Merge commit '437d1e2c964faf182375169640f0561070dae346' into subtree-stuff

Author: thomaseizinger

elements-fun/src/bip143.rs

@@ -0,0 +1,194 @@
+// Rust Bitcoin Library
+// Written in 2018 by
+//     Andrew Poelstra <[email protected]>
+// To the extent possible under law, the author(s) have dedicated all
+// copyright and related and neighboring rights to this software to
+// the public domain worldwide. This software is distributed without
+// any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication
+// along with this software.
+// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+//
+
+//! BIP143 Implementation
+//!
+//! Implementation of BIP143 Segwit-style signatures. Should be sufficient
+//! to create signatures for Segwit transactions (which should be pushed into
+//! the appropriate place in the `Transaction::witness` array) or bcash
+//! signatures, which are placed in the scriptSig.
+//!
+
+use crate::{
+    encode::{self, Encodable},
+    hash_types::SigHash,
+    script::Script,
+    transaction::{SigHashType, Transaction},
+};
+use bitcoin_hashes::{sha256d, Hash};
+use std::{io, ops::Deref};
+
+/// A replacement for SigHashComponents which supports all sighash modes
+pub struct SigHashCache<R: Deref<Target = Transaction>> {
+    /// Access to transaction required for various introspection
+    tx: R,
+    /// Hash of all the previous outputs, computed as required
+    hash_prevouts: Option<sha256d::Hash>,
+    /// Hash of all the input sequence nos, computed as required
+    hash_sequence: Option<sha256d::Hash>,
+    /// Hash of all the outputs in this transaction, computed as required
+    hash_outputs: Option<sha256d::Hash>,
+    /// Hash of all the issunaces in this transaction, computed as required
+    hash_issuances: Option<sha256d::Hash>,
+}
+
+impl<R: Deref<Target = Transaction>> SigHashCache<R> {
+    /// Compute the sighash components from an unsigned transaction and auxiliary
+    /// in a lazy manner when required.
+    /// For the generated sighashes to be valid, no fields in the transaction may change except for
+    /// script_sig and witnesses.
+    pub fn new(tx: R) -> Self {
+        SigHashCache {
+            tx: tx,
+            hash_prevouts: None,
+            hash_sequence: None,
+            hash_outputs: None,
+            hash_issuances: None,
+        }
+    }
+
+    /// Calculate hash for prevouts
+    pub fn hash_prevouts(&mut self) -> sha256d::Hash {
+        let hash_prevout = &mut self.hash_prevouts;
+        let input = &self.tx.input;
+        *hash_prevout.get_or_insert_with(|| {
+            let mut enc = sha256d::Hash::engine();
+            for txin in input {
+                txin.previous_output.consensus_encode(&mut enc).unwrap();
+            }
+            sha256d::Hash::from_engine(enc)
+        })
+    }
+
+    /// Calculate hash for input sequence values
+    pub fn hash_sequence(&mut self) -> sha256d::Hash {
+        let hash_sequence = &mut self.hash_sequence;
+        let input = &self.tx.input;
+        *hash_sequence.get_or_insert_with(|| {
+            let mut enc = sha256d::Hash::engine();
+            for txin in input {
+                txin.sequence.consensus_encode(&mut enc).unwrap();
+            }
+            sha256d::Hash::from_engine(enc)
+        })
+    }
+
+    /// Calculate hash for issuances
+    pub fn hash_issuances(&mut self) -> sha256d::Hash {
+        let hash_issuance = &mut self.hash_issuances;
+        let input = &self.tx.input;
+        *hash_issuance.get_or_insert_with(|| {
+            let mut enc = sha256d::Hash::engine();
+            for txin in input {
+                if txin.has_issuance() {
+                    txin.asset_issuance.consensus_encode(&mut enc).unwrap();
+                } else {
+                    0u8.consensus_encode(&mut enc).unwrap();
+                }
+            }
+            sha256d::Hash::from_engine(enc)
+        })
+    }
+
+    /// Calculate hash for outputs
+    pub fn hash_outputs(&mut self) -> sha256d::Hash {
+        let hash_output = &mut self.hash_outputs;
+        let output = &self.tx.output;
+        *hash_output.get_or_insert_with(|| {
+            let mut enc = sha256d::Hash::engine();
+            for txout in output {
+                txout.consensus_encode(&mut enc).unwrap();
+            }
+            sha256d::Hash::from_engine(enc)
+        })
+    }
+
+    /// 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();
+
+        self.tx.version.consensus_encode(&mut writer)?;
+
+        if !anyone_can_pay {
+            self.hash_prevouts().consensus_encode(&mut writer)?;
+        } else {
+            zero_hash.consensus_encode(&mut writer)?;
+        }
+
+        if !anyone_can_pay && sighash != SigHashType::Single && sighash != SigHashType::None {
+            self.hash_sequence().consensus_encode(&mut writer)?;
+        } else {
+            zero_hash.consensus_encode(&mut writer)?;
+        }
+
+        // Elements: Push the hash issuance zero hash as required
+        // If required implement for issuance, but not necessary as of now
+        if !anyone_can_pay {
+            self.hash_issuances().consensus_encode(&mut writer)?;
+        } else {
+            zero_hash.consensus_encode(&mut writer)?;
+        }
+
+        // input specific values
+        {
+            let txin = &self.tx.input[input_index];
+
+            txin.previous_output.consensus_encode(&mut writer)?;
+            script_code.consensus_encode(&mut writer)?;
+            value.consensus_encode(&mut writer)?;
+            txin.sequence.consensus_encode(&mut writer)?;
+            if txin.has_issuance() {
+                txin.asset_issuance.consensus_encode(&mut writer)?;
+            }
+        }
+
+        // hashoutputs
+        if sighash != SigHashType::Single && sighash != SigHashType::None {
+            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)?;
+            SigHash::from_engine(single_enc).consensus_encode(&mut writer)?;
+        } else {
+            zero_hash.consensus_encode(&mut writer)?;
+        }
+
+        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.
+    pub fn signature_hash(
+        &mut self,
+        input_index: usize,
+        script_code: &Script,
+        value: u64,
+        sighash_type: SigHashType,
+    ) -> SigHash {
+        let mut enc = SigHash::engine();
+        self.encode_signing_data_to(&mut enc, input_index, script_code, value, sighash_type)
+            .expect("engines don't error");
+        SigHash::from_engine(enc)
+    }
+}

