diff --git a/lib/utils.js b/lib/utils.js
index 6eeebbca..214b689b 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -1,5 +1,6 @@
 
 var BN = require('../node_modules/elliptic/node_modules/bn.js/lib/bn.js');
+var hash = require('../node_modules/elliptic/node_modules/hash.js/lib/hash.js');
 
 
 // See: https://github.com/emn178/js-sha3
@@ -180,8 +181,18 @@ function keccak(message) {
 };
 
 // Quick sanity check
-if (keccak(new Buffer('ricmoo')) !== 'b05e424817fb90aa7a79e9da5c5f94070a316219c6ebb863a9ff7ca357dc9fa9') {
-    throw new Error('problem with sh3?!');
+//if (keccak(new Buffer('ricmoo')) !== 'b05e424817fb90aa7a79e9da5c5f94070a316219c6ebb863a9ff7ca357dc9fa9') {
+//    throw new Error('problem with sh3?!');
+//}
+
+function sha256(data) {
+    if (typeof(data) === 'string') {
+        data = new Buffer(data, 'utf8');
+    } else if (!Buffer.isBuffer(data)) {
+        throw new Error('must be a sting');
+    }
+
+    return (new Buffer(hash.sha256().update(data).digest('hex'), 'hex'));
 }
 
 function sha3(data) {
@@ -215,9 +226,17 @@ function bnToBuffer(bn) {
     return stripZeros(new Buffer(hex, 'hex'));
 }
 
+function isHexString(value, length) {
+    if (typeof(value) !== 'string' || !value.match(/^0x[0-9A-Fa-f]*$/)) {
+        return false
+    }
+    if (length && value.length !== 2 + 2 * length) { return false; }
+    return true;
+}
+
 function hexOrBuffer(value, name) {
     if (!Buffer.isBuffer(value)) {
-        if (typeof(value) !== 'string' || !value.match(/^0x[0-9A-Fa-f]*$/)) {
+        if (!isHexString(value)) {
             var error = new Error(name ? ('invalid ' + name) : 'invalid hex or buffer');
             error.reason = 'invalid hex string';
             error.value = value;
@@ -250,9 +269,11 @@ module.exports = {
     defineProperty: defineProperty,
 
     bnToBuffer: bnToBuffer,
+    isHexString: isHexString,
     hexOrBuffer: hexOrBuffer,
     hexlify: hexlify,
     stripZeros: stripZeros,
 
+    sha256: sha256,
     sha3: sha3,
 }