diff --git a/src/ecdsa.js b/src/ecdsa.js
index 82fd419..c68daa2 100644
--- a/src/ecdsa.js
+++ b/src/ecdsa.js
@@ -1,3 +1,4 @@
+var assert = require('assert')
 var BigInteger = require('./bigi')
 var ECPointFp = require('./ec').ECPointFp
 
@@ -35,7 +36,10 @@ function implShamirsTrick(P, k, Q, l) {
   return R
 }
 
-function deterministicGenerateK(hash,key) {
+function deterministicGenerateK(hash, secret) {
+  assert(Array.isArray(hash))
+  assert(Array.isArray(secret))
+
   var vArr = []
   var kArr = []
   for (var i = 0;i < 32;i++) vArr.push(1)
@@ -43,10 +47,10 @@ function deterministicGenerateK(hash,key) {
   var v = convert.bytesToWordArray(vArr)
   var k = convert.bytesToWordArray(kArr)
 
-  k = HmacSHA256(convert.bytesToWordArray(vArr.concat([0]).concat(key).concat(hash)), k)
+  k = HmacSHA256(convert.bytesToWordArray(vArr.concat([0]).concat(secret).concat(hash)), k)
   v = HmacSHA256(v, k)
   vArr = convert.wordArrayToBytes(v)
-  k = HmacSHA256(convert.bytesToWordArray(vArr.concat([1]).concat(key).concat(hash)), k)
+  k = HmacSHA256(convert.bytesToWordArray(vArr.concat([1]).concat(secret).concat(hash)), k)
   v = HmacSHA256(v,k)
   v = HmacSHA256(v,k)
   vArr = convert.wordArrayToBytes(v)
@@ -54,7 +58,11 @@ function deterministicGenerateK(hash,key) {
 }
 
 var ecdsa = {
+  deterministicGenerateK: deterministicGenerateK,
   sign: function (hash, priv) {
+    if (Buffer.isBuffer(hash)) hash = Array.prototype.slice.call(hash)
+    if (Buffer.isBuffer(priv)) priv = Array.prototype.slice.call(priv)
+
     var d = priv
     var n = ecparams.getN()
     var e = BigInteger.fromBuffer(hash)
diff --git a/test/ecdsa.js b/test/ecdsa.js
index fc5803b..bdb7a44 100644
--- a/test/ecdsa.js
+++ b/test/ecdsa.js
@@ -10,6 +10,18 @@ var ECPubKey = require('..').ECPubKey
 var Message = require('..').Message
 
 describe('ecdsa', function() {
+  // FIXME: needs much better tests than this
+  describe('deterministicGenerateK', function() {
+    it('produces deterministic K values', function() {
+      var secret = [4]
+
+      var k1 = ecdsa.deterministicGenerateK([1], secret)
+      var k2 = ecdsa.deterministicGenerateK([2], secret)
+
+      assert.notDeepEqual(k1, k2)
+    })
+  })
+
   describe('recoverPubKey', function() {
     it('succesfully recovers a public key', function() {
       var addr = 'mgQK8S6CfSXKjPmnujArSmVxafeJfrZsa3'
@@ -24,7 +36,7 @@ describe('ecdsa', function() {
   describe('sign/verify', function() {
     it('Signing and Verifying', function () {
       var s1 = ECKey.makeRandom()
-      var sig_a = s1.sign(BigInteger.ZERO)
+      var sig_a = s1.sign([0])
 
       assert.ok(sig_a, 'Sign null')
       assert.ok(s1.pub.verify(BigInteger.ZERO, sig_a))
@@ -59,7 +71,7 @@ describe('ecdsa', function() {
 
     it('should sign with low S value', function() {
       var priv = ECKey.fromHex('ca48ec9783cf3ad0dfeff1fc254395a2e403cbbc666477b61b45e31d3b8ab458')
-      var message = 'Vires in numeris'
+      var message = new Buffer('Vires in numeris')
       var signature = priv.sign(message)
       var parsed = ecdsa.parseSig(signature)
 
diff --git a/test/eckey.js b/test/eckey.js
index 994d8e8..2549cfc 100644
--- a/test/eckey.js
+++ b/test/eckey.js
@@ -124,7 +124,7 @@ describe('ECKey', function() {
   describe('signing', function() {
     var hpriv = 'ca48ec9783cf3ad0dfeff1fc254395a2e403cbbc666477b61b45e31d3b8ab458'
     var hcpub = '024b12d9d7c77db68388b6ff7c89046174c871546436806bcd80d07c28ea811992'
-    var message = 'Vires in numeris'
+    var message = new Buffer('Vires in numeris')
 
     it('should verify against the private key', function() {
       var priv = ECKey.fromHex(hpriv)