elements-fun/src/lib.rs

@@ -34,6 +34,7 @@ extern crate serde_crate as serde;
 #[macro_use]
 mod internal_macros;
 pub mod address;
+pub mod bip143;
 pub mod blech32;
 mod block;
 pub mod confidential;
@@ -62,5 +63,5 @@ pub use script::Script;
 pub use transaction::{
     AssetIssuance, ConfidentialAssetIssuance, ConfidentialTxOut, ExplicitAsset,
     ExplicitAssetIssuance, ExplicitTxOut, ExplicitValue, OutPoint, PeginData, PegoutData,
-    Transaction, TxIn, TxInWitness, TxOut, TxOutWitness, UnblindedTxOut,
+    SigHashType, Transaction, TxIn, TxInWitness, TxOut, TxOutWitness, UnblindedTxOut,
 };

elements-fun/src/script.rs

@@ -30,11 +30,13 @@ use std::{default::Default, fmt, io, ops};
 use serde;
 
 use crate::{
+    bech32,
     encode::{self, Decodable, Encodable},
-    opcodes, ScriptHash, WScriptHash,
+    opcodes, PubkeyHash, ScriptHash, WPubkeyHash, WScriptHash,
 };
 
 use bitcoin::PublicKey;
+use bitcoin_hashes::Hash;
 
 #[derive(Clone, Default, PartialOrd, Ord, PartialEq, Eq, Hash)]
 /// A Bitcoin script
@@ -218,6 +220,75 @@ impl Script {
         Script(vec![].into_boxed_slice())
     }
 
+    /// Generates P2PK-type of scriptPubkey
+    pub fn new_p2pk(pubkey: &PublicKey) -> Script {
+        Builder::new()
+            .push_key(pubkey)
+            .push_opcode(opcodes::all::OP_CHECKSIG)
+            .into_script()
+    }
+
+    /// Generates P2PKH-type of scriptPubkey
+    pub fn new_p2pkh(pubkey_hash: &PubkeyHash) -> Script {
+        Builder::new()
+            .push_opcode(opcodes::all::OP_DUP)
+            .push_opcode(opcodes::all::OP_HASH160)
+            .push_slice(&pubkey_hash[..])
+            .push_opcode(opcodes::all::OP_EQUALVERIFY)
+            .push_opcode(opcodes::all::OP_CHECKSIG)
+            .into_script()
+    }
+
+    /// Generates P2SH-type of scriptPubkey with a given hash of the redeem script
+    pub fn new_p2sh(script_hash: &ScriptHash) -> Script {
+        Builder::new()
+            .push_opcode(opcodes::all::OP_HASH160)
+            .push_slice(&script_hash[..])
+            .push_opcode(opcodes::all::OP_EQUAL)
+            .into_script()
+    }
+
+    /// Generates P2WPKH-type of scriptPubkey
+    pub fn new_v0_wpkh(pubkey_hash: &WPubkeyHash) -> Script {
+        Script::new_witness_program(bech32::u5::try_from_u8(0).unwrap(), &pubkey_hash.to_vec())
+    }
+
+    /// Generates P2WSH-type of scriptPubkey with a given hash of the redeem script
+    pub fn new_v0_wsh(script_hash: &WScriptHash) -> Script {
+        Script::new_witness_program(bech32::u5::try_from_u8(0).unwrap(), &script_hash.to_vec())
+    }
+
+    /// Generates P2WSH-type of scriptPubkey with a given hash of the redeem script
+    pub fn new_witness_program(ver: bech32::u5, program: &[u8]) -> Script {
+        let mut verop = ver.to_u8();
+        assert!(verop <= 16, "incorrect witness version provided: {}", verop);
+        if verop > 0 {
+            verop = 0x50 + verop;
+        }
+        Builder::new()
+            .push_opcode(verop.into())
+            .push_slice(&program)
+            .into_script()
+    }
+
+    /// Generates OP_RETURN-type of scriptPubkey for a given data
+    pub fn new_op_return(data: &[u8]) -> Script {
+        Builder::new()
+            .push_opcode(opcodes::all::OP_RETURN)
+            .push_slice(data)
+            .into_script()
+    }
+
+    /// Returns 160-bit hash of the script
+    pub fn script_hash(&self) -> ScriptHash {
+        ScriptHash::hash(&self.as_bytes())
+    }
+
+    /// Returns 256-bit hash of the script for P2WSH outputs
+    pub fn wscript_hash(&self) -> WScriptHash {
+        WScriptHash::hash(&self.as_bytes())
+    }
+
     /// The length in bytes of the script
     pub fn len(&self) -> usize {
         self.0.len()
@@ -245,7 +316,6 @@ impl Script {
 
