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Merge pull request #485 from ipaljak-tbtl/expose-tx-signature-data 

Expose serialized data for transaction signatures
This commit is contained in:
Andrew Poelstra 2020-10-09 13:24:51 +00:00 committed by GitHub
parent fc60a7fc25 e66caab956
commit 3618d7a41d
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 91 additions and 44 deletions
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68
src/blockdata/transaction.rs
View File

@ -302,30 +302,35 @@ impl Transaction {
Wtxid::from_engine(enc)
}
/// Computes a signature hash for a given input index with a given sighash flag.
/// To actually produce a scriptSig, this hash needs to be run through an
/// ECDSA signer, the SigHashType appended to the resulting sig, and a
/// script written around this, but this is the general (and hard) part.
/// Encodes the signing data from which a signature hash for a given input index with a given
/// sighash flag can be computed. To actually produce a scriptSig, this hash needs to be run
/// through an ECDSA signer, the SigHashType appended to the resulting sig, and a script
/// written around this, but this is the general (and hard) part.
///
/// *Warning* This does NOT attempt to support OP_CODESEPARATOR. In general
/// this would require evaluating `script_pubkey` to determine which separators
/// get evaluated and which don't, which we don't have the information to
/// determine.
/// *Warning* This does NOT attempt to support OP_CODESEPARATOR. In general this would require
/// evaluating `script_pubkey` to determine which separators get evaluated and which don't,
/// which we don't have the information to determine.
///
/// # Panics
/// Panics if `input_index` is greater than or equal to `self.input.len()`
/// # Panics Panics if `input_index` is greater than or equal to `self.input.len()`
///
pub fn signature_hash(&self, input_index: usize, script_pubkey: &Script, sighash_u32: u32) -> SigHash {
pub fn encode_signing_data_to<Write: io::Write>(
&self,
mut writer: Write,
input_index: usize,
script_pubkey: &Script,
sighash_u32: u32
) -> Result<(), encode::Error> {
assert!(input_index < self.input.len()); // Panic on OOB
let (sighash, anyone_can_pay) = SigHashType::from_u32(sighash_u32).split_anyonecanpay_flag();
// Special-case sighash_single bug because this is easy enough.
if sighash == SigHashType::Single && input_index >= self.output.len() {
return SigHash::from_slice(&[1, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0]).unwrap();
writer.write_all(&[1, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0])?;
return Ok(());
}
// Build tx to sign
@ -368,11 +373,34 @@ impl Transaction {
_ => unreachable!()
};
// hash the result
let mut engine = SigHash::engine();
tx.consensus_encode(&mut engine).unwrap();
tx.consensus_encode(&mut writer)?;
let sighash_arr = endian::u32_to_array_le(sighash_u32);
sighash_arr.consensus_encode(&mut engine).unwrap();
SigHash::from_engine(engine)
sighash_arr.consensus_encode(&mut writer)?;
Ok(())
}
/// Computes a signature hash for a given input index with a given sighash flag.
/// To actually produce a scriptSig, this hash needs to be run through an
/// ECDSA signer, the SigHashType appended to the resulting sig, and a
/// script written around this, but this is the general (and hard) part.
///
/// *Warning* This does NOT attempt to support OP_CODESEPARATOR. In general
/// this would require evaluating `script_pubkey` to determine which separators
/// get evaluated and which don't, which we don't have the information to
/// determine.
///
/// # Panics
/// Panics if `input_index` is greater than or equal to `self.input.len()`
///
pub fn signature_hash(
&self,
input_index: usize,
script_pubkey: &Script,
sighash_u32: u32
) -> Result<SigHash, encode::Error> {
let mut engine = SigHash::engine();
self.encode_signing_data_to(&mut engine, input_index, script_pubkey, sighash_u32)?;
Ok(SigHash::from_engine(engine))
}
/// Gets the "weight" of this transaction, as defined by BIP141. For transactions with an empty
@ -869,7 +897,7 @@ mod tests {
raw_expected.reverse();
let expected_result = SigHash::from_slice(&raw_expected[..]).unwrap();
let actual_result = tx.signature_hash(input_index, &script, hash_type as u32);
let actual_result = tx.signature_hash(input_index, &script, hash_type as u32).unwrap();
assert_eq!(actual_result, expected_result);
}

