398 lines
16 KiB
Rust
398 lines
16 KiB
Rust
// Rust Bitcoin Library
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// Written in 2015 by
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// Andrew Poelstra <apoelstra@wpsoftware.net>
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//
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// To the extent possible under law, the author(s) have dedicated all
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// copyright and related and neighboring rights to this software to
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// the public domain worldwide. This software is distributed without
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// any warranty.
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//
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// You should have received a copy of the CC0 Public Domain Dedication
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// along with this software.
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// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
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//
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//! Pay-to-contract-hash support
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//!
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//! See Appendix A of the Blockstream sidechains whitepaper
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//! at <http://blockstream.com/sidechains.pdf> for details of
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//! what this does.
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#![cfg_attr(not(test), deprecated)]
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use prelude::*;
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use core::fmt;
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#[cfg(feature = "std")] use std::error;
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use secp256k1::{self, Secp256k1};
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use PrivateKey;
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use PublicKey;
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use hashes::{sha256, Hash, HashEngine, Hmac, HmacEngine};
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use blockdata::{opcodes, script};
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use hash_types::ScriptHash;
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use network::constants::Network;
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use util::address;
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/// Encoding of "pubkey here" in script; from Bitcoin Core `src/script/script.h`
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static PUBKEY: u8 = 0xFE;
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/// A contract-hash error
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#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy)]
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pub enum Error {
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/// Other secp256k1 related error
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Secp(secp256k1::Error),
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/// Script parsing error
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Script(script::Error),
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/// Encountered an uncompressed key in a script we were deserializing. The
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/// reserialization will compress it which might be surprising so we call
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/// this an error.
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UncompressedKey,
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/// Expected a public key when deserializing a script, but we got something else.
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ExpectedKey,
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/// Expected some sort of CHECKSIG operator when deserializing a script, but
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/// we got something else.
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ExpectedChecksig,
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/// Did not have enough keys to instantiate a script template
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TooFewKeys(usize),
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/// Had too many keys; template does not match key list
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TooManyKeys(usize)
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}
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impl fmt::Display for Error {
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fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
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match *self {
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Error::Secp(ref e) => fmt::Display::fmt(&e, f),
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Error::Script(ref e) => fmt::Display::fmt(&e, f),
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Error::UncompressedKey => f.write_str("encountered uncompressed secp public key"),
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Error::ExpectedKey => f.write_str("expected key when deserializing script"),
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Error::ExpectedChecksig => f.write_str("expected OP_*CHECKSIG* when deserializing script"),
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Error::TooFewKeys(n) => write!(f, "got {} keys, which was not enough", n),
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Error::TooManyKeys(n) => write!(f, "got {} keys, which was too many", n)
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}
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}
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}
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#[cfg(feature = "std")]
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impl ::std::error::Error for Error {
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fn cause(&self) -> Option<&dyn error::Error> {
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match *self {
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Error::Secp(ref e) => Some(e),
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Error::Script(ref e) => Some(e),
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_ => None
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}
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}
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}
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/// An element of a script template
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#[derive(Copy, Clone, PartialEq, Eq, Debug)]
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enum TemplateElement {
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Op(opcodes::All),
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Key
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}
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/// A script template
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#[derive(Clone, PartialEq, Eq, Debug)]
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pub struct Template(Vec<TemplateElement>);
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impl Template {
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/// Instantiate a template
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pub fn to_script(&self, keys: &[PublicKey]) -> Result<script::Script, Error> {
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let mut key_index = 0;
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let mut ret = script::Builder::new();
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for elem in &self.0 {
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ret = match *elem {
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TemplateElement::Op(opcode) => ret.push_opcode(opcode),
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TemplateElement::Key => {
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if key_index == keys.len() {
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return Err(Error::TooFewKeys(key_index));
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}
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key_index += 1;
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ret.push_key(&keys[key_index - 1])
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}
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}
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}
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if key_index == keys.len() {
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Ok(ret.into_script())
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} else {
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Err(Error::TooManyKeys(keys.len()))
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}
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}
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/// Returns the number of keys this template requires to instantiate
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pub fn required_keys(&self) -> usize {
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self.0.iter().filter(|e| **e == TemplateElement::Key).count()
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}
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/// If the first push in the template is a number, return this number. For the
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/// common case of standard multisig templates, such a number will exist and
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/// will represent the number of signatures that are required for the script
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/// to pass.
