diff --git a/Script.js b/Script.js
index bce3f11..fe59127 100644
--- a/Script.js
+++ b/Script.js
@@ -66,6 +66,15 @@ function spec(b) {
     }
   };
 
+  Script.prototype.isPushOnly = function ()
+  {
+    for (var i = 0; i < this.chunks.length; i++)
+      if (!Buffer.isBuffer(this.chunks[i]))
+        return false;
+
+    return true;
+  };
+
   Script.prototype.isP2SH = function ()
   {
     return (this.chunks.length == 3 &&
diff --git a/ScriptInterpreter.js b/ScriptInterpreter.js
index e90796d..86ffe5c 100644
--- a/ScriptInterpreter.js
+++ b/ScriptInterpreter.js
@@ -1,6 +1,7 @@
 require('classtool');
 
 function spec(b) {
+  var assert = require('assert');
   var config = b.config || require('./config');
   var log = b.log || require('./util/log')(config);
 
@@ -758,6 +759,11 @@ function spec(b) {
     return this.stack[this.stack.length-offset];
   };
 
+  ScriptInterpreter.prototype.stackBack = function stackBack() 
+  {
+    return this.stack[-1];
+  };
+
   /**
    * Pop the top element off the stack and return it.
    */
@@ -911,6 +917,88 @@ function spec(b) {
     return si;
   };
 
+  function verifyStep4(scriptSig, scriptPubKey, txTo, nIn,
+		       hashType, opts, callback, si, siCopy)
+  {
+	if (siCopy.stack.length == 0) {
+		callback(null, false);
+		return;
+	}
+	
+	callback(null, castBool(siCopy.stackBack()));
+  }
+
+  function verifyStep3(scriptSig, scriptPubKey, txTo, nIn,
+		       hashType, opts, callback, si, siCopy)
+  {
+	if (si.stack.length == 0) {
+		callback(null, false);
+		return;
+	}
+  	if (castBool(si.stackBack()) == false) {
+		callback(null, false);
+		return;
+	}
+
+	// if not P2SH, we're done
+	if (!opts.verifyP2SH || !scriptPubKey.isP2SH()) {
+		callback(null, true);
+		return;
+	}
+
+	if (!scriptSig.isPushOnly()) {
+		callback(null, false);
+		return;
+	}
+
+	assert.notEqual(siCopy.length, 0);
+
+	var subscript = new Script(siCopy.stackPop());
+
+	ok = true;
+	siCopy.eval(subscript, txTo, nIn, hashType, function (err) {
+		if (err)
+			callback(err);
+		else
+			verifyStep4(scriptSig, scriptPubKey, txTo, nIn,
+				    hashType, opts, callback, si, siCopy);
+	});
+  }
+
+  function verifyStep2(scriptSig, scriptPubKey, txTo, nIn,
+		       hashType, opts, callback, si, siCopy)
+  {
+	if (opts.verifyP2SH) {
+		si.stack.forEach(function(item) {
+			siCopy.stack.push(item);
+		});
+	}
+
+	si.eval(scriptPubKey, txTo, nIn, hashType, function (err) {
+		if (err)
+			callback(err);
+		else
+			verifyStep3(scriptSig, scriptPubKey, txTo, nIn,
+				    hashType, opts, callback, si, siCopy);
+	});
+  }
+
+  ScriptInterpreter.verifyFull =
+  function verifyFull(scriptSig, scriptPubKey, txTo, nIn, hashType,
+  		      opts, callback)
+  {
+  	var si = new ScriptInterpreter();
+  	var siCopy = new ScriptInterpreter();
+
+	si.eval(scriptSig, txTo, nIn, hashType, function (err) {
+		if (err)
+			callback(err);
+		else
+			verifyStep2(scriptSig, scriptPubKey, txTo, nIn,
+				    hashType, opts, callback, si, siCopy);
+	});
+  };
+
   var checkSig = ScriptInterpreter.checkSig =
   function (sig, pubkey, scriptCode, tx, n, hashType, callback) {
     if (!sig.length) {