separate hash and hmac functions

Author: dominictarr

create-hash.js

@@ -0,0 +1,30 @@
+
+var algs = {
+  sha1   : require('sha.js/sha1'),
+  sha256 : require('sha.js/sha256'),
+  md5    : toConstructor(require('./md5'))
+}
+
+function toConstructor (fn) {
+  return function () {
+    var buffers = []
+    var m= {
+      update: function (data, enc) {
+        if(!Buffer.isBuffer(data)) data = new Buffer(data, enc)
+        buffers.push(data)
+        return this
+      },
+      digest: function (enc) {
+        var buf = Buffer.concat(buffers)
+        var r = fn(buf)
+        buffers = null
+        return enc ? r.toString(enc) : r
+      }
+    }
+    return m
+  }
+}
+
+module.exports = function (alg) {
+  return new algs[alg]()
+}

create-hmac.js

@@ -0,0 +1,51 @@
+var createHash = require('./create-hash')
+
+var blocksize = 64
+var zeroBuffer = new Buffer(blocksize); zeroBuffer.fill(0)
+
+function hmac(fn, key, data) {
+  if(!Buffer.isBuffer(key)) key = new Buffer(key)
+  if(!Buffer.isBuffer(data)) data = new Buffer(data)
+
+  if(key.length > blocksize) {
+    key = fn(key)
+  } else if(key.length < blocksize) {
+    key = Buffer.concat([key, zeroBuffer], blocksize)
+  }
+
+  var ipad = new Buffer(blocksize), opad = new Buffer(blocksize)
+  for(var i = 0; i < blocksize; i++) {
+    ipad[i] = key[i] ^ 0x36
+    opad[i] = key[i] ^ 0x5C
+  }
+
+  var hash = fn(Buffer.concat([ipad, data]))
+  return fn(Buffer.concat([opad, hash]))
+}
+
+
+module.exports = createHmac
+
+function createHmac (alg, key) {
+  if(!Buffer.isBuffer(key)) key = new Buffer(key)
+//  if(!Buffer.isBuffer(data)) data = new Buffer(data)
+
+  if(key.length > blocksize) {
+    key = createHash(alg).update(key).digest()
+  } else if(key.length < blocksize) {
+    key = Buffer.concat([key, zeroBuffer], blocksize)
+  }
+
+  var ipad = new Buffer(blocksize), opad = new Buffer(blocksize)
+  for(var i = 0; i < blocksize; i++) {
+    ipad[i] = key[i] ^ 0x36
+    opad[i] = key[i] ^ 0x5C
+  }
+  hash = createHash(alg).update(ipad)//.update(data)
+  var digest = hash.digest
+  hash.digest = function (enc) {
+    var h = digest.call(hash)
+    return createHash(alg).update(opad).update(h).digest(enc)
+  }
+  return hash
+}