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pub fn first_push_as_number(&self) -> Option<usize> {
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if !self.0.is_empty() {
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if let TemplateElement::Op(op) = self.0[0] {
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if let opcodes::Class::PushNum(n) = op.classify() {
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if n >= 0 {
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return Some(n as usize);
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}
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}
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}
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}
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None
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}
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}
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impl<'a> From<&'a [u8]> for Template {
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fn from(slice: &'a [u8]) -> Template {
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Template(slice.iter().map(|&byte| {
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if byte == PUBKEY {
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TemplateElement::Key
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} else {
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TemplateElement::Op(opcodes::All::from(byte))
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}
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}).collect())
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}
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}
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/// Tweak a single key using some arbitrary data
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pub fn tweak_key<C: secp256k1::Verification>(secp: &Secp256k1<C>, mut key: PublicKey, contract: &[u8]) -> PublicKey {
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let hmac_result = compute_tweak(&key, contract);
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key.key.add_exp_assign(secp, &hmac_result[..]).expect("HMAC cannot produce invalid tweak");
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key
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}
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/// Tweak keys using some arbitrary data
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pub fn tweak_keys<C: secp256k1::Verification>(secp: &Secp256k1<C>, keys: &[PublicKey], contract: &[u8]) -> Vec<PublicKey> {
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keys.iter().cloned().map(|key| tweak_key(secp, key, contract)).collect()
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}
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/// Compute a tweak from some given data for the given public key
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pub fn compute_tweak(pk: &PublicKey, contract: &[u8]) -> Hmac<sha256::Hash> {
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let mut hmac_engine: HmacEngine<sha256::Hash> = if pk.compressed {
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HmacEngine::new(&pk.key.serialize())
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} else {
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HmacEngine::new(&pk.key.serialize_uncompressed())
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};
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hmac_engine.input(contract);
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Hmac::from_engine(hmac_engine)
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}
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/// Tweak a secret key using some arbitrary data (calls `compute_tweak` internally)
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pub fn tweak_secret_key<C: secp256k1::Signing>(secp: &Secp256k1<C>, key: &PrivateKey, contract: &[u8]) -> Result<PrivateKey, Error> {
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// Compute public key
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let pk = PublicKey::from_private_key(secp, &key);
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// Compute tweak
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let hmac_sk = compute_tweak(&pk, contract);
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// Execute the tweak
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let mut key = *key;
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key.key.add_assign(&hmac_sk[..]).map_err(Error::Secp)?;
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// Return
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Ok(key)
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}
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/// Takes a contract, template and key set and runs through all the steps
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pub fn create_address<C: secp256k1::Verification>(secp: &Secp256k1<C>,
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network: Network,
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contract: &[u8],
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keys: &[PublicKey],
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template: &Template)
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-> Result<address::Address, Error> {
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let keys = tweak_keys(secp, keys, contract);
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let script = template.to_script(&keys)?;
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Ok(address::Address {
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network: network,
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payload: address::Payload::ScriptHash(
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ScriptHash::hash(&script[..])
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)
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})
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}
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/// Extract the keys and template from a completed script
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pub fn untemplate(script: &script::Script) -> Result<(Template, Vec<PublicKey>), Error> {
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let mut ret = script::Builder::new();
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let mut retkeys = vec![];
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#[derive(Copy, Clone, PartialEq, Eq)]
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enum Mode {
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SeekingKeys,
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CopyingKeys,
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SeekingCheckMulti
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}
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let mut mode = Mode::SeekingKeys;
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for instruction in script.instructions() {
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if let Err(e) = instruction {
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return Err(Error::Script(e));
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}
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match instruction.unwrap() {
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script::Instruction::PushBytes(data) => {
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let n = data.len();
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ret = match PublicKey::from_slice(data) {
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Ok(key) => {
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if n == 65 { return Err(Error::UncompressedKey); }
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if mode == Mode::SeekingCheckMulti { return Err(Error::ExpectedChecksig); }
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retkeys.push(key);
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mode = Mode::CopyingKeys;
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ret.push_opcode(opcodes::All::from(PUBKEY))
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}
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Err(_) => {
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// Arbitrary pushes are only allowed before we've found any keys.
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// Otherwise we have to wait for a N CHECKSIG pair.