     /// Compute the P2SH output corresponding to this redeem script
     pub fn to_p2sh(&self) -> Script {
-        use bitcoin::hashes::Hash;
         Builder::new()
             .push_opcode(opcodes::all::OP_HASH160)
             .push_slice(&ScriptHash::hash(&self.0)[..])
@@ -256,7 +326,6 @@ impl Script {
     /// Compute the P2WSH output corresponding to this witnessScript (aka the "witness redeem
     /// script")
     pub fn to_v0_p2wsh(&self) -> Script {
-        use bitcoin::hashes::Hash;
         Builder::new()
             .push_int(0)
             .push_slice(&WScriptHash::hash(&self.0)[..])

elements-fun/src/transaction.rs

@@ -1435,6 +1435,61 @@ impl Decodable for Transaction {
         }
     }
 }
+/// Hashtype of a transaction, encoded in the last byte of a signature
+/// Fixed values so they can be casted as integer types for encoding
+#[derive(PartialEq, Eq, Debug, Copy, Clone)]
+pub enum SigHashType {
+    /// 0x1: Sign all outputs
+    All = 0x01,
+    /// 0x2: Sign no outputs --- anyone can choose the destination
+    None = 0x02,
+    /// 0x3: Sign the output whose index matches this input's index. If none exists,
+    /// sign the hash `0000000000000000000000000000000000000000000000000000000000000001`.
+    /// (This rule is probably an unintentional C++ism, but it's consensus so we have
+    /// to follow it.)
+    Single = 0x03,
+    /// 0x81: Sign all outputs but only this input
+    AllPlusAnyoneCanPay = 0x81,
+    /// 0x82: Sign no outputs and only this input
+    NonePlusAnyoneCanPay = 0x82,
+    /// 0x83: Sign one output and only this input (see `Single` for what "one output" means)
+    SinglePlusAnyoneCanPay = 0x83,
+}
+
+impl SigHashType {
+    /// Break the sighash flag into the "real" sighash flag and the ANYONECANPAY boolean
+    pub(crate) fn split_anyonecanpay_flag(self) -> (SigHashType, bool) {
+        match self {
+            SigHashType::All => (SigHashType::All, false),
+            SigHashType::None => (SigHashType::None, false),
+            SigHashType::Single => (SigHashType::Single, false),
+            SigHashType::AllPlusAnyoneCanPay => (SigHashType::All, true),
+            SigHashType::NonePlusAnyoneCanPay => (SigHashType::None, true),
+            SigHashType::SinglePlusAnyoneCanPay => (SigHashType::Single, true),
+        }
+    }
+
+    /// Reads a 4-byte uint32 as a sighash type
+    pub fn from_u32(n: u32) -> SigHashType {
+        match n & 0x9f {
+            // "real" sighashes
+            0x01 => SigHashType::All,
+            0x02 => SigHashType::None,
+            0x03 => SigHashType::Single,
+            0x81 => SigHashType::AllPlusAnyoneCanPay,
+            0x82 => SigHashType::NonePlusAnyoneCanPay,
+            0x83 => SigHashType::SinglePlusAnyoneCanPay,
+            // catchalls
+            x if x & 0x80 == 0x80 => SigHashType::AllPlusAnyoneCanPay,
+            _ => SigHashType::All,
+        }
+    }
+
+    /// Converts to a u32
+    pub fn as_u32(self) -> u32 {
+        self as u32
+    }
+}
 
 #[cfg(test)]
 mod tests {