diff --git a/lib/ecdsa.js b/lib/ecdsa.js
index 552cd7f..8debeb8 100644
--- a/lib/ecdsa.js
+++ b/lib/ecdsa.js
@@ -6,10 +6,10 @@ var Privkey = require('./privkey');
 var Pubkey = require('./pubkey');
 var Random = require('./random');
 
-var ECDSA = function ECDSA(hash, key, sig, k) {
+var ECDSA = function ECDSA(hashbuf, key, sig, k) {
   if (!(this instanceof ECDSA))
-    return new ECDSA(hash, key, sig, k);
-  this.hash = hash;
+    return new ECDSA(hashbuf, key, sig, k);
+  this.hashbuf = hashbuf;
   this.key = key;
   this.sig = sig;
   this.k = k;
@@ -36,8 +36,8 @@ ECDSA.prototype.calci = function() {
 
 ECDSA.prototype.fromString = function(str) {
   var obj = JSON.parse(str);
-  if (obj.hash)
-    this.hash = new Buffer(obj.hash, 'hex');
+  if (obj.hashbuf)
+    this.hashbuf = new Buffer(obj.hashbuf, 'hex');
   if (obj.key)
     this.key = Key().fromString(obj.key);
   if (obj.sig)
@@ -62,7 +62,7 @@ ECDSA.prototype.sig2pubkey = function() {
   if (!(i === 0 || i === 1 || i === 2 || i === 3))
     throw new Error('signature: i must be equal to 0, 1, 2, or 3');
 
-  var e = BN().fromBuffer(this.hash);
+  var e = BN().fromBuffer(this.hashbuf);
   var r = this.sig.r;
   var s = this.sig.s;
 
@@ -103,7 +103,7 @@ ECDSA.prototype.sig2pubkey = function() {
 };
 
 ECDSA.prototype.sigError = function() {
-  if (!Buffer.isBuffer(this.hash) || this.hash.length !== 32)
+  if (!Buffer.isBuffer(this.hashbuf) || this.hashbuf.length !== 32)
     return 'Invalid hash';
 
   try {
@@ -118,7 +118,7 @@ ECDSA.prototype.sigError = function() {
    || !(s.gt(0) && s.lt(Point.getN())))
     return 'r and s not in range';
 
-  var e = BN().fromBuffer(this.hash);
+  var e = BN().fromBuffer(this.hashbuf);
   var n = Point.getN();
   var sinv = s.invm(n);
   var u1 = sinv.mul(e).mod(n);
@@ -135,17 +135,17 @@ ECDSA.prototype.sigError = function() {
 };
 
 ECDSA.prototype.sign = function() {
-  var hash = this.hash;
+  var hashbuf = this.hashbuf;
   var privkey = this.key.privkey;
   var k = this.k;
   var d = privkey.bn;
 
-  if (!hash || !privkey || !k || !d)
+  if (!hashbuf || !privkey || !k || !d)
     throw new Error('ecdsa: invalid parameters');
 
   var N = Point.getN();
   var G = Point.getG();
-  var e = BN().fromBuffer(hash);
+  var e = BN().fromBuffer(hashbuf);
 
   do {
     var Q = G.mul(k);
@@ -164,8 +164,8 @@ ECDSA.prototype.signRandomK = function() {
 
 ECDSA.prototype.toString = function() {
   var obj = {};
-  if (this.hash)
-    obj.hash = this.hash.toString('hex');
+  if (this.hashbuf)
+    obj.hashbuf = this.hashbuf.toString('hex');
   if (this.key)
     obj.key = this.key.toString();
   if (this.sig)