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match mode {
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Mode::SeekingKeys => { ret.push_slice(data) }
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Mode::CopyingKeys => { return Err(Error::ExpectedKey); },
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Mode::SeekingCheckMulti => { return Err(Error::ExpectedChecksig); }
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}
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}
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}
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}
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script::Instruction::Op(op) => {
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match op.classify() {
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// CHECKSIG should only come after a list of keys
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opcodes::Class::Ordinary(opcodes::Ordinary::OP_CHECKSIG) |
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opcodes::Class::Ordinary(opcodes::Ordinary::OP_CHECKSIGVERIFY) => {
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if mode == Mode::SeekingKeys { return Err(Error::ExpectedKey); }
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mode = Mode::SeekingKeys;
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}
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// CHECKMULTISIG should only come after a number
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opcodes::Class::Ordinary(opcodes::Ordinary::OP_CHECKMULTISIG) |
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opcodes::Class::Ordinary(opcodes::Ordinary::OP_CHECKMULTISIGVERIFY) => {
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if mode == Mode::SeekingKeys { return Err(Error::ExpectedKey); }
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if mode == Mode::CopyingKeys { return Err(Error::ExpectedKey); }
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mode = Mode::SeekingKeys;
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}
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// Numbers after keys mean we expect a CHECKMULTISIG.
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opcodes::Class::PushNum(_) => {
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if mode == Mode::SeekingCheckMulti { return Err(Error::ExpectedChecksig); }
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if mode == Mode::CopyingKeys { mode = Mode::SeekingCheckMulti; }
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}
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// All other opcodes do nothing
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_ => {}
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}
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ret = ret.push_opcode(op);
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}
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}
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}
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Ok((Template::from(&ret[..]), retkeys))
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}
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#[cfg(test)]
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mod tests {
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use secp256k1::Secp256k1;
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use hashes::hex::FromHex;
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use secp256k1::rand::thread_rng;
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use core::str::FromStr;
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use blockdata::script::Script;
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use network::constants::Network;
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use super::*;
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use PublicKey;
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macro_rules! hex (($hex:expr) => (Vec::from_hex($hex).unwrap()));
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macro_rules! hex_key (($hex:expr) => (PublicKey::from_slice(&hex!($hex)).unwrap()));
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macro_rules! alpha_template(() => (Template::from(&hex!("55fefefefefefefe57AE")[..])));
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macro_rules! alpha_keys(() => (
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&[hex_key!("0269992fb441ae56968e5b77d46a3e53b69f136444ae65a94041fc937bdb28d933"),
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hex_key!("021df31471281d4478df85bfce08a10aab82601dca949a79950f8ddf7002bd915a"),
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hex_key!("02174c82021492c2c6dfcbfa4187d10d38bed06afb7fdcd72c880179fddd641ea1"),
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hex_key!("033f96e43d72c33327b6a4631ccaa6ea07f0b106c88b9dc71c9000bb6044d5e88a"),
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hex_key!("0313d8748790f2a86fb524579b46ce3c68fedd58d2a738716249a9f7d5458a15c2"),
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hex_key!("030b632eeb079eb83648886122a04c7bf6d98ab5dfb94cf353ee3e9382a4c2fab0"),
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hex_key!("02fb54a7fcaa73c307cfd70f3fa66a2e4247a71858ca731396343ad30c7c4009ce")]
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));
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#[test]
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fn sanity() {
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let secp = Secp256k1::new();
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let keys = alpha_keys!();
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// This is the first withdraw ever, in alpha a94f95cc47b444c10449c0eed51d895e4970560c4a1a9d15d46124858abc3afe
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let contract = hex!("5032534894ffbf32c1f1c0d3089b27c98fd991d5d7329ebd7d711223e2cde5a9417a1fa3e852c576");
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let addr = create_address(&secp, Network::Testnet, &contract, keys, &alpha_template!()).unwrap();
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assert_eq!(addr.to_string(), "2N3zXjbwdTcPsJiy8sUK9FhWJhqQCxA8Jjr".to_owned());
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}
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#[test]
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fn script() {
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let alpha_keys = alpha_keys!();
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let alpha_template = alpha_template!();
