adding some signature methods for script interpreting

lib/crypto/signature.js

@@ -10,8 +10,7 @@ var Signature = function Signature(r, s) {
       r: r,
       s: s
     });
-  }
-  else if (r) {
+  } else if (r) {
     var obj = r;
     this.set(obj);
   }
@@ -132,13 +131,17 @@ Signature.prototype.toCompact = function(i, compressed) {
 
   if (!(i === 0 || i === 1 || i === 2 || i === 3))
     throw new Error('i must be equal to 0, 1, 2, or 3');
-  
+
   var val = i + 27 + 4;
   if (compressed === false)
     val = val - 4;
   var b1 = new Buffer([val]);
-  var b2 = this.r.toBuffer({size: 32});
-  var b3 = this.s.toBuffer({size: 32});
+  var b2 = this.r.toBuffer({
+    size: 32
+  });
+  var b3 = this.s.toBuffer({
+    size: 32
+  });
   return Buffer.concat([b1, b2, b3]);
 };
 
@@ -168,6 +171,115 @@ Signature.prototype.toString = function() {
   return buf.toString('hex');
 };
 
+/**
+ * This function is translated from bitcoind's IsDERSignature and is used in
+ * the script interpreter.  This "DER" format actually includes an extra byte,
+ * the nhashtype, at the end. It is really the tx format, not DER format.
+ *
+ * A canonical signature exists of: [30] [total len] [02] [len R] [R] [02] [len S] [S] [hashtype]
+ * Where R and S are not negative (their first byte has its highest bit not set), and not
+ * excessively padded (do not start with a 0 byte, unless an otherwise negative number follows,
+ * in which case a single 0 byte is necessary and even required).
+ *
+ * See https://bitcointalk.org/index.php?topic=8392.msg127623#msg127623
+ */
+Signature.isTxDER = function(buf) {
+  if (buf.length < 9) {
+    //  Non-canonical signature: too short
+    return false;
+  }
+  if (buf.length > 73) {
+    // Non-canonical signature: too long
+    return false;
+  }
+  if (buf[0] !== 0x30) {
+    //  Non-canonical signature: wrong type
+    return false;
+  }
+  if (buf[1] !== buf.length - 3) {
+    //  Non-canonical signature: wrong length marker
+    return false;
+  }
+  var nLenR = buf[3];
+  if (5 + nLenR >= buf.length) {
+    //  Non-canonical signature: S length misplaced
+    return false;
+  }
+  var nLenS = buf[5 + nLenR];
+  if ((nLenR + nLenS + 7) !== buf.length) {
+    //  Non-canonical signature: R+S length mismatch
+    return false;
+  }
+
+  var R = buf.slice(4);
+  if (buf[4 - 2] !== 0x02) {
+    //  Non-canonical signature: R value type mismatch
+    return false;
+  }
+  if (nLenR === 0) {
+    //  Non-canonical signature: R length is zero
+    return false;
+  }
+  if (R[0] & 0x80) {
+    //  Non-canonical signature: R value negative
+    return false;
+  }
+  if (nLenR > 1 && (R[0] === 0x00) && !(R[1] & 0x80)) {
+    //  Non-canonical signature: R value excessively padded
+    return false;
+  }
+
+  var S = buf.slice(6 + nLenR);
+  if (buf[6 + nLenR - 2] !== 0x02) {
+    //  Non-canonical signature: S value type mismatch
+    return false;
+  }
+  if (nLenS === 0) {
+    //  Non-canonical signature: S length is zero
+    return false;
+  }
+  if (S[0] & 0x80) {
+    //  Non-canonical signature: S value negative
+    return false;
+  }
+  if (nLenS > 1 && (S[0] === 0x00) && !(S[1] & 0x80)) {
+    //  Non-canonical signature: S value excessively padded
+    return false;
+  }
+  return true;
+};
+
+/**
+ * Compares to bitcoind's IsLowDERSignature
+ * See also ECDSA signature algorithm which enforces this.
+ * See also BIP 62, "low S values in signatures"
+ */
+Signature.prototype.hasLowS = function() {
+  if (this.s.lt(1) ||
+    this.s.gt(BN('7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B20A0'))) {
+    return false;
+  }
+  return true;
+};
+
+/**
+ * @returns true if the nhashtype is exactly equal to one of the standard options or combinations thereof.
+ * Translated from bitcoind's IsDefinedHashtypeSignature
+ */
+Signature.prototype.hasDefinedHashtype = function() {
+  if (this.nhashtype < Signature.SIGHASH_ALL || this.nhashtype > Signature.SIGHASH_SINGLE) {
+    return false;
+  }
+  return true;
+};
+
+Signature.prototype.toTxFormat = function() {
+  var derbuf = this.toDER();
+  var buf = new Buffer(1);
+  buf.writeUInt8(this.nhashtype, 0);
+  return Buffer.concat([derbuf, buf]);
+};
+
 Signature.SIGHASH_ALL = 0x01;
 Signature.SIGHASH_NONE = 0x02;
 Signature.SIGHASH_SINGLE = 0x03;

lib/script.js

@@ -264,11 +264,11 @@ Script.prototype.isPublicKeyIn = function() {
  * @returns true if this is a p2sh output script
  */
 Script.prototype.isScriptHashOut = function() {
-  return this.chunks.length === 3 &&
-    this.chunks[0].opcodenum === Opcode.OP_HASH160 &&
-    this.chunks[1].buf &&
-    this.chunks[1].buf.length === 20 &&
-    this.chunks[2].opcodenum === Opcode.OP_EQUAL;
+  var buf = this.toBuffer();
+  return (buf.length === 23 &&
+    buf[0] === Opcode.OP_HASH160 &&
+    buf[1] === 0x14 &&
+    buf[22] === Opcode.OP_EQUAL);
 };
 
