Merge pull request #11315 from pauljt/bug888911

Bug 888911 -  Implement an increasing lockout delay to prevent passcode

apps/system/js/lockscreen.js

@@ -74,6 +74,11 @@ var LockScreen = {
   */
   kPassCodeErrorTimeout: 500,
 
+  /*
+  * Counter after incorrect attempt
+  */
+  kPassCodeErrorCounter: 0,
+
   /*
   * Airplane mode
   */
@@ -982,6 +987,8 @@ var LockScreen = {
       var self = this;
       this.overlay.dataset.passcodeStatus = 'success';
       this.passCodeError = 0;
+      this.kPassCodeErrorTimeout = 500;
+      this.kPassCodeErrorCounter = 0;
 
       var transitionend = function() {
         self.passcodeCode.removeEventListener('transitionend', transitionend);
@@ -990,6 +997,11 @@ var LockScreen = {
       this.passcodeCode.addEventListener('transitionend', transitionend);
     } else {
       this.overlay.dataset.passcodeStatus = 'error';
+      this.kPassCodeErrorCounter++;
+      //double delay if >5 failed attempts
+      if (this.kPassCodeErrorCounter > 5) {
+        this.kPassCodeErrorTimeout = 2 * this.kPassCodeErrorTimeout;
+      }
       if ('vibrate' in navigator)
         navigator.vibrate([50, 50, 50]);