feat: add support for p2wpkh and p2wsh

Author: educifuentes

lib/bitcoin/script.rb

@@ -1,5 +1,6 @@
 require_relative '../bitcoin_data_io'
 require_relative '../encoding_helper'
+require_relative '../hash_helper'
 require_relative './op'
 
 module Bitcoin
@@ -88,14 +89,14 @@ def serialize
       encode_varint(raw.length) + raw
     end
 
-    def evaluate(z) # rubocop:disable Metrics/MethodLength
+    def evaluate(z, witness: nil)
       cmds = @cmds.clone
       stack = []
       altstack = []
 
       while cmds.any?
         cmd = cmds.shift
-        return false unless resolve_cmd(cmd, cmds, stack, altstack, z)
+        return false unless resolve_cmd(cmd, cmds, stack, altstack, z, witness: witness)
       end
 
       return false if stack.empty? || stack.pop.empty?
@@ -110,6 +111,18 @@ def p2sh?(cmds = @cmds)
       && cmds[2] == 135
     end
 
+    def p2wpkh?(cmds = @cmds)
+      cmds.length == 2 \
+      && cmds[0] == 0 \
+      && cmds[1].is_a?(String) && cmds[1].length == 20
+    end
+
+    def p2wsh?(cmds = @cmds)
+      cmds.length == 2 \
+      && cmds[0] == 0 \
+      && cmds[1].is_a?(String) && cmds[1].length == 32
+    end
+
     def self.p2pkh(hash160)
       Script.new([118, 169, hash160, 136, 172])
     end
@@ -124,14 +137,18 @@ def self.p2wsh(hash256)
 
     private
 
-    def resolve_cmd(cmd, cmds, stack, altstack, z)
+    def resolve_cmd(cmd, cmds, stack, altstack, z, witness: nil)
       if cmd.is_a? Integer
         return execute_operation(cmd, cmds, stack, altstack, z)
       else
         stack.append(cmd)
 
         if p2sh?(cmds)
           return execute_p2sh(cmd, cmds, stack)
+        elsif p2wpkh?
+          return execute_p2wpkh(cmds, stack, witness)
+        elsif p2wsh?
+          return execute_p2wsh(cmds, stack, witness)
         end
       end
 
@@ -154,6 +171,30 @@ def execute_p2sh(cmd, cmds, stack)
       cmds.concat self.class.parse(stream).cmds
     end
 
+    def execute_p2wpkh(cmds, stack, witness)
+      h160 = stack.pop
+      stack.pop
+      cmds.concat witness
+      cmds.concat self.class.p2wpkh(h160).cmds
+    end
+
+    def execute_p2wsh(cmds, stack, witness)
+      s256_stack = stack.pop
+      stack.pop
+      cmds.concat witness[0...-1]
+      witness_script = witness.last
+      s256_script = HashHelper.hash256(witness_script)
+
+      unless s256_stack == s256_script
+        raise "Witness script hash mismatch: \n"\
+          "stack: #{bytes_to_hex(s256_stack)} \n"\
+          "script: #{bytes_to_hex(s256_script)}"
+      end
+
+      stream = encode_varint(witness_script.size) + witness_script
+      cmds.concat parse(stream).cmds
+    end
+
     def raw_serialize
       @cmds.map do |cmd|
         cmd.is_a?(Integer) ? int_to_little_endian(cmd, 1) : serialized_element_prefix(cmd) + cmd

lib/bitcoin/tx.rb

@@ -263,17 +263,41 @@ def hash_outputs
     def verify_input(input_index)
       tx_in = ins[input_index]
       script_pubkey = tx_in.script_pubkey testnet: @testnet
+      z, witness = build_z_and_witness(script_pubkey, tx_in, input_index)
 