 /** 
@@ -669,4 +669,61 @@ Script.fromAddress = function(address) {
   throw new errors.Script.UnrecognizedAddress(address);
 };
 
+/**
+ * Analagous to bitcoind's FindAndDelete. Find and delete equivalent chunks,
+ * typically used with push data chunks.  Note that this will find and delete
+ * not just the same data, but the same data with the same push data op as
+ * produced by default. i.e., if a pushdata in a tx does not use the minimal
+ * pushdata op, then when you try to remove the data it is pushing, it will not
+ * be removed, because they do not use the same pushdata op.
+ */
+Script.prototype.findAndDelete = function(script) {
+  var buf = script.toBuffer();
+  var hex = buf.toString('hex');
+  for (var i = 0; i < this.chunks.length; i++) {
+    var script2 = Script({
+      chunks: [this.chunks[i]]
+    });
+    var buf2 = script2.toBuffer();
+    var hex2 = buf2.toString('hex');
+    if (hex === hex2) {
+      this.chunks.splice(i, 1);
+    }
+  }
+  return this;
+};
+
+/**
+ * @returns true if the chunk {i} is the smallest way to push that particular data.
+ * Comes from bitcoind's script interpreter CheckMinimalPush function
+ */
+Script.prototype.checkMinimalPush = function(i) {
+  var chunk = this.chunks[i];
+  var buf = chunk.buf;
+  var opcodenum = chunk.opcodenum;
+  if (!buf) {
+    return true;
+  }
+  if (buf.length === 0) {
+    // Could have used OP_0.
+    return opcodenum === Opcode.OP_0;
+  } else if (buf.length === 1 && buf[0] >= 1 && buf[0] <= 16) {
+    // Could have used OP_1 .. OP_16.
+    return opcodenum === Opcode.OP_1 + (buf[0] - 1);
+  } else if (buf.length === 1 && buf[0] === 0x81) {
+    // Could have used OP_1NEGATE
+    return opcodenum === Opcode.OP_1NEGATE;
+  } else if (buf.length <= 75) {
+    // Could have used a direct push (opcode indicating number of bytes pushed + those bytes).
+    return opcodenum === buf.length;
+  } else if (buf.length <= 255) {
+    // Could have used OP_PUSHDATA.
+    return opcodenum === Opcode.OP_PUSHDATA1;
+  } else if (buf.length <= 65535) {
+    // Could have used OP_PUSHDATA2.
+    return opcodenum === Opcode.OP_PUSHDATA2;
+  }
+  return true;
+};
+
 module.exports = Script;

lib/script_interpreter.js

@@ -210,7 +210,7 @@ ScriptInterpreter.prototype.step = function() {
   this.pc++;
   var opcodenum = chunk.opcodenum;
   if (_.isUndefined(opcodenum)) {
-    this.errstr = 'SCRIPT_ERR_BAD_OPCODE';
+    this.errstr = 'SCRIPT_ERR_UNDEFINED_OPCODE';
     return false;
   }
   if (chunk.buf && chunk.buf.length > ScriptInterpreter.MAX_SCRIPT_ELEMENT_SIZE) {
@@ -257,7 +257,6 @@ ScriptInterpreter.prototype.step = function() {
       this.stack.push(chunk.buf);
     }
   } else if (fExec || (Opcode.OP_IF <= opcodenum && opcodenum <= Opcode.OP_ENDIF)) {
-    console.log('STEP!' + JSON.stringify(chunk));
     switch (opcodenum) {
       // Push value
       case Opcode.OP_1NEGATE:
@@ -902,9 +901,9 @@ ScriptInterpreter.prototype.step = function() {
           // stack.push_back(fSuccess ? vchTrue : vchFalse);
           this.stack.push(fSuccess ? ScriptInterpreter.true : ScriptInterpreter.false);
           if (opcodenum === Opcode.OP_CHECKSIGVERIFY) {
-            if (fSuccess)
+            if (fSuccess) {
               this.stack.pop();
-            else {
+            } else {
               this.errstr = 'SCRIPT_ERR_CHECKSIGVERIFY';
               return false;
             }
@@ -962,7 +961,7 @@ ScriptInterpreter.prototype.step = function() {
           // Drop the signatures, since there's no way for a signature to sign itself
           for (var k = 0; k < nSigsCount; k++) {
             var bufSig = this.stack[this.stack.length - isig - k];
-            subscript.findAndDelete(Script().writeBuffer(bufSig));
+            subscript.findAndDelete(Script().add(bufSig));
           }
 
           var fSuccess = true;
@@ -1064,8 +1063,10 @@ ScriptInterpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin,
     return false;
   }
 
