From 3dacd57fef88563c8e61e2645fe38bbfe4e9d071 Mon Sep 17 00:00:00 2001
From: hashlag <hashlag@hashlag.local>
Date: Sun, 6 Sep 2026 02:45:45 +0300
Subject: [PATCH] Replace Decryptor CRTP base with a concept.

---
 Chaos/Cipher/Block/Decryptor.hpp              | 49 ++++++-------------
 Chaos/Cipher/Block/Des/DesCrypt.hpp           |  4 +-
 ChaosTests/Cipher/Block/Des/DesCryptTests.cpp | 18 +++----
 3 files changed, 28 insertions(+), 43 deletions(-)

diff --git a/Chaos/Cipher/Block/Decryptor.hpp b/Chaos/Cipher/Block/Decryptor.hpp
index e27c130..d3eeb23 100644
--- a/Chaos/Cipher/Block/Decryptor.hpp
+++ b/Chaos/Cipher/Block/Decryptor.hpp
@@ -1,44 +1,27 @@
 #ifndef CHAOS_CIPHER_BLOCK_DECRYPTOR_HPP
 #define CHAOS_CIPHER_BLOCK_DECRYPTOR_HPP
 
+#include <concepts>
+#include <cstdint>
+#include <type_traits>
+
 namespace Chaos::Cipher::Block
 {
 
 template<typename T>
-class Decryptor
+concept Decryptor = requires(T decryptor,
+                             typename T::Block block,
+                             uint8_t * outBegin, uint8_t * outEnd,
+                             uint8_t * inBegin, uint8_t * inEnd)
 {
-public:
-    template<typename OutputIt, typename InputIt>
-    void DecryptBlock(OutputIt outBegin, OutputIt outEnd,
-                      InputIt inBegin, InputIt inEnd) const
-    {
-        Impl().DecryptBlock(outBegin, outEnd, inBegin, inEnd);
-    }
-
-    template<typename Block>
-    auto DecryptBlock(Block block) const
-    {
-        return Impl().DecryptBlock(block);
-    }
-
-    auto GetBlockSize() const
-    {
-        return Impl().GetBlockSize();
-    }
-
-protected:
-    Decryptor() = default;
-
-private:
-    const T & Impl() const
-    {
-        return static_cast<const T &>(*this);
-    }
-
-    T & Impl()
-    {
-        return static_cast<T &>(*this);
-    }
+    typename T::Block;
+    typename T::Key;
+    requires std::constructible_from<T, typename T::Key>;
+    requires std::unsigned_integral<std::remove_cvref_t<decltype(T::BlockSize)>>;
+    requires std::unsigned_integral<std::remove_cvref_t<decltype(T::KeySize)>>;
+    decryptor.DecryptBlock(outