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Merge pull request #247 from apoelstra/2019-03-contracthash 

contracthash: use `PublicKey` and `PrivateKey` types; minor cleanups
This commit is contained in:
Andrew Poelstra 2019-03-21 23:05:43 +00:00 committed by GitHub
parent cea49b6522 dc6189dbb2
commit b94d0fcf24
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 74 additions and 35 deletions
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2
Cargo.toml
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@ -1,6 +1,6 @@
[package]
name = "bitcoin"
version = "0.17.1"
version = "0.18.0"
authors = ["Andrew Poelstra <apoelstra@wpsoftware.net>"]
license = "CC0-1.0"
homepage = "https://github.com/rust-bitcoin/rust-bitcoin/"

107
src/util/contracthash.rs
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@ -19,7 +19,8 @@
//! what this does.
use secp256k1::{self, Secp256k1};
use secp256k1::key::{PublicKey, SecretKey};
use PrivateKey;
use PublicKey;
use bitcoin_hashes::{hash160, sha256, Hash, HashEngine, Hmac, HmacEngine};
use blockdata::{opcodes, script};
@ -34,9 +35,6 @@ static PUBKEY: u8 = 0xFE;
/// A contract-hash error
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum Error {
/// Contract hashed to an out-of-range value (this is basically impossible
/// and much more likely suggests memory corruption or hardware failure)
BadTweak(secp256k1::Error),
/// Other secp256k1 related error
Secp(secp256k1::Error),
/// Script parsing error
@ -59,7 +57,6 @@ pub enum Error {
impl fmt::Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
match *self {
Error::BadTweak(ref e) |
Error::Secp(ref e) => fmt::Display::fmt(&e, f),
Error::Script(ref e) => fmt::Display::fmt(&e, f),
Error::UncompressedKey => f.write_str("encountered uncompressed secp public key"),
@ -74,7 +71,6 @@ impl fmt::Display for Error {
impl error::Error for Error {
fn cause(&self) -> Option<&error::Error> {
match *self {
Error::BadTweak(ref e) |
Error::Secp(ref e) => Some(e),
Error::Script(ref e) => Some(e),
_ => None
@ -83,7 +79,6 @@ impl error::Error for Error {
fn description(&self) -> &'static str {
match *self {
Error::BadTweak(_) => "bad public key tweak",
Error::Secp(_) => "libsecp256k1 error",
Error::Script(_) => "script error",
Error::UncompressedKey => "encountered uncompressed secp public key",
@ -119,7 +114,7 @@ impl Template {
return Err(Error::TooFewKeys(key_index));
}
key_index += 1;
ret.push_slice(&keys[key_index - 1].serialize()[..])
ret.push_key(&keys[key_index - 1])
}
}
}
@ -165,37 +160,38 @@ impl<'a> From<&'a [u8]> for Template {
}
}
/// Tweak a single key using some arbitrary data
pub fn tweak_key<C: secp256k1::Verification>(secp: &Secp256k1<C>, mut key: PublicKey, contract: &[u8]) -> PublicKey {
let hmac_result = compute_tweak(&key, contract);
key.key.add_exp_assign(secp, &hmac_result[..]).expect("HMAC cannot produce invalid tweak");
key
}
/// Tweak keys using some arbitrary data
pub fn tweak_keys<C: secp256k1::Verification>(secp: &Secp256k1<C>, keys: &[PublicKey], contract: &[u8]) -> Result<Vec<PublicKey>, Error> {
let mut ret = Vec::with_capacity(keys.len());
for mut key in keys.iter().cloned() {
let mut hmac_engine: HmacEngine<sha256::Hash> = HmacEngine::new(&key.serialize());
hmac_engine.input(contract);
let hmac_result: Hmac<sha256::Hash> = Hmac::from_engine(hmac_engine);
let hmac_sk = SecretKey::from_slice(&hmac_result[..]).map_err(Error::BadTweak)?;
key.add_exp_assign(secp, &hmac_sk[..]).map_err(Error::Secp)?;
ret.push(key);
}
Ok(ret)
pub fn tweak_keys<C: secp256k1::Verification>(secp: &Secp256k1<C>, keys: &[PublicKey], contract: &[u8]) -> Vec<PublicKey> {
keys.iter().cloned().map(|key| tweak_key(secp, key, contract)).collect()
}
/// Compute a tweak from some given data for the given public key
pub fn compute_tweak(pk: &PublicKey, contract: &[u8]) -> Result<SecretKey, Error> {
let mut hmac_engine: HmacEngine<sha256::Hash> = HmacEngine::new(&pk.serialize());
pub fn compute_tweak(pk: &PublicKey, contract: &[u8]) -> Hmac<sha256::Hash> {
let mut hmac_engine: HmacEngine<sha256::Hash> = if pk.compressed {
HmacEngine::new(&pk.key.serialize())
} else {
HmacEngine::new(&pk.key.serialize_uncompressed())
};
hmac_engine.input(contract);
let hmac_result: Hmac<sha256::Hash> = Hmac::from_engine(hmac_engine);
SecretKey::from_slice(&hmac_result[..]).map_err(Error::BadTweak)
Hmac::from_engine(hmac_engine)
}
/// Tweak a secret key using some arbitrary data (calls `compute_tweak` internally)
pub fn tweak_secret_key<C: secp256k1::Signing>(secp: &Secp256k1<C>, key: &SecretKey, contract: &[u8]) -> Result<SecretKey, Error> {
pub fn tweak_secret_key<C: secp256k1::Signing>(secp: &Secp256k1<C>, key: &PrivateKey, contract: &[u8]) -> Result<PrivateKey, Error> {
// Compute public key
let pk = PublicKey::from_secret_key(secp, &key);
let pk = PublicKey::from_private_key(secp, &key);
// Compute tweak
let hmac_sk = compute_tweak(&pk, contract)?;
let hmac_sk = compute_tweak(&pk, contract);
// Execute the tweak
let mut key = *key;
key.add_assign(&hmac_sk[..]).map_err(Error::Secp)?;
key.key.add_assign(&hmac_sk[..]).map_err(Error::Secp)?;
// Return
Ok(key)
}
@ -207,7 +203,7 @@ pub fn create_address<C: secp256k1::Verification>(secp: &Secp256k1<C>,
keys: &[PublicKey],
template: &Template)
-> Result<address::Address, Error> {
let keys = tweak_keys(secp, keys, contract)?;
let keys = tweak_keys(secp, keys, contract);
let script = template.to_script(&keys)?;
Ok(address::Address {
network: network,
@ -287,14 +283,15 @@ pub fn untemplate(script: &script::Script) -> Result<(Template, Vec<PublicKey>),
#[cfg(test)]
mod tests {
use secp256k1::Secp256k1;
use secp256k1::key::PublicKey;
use hex::decode as hex_decode;
use rand::thread_rng;
use std::str::FromStr;
use blockdata::script::Script;
use network::constants::Network;
use super::*;
use PublicKey;
macro_rules! hex (($hex:expr) => (hex_decode($hex).unwrap()));
macro_rules! hex_key (($hex:expr) => (PublicKey::from_slice(&hex!($hex)).unwrap()));
@ -339,21 +336,63 @@ mod tests {
let (sk2, pk2) = secp.generate_keypair(&mut thread_rng());
let (sk3, pk3) = secp.generate_keypair(&mut thread_rng());
let pks = [pk1, pk2, pk3];
let sk1 = PrivateKey {
key: sk1,
compressed: true,
network: Network::Bitcoin,
};
let sk2 = PrivateKey {
key: sk2,
compressed: false,
network: Network::Bitcoin,
};
let sk3 = PrivateKey {
key: sk3,
compressed: true,
network: Network::Bitcoin,
};
let pks = [
PublicKey { key: pk1, compressed: true },
PublicKey { key: pk2, compressed: false },
PublicKey { key: pk3, compressed: true },
];
let contract = b"if bottle mt dont remembr drink wont pay";
// Directly compute tweaks on pubkeys
let tweaked_pks = tweak_keys(&secp, &pks, &contract[..]).unwrap();
let tweaked_pks = tweak_keys(&secp, &pks, &contract[..]);
// Compute tweaks on secret keys
let tweaked_pk1 = PublicKey::from_secret_key(&secp, &tweak_secret_key(&secp, &sk1, &contract[..]).unwrap());
let tweaked_pk2 = PublicKey::from_secret_key(&secp, &tweak_secret_key(&secp, &sk2, &contract[..]).unwrap());
let tweaked_pk3 = PublicKey::from_secret_key(&secp, &tweak_secret_key(&secp, &sk3, &contract[..]).unwrap());
let tweaked_pk1 = PublicKey::from_private_key(&secp, &tweak_secret_key(&secp, &sk1, &contract[..]).unwrap());
let tweaked_pk2 = PublicKey::from_private_key(&secp, &tweak_secret_key(&secp, &sk2, &contract[..]).unwrap());
let tweaked_pk3 = PublicKey::from_private_key(&secp, &tweak_secret_key(&secp, &sk3, &contract[..]).unwrap());
// Check equality
assert_eq!(tweaked_pks[0], tweaked_pk1);
assert_eq!(tweaked_pks[1], tweaked_pk2);
assert_eq!(tweaked_pks[2], tweaked_pk3);
}
#[test]
fn tweak_fixed_vector() {
let secp = Secp256k1::new();
let pks = [
PublicKey::from_str("02ba604e6ad9d3864eda8dc41c62668514ef7d5417d3b6db46e45cc4533bff001c").unwrap(),
PublicKey::from_str("0365c0755ea55ce85d8a1900c68a524dbfd1c0db45ac3b3840dbb10071fe55e7a8").unwrap(),
PublicKey::from_str("0202313ca315889b2e69c94cf86901119321c7288139ba53ac022b7af3dc250054").unwrap(),
];
let tweaked_pks = [
PublicKey::from_str("03b3597221b5982a3f1a77aed50f0015d1b6edfc69023ef7f25cfac0e8af1b2041").unwrap(),
PublicKey::from_str("0296ece1fd954f7ae94f8d6bad19fd6d583f5b36335cf13135a3053a22f3c1fb05").unwrap(),
PublicKey::from_str("0230bb1ca5dbc7fcf49294c2c3e582e5582eabf7c87e885735dc774da45d610e51").unwrap(),
];
let contract = b"if bottle mt dont remembr drink wont pay";
// Directly compute tweaks on pubkeys
assert_eq!(
tweak_keys(&secp, &pks, &contract[..]),
tweaked_pks
);
}
#[test]
fn bad_key_number() {
let alpha_keys = alpha_keys!();