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Merge rust-bitcoin/rust-bitcoin#696: Taproot tweaks generalization & KeyPair support 

7405836411 Fix warning about deprecated method use (Dr Maxim Orlovsky)
f39b1300fa CI: do not fail fast (Dr Maxim Orlovsky)
f77c57195a Making Script method new_* names more consistent (Dr Maxim Orlovsky)
91b68a468d Taproot-related methods for Script type (Dr Maxim Orlovsky)
599c5f9488 Generalizing taproot key tweaking for KeyPairs (Dr Maxim Orlovsky)

Pull request description:

  * Adds taproot-related methods to `Script`
  * Fixes API for existing taproot methods
  * Generalizes `TapTweak` trait to work with both public keys and key pairs

  ~~UPD: PR is pending https://github.com/rust-bitcoin/rust-secp256k1/pull/342~~

ACKs for top commit:
  sanket1729:
    ACK 7405836411
  apoelstra:
    ACK 7405836411

Tree-SHA512: 4a76dfffa1452baadc15e19812831ef9d2e66794c090a8fc123388d7119b2c8a1f0420ce723ad22e01683c8198711fe62e0cdf00c9ad2d2974606383baaf1cb0
This commit is contained in:
sanket1729 2022-01-13 10:06:11 +05:30
parent bc9388e24a 7405836411
commit 7d62277f83
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GPG Key ID: 648FFB183E0870A2
4 changed files with 151 additions and 18 deletions
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1
.github/workflows/rust.yml vendored
View File

@ -7,6 +7,7 @@ jobs:
name: Tests
runs-on: ubuntu-latest
strategy:
fail-fast: false
matrix:
include:
- rust: stable

68
src/blockdata/script.rs
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@ -41,6 +41,9 @@ use policy::DUST_RELAY_TX_FEE;
use util::ecdsa::PublicKey;
use util::address::WitnessVersion;
use util::taproot::{LeafVersion, TapBranchHash, TapLeafHash};
use secp256k1::{Secp256k1, Verification};
use schnorr::{TapTweak, TweakedPublicKey, UntweakedPublicKey};
/// A Bitcoin script.
#[derive(Clone, Default, PartialOrd, Ord, PartialEq, Eq, Hash)]
@ -312,13 +315,40 @@ impl Script {
}
/// Generates P2WPKH-type of scriptPubkey
#[deprecated(since = "0.28.0", note = "use Script::new_v0_p2wpkh method instead")]
pub fn new_v0_wpkh(pubkey_hash: &WPubkeyHash) -> Script {
Script::new_witness_program(WitnessVersion::V0, &pubkey_hash.to_vec())
Script::new_v0_p2wpkh(pubkey_hash)
}
/// Generates P2WPKH-type of scriptPubkey
pub fn new_v0_p2wpkh(pubkey_hash: &WPubkeyHash) -> Script {
Script::new_witness_program(WitnessVersion::V0, &pubkey_hash[..])
}
/// Generates P2WSH-type of scriptPubkey with a given hash of the redeem script
#[deprecated(since = "0.28.0", note = "use Script::new_v0_p2wsh method instead")]
pub fn new_v0_wsh(script_hash: &WScriptHash) -> Script {
Script::new_witness_program(WitnessVersion::V0, &script_hash.to_vec())
Script::new_v0_p2wsh(script_hash)
}
/// Generates P2WSH-type of scriptPubkey with a given hash of the redeem script
pub fn new_v0_p2wsh(script_hash: &WScriptHash) -> Script {
Script::new_witness_program(WitnessVersion::V0, &script_hash[..])
}
/// Generates P2TR for script spending path using an internal public key and some optional
/// script tree merkle root.
pub fn new_v1_p2tr<C: Verification>(secp: &Secp256k1<C>, internal_key: UntweakedPublicKey, merkle_root: Option<TapBranchHash>) -> Script {
