diff --git a/lib_btc.js b/lib_btc.js
index 3449269..7c8c588 100644
--- a/lib_btc.js
+++ b/lib_btc.js
@@ -2651,6 +2651,15 @@
 
             return coinjs.verifySignature(h1, s1, p2);
         }
+
+        coinjs.dSHA256 = function(data){
+            var t1,t2,t3 ;
+            t1= Crypto.SHA256(Crypto.util.hexToBytes(data));
+            t2= Crypto.util.hexToBytes(t1);
+            t3= Crypto.SHA256(t2);
+            return t3;
+        }
+
         coinjs.random = function (length) {
             var r = "";
             var l = length || 25;