fead(opcodes): Add opcode OP_HASH256 (#158)

README.md

@@ -268,7 +268,7 @@ pie showData
 | opSha1 | 0xa7 | ✅ | The input is hashed using SHA-1. |
 | opSha256 | 0xa8 | ✅ | The input is hashed using SHA-256. |
 | opHash160 | 0xa9 | ✅ | The input is hashed twice: first with SHA-256 and then with RIPEMD-160. |
-| opHash256 | 0xaa | ❌ | The input is hashed two times with SHA-256. |
+| opHash256 | 0xaa | ✅ | The input is hashed two times with SHA-256. |
 | opCodeSeparator | 0xab | ❌ | All of the signature checking words will only match signatures to the data after the most recently-executed opCODESEPARATOR. |
 | opCheckSig | 0xac | ✅ | The entire transaction's outputs, inputs, and script are hashed. The signature used by opCHECKSIG must be a valid signature for this hash and public key. If it is, 1 is returned, 0 otherwise. |
 | opCheckSigVerify | 0xad | ❌ | Same as opCHECKSIG, but opVERIFY is executed afterward. |

src/script/engine.zig

@@ -154,6 +154,7 @@ pub const Engine = struct {
  Opcode.OP_RIPEMD160 => try self.opRipemd160(),
  Opcode.OP_SHA256 => try self.opSha256(),
  Opcode.OP_HASH160 => try self.opHash160(),
+ Opcode.OP_HASH256 => try self.opHash256(),
  Opcode.OP_CHECKSIG => try self.opCheckSig(),
  Opcode.OP_NIP => try self.opNip(),
  Opcode.OP_OVER => try self.opOver(),
@@ -486,6 +487,18 @@ pub const Engine = struct {
  try self.stack.pushByteArray(&hash_160);
  }
 
+ /// OP_HASH256: The input is hashed two times with SHA-256.
+ fn opHash256(self: *Engine) EngineError!void {
+ const data = try self.stack.pop();
+ defer self.allocator.free(data);
+
+ var digest: [Sha256.digest_length]u8 = undefined;
+ Sha256.hash(data, &digest, .{});
+ Sha256.hash(&digest, &digest, .{});
+
+ try self.stack.pushByteArray(&digest);
+ }
+
  /// OP_CHECKSIG: Verify a signature
  ///
  /// # Returns
@@ -537,6 +550,51 @@ pub const Engine = struct {
  }
 };
 
+test "Script execution - OP_HASH256" {
+ const allocator = std.testing.allocator;
+
+ const script_bytes = [_]u8{
+ Opcode.OP_1.toBytes(),
+ Opcode.OP_HASH256.toBytes(),
+ };
+ const script = Script.init(&script_bytes);
+
+ var engine = Engine.init(allocator, script, .{});
+ defer engine.deinit();
+
+ try engine.execute();
+
+ const hex_string = "9C12CFDC04C74584D787AC3D23772132C18524BC7AB28DEC4219B8FC5B425F70";
+ var expected_output: [hex_string.len / 2]u8 = undefined;
+ _ = try std.fmt.hexToBytes(&expected_output, hex_string);
+
+ try std.testing.expectEqual(1, engine.stack.len());
+ try std.testing.expectEqualSlices(u8, &expected_output, try engine.stack.peek(0));
+}
+
+test "Script execution - OP_HASH256 (double)" {
+ const allocator = std.testing.allocator;
+
+ const script_bytes = [_]u8{
+ Opcode.OP_14.toBytes(),
+ Opcode.OP_HASH256.toBytes(),
+ Opcode.OP_HASH256.toBytes(),
+ };
+ const script = Script.init(&script_bytes);
+
+ var engine = Engine.init(allocator, script, .{});
+ defer engine.deinit();
+
+ try engine.execute();
+
+ const hex_string = "26AA6C7A9B46E9C409F09C179F7DEFF54F7AF5571D38DE5E5D9BA3932B91F55B";
+ var expected_output: [hex_string.len / 2]u8 = undefined;
+ _ = try std.fmt.hexToBytes(&expected_output, hex_string);
+
+ try std.testing.expectEqual(1, engine.stack.len());
+ try std.testing.expectEqualSlices(u8, &expected_output, try engine.stack.peek(0));
+}
+
 // Testing SHA1 against known vectors
 test "opSha1 function test" {
  const test_cases = [_]struct {