490bd045f24d2c0000000000ffffffff01e02be50e0000000017a914b53bb0dc1db8c8d803e3e39f784d42e4737ffa0d8700000000must create this PSBT:
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
Given the above PSBT, a signer with the following keys:
- cQxozhqme9dcDbxT97uDu1P32Cnywc5nAMhPtQwyWhVgQnP43WGH
- cP3ArXq5BpHE94R4buJ5uma4pyKvaWXUd5Bpsy3hS2zA69X9KMnM
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
Given the above blank PSBT, a signer with the following keys:
- cUL8UxFiJjnLkkZwmmXDxmaNRQfEMDP44eZnSaiYR3KUJNv82chM
- cNQm3eSF9rQnpoUB8xThUVDfaeRVEckPK11rGB6LjweFdhwcCS4A
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
Given both of the above PSBTs, a combiner must create this PSBT:
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
Given the above PSBT, a finalizer must create this complete Bitcoin transaction:
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
- ^ Why is the separator here 0x00 instead of 0xff? The separator here is used to distinguish between each chunk of data. A separator of 0x00 would mean that the unserializer can read it as a key length of 0, which would never occur with actual keys. It can thus be used as a separator and allow for easier unserializer implementation.
- ^ Why are redeem scripts and witness scripts global Redeem scripts and witness scripts are global data to avoid duplication. Instead of specifying a redeems script and witness script multiple times in inputs that need those scripts, they are specified once in the global data.
- ^ Why are outputs' redeem scripts and witness scripts included? Redeem scripts and witness scripts spent to by an output in this transaction are included so that the user can verify that the transaction they are signing is creating the correct outputs that have the correct redeem and witness scripts. This is best used when the PSBT creator is not trusted by the signers.
- ^ Why use 4 bytes for psbt? The transaction format needed to start with a 5 byte header which uniquely identifies it. The first bytes were chosen to be the ASCII for psbt because that stands for Partially Signed Bitcoin Transaction.
- ^ Why Use a separator after the magic bytes? The separator is part of the 5 byte header for PSBT. This byte is a separator of 0xff because this will cause any non-PSBT unserializer to fail to properly unserialize the PSBT as a normal transaction. Likewise, since the 5 byte header is fixed, no transaction in the non-PSBT format will be able to be unserialized by a PSBT unserializer.
- ^ Why are all separators required? The separators are required so that the unserializer knows which input it is unserializing data for.
The reference implementation of the PSBT format is available at https://github.com/achow101/bitcoin/tree/psbt.
Special thanks to Pieter Wuille for suggesting that such a transaction format should be made and for coming up with the name and abbreviation of PSBT.
Thanks to Pieter Wuille, Gregory Maxwell, Jonathan Underwood, and Daniel Cousens for additional comments and suggestions for improving this proposal.
Any data types, their associated scope and BIP number must be defined here
| Scope | Type values | BIP Number |
|---|---|---|
| Global | 0,1,2,3,4 | BIP 174 |
| Input | 0,1,2,3,4 | BIP 174 |