Merge pull request #50 from mikepb/v2

Fix totp.verifyDelta() returning incorrect delta

index.js

@@ -167,6 +167,11 @@ exports.hotp.verifyDelta = function hotpVerifyDelta (options) {
   // parse token to integer
   token = parseInt(token, 10);
 
+  // fail if token is NA
+  if (isNaN(token)) {
+    return;
+  }
+
   // loop from C to C + W inclusive
   for (i = counter; i <= counter + window; ++i) {
     options.counter = i;
@@ -339,7 +344,14 @@ exports.totp.verifyDelta = function totpVerifyDelta (options) {
   options.window += window;
 
   // pass to hotp.verifyDelta
-  return exports.hotp.verifyDelta(options);
+  var delta = exports.hotp.verifyDelta(options);
+
+  // adjust for two-sided window
+  if (delta) {
+    delta.delta -= window;
+  }
+
+  return delta;
 };
 
 /**

test/hotp_test.js

@@ -73,4 +73,30 @@ describe('HOTP Counter-Based Algorithm Test', function () {
       assert.equal(topic, '90693936');
     });
   });
+
+  describe('hotp.verifyDelta()', function () {
+    var secret = 'rNONHRni6BAk7y2TiKrv';
+    it('should get current TOTP value', function () {
+      this.token = speakeasy.totp({secret: secret, counter: 1});
+      assert.equal(this.token, '314097');
+    });
+    it('should get delta with varying window lengths', function () {
+      var delta;
+
+      delta = speakeasy.totp.verifyDelta({
+        secret: secret, token: '314097', counter: 1, window: 0
+      });
+      assert.isObject(delta); assert.strictEqual(delta.delta, 0);
+
+      delta = speakeasy.totp.verifyDelta({
+        secret: secret, token: '314097', counter: 1, window: 2
+      });
+      assert.isObject(delta); assert.strictEqual(delta.delta, 0);
+
+      delta = speakeasy.totp.verifyDelta({
+        secret: secret, token: '314097', counter: 1, window: 3
+      });
+      assert.isObject(delta); assert.strictEqual(delta.delta, 0);
+    });
+  });
 });