let (output_key, _) = internal_key.tap_tweak(secp, merkle_root);
Script::new_witness_program(WitnessVersion::V1, &output_key.serialize())
}
/// Generates P2TR for key spending path for a known [`TweakedPublicKey`].
///
/// NB: Make sure that the used key is indeed tweaked (for instance, it comes from `rawtr`
/// descriptor content); otherwise please use [`Script::new_v1_p2tr`] method.
pub fn new_v1_p2tr_tweaked(output_key: TweakedPublicKey) -> Script {
Script::new_witness_program(WitnessVersion::V1, &output_key.serialize())
}
/// Generates P2WSH-type of scriptPubkey with a given hash of the redeem script
@ -370,7 +400,21 @@ impl Script {
/// Compute the P2WSH output corresponding to this witnessScript (aka the "witness redeem
/// script")
pub fn to_v0_p2wsh(&self) -> Script {
Script::new_v0_wsh(&self.wscript_hash())
Script::new_v0_p2wsh(&self.wscript_hash())
}
/// Compute P2TR output with a given internal key and a single script spending path equal to the
/// current script, assuming that the script is a Tapscript
#[inline]
pub fn to_v1_p2tr<C: Verification>(&self, secp: &Secp256k1<C>, internal_key: UntweakedPublicKey) -> Script {
let leaf_hash = TapLeafHash::from_script(&self, LeafVersion::TapScript);
let merkle_root = TapBranchHash::from_inner(leaf_hash.into_inner());
Script::new_v1_p2tr(&secp, internal_key, Some(merkle_root))
}
#[inline]
fn witness_version(&self) -> Option<WitnessVersion> {
WitnessVersion::from_opcode(self.0[0].into()).ok()
}
/// Checks whether a script pubkey is a p2sh output
@ -428,18 +472,26 @@ impl Script {
#[inline]
pub fn is_v0_p2wsh(&self) -> bool {
self.0.len() == 34 &&
self.0[0] == opcodes::all::OP_PUSHBYTES_0.into_u8() &&
self.0[1] == opcodes::all::OP_PUSHBYTES_32.into_u8()
self.witness_version() == Some(WitnessVersion::V0) &&
self.0[1] == opcodes::all::OP_PUSHBYTES_32.into_u8()
}
/// Checks whether a script pubkey is a p2wpkh output
#[inline]
pub fn is_v0_p2wpkh(&self) -> bool {
self.0.len() == 22 &&
self.0[0] == opcodes::all::OP_PUSHBYTES_0.into_u8() &&
self.witness_version() == Some(WitnessVersion::V0) &&
self.0[1] == opcodes::all::OP_PUSHBYTES_20.into_u8()
}
/// Checks whether a script pubkey is a P2TR output
#[inline]
pub fn is_v1_p2tr(&self) -> bool {
self.0.len() == 34 &&
self.witness_version() == Some(WitnessVersion::V1) &&
self.0[1] == opcodes::all::OP_PUSHBYTES_32.into_u8()
}
/// Check if this is an OP_RETURN output
pub fn is_op_return (&self) -> bool {
!self.0.is_empty() && (opcodes::All::from(self.0[0]) == opcodes::all::OP_RETURN)
@ -1042,7 +1094,7 @@ mod test {
assert!(Script::new_p2pkh(&pubkey_hash).is_p2pkh());
let wpubkey_hash = WPubkeyHash::hash(&pubkey.inner.serialize());
assert!(Script::new_v0_wpkh(&wpubkey_hash).is_v0_p2wpkh());
assert!(Script::new_v0_p2wpkh(&wpubkey_hash).is_v0_p2wpkh());
let script = Builder::new().push_opcode(opcodes::all::OP_NUMEQUAL)
.push_verify()
@ -1053,7 +1105,7 @@ mod test {
assert_eq!(script.to_p2sh(), p2sh);
let wscript_hash = WScriptHash::hash(&script.serialize());
let p2wsh = Script::new_v0_wsh(&wscript_hash);
let p2wsh = Script::new_v0_p2wsh(&wscript_hash);
assert!(p2wsh.is_v0_p2wsh());
assert_eq!(script.to_v0_p2wsh(), p2wsh);