67
src/util/bip143.rs
View File

@ -23,8 +23,9 @@ use hashes::{Hash, sha256d};
use hash_types::SigHash;
use blockdata::script::Script;
use blockdata::transaction::{Transaction, TxIn, SigHashType};
use consensus::encode::Encodable;
use consensus::{encode, Encodable};
use std::io;
use std::ops::{Deref, DerefMut};
/// Parts of a sighash which are common across inputs or signatures, and which are
@ -168,27 +169,32 @@ impl<R: Deref<Target=Transaction>> SigHashCache<R> {
})
}
/// Compute the BIP143 sighash for any flag type. See SighashComponents::sighash_all simpler
/// API for the most common case
pub fn signature_hash(&mut self, input_index: usize, script_code: &Script, value: u64, sighash_type: SigHashType) -> SigHash {
/// Encode the BIP143 signing data for any flag type into a given object implementing a
/// std::io::Write trait.
pub fn encode_signing_data_to<Write: io::Write>(
&mut self,
mut writer: Write,
input_index: usize,
script_code: &Script,
value: u64,
sighash_type: SigHashType,
) -> Result<(), encode::Error> {
let zero_hash = sha256d::Hash::default();
let (sighash, anyone_can_pay) = sighash_type.split_anyonecanpay_flag();
let mut enc = SigHash::engine();
self.tx.version.consensus_encode(&mut enc).unwrap();
self.tx.version.consensus_encode(&mut writer)?;
if !anyone_can_pay {
self.hash_prevouts().consensus_encode(&mut enc).unwrap();
self.hash_prevouts().consensus_encode(&mut writer)?;
} else {
zero_hash.consensus_encode(&mut enc).unwrap();
zero_hash.consensus_encode(&mut writer)?;
}
if !anyone_can_pay && sighash != SigHashType::Single && sighash != SigHashType::None {
self.hash_sequence().consensus_encode(&mut enc).unwrap();
self.hash_sequence().consensus_encode(&mut writer)?;
} else {
zero_hash.consensus_encode(&mut enc).unwrap();
zero_hash.consensus_encode(&mut writer)?;
}
{
@ -196,26 +202,39 @@ impl<R: Deref<Target=Transaction>> SigHashCache<R> {
txin
.previous_output
.consensus_encode(&mut enc)
.unwrap();
script_code.consensus_encode(&mut enc).unwrap();
value.consensus_encode(&mut enc).unwrap();
txin.sequence.consensus_encode(&mut enc).unwrap();
.consensus_encode(&mut writer)?;
script_code.consensus_encode(&mut writer)?;
value.consensus_encode(&mut writer)?;
txin.sequence.consensus_encode(&mut writer)?;
}
if sighash != SigHashType::Single && sighash != SigHashType::None {
self.hash_outputs().consensus_encode(&mut enc).unwrap();
self.hash_outputs().consensus_encode(&mut writer)?;
} else if sighash == SigHashType::Single && input_index < self.tx.output.len() {
let mut single_enc = SigHash::engine();
self.tx.output[input_index].consensus_encode(&mut single_enc).unwrap();
SigHash::from_engine(single_enc).consensus_encode(&mut enc).unwrap();
self.tx.output[input_index].consensus_encode(&mut single_enc)?;
SigHash::from_engine(single_enc).consensus_encode(&mut writer)?;
} else {
zero_hash.consensus_encode(&mut enc).unwrap();
zero_hash.consensus_encode(&mut writer)?;
}
self.tx.lock_time.consensus_encode(&mut enc).unwrap();
sighash_type.as_u32().consensus_encode(&mut enc).unwrap();
SigHash::from_engine(enc)
self.tx.lock_time.consensus_encode(&mut writer)?;
sighash_type.as_u32().consensus_encode(&mut writer)?;
Ok(())
}
/// Compute the BIP143 sighash for any flag type. See SighashComponents::sighash_all simpler
/// API for the most common case
pub fn signature_hash(
&mut self,
input_index: usize,
script_code: &Script,
value: u64,
sighash_type: SigHashType
) -> Result<SigHash, encode::Error> {
let mut enc = SigHash::engine();
self.encode_signing_data_to(&mut enc, input_index, script_code, value, sighash_type)?;
Ok(SigHash::from_engine(enc))
}
}
@ -273,7 +292,7 @@ mod tests {
let expected_result = SigHash::from_slice(&raw_expected[..]).unwrap();
let mut cache = SigHashCache::new(&tx);
let sighash_type = SigHashType::from_u32(hash_type);
let actual_result = cache.signature_hash(input_index, &script, value, sighash_type);
let actual_result = cache.signature_hash(input_index, &script, value, sighash_type).unwrap();
assert_eq!(actual_result, expected_result);
}