Methods for synchronization

4 files changed, 61 insertions, 0 deletions

diff --git a/TwoStepsAuthenticator.UnitTests/CounterAuthenticatorTests.cs b/TwoStepsAuthenticator.UnitTests/CounterAuthenticatorTests.cs
index 4738ba1..ecb96c0 100644
--- a/TwoStepsAuthenticator.UnitTests/CounterAuthenticatorTests.cs
+++ b/TwoStepsAuthenticator.UnitTests/CounterAuthenticatorTests.cs
@@ -38,5 +38,17 @@ namespace TwoStepsAuthenticator.UnitTests {
 
         }
 
+        [Test]
+        public void VerifyUsedCounter() {
+            var authenticator = new CounterAuthenticator();
+
+            // Test Values from http://www.ietf.org/rfc/rfc4226.txt - Appendix D
+            var base32Secret = Base32Encoding.ToString(Encoding.ASCII.GetBytes("12345678901234567890"));
+
+            long usedCounter;
+            Assert.True(authenticator.CheckCode(base32Secret, "520489", 0L, out usedCounter));
+
+            Assert.AreEqual(usedCounter, 9L);
+        }
     }
 }
diff --git a/TwoStepsAuthenticator.UnitTests/TimeAuthenticatorTests.cs b/TwoStepsAuthenticator.UnitTests/TimeAuthenticatorTests.cs
index 3d19ea2..3dc6d86 100644
--- a/TwoStepsAuthenticator.UnitTests/TimeAuthenticatorTests.cs
+++ b/TwoStepsAuthenticator.UnitTests/TimeAuthenticatorTests.cs
@@ -30,5 +30,20 @@ namespace TwoStepsAuthenticator.UnitTests {
             Assert.IsTrue(authenticator.CheckCode(secret, code));
 
         }
+
+        [Test]
+        public void VerifyUsedTime() {
+            var date = DateTime.Parse("2013-12-05 17:23:50 +0100");
+            var authenticator = new TimeAuthenticator(() => date);
+
+            DateTime usedTime;
+
+            Assert.True(authenticator.CheckCode("H22Q7WAMQYFZOJ2Q", "696227", out usedTime));
+
+            // 17:23:50 - 30s
+            Assert.AreEqual(usedTime.Hour, 17);
+            Assert.AreEqual(usedTime.Minute, 23);
+            Assert.AreEqual(usedTime.Second, 20);
+        }
     }
 }
diff --git a/TwoStepsAuthenticator/CounterAuthenticator.cs b/TwoStepsAuthenticator/CounterAuthenticator.cs
index 90b0ee4..b9ed5d2 100644
--- a/TwoStepsAuthenticator/CounterAuthenticator.cs
+++ b/TwoStepsAuthenticator/CounterAuthenticator.cs
@@ -38,13 +38,31 @@ namespace TwoStepsAuthenticator {
         /// <param name="counter">Current Counter Position</param>
         /// <returns>true if any code from counter to counter + WindowSize matches</returns>
         public bool CheckCode(string secret, string code, long counter) {
+            long successfulSequenceNumber = 0L;
+
+            return CheckCode(secret, code, counter, out successfulSequenceNumber);
+        }
+
+        /// <summary>
+        /// Checks if the passed code is valid.
+        /// </summary>
+        /// <param name="secret">Shared Secret</param>
+        /// <param name="code">OTP</param>
+        /// <param name="counter">Current Counter Position</param>
+        /// <param name="usedCounter">Matching counter value if successful</param>
+        /// <returns>true if any code from counter to counter + WindowSize matches</returns>
+        public bool CheckCode(string secret, string code, long counter, out long usedCounter) {
             var codeMatch = false;
+            long successfulSequenceNumber = 0L;
+
             for (int i = 0; i <= WindowSize; i++) {
                 if (ConstantTimeEquals(GetCode(secret, counter + i), code)) {
                     codeMatch = true;
+                    successfulSequenceNumber = counter + i;
                 }
             }
 
+            usedCounter = successfulSequenceNumber;
             return codeMatch;
         }
     }
diff --git a/TwoStepsAuthenticator/TimeAuthenticator.cs b/TwoStepsAuthenticator/TimeAuthenticator.cs
index a461520..8e8e462 100644
--- a/TwoStepsAuthenticator/TimeAuthenticator.cs
+++ b/TwoStepsAuthenticator/TimeAuthenticator.cs
@@ -45,7 +45,21 @@ namespace TwoStepsAuthenticator {
         /// <param name="code">OTP</param>
         /// <returns>true if code matches</returns>
         public bool CheckCode(string secret, string code) {
+            DateTime successfulTime = DateTime.MinValue;
+
+            return CheckCode(secret, code, out successfulTime);
+        }
+
+        /// <summary>
+        /// Checks if the passed code is valid.
+        /// </summary>
+        /// <param name="secret">Shared Secret</param>
+        /// <param name="code">OTP</param>
+        /// <param name="usedDateTime">Matching time if successful</param>
+        /// <returns>true if code matches</returns>
+        public bool CheckCode(string secret, string code, out DateTime usedDateTime) {
             var baseTime = NowFunc();
+            DateTime successfulTime = DateTime.MinValue;
 
             // We need to do this in constant time
             var codeMatch = false;
@@ -53,9 +67,11 @@ namespace TwoStepsAuthenticator {
                 var checkTime = baseTime.AddSeconds(30 * i);
                 if (ConstantTimeEquals(GetCode(secret, checkTime), code)) {
                     codeMatch = true;
+                    successfulTime = checkTime;
                 }
             }
 
+            usedDateTime = successfulTime;
             return codeMatch;
         }
     }