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Merge rust-bitcoin/rust-bitcoin#718: Converting LeafVersion into an enum 

ef8a3a839e Introduce FutureLeafVersion (Dr Maxim Orlovsky)
b028385a72 Improve docs in LeafVersion (Dr Maxim Orlovsky)
839c022f29 Make serde for LeafVersion to have byte representation (Dr Maxim Orlovsky)
67b8db05a8 Converting LeafVersion into an enum (Dr Maxim Orlovsky)
2405417432 Use TAPROOT_ANNEX_PREFIX in sighash module (Dr Maxim Orlovsky)

Pull request description:

  The original `LeafVersion` implementation was just a newtype around `u8`. I think that having enum explicitly listing consensus script implementation rules may be more beneficial in terms of both code readibility and future use of multiple script types, where `LeafVersion` may operate as a context object provided to `Script` to specify interpretation rules for particular op codes.

ACKs for top commit:
  Kixunil:
    ACK ef8a3a839e
  sanket1729:
    crACK ef8a3a839e. Waiting a day to let others complete review before merging.
  apoelstra:
    ACK ef8a3a839e

Tree-SHA512: 3356d2b9b00cf904edfece26d26ffbc646ba74446cc23ec4b2b4026ed50861285802f077226e30ba8fed466f68f8e8556c729ce48cb38581b1d95a02a6fde9cf
This commit is contained in:
Andrew Poelstra 2022-01-09 15:24:52 +00:00
parent 2ec9af3d35 ef8a3a839e
commit 8e9f99b620
No known key found for this signature in database
GPG Key ID: C588D63CE41B97C1
3 changed files with 120 additions and 37 deletions
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8
src/util/psbt/serialize.rs
View File

@ -259,7 +259,7 @@ impl Serialize for (Script, LeafVersion) {
fn serialize(&self) -> Vec<u8> { fn serialize(&self) -> Vec<u8> {
let mut buf = Vec::with_capacity(self.0.len() + 1); let mut buf = Vec::with_capacity(self.0.len() + 1);
buf.extend(self.0.as_bytes()); buf.extend(self.0.as_bytes());
buf.push(self.1.as_u8()); buf.push(self.1.into_consensus());
buf buf
} }
} }
@ -271,7 +271,7 @@ impl Deserialize for (Script, LeafVersion) {
} }
// The last byte is LeafVersion. // The last byte is LeafVersion.
let script = Script::deserialize(&bytes[..bytes.len() - 1])?; let script = Script::deserialize(&bytes[..bytes.len() - 1])?;
let leaf_ver = LeafVersion::from_u8(bytes[bytes.len() - 1]) let leaf_ver = LeafVersion::from_consensus(bytes[bytes.len() - 1])
.map_err(|_| encode::Error::ParseFailed("invalid leaf version"))?; .map_err(|_| encode::Error::ParseFailed("invalid leaf version"))?;
Ok((script, leaf_ver)) Ok((script, leaf_ver))
} }
@ -307,7 +307,7 @@ impl Serialize for TapTree {
// TaprootMerkleBranch can only have len atmost 128(TAPROOT_CONTROL_MAX_NODE_COUNT). // TaprootMerkleBranch can only have len atmost 128(TAPROOT_CONTROL_MAX_NODE_COUNT).
// safe to cast from usize to u8 // safe to cast from usize to u8
buf.push(leaf_info.merkle_branch.as_inner().len() as u8); buf.push(leaf_info.merkle_branch.as_inner().len() as u8);
buf.push(leaf_info.ver.as_u8()); buf.push(leaf_info.ver.into_consensus());
leaf_info.script.consensus_encode(&mut buf).expect("Vecs dont err"); leaf_info.script.consensus_encode(&mut buf).expect("Vecs dont err");
} }
buf buf
@ -329,7 +329,7 @@ impl Deserialize for TapTree {
bytes_iter.nth(consumed - 1); bytes_iter.nth(consumed - 1);
} }
let leaf_version = LeafVersion::from_u8(*version) let leaf_version = LeafVersion::from_consensus(*version)
.map_err(|_| encode::Error::ParseFailed("Leaf Version Error"))?; .map_err(|_| encode::Error::ParseFailed("Leaf Version Error"))?;
builder = builder.add_leaf_with_ver(usize::from(*depth), script, leaf_version) builder = builder.add_leaf_with_ver(usize::from(*depth), script, leaf_version)
.map_err(|_| encode::Error::ParseFailed("Tree not in DFS order"))?; .map_err(|_| encode::Error::ParseFailed("Tree not in DFS order"))?;