+      combined = tx_in.script_sig + script_pubkey
+      combined.evaluate(z, witness: witness)
+    end
+
+    def build_z_and_witness(script_pubkey, tx_in, input_index) # rubocop:disable Metrics/MethodLength
       if script_pubkey.p2sh?
         cmd = tx_in.script_sig.cmds[-1]
         raw_redeem = encode_varint(cmd.length) + cmd
         redeem_script = Script.parse(StringIO.new(raw_redeem))
+
+        if redeem_script.p2wpkh?
+          [sig_hash_bip143(input_index, redeem_script), tx_in.witness]
+        elsif redeem_script.p2wsh?
+          build_z_from_witness(tx_in, input_index)
+        else
+          [sig_hash(input_index, redeem_script), nil]
+        end
+
+      elsif script_pubkey.p2wpkh?
+        [sig_hash_bip143(input_index, redeem_script: redeem_script), tx_in.witness]
+      elsif script_pubkey.p2wsh?
+        build_z_from_witness(tx_in, input_index)
       else
-        redeem_script = nil
+        [sig_hash(input_index), nil]
       end
-      z = sig_hash(input_index, redeem_script)
-      combined = tx_in.script_sig + script_pubkey
-      combined.evaluate(z)
+    end
+
+    def build_z_from_witness(tx_in, input_index)
+      cmd = tx_in.witness.last
+      raw_witness = encode_varint(cmd.size) + cmd
+      witness_script = Script.parse(StringIO.new(raw_witness))
+
+      [sig_hash_bip143(input_index, witness_script: witness_script), tx_in.witness]
     end
 
     def verify?

spec/bitcoin/script_spec.rb

@@ -1,6 +1,7 @@
 require 'bitcoin/script'
 require 'bitcoin/op'
 require 'encoding_helper'
+require 'pry'
 
 RSpec.describe Bitcoin::Script do
   def _raw_script(hex_script)
@@ -222,6 +223,75 @@ def _raw_script(hex_script)
     end
   end
 
+  describe '#p2wpkh?' do
+    let!(:script) { described_class.new(commands) }
+    let(:commands) { [] }
+
+    context "when the script matches the p2wpkh pattern" do
+      let(:hash160) { HashHelper.hash160('') }
+      let(:commands) do
+        [
+          0,
+          hash160
+        ]
+      end
+      let!(:script) { described_class.new(commands) }
+
+      it 'returns true' do
+        expect(script.p2wpkh?).to be true
+      end
+    end
+
+    context "when the script does not match the p2wpkh pattern" do
+      let(:commands) do
+        [
+          '',
+          18,
+          135
+        ]
+      end
+      let!(:script) { described_class.new(commands) }
+
+      it 'returns false' do
+        expect(script.p2wpkh?).to be false
+      end
+    end
+  end
+
+  describe '#p2wsh?' do
+    let!(:script) { described_class.new(commands) }
+    let(:commands) { [] }
+
+    context "when the script matches the p2wsh pattern" do
+      let(:hash256) { HashHelper.hash256('') }
+      let(:commands) do
+        [
+          0,
+          hash256
+        ]
+      end
+      let!(:script) { described_class.new(commands) }
+
+      it 'returns true' do
+        expect(script.p2wsh?).to be true
+      end
+    end
+
+    context "when the script does not match the p2wsh pattern" do
+      let(:commands) do
+        [
+          '',
+          18
+        ]
+      end
+      let!(:script) { described_class.new(commands) }
+
+      it 'returns false' do
+        expect(script.p2wsh?).to be false
+      end
+    end
+  end
+
   describe "#+" do
     it "adds the commands arrays" do
       script1 = described_class.new([1, 2])