2
src/util/misc.rs
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@ -320,7 +320,7 @@ mod tests {
let msg = secp256k1::Message::from_slice(&msg_hash).unwrap();
let privkey = secp256k1::SecretKey::new(&mut secp256k1::rand::thread_rng());
let secp_sig = secp.sign_recoverable(&msg, &privkey);
let secp_sig = secp.sign_ecdsa_recoverable(&msg, &privkey);
let signature = super::MessageSignature {
signature: secp_sig,
compressed: true,

98
src/util/schnorr.rs
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@ -26,10 +26,10 @@ use hashes::Hash;
use util::taproot::{TapBranchHash, TapTweakHash};
use SchnorrSigHashType;
/// Untweaked Schnorr public key
/// Untweaked BIP-340 X-coord-only public key
pub type UntweakedPublicKey = XOnlyPublicKey;
/// Tweaked Schnorr public key
/// Tweaked BIP-340 X-coord-only public key
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct TweakedPublicKey(XOnlyPublicKey);
@ -45,29 +45,59 @@ impl fmt::Display for TweakedPublicKey {
}
}
/// A trait for tweaking Schnorr public keys
/// Untweaked BIP-340 key pair
pub type UntweakedKeyPair = KeyPair;
/// Tweaked BIP-340 key pair
#[derive(Clone)]
#[cfg_attr(feature = "std", derive(Debug))]
// TODO: Add other derives once secp256k1 v0.21.3 released
pub struct TweakedKeyPair(KeyPair);
/// A trait for tweaking BIP340 key types (x-only public keys and key pairs).
pub trait TapTweak {
/// Tweaks an untweaked public key given an untweaked key and optional script tree merkle root.
/// Tweaked key type with optional auxiliary information
type TweakedAux;
/// Tweaked key type
type TweakedKey;
/// Tweaks an untweaked key with corresponding public key value and optional script tree merkle
/// root. For the [`KeyPair`] type this also tweaks the private key in the pair.
///
/// This is done by using the equation Q = P + H(P|c)G, where
/// * Q is the tweaked key
/// * P is the internal key
/// * Q is the tweaked public key
/// * P is the internal public key
/// * H is the hash function
/// * c is the commitment data
/// * G is the generator point
///
/// # Returns
/// The tweaked key and its parity.
fn tap_tweak<C: Verification>(self, secp: &Secp256k1<C>, merkle_root: Option<TapBranchHash>) -> (TweakedPublicKey, secp256k1::Parity);
fn tap_tweak<C: Verification>(self, secp: &Secp256k1<C>, merkle_root: Option<TapBranchHash>) -> Self::TweakedAux;
/// Directly converts an [`UntweakedPublicKey`] to a [`TweakedPublicKey`]
///
/// This method is dangerous and can lead to loss of funds if used incorrectly.
/// Specifically, in multi-party protocols a peer can provide a value that allows them to steal.
fn dangerous_assume_tweaked(self) -> TweakedPublicKey;
fn dangerous_assume_tweaked(self) -> Self::TweakedKey;
}
impl TapTweak for UntweakedPublicKey {
type TweakedAux = (TweakedPublicKey, secp256k1::Parity);
type TweakedKey = TweakedPublicKey;
/// Tweaks an untweaked public key with corresponding public key value and optional script tree
/// merkle root.
///
/// This is done by using the equation Q = P + H(P|c)G, where
/// * Q is the tweaked public key
/// * P is the internal public key
/// * H is the hash function
/// * c is the commitment data
/// * G is the generator point
///
/// # Returns
/// The tweaked key and its parity.
fn tap_tweak<C: Verification>(self, secp: &Secp256k1<C>, merkle_root: Option<TapBranchHash>) -> (TweakedPublicKey, secp256k1::Parity) {
let tweak_value = TapTweakHash::from_key_and_tweak(self, merkle_root).into_inner();
let mut output_key = self.clone();
@ -82,9 +112,42 @@ impl TapTweak for UntweakedPublicKey {
}
}
impl TapTweak for UntweakedKeyPair {
type TweakedAux = TweakedKeyPair;
type TweakedKey = TweakedKeyPair;
/// Tweaks private and public keys within an untweaked [`KeyPair`] with corresponding public key
/// value and optional script tree merkle root.
///
/// This is done by tweaking private key within the pair using the equation q = p + H(P|c), where
/// * q is the tweaked private key
/// * p is the internal private key
/// * H is the hash function
/// * c is the commitment data
/// The public key is generated from a private key by multiplying with generator point, Q = qG.
///
/// # Returns
/// The tweaked key and its parity.
fn tap_tweak<C: Verification>(self, secp: &Secp256k1<C>, merkle_root: Option<TapBranchHash>) -> TweakedKeyPair {
let pubkey = XOnlyPublicKey::from_keypair(&self);
let tweak_value = TapTweakHash::from_key_and_tweak(pubkey, merkle_root).into_inner();
let mut output_key = self.clone();
output_key.tweak_add_assign(&secp, &tweak_value).expect("Tap tweak failed");
TweakedKeyPair(output_key)
}
fn dangerous_assume_tweaked(self) -> TweakedKeyPair {
TweakedKeyPair(self)
}
}
impl TweakedPublicKey {
/// Creates a new [`TweakedPublicKey`] from a [`XOnlyPublicKey`]. No tweak is applied, consider
/// calling `tap_tweak` on an [`UntweakedPublicKey`] instead of using this constructor.
///
/// This method is dangerous and can lead to loss of funds if used incorrectly.
/// Specifically, in multi-party protocols a peer can provide a value that allows them to steal.
#[inline]
pub fn dangerous_assume_tweaked(key: XOnlyPublicKey) -> TweakedPublicKey {
TweakedPublicKey(key)
}
@ -108,6 +171,24 @@ impl TweakedPublicKey {
}
}
impl TweakedKeyPair {
/// Creates a new [`TweakedKeyPair`] from a [`KeyPair`]. No tweak is applied, consider
/// calling `tap_tweak` on an [`UntweakedKeyPair`] instead of using this constructor.
///
/// This method is dangerous and can lead to loss of funds if used incorrectly.
/// Specifically, in multi-party protocols a peer can provide a value that allows them to steal.
#[inline]
pub fn dangerous_assume_tweaked(pair: KeyPair) -> TweakedKeyPair {
TweakedKeyPair(pair)
}
/// Returns the underlying key pair
#[inline]
pub fn into_inner(self) -> KeyPair {
self.0
}
}
/// A BIP340-341 serialized schnorr signature with the corresponding hash type.
#[derive(Debug, Copy, Clone, PartialEq, Eq, PartialOrd, Ord)]
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
@ -119,7 +200,6 @@ pub struct SchnorrSig {
}
impl SchnorrSig {
/// Deserialize from slice
pub fn from_slice(sl: &[u8]) -> Result<Self, SchnorrSigError> {
match sl.len() {