GoogleOauth2.0 First implementation

First try for GoogleOauth2.0

express-server/node_modules/keygrip/index.js

@@ -0,0 +1,71 @@
+/*!
+ * keygrip
+ * Copyright(c) 2011-2014 Jed Schmidt
+ * MIT Licensed
+ */
+
+'use strict'
+
+var crypto = require("crypto")
+  
+function Keygrip(keys, algorithm, encoding) {
+  if (!algorithm) algorithm = "sha1";
+  if (!encoding) encoding = "base64";
+  if (!(this instanceof Keygrip)) return new Keygrip(keys, algorithm, encoding)
+
+  if (!keys || !(0 in keys)) {
+    throw new Error("Keys must be provided.")
+  }
+
+  function sign(data, key) {
+    return crypto
+      .createHmac(algorithm, key)
+      .update(data).digest(encoding)
+      .replace(/\/|\+|=/g, function(x) {
+        return ({ "/": "_", "+": "-", "=": "" })[x]
+      })
+  }
+
+  this.sign = function(data){ return sign(data, keys[0]) }
+
+  this.verify = function(data, digest) {
+    return this.index(data, digest) > -1
+  }
+
+  this.index = function(data, digest) {
+    for (var i = 0, l = keys.length; i < l; i++) {
+      if (constantTimeCompare(digest, sign(data, keys[i]))) return i
+    }
+
+    return -1
+  }
+}
+
+Keygrip.sign = Keygrip.verify = Keygrip.index = function() {
+  throw new Error("Usage: require('keygrip')(<array-of-keys>)")
+}
+
+//http://codahale.com/a-lesson-in-timing-attacks/
+var constantTimeCompare = function(val1, val2){
+    if(val1 == null && val2 != null){
+        return false;
+    } else if(val2 == null && val1 != null){
+        return false;
+    } else if(val1 == null && val2 == null){
+        return true;
+    }
+
+    if(val1.length !== val2.length){
+        return false;
+    }
+
+    var result = 0;
+
+    for(var i = 0; i < val1.length; i++){
+        result |= val1.charCodeAt(i) ^ val2.charCodeAt(i); //Don't short circuit
+    }
+
+    return result === 0;
+};
+
+module.exports = Keygrip