spec/bitcoin/tx_spec.rb

@@ -225,6 +225,27 @@ def bytes_to_hex(_bytes)
         expect(tx.verify_input(0)).to be true
       end
     end
+
+    context 'when tx is segwit and the script pubkey is p2wpkh' do
+      let(:tx_p2wpkh) { described_class.parse raw_tx_sw, tx_fetcher: tx_fetcher }
+
+      it 'verifies unlocking script unlocks the script' do
+        skip
+        expect(tx_p2wpkh.verify_input(0)).to be true
+      end
+    end
+
+    context 'when tx is segwit and the script pubkey is p2wsh' do
+      let(:raw_tx_p2wsh) do
+        resolve_tx '98abf6f18cedc5e527775ff2b0d4235b16fd40774c33ab7c599e20099fd11259'
+      end
+      let(:tx_p2wsh) { described_class.parse raw_tx_p2wsh, tx_fetcher: tx_fetcher }
+
+      it 'verifies unlocking script unlocks the script' do
+        skip
+        expect(tx_p2wsh.verify_input(0)).to be true
+      end
+    end
   end
 
   describe '#sign_input' do

spec/fixtures/transactions.json

@@ -17,5 +17,7 @@
   "d37f9e7282f81b7fd3af0fde8b462a1c28024f1d83cf13637ec18d03f4518feb": "0100000001b74780c0b9903472f84f8697a7449faebbfb1af659ecb8148ce8104347f3f72d010000006b483045022100bb8792c98141bcf4dab4fd4030743b4eff9edde59cec62380c60ffb90121ab7802204b439e3572b51382540c3b652b01327ee8b14cededc992fbc69b1e077a2c3f9f0121027c975c8bdc9717de310998494a2ae63f01b7a390bd34ef5b4c346fa717cba012ffffffff01a627c901000000001976a914af24b3f3e987c23528b366122a7ed2af199b36bc88ac00000000",
   "d869f854e1f8788bcff294cc83b280942a8c728de71eb709a2c29d10bfe21b7c": "0100000000010115e180dc28a2327e687facc33f10f2a20da717e5548406f7ae8b4c811072f8560100000000ffffffff0100b4f505000000001976a9141d7cd6c75c2e86f4cbf98eaed221b30bd9a0b92888ac02483045022100df7b7e5cda14ddf91290e02ea10786e03eb11ee36ec02dd862fe9a326bbcb7fd02203f5b4496b667e6e281cc654a2da9e4f08660c620a1051337fa8965f727eb19190121038262a6c6cec93c2d3ecd6c6072efea86d02ff8e3328bbd0242b20af3425990ac00000000",
   "9b4fc533a9a69ed0eb030b08e40150999a8aa871e918345cb19855298c103ba3":
-  "02000000000101e874ba97f9d35aa2814023894c732c83745fc629a0f5b82e58d6e4efa583be2c0000000000ffffffff0274b10200000000001976a91433e73d0a40a60d02d19c8b8d38ad6da14306683b88ac4c3c21000000000016001424ca8b17be9dfa365929dc9251da7d1533ca8b5e024730440220635a9629c9eb17f7ebbfc200e674aff253ec4213c3e6d3207e86886af9f6a751022072e2d54a9b8079e37cefd856ccf3c2383858346f55197d32c3a7fad18eac48e0012102550e51f143d27ed811e8cdf9008a21211bf26c73866a4b077117496b432421bd00000000"
+  "02000000000101e874ba97f9d35aa2814023894c732c83745fc629a0f5b82e58d6e4efa583be2c0000000000ffffffff0274b10200000000001976a91433e73d0a40a60d02d19c8b8d38ad6da14306683b88ac4c3c21000000000016001424ca8b17be9dfa365929dc9251da7d1533ca8b5e024730440220635a9629c9eb17f7ebbfc200e674aff253ec4213c3e6d3207e86886af9f6a751022072e2d54a9b8079e37cefd856ccf3c2383858346f55197d32c3a7fad18eac48e0012102550e51f143d27ed811e8cdf9008a21211bf26c73866a4b077117496b432421bd00000000",
+  "98abf6f18cedc5e527775ff2b0d4235b16fd40774c33ab7c599e20099fd11259":
+  "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"
 }