diff --git a/Chaos/Cipher/Arc4/Arc4Crypt.hpp b/Chaos/Cipher/Arc4/Arc4Crypt.hpp
index 3b30d2d..6d0a637 100644
--- a/Chaos/Cipher/Arc4/Arc4Crypt.hpp
+++ b/Chaos/Cipher/Arc4/Arc4Crypt.hpp
@@ -2,6 +2,7 @@
 #define CHAOS_CIPHER_ARC4CRYPT_HPP
 
 #include "Arc4Gen.hpp"
+#include "Service/SeArray.hpp"
 #include "Service/ChaosException.hpp"
 
 namespace Chaos::Cipher::Arc4
@@ -29,13 +30,15 @@ public:
     template<typename OutputIt, typename InputIt>
     void Encrypt(OutputIt out, InputIt in, uint64_t count)
     {
-        // TODO:
+        EnsureInitialized();
+        EncryptDecryptImpl(out, in, count);
     }
 
     template<typename OutputIt, typename InputIt>
     void Decrypt(OutputIt out, InputIt in, uint64_t count)
     {
-        // TODO:
+        EnsureInitialized();
+        EncryptDecryptImpl(out, in, count);
     }
 
 private:
@@ -56,6 +59,25 @@ private:
         Gen_.Rekey(keyBegin, keyEnd);
         IsInitialized_ = true;
     }
+
+    template<typename OutputIt, typename InputIt>
+    void EncryptDecryptImpl(OutputIt out, InputIt in, uint64_t count)
+    {
+        Service::SeArray<uint8_t, 512> keyBuf;
+
+        while (count > 0)
+        {
+            uint64_t keyMaterialBytes = std::min(keyBuf.Size(), count);
+            Gen_.Generate(keyBuf.Begin(), keyMaterialBytes);
+
+            for (auto keyBufIt = keyBuf.Begin();
+                 keyMaterialBytes > 0 && count > 0;
+                 ++keyBufIt, --keyMaterialBytes, --count)
+            {
+                *out++ = *in++ ^ *keyBufIt;
+            }
+        }
+    }
 };
 
 } // namespace Chaos::Cipher::Arc4
diff --git a/ChaosTests/CMakeLists.txt b/ChaosTests/CMakeLists.txt
index d484fc0..6ee8ee2 100644
--- a/ChaosTests/CMakeLists.txt
+++ b/ChaosTests/CMakeLists.txt
@@ -15,6 +15,7 @@ set(ChaosTests_SOURCE Hash/Md4HasherTests.cpp
                       Hash/Md5HasherTests.cpp
                       Mac/HmacTests.cpp
                       Cipher/Arc4GenTests.cpp
+                      Cipher/Arc4CryptTests.cpp
                       Service/SeArrayTests.cpp)
 
 add_executable(ChaosTests ${ChaosTests_SOURCE})
diff --git a/ChaosTests/Cipher/Arc4CryptTests.cpp b/ChaosTests/Cipher/Arc4CryptTests.cpp
new file mode 100644
index 0000000..9f98c6e
--- /dev/null
+++ b/ChaosTests/Cipher/Arc4CryptTests.cpp
@@ -0,0 +1,65 @@
+#include <gtest/gtest.h>
+#include <vector>
+#include <string>
+
+#include "Cipher/Arc4/Arc4Crypt.hpp"
+
+using namespace Chaos::Cipher::Arc4;
+
+static std::vector<uint8_t> StrToU8Vec(const char * str)
+{
+    std::vector<uint8_t> result;
+    result.reserve(strlen(str));
+
+    for (; *str != '\0'; ++str)
+    {
+        result.push_back(static_cast<uint8_t>(*str));
+    }
+
+    return result;
+}
+
+static std::string U8VecToStr(const std::vector<uint8_t> & vec)
+{
+    std::string result;
+    result.reserve(vec.size());
+
+    for (auto it = vec.begin(); it != vec.end(); ++it)
+    {
+        result.push_back(static_cast<char>(*it));
+    }
+
+    return result;
+}
+
+TEST(Arc4CryptTests, BasicTest)
+{
+    const std::vector<uint8_t> key = StrToU8Vec("Secret");
+    const std::vector<uint8_t> data = StrToU8Vec("Attack at dawn");
+
+    std::vector<uint8_t> ciphertext;
+    ciphertext.resize(data.size());
+
+    {
+        Arc4Crypt arc4;
+        arc4.Rekey(key.begin(), key.end());
+
+        arc4.Encrypt(ciphertext.begin(), data.begin(), data.size());
+    }
+
+    ASSERT_EQ(std::vector<uint8_t>({ 0x45, 0xA0, 0x1F, 0x64, 0x5F, 0xC3, 0x5B,
+                                     0x38, 0x35, 0x52, 0x54, 0x4B, 0x9B, 0xF5 }),
+              ciphertext);
+
+    std::vector<uint8_t> recoveredData;
+    recoveredData.resize(data.size());
+
+    {
+        Arc4Crypt arc4;
+        arc4.Rekey(key.begin(), key.end());
+
+        arc4.Decrypt(recoveredData.begin(), ciphertext.begin(), ciphertext.size());
+    }
+
+    ASSERT_EQ(data, recoveredData);
+}