use crypto random numbers

node_modules/kaefer/lib/server.js

@@ -78,7 +78,7 @@ Server.prototype.getConnection = function(id) {
         }
     }
     
-    id = util.uid();
+    id = util.uid(10);
     transport = this.sockets[id] = new ReliableSocket(new ReconnectSocket(), this.socketOptions);
     transport.on("disconnect", this.disconnect.bind(this, transport));
     transport.id = id;

node_modules/kaefer/lib/util.js

@@ -4,8 +4,31 @@ exports.inherits = function(Child, Parent) {
   Child.prototype = Object.create(Parent.prototype, { constructor: { value: Child }});
 }
 
-exports.uid = function() {
-    return (Date.now() + Math.random() * 0x100000000).toString(36) + (Math.random() * 0x100000000).toString(36);
+var isNode = (typeof global !== "undefined" && ({}).toString.call(global) == '[object global]');
+var isBrowser = (typeof window !== "undefined" && ({}).toString.call(window) == '[object window]');
+
+if (isNode) {
+    exports.uid = function(length) {
+        return (require("crypto")
+            .randomBytes(length)
+            .toString("base64")
+            .slice(0, length)
+        );
+    };
+} else if (isBrowser && window.crypto && window.crypto.getRandomValues) {
+    exports.uid = function(length) {
+        var values = new Uint8Array(length);
+        window.crypto.getRandomValues(values);
+        return btoa(String.fromCharCode.apply(null, values)).slice(0, 10);
+    };
+} else {
+    exports.uid = function(length) {
+        var arr = [];
+        for (var i = 0; i < length; i++) {
+            arr[i] = Math.floor(Math.random() * 255);
+        }
+        return btoa(String.fromCharCode.apply(null, values)).slice(0, 10);
+    };
 }
 
 });