8
src/util/sighash.rs
View File

@ -27,7 +27,7 @@ use core::fmt;
use core::ops::{Deref, DerefMut}; use core::ops::{Deref, DerefMut};
use hashes::{sha256, sha256d, Hash}; use hashes::{sha256, sha256d, Hash};
use io; use io;
use util::taproot::{TapLeafHash, TapSighashHash}; use util::taproot::{TapLeafHash, TAPROOT_ANNEX_PREFIX, TapSighashHash};
use SigHash; use SigHash;
use {Script, Transaction, TxOut}; use {Script, Transaction, TxOut};
@ -229,13 +229,13 @@ impl<'s> ScriptPath<'s> {
} }
/// Create a new ScriptPath structure using default leaf version value /// Create a new ScriptPath structure using default leaf version value
pub fn with_defaults(script: &'s Script) -> Self { pub fn with_defaults(script: &'s Script) -> Self {
Self::new(script, LeafVersion::default()) Self::new(script, LeafVersion::TapScript)
} }
/// Compute the leaf hash /// Compute the leaf hash
pub fn leaf_hash(&self) -> TapLeafHash { pub fn leaf_hash(&self) -> TapLeafHash {
let mut enc = TapLeafHash::engine(); let mut enc = TapLeafHash::engine();
self.leaf_version.as_u8().consensus_encode(&mut enc).expect("Writing to hash enging should never fail"); self.leaf_version.into_consensus().consensus_encode(&mut enc).expect("Writing to hash enging should never fail");
self.script.consensus_encode(&mut enc).expect("Writing to hash enging should never fail"); self.script.consensus_encode(&mut enc).expect("Writing to hash enging should never fail");
TapLeafHash::from_engine(enc) TapLeafHash::from_engine(enc)
@ -725,7 +725,7 @@ pub struct Annex<'a>(&'a [u8]);
impl<'a> Annex<'a> { impl<'a> Annex<'a> {
/// Creates a new `Annex` struct checking the first byte is `0x50` /// Creates a new `Annex` struct checking the first byte is `0x50`
pub fn new(annex_bytes: &'a [u8]) -> Result<Self, Error> { pub fn new(annex_bytes: &'a [u8]) -> Result<Self, Error> {
if annex_bytes.first() == Some(&0x50) { if annex_bytes.first() == Some(&TAPROOT_ANNEX_PREFIX) {
Ok(Annex(annex_bytes)) Ok(Annex(annex_bytes))
} else { } else {
Err(Error::WrongAnnex) Err(Error::WrongAnnex)

