diff --git a/Chaos/Cipher/Des/DesCrypt.hpp b/Chaos/Cipher/Des/DesCrypt.hpp
index e9ac70f..b2dda46 100644
--- a/Chaos/Cipher/Des/DesCrypt.hpp
+++ b/Chaos/Cipher/Des/DesCrypt.hpp
@@ -280,6 +280,11 @@ public:
             Inner_::Bitwise::CrunchUInt64(out, decrypted);
         }
 
+        uint64_t DecryptBlock(uint64_t block)
+        {
+            return DesCrypt::ProcessBlock(block, Schedule_);
+        }
+
     private:
         Inner_::KeySchedule Schedule_;
     };
diff --git a/ChaosTests/Cipher/DesCryptTests.cpp b/ChaosTests/Cipher/DesCryptTests.cpp
index aad6d27..b98a502 100644
--- a/ChaosTests/Cipher/DesCryptTests.cpp
+++ b/ChaosTests/Cipher/DesCryptTests.cpp
@@ -245,6 +245,50 @@ TEST(DesCryptTests, DecryptTest)
     }
 }
 
+TEST(DesCryptTests, DecryptUInt64BlockTest)
+{
+    struct Helper
+    {
+        uint64_t operator()(uint64_t data,
+                            const std::array<uint8_t, 8> & key) const
+        {
+            DesCrypt::Key desKey(key.begin(), key.end());
+            DesCrypt::Decryptor dec(desKey);
+
+            return dec.DecryptBlock(data);
+        }
+    };
+
+    Helper des;
+
+    {
+        uint64_t data = 0x85e813540f0ab405;
+        std::array<uint8_t, 8> key = { 0x13, 0x34, 0x57, 0x79, 0x9b, 0xbc, 0xdf, 0xf1 };
+
+        uint64_t expected = 0x0123456789abcdef;
+
+        ASSERT_EQ(expected, des(data, key));
+    }
+
+    {
+        uint64_t data = 0x07e87faab3171318;
+        std::array<uint8_t, 8> key = { 0x44, 0xbf, 0x32, 0x19, 0x99, 0x25, 0x81, 0x51 };
+
+        uint64_t expected = 0xaaf383162d2e6bcb;
+
+        ASSERT_EQ(expected, des(data, key));
+    }
+
+    {
+        uint64_t data = 0x422788a67b6c18ed;
+        std::array<uint8_t, 8> key = { 0xda, 0xec, 0x68, 0xae, 0x83, 0xe0, 0x1e, 0xab };
+
+        uint64_t expected = 0xe51a9fd419a79344;
+
+        ASSERT_EQ(expected, des(data, key));
+    }
+}
+
 TEST(DesCryptTests, DecryptShortDataTest)
 {
     struct Helper