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let alpha_redeem = Script::from(hex!("55210269992fb441ae56968e5b77d46a3e53b69f136444ae65a94041fc937bdb28d93321021df31471281d4478df85bfce08a10aab82601dca949a79950f8ddf7002bd915a2102174c82021492c2c6dfcbfa4187d10d38bed06afb7fdcd72c880179fddd641ea121033f96e43d72c33327b6a4631ccaa6ea07f0b106c88b9dc71c9000bb6044d5e88a210313d8748790f2a86fb524579b46ce3c68fedd58d2a738716249a9f7d5458a15c221030b632eeb079eb83648886122a04c7bf6d98ab5dfb94cf353ee3e9382a4c2fab02102fb54a7fcaa73c307cfd70f3fa66a2e4247a71858ca731396343ad30c7c4009ce57ae"));
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let (template, keys) = untemplate(&alpha_redeem).unwrap();
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assert_eq!(keys, alpha_keys);
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assert_eq!(template, alpha_template);
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}
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#[test]
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fn tweak_secret() {
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let secp = Secp256k1::new();
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let (sk1, pk1) = secp.generate_keypair(&mut thread_rng());
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let (sk2, pk2) = secp.generate_keypair(&mut thread_rng());
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let (sk3, pk3) = secp.generate_keypair(&mut thread_rng());
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let sk1 = PrivateKey::new(sk1, Network::Bitcoin);
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let sk2 = PrivateKey::new_uncompressed(sk2, Network::Bitcoin);
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let sk3 = PrivateKey::new(sk3, Network::Bitcoin);
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let pks = [
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PublicKey::new(pk1),
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PublicKey::new_uncompressed(pk2),
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PublicKey::new(pk3),
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];
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let contract = b"if bottle mt dont remembr drink wont pay";
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// Directly compute tweaks on pubkeys
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let tweaked_pks = tweak_keys(&secp, &pks, &contract[..]);
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// Compute tweaks on secret keys
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let tweaked_pk1 = PublicKey::from_private_key(&secp, &tweak_secret_key(&secp, &sk1, &contract[..]).unwrap());
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let tweaked_pk2 = PublicKey::from_private_key(&secp, &tweak_secret_key(&secp, &sk2, &contract[..]).unwrap());
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let tweaked_pk3 = PublicKey::from_private_key(&secp, &tweak_secret_key(&secp, &sk3, &contract[..]).unwrap());
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// Check equality
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assert_eq!(tweaked_pks[0], tweaked_pk1);
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assert_eq!(tweaked_pks[1], tweaked_pk2);
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assert_eq!(tweaked_pks[2], tweaked_pk3);
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}
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#[test]
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fn tweak_fixed_vector() {
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let secp = Secp256k1::new();
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let pks = [
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PublicKey::from_str("02ba604e6ad9d3864eda8dc41c62668514ef7d5417d3b6db46e45cc4533bff001c").unwrap(),
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PublicKey::from_str("0365c0755ea55ce85d8a1900c68a524dbfd1c0db45ac3b3840dbb10071fe55e7a8").unwrap(),
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PublicKey::from_str("0202313ca315889b2e69c94cf86901119321c7288139ba53ac022b7af3dc250054").unwrap(),
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];
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let tweaked_pks = [
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PublicKey::from_str("03b3597221b5982a3f1a77aed50f0015d1b6edfc69023ef7f25cfac0e8af1b2041").unwrap(),
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PublicKey::from_str("0296ece1fd954f7ae94f8d6bad19fd6d583f5b36335cf13135a3053a22f3c1fb05").unwrap(),
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PublicKey::from_str("0230bb1ca5dbc7fcf49294c2c3e582e5582eabf7c87e885735dc774da45d610e51").unwrap(),
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];
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let contract = b"if bottle mt dont remembr drink wont pay";
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// Directly compute tweaks on pubkeys
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assert_eq!(
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tweak_keys(&secp, &pks, &contract[..]),
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tweaked_pks
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);
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}
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#[test]
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fn bad_key_number() {
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let alpha_keys = alpha_keys!();
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let template_short = Template::from(&hex!("55fefefefefefe57AE")[..]);
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let template_long = Template::from(&hex!("55fefefefefefefefe57AE")[..]);
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let template = Template::from(&hex!("55fefefefefefefe57AE")[..]);
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assert_eq!(template_short.required_keys(), 6);
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assert_eq!(template_long.required_keys(), 8);
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assert_eq!(template.required_keys(), 7);
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assert_eq!(template_short.to_script(alpha_keys), Err(Error::TooManyKeys(7)));
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assert_eq!(template_long.to_script(alpha_keys), Err(Error::TooFewKeys(7)));
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assert!(template.to_script(alpha_keys).is_ok());
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}
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}
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