141
src/util/taproot.rs
View File

@ -15,6 +15,7 @@
//! //!
//! This module provides support for taproot tagged hashes. //! This module provides support for taproot tagged hashes.
//! //!
use prelude::*; use prelude::*;
use io; use io;
use secp256k1::{self, Secp256k1}; use secp256k1::{self, Secp256k1};
@ -120,7 +121,7 @@ impl TapLeafHash {
/// function to compute leaf hash from components /// function to compute leaf hash from components
pub fn from_script(script: &Script, ver: LeafVersion) -> TapLeafHash { pub fn from_script(script: &Script, ver: LeafVersion) -> TapLeafHash {
let mut eng = TapLeafHash::engine(); let mut eng = TapLeafHash::engine();
ver.as_u8() ver.into_consensus()
.consensus_encode(&mut eng) .consensus_encode(&mut eng)
.expect("engines don't error"); .expect("engines don't error");
script script
@ -142,6 +143,8 @@ pub const TAPROOT_LEAF_MASK: u8 = 0xfe;
/// Tapscript leaf version /// Tapscript leaf version
// https://github.com/bitcoin/bitcoin/blob/e826b22da252e0599c61d21c98ff89f366b3120f/src/script/interpreter.h#L226 // https://github.com/bitcoin/bitcoin/blob/e826b22da252e0599c61d21c98ff89f366b3120f/src/script/interpreter.h#L226
pub const TAPROOT_LEAF_TAPSCRIPT: u8 = 0xc0; pub const TAPROOT_LEAF_TAPSCRIPT: u8 = 0xc0;
/// Taproot annex prefix
pub const TAPROOT_ANNEX_PREFIX: u8 = 0x50;
/// Tapscript control base size /// Tapscript control base size
// https://github.com/bitcoin/bitcoin/blob/e826b22da252e0599c61d21c98ff89f366b3120f/src/script/interpreter.h#L227 // https://github.com/bitcoin/bitcoin/blob/e826b22da252e0599c61d21c98ff89f366b3120f/src/script/interpreter.h#L227
pub const TAPROOT_CONTROL_BASE_SIZE: usize = 33; pub const TAPROOT_CONTROL_BASE_SIZE: usize = 33;
@ -152,6 +155,7 @@ pub const TAPROOT_CONTROL_MAX_SIZE: usize =
// type alias for versioned tap script corresponding merkle proof // type alias for versioned tap script corresponding merkle proof
type ScriptMerkleProofMap = BTreeMap<(Script, LeafVersion), BTreeSet<TaprootMerkleBranch>>; type ScriptMerkleProofMap = BTreeMap<(Script, LeafVersion), BTreeSet<TaprootMerkleBranch>>;
/// Data structure for representing Taproot spending information. /// Data structure for representing Taproot spending information.
/// Taproot output corresponds to a combination of a /// Taproot output corresponds to a combination of a
/// single public key condition (known the internal key), and zero or more /// single public key condition (known the internal key), and zero or more
@ -216,7 +220,7 @@ impl TaprootSpendInfo {
{ {
let mut node_weights = BinaryHeap::<(Reverse<u64>, NodeInfo)>::new(); let mut node_weights = BinaryHeap::<(Reverse<u64>, NodeInfo)>::new();
for (p, leaf) in script_weights { for (p, leaf) in script_weights {
node_weights.push((Reverse(p as u64), NodeInfo::new_leaf_with_ver(leaf, LeafVersion::default()))); node_weights.push((Reverse(p as u64), NodeInfo::new_leaf_with_ver(leaf, LeafVersion::TapScript)));
} }
if node_weights.is_empty() { if node_weights.is_empty() {
return Err(TaprootBuilderError::IncompleteTree); return Err(TaprootBuilderError::IncompleteTree);
@ -409,7 +413,7 @@ impl TaprootBuilder {
/// See [`TaprootBuilder::add_leaf_with_ver`] for adding a leaf with specific version /// See [`TaprootBuilder::add_leaf_with_ver`] for adding a leaf with specific version
/// See [Wikipedia](https://en.wikipedia.org/wiki/Depth-first_search) for more details /// See [Wikipedia](https://en.wikipedia.org/wiki/Depth-first_search) for more details
pub fn add_leaf(self, depth: usize, script: Script) -> Result<Self, TaprootBuilderError> { pub fn add_leaf(self, depth: usize, script: Script) -> Result<Self, TaprootBuilderError> {
self.add_leaf_with_ver(depth, script, LeafVersion::default()) self.add_leaf_with_ver(depth, script, LeafVersion::TapScript)
} }
/// Add a hidden/omitted node at a depth `depth` to the builder. /// Add a hidden/omitted node at a depth `depth` to the builder.
@ -680,7 +684,7 @@ impl ControlBlock {
return Err(TaprootError::InvalidControlBlockSize(sl.len())); return Err(TaprootError::InvalidControlBlockSize(sl.len()));
} }
let output_key_parity = secp256k1::Parity::from((sl[0] & 1) as i32); let output_key_parity = secp256k1::Parity::from((sl[0] & 1) as i32);