-  if (!this.evaluate())
+  // evaluate scriptSig
+  if (!this.evaluate()) {
     return false;
+  }
 
   if (flags & ScriptInterpreter.SCRIPT_VERIFY_P2SH)
     var stackCopy = this.stack.slice();
@@ -1080,11 +1081,11 @@ ScriptInterpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin,
     flags: flags
   });
 
+  // evaluate scriptPubkey
   if (!this.evaluate())
     return false;
 
   if (this.stack.length === 0) {
-    console.log('stack 0');
     this.errstr = 'SCRIPT_ERR_EVAL_FALSE';
     return false;
   }
@@ -1109,19 +1110,20 @@ ScriptInterpreter.prototype.verify = function(scriptSig, scriptPubkey, tx, nin,
     if (stackCopy.length === 0)
       throw new Error('internal error - stack copy empty');
 
-    var pubkeySerialized = stackCopy[stackCopy.length - 1];
-    var scriptPubkey2 = Script.fromBuffer(pubkeySerialized);
+    var redeemScriptSerialized = stackCopy[stackCopy.length - 1];
+    var redeemScript = Script.fromBuffer(redeemScriptSerialized);
     stackCopy.pop();
 
     this.initialize();
     this.set({
-      script: scriptPubkey2,
+      script: redeemScript,
       stack: stackCopy,
       tx: tx,
       nin: nin,
       flags: flags
     });
 
+    // evaluate redeemScript
     if (!this.evaluate())
     // serror is set
       return false;

test/crypto/signature.js

@@ -151,7 +151,6 @@ describe('Signature', function() {
   });
 
   describe('#toString', function() {
-
     it('should convert this signature in to hex DER', function() {
       var r = BN('63173831029936981022572627018246571655303050627048489594159321588908385378810');
       var s = BN('4331694221846364448463828256391194279133231453999942381442030409253074198130');
@@ -162,7 +161,41 @@ describe('Signature', function() {
       var hex = sig.toString();
       hex.should.equal('30450221008bab1f0a2ff2f9cb8992173d8ad73c229d31ea8e10b0f4d4ae1a0d8ed76021fa02200993a6ec81755b9111762fc2cf8e3ede73047515622792110867d12654275e72');
     });
+  });
+
+
+  describe('@isTxDER', function() {
+    it('should know this is a DER signature', function() {
+      var sighex = '3042021e17cfe77536c3fb0526bd1a72d7a8e0973f463add210be14063c8a9c37632022061bfa677f825ded82ba0863fb0c46ca1388dd3e647f6a93c038168b59d131a5101';
+      var sigbuf = new Buffer(sighex, 'hex');
+      Signature.isTxDER(sigbuf).should.equal(true);
+    });
 
+    it('should know this is not a DER signature', function() {
+      //for more extensive tests, see the script interpreter
+      var sighex = '3042021e17cfe77536c3fb0526bd1a72d7a8e0973f463add210be14063c8a9c37632022061bfa677f825ded82ba0863fb0c46ca1388dd3e647f6a93c038168b59d131a5101';
+      var sigbuf = new Buffer(sighex, 'hex');
+      sigbuf[0] = 0x31;
+      Signature.isTxDER(sigbuf).should.equal(false);
+    });
+  });
+  describe('#hasLowS', function() {
+    it('should detect high and low S', function() {
+      var r = BN('63173831029936981022572627018246571655303050627048489594159321588908385378810');
+      var s = BN('4331694221846364448463828256391194279133231453999942381442030409253074198130');
+      var s2 = BN('7FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF5D576E7357A4501DDFE92F46681B2000');
+      var sig = new Signature({
+        r: r,
+        s: s
+      });
+      var sig2 = new Signature({
+        r: r,
+        s: s2
+      });
+      sig2.hasLowS().should.equal(true);
+      sig.hasLowS().should.equal(false);
+
+    });
   });
 
 });

test/script.js

@@ -524,4 +524,20 @@ describe('Script', function() {
     });
   });
 
+
+  describe('#findAndDelete', function() {
+    it('should find and delete this buffer', function() {
+      Script('OP_RETURN 2 0xf0f0')
+        .findAndDelete(Script('2 0xf0f0'))
+        .toString()
+        .should.equal('OP_RETURN');
+    });
+    it('should do nothing', function() {
+      Script('OP_RETURN 2 0xf0f0')
+        .findAndDelete(Script('2 0xffff'))
+        .toString()
+        .should.equal('OP_RETURN 2 0xf0f0');
+    });
+  });
+
 });

test/script_interpreter.js

@@ -243,6 +243,7 @@ describe('ScriptInterpreter', function() {
         var spendtx = Transaction();
 
         var interp = ScriptInterpreter();
+        console.log(scriptSig.toString() + ' ' + scriptPubkey.toString());
         var verified = interp.verify(scriptSig, scriptPubkey, spendtx, 0, flags);
         console.log(interp.errstr);
         verified.should.equal(true);