let leaf_version = LeafVersion::from_u8(sl[0] & TAPROOT_LEAF_MASK)?; let leaf_version = LeafVersion::from_consensus(sl[0] & TAPROOT_LEAF_MASK)?;
let internal_key = UntweakedPublicKey::from_slice(&sl[1..TAPROOT_CONTROL_BASE_SIZE]) let internal_key = UntweakedPublicKey::from_slice(&sl[1..TAPROOT_CONTROL_BASE_SIZE])
.map_err(TaprootError::InvalidInternalKey)?; .map_err(TaprootError::InvalidInternalKey)?;
let merkle_branch = TaprootMerkleBranch::from_slice(&sl[TAPROOT_CONTROL_BASE_SIZE..])?; let merkle_branch = TaprootMerkleBranch::from_slice(&sl[TAPROOT_CONTROL_BASE_SIZE..])?;
@ -700,7 +704,7 @@ impl ControlBlock {
/// Serialize to a writer. Returns the number of bytes written /// Serialize to a writer. Returns the number of bytes written
pub fn encode<Write: io::Write>(&self, mut writer: Write) -> io::Result<usize> { pub fn encode<Write: io::Write>(&self, mut writer: Write) -> io::Result<usize> {
let first_byte: u8 = i32::from(self.output_key_parity) as u8 | self.leaf_version.as_u8(); let first_byte: u8 = i32::from(self.output_key_parity) as u8 | self.leaf_version.into_consensus();
let mut bytes_written = 0; let mut bytes_written = 0;
bytes_written += writer.write(&[first_byte])?; bytes_written += writer.write(&[first_byte])?;
bytes_written += writer.write(&self.internal_key.serialize())?; bytes_written += writer.write(&self.internal_key.serialize())?;
@ -756,20 +760,54 @@ impl ControlBlock {
} }
} }
/// The leaf version for tapleafs /// Inner type representing future (non-tapscript) leaf versions. See [`LeafVersion::Future`].
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)] ///
#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))] /// NB: NO PUBLIC CONSTRUCTOR!
pub struct LeafVersion(u8); /// The only way to construct this is by converting u8 to LeafVersion and then extracting it.
#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Ord, PartialOrd)]
pub struct FutureLeafVersion(u8);
impl Default for LeafVersion { impl FutureLeafVersion {
fn default() -> Self { pub(self) fn from_consensus(version: u8) -> Result<FutureLeafVersion, TaprootError> {
LeafVersion(TAPROOT_LEAF_TAPSCRIPT) match version {
TAPROOT_LEAF_TAPSCRIPT => unreachable!("FutureLeafVersion::from_consensus should be never called for 0xC0 value"),
TAPROOT_ANNEX_PREFIX => Err(TaprootError::InvalidTaprootLeafVersion(TAPROOT_ANNEX_PREFIX)),
odd if odd & 0xFE != odd => Err(TaprootError::InvalidTaprootLeafVersion(odd)),
even => Ok(FutureLeafVersion(even))
}
}
/// Get consensus representation of the future leaf version.
#[inline]
pub fn into_consensus(self) -> u8 {
self.0
} }
} }
impl fmt::Display for FutureLeafVersion {
#[inline]
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
fmt::Display::fmt(&self.0, f)
}
}
/// The leaf version for tapleafs
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum LeafVersion {
/// BIP-342 tapscript
TapScript,
/// Future leaf version
Future(FutureLeafVersion)
}
impl LeafVersion { impl LeafVersion {
/// Obtain LeafVersion from u8, will error when last bit of ver is even or /// Obtain LeafVersion from consensus byte representation.
/// when ver is 0x50 (ANNEX_TAG) ///
/// # Errors
/// - If the last bit of the `version` is odd.
/// - If the `version` is 0x50 ([`TAPROOT_ANNEX_PREFIX`]).
/// - If the `version` is not a valid [`LeafVersion`] byte.
// Text from BIP341: // Text from BIP341:
// In order to support some forms of static analysis that rely on // In order to support some forms of static analysis that rely on
// being able to identify script spends without access to the output being // being able to identify script spends without access to the output being
@ -779,23 +817,68 @@ impl LeafVersion {
// or an opcode that is not valid as the first opcode). // or an opcode that is not valid as the first opcode).
// The values that comply to this rule are the 32 even values between // The values that comply to this rule are the 32 even values between
// 0xc0 and 0xfe and also 0x66, 0x7e, 0x80, 0x84, 0x96, 0x98, 0xba, 0xbc, 0xbe // 0xc0 and 0xfe and also 0x66, 0x7e, 0x80, 0x84, 0x96, 0x98, 0xba, 0xbc, 0xbe
pub fn from_u8(ver: u8) -> Result<Self, TaprootError> { pub fn from_consensus(version: u8) -> Result<Self, TaprootError> {
if ver & TAPROOT_LEAF_MASK == ver && ver != 0x50 { match version {
Ok(LeafVersion(ver)) TAPROOT_LEAF_TAPSCRIPT => Ok(LeafVersion::TapScript),
} else { TAPROOT_ANNEX_PREFIX => Err(TaprootError::InvalidTaprootLeafVersion(TAPROOT_ANNEX_PREFIX)),
Err(TaprootError::InvalidTaprootLeafVersion(ver)) future => FutureLeafVersion::from_consensus(future).map(LeafVersion::Future),
} }
} }
/// Get the inner version from LeafVersion /// Get consensus representation of the [`LeafVersion`].
pub fn as_u8(&self) -> u8 { pub fn into_consensus(self) -> u8 {
self.0 match self {
LeafVersion::TapScript => TAPROOT_LEAF_TAPSCRIPT,
LeafVersion::Future(version) => version.into_consensus(),
}
} }
} }
impl Into<u8> for LeafVersion { impl fmt::Display for LeafVersion {
fn into(self) -> u8 { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.0 match (self, f.alternate()) {
(LeafVersion::TapScript, false) => f.write_str("tapscript"),
(LeafVersion::TapScript, true) => fmt::Display::fmt(&TAPROOT_LEAF_TAPSCRIPT, f),
(LeafVersion::Future(version), false) => write!(f, "future_script_{:#02x}", version.0),
(LeafVersion::Future(version), true) => fmt::Display::fmt(version, f),
}
}
}
#[cfg(feature = "serde")]
#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
impl ::serde::Serialize for LeafVersion {
fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
where
S: ::serde::Serializer,
{
serializer.serialize_u8(self.into_consensus())
}
}
#[cfg(feature = "serde")]
#[cfg_attr(docsrs, doc(cfg(feature = "serde")))]
impl<'de> ::serde::Deserialize<'de> for LeafVersion {
fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: ::serde::Deserializer<'de> {
struct U8Visitor;
impl<'de> ::serde::de::Visitor<'de> for U8Visitor {
type Value = LeafVersion;
fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
formatter.write_str("a valid consensus-encoded taproot leaf version")
}
fn visit_u8<E>(self, value: u8) -> Result<Self::Value, E>
where
E: ::serde::de::Error,
{
LeafVersion::from_consensus(value).map_err(|_| {
E::invalid_value(::serde::de::Unexpected::Unsigned(value as u64), &"consensus-encoded leaf version as u8")
})
}
}
deserializer.deserialize_u8(U8Visitor)
} }
} }
@ -1063,7 +1146,7 @@ mod test {
length, length,
tree_info tree_info
.script_map .script_map
.get(&(Script::from_hex(script).unwrap(), LeafVersion::default())) .get(&(Script::from_hex(script).unwrap(), LeafVersion::TapScript))
.expect("Present Key") .expect("Present Key")
.iter() .iter()
.next() .next()
@ -1078,7 +1161,7 @@ mod test {
// Try to create and verify a control block from each path // Try to create and verify a control block from each path
for (_weights, script) in script_weights { for (_weights, script) in script_weights {
let ver_script = (script, LeafVersion::default()); let ver_script = (script, LeafVersion::TapScript);
let ctrl_block = tree_info.control_block(&ver_script).unwrap(); let ctrl_block = tree_info.control_block(&ver_script).unwrap();
assert!(ctrl_block.verify_taproot_commitment(&secp, &output_key, &ver_script.0)) assert!(ctrl_block.verify_taproot_commitment(&secp, &output_key, &ver_script.0))
} }
@ -1114,7 +1197,7 @@ mod test {
let output_key = tree_info.output_key(); let output_key = tree_info.output_key();
for script in vec![a, b, c, d, e] { for script in vec![a, b, c, d, e] {
let ver_script = (script, LeafVersion::default()); let ver_script = (script, LeafVersion::TapScript);
let ctrl_block = tree_info.control_block(&ver_script).unwrap(); let ctrl_block = tree_info.control_block(&ver_script).unwrap();
assert!(ctrl_block.verify_taproot_commitment(&secp, &output_key, &ver_script.0)) assert!(ctrl_block.verify_taproot_commitment(&secp, &output_key, &ver_script.0))
} }
@ -1137,7 +1220,7 @@ mod test {
} }
} else { } else {
let script = Script::from_str(v["script"].as_str().unwrap()).unwrap(); let script = Script::from_str(v["script"].as_str().unwrap()).unwrap();
let ver = LeafVersion::from_u8(v["leafVersion"].as_u64().unwrap() as u8).unwrap(); let ver = LeafVersion::from_consensus(v["leafVersion"].as_u64().unwrap() as u8).unwrap();
leaves.push((script.clone(), ver)); leaves.push((script.clone(), ver));
builder = builder.add_leaf_with_ver(depth, script, ver).unwrap(); builder = builder.add_leaf_with_ver(depth, script, ver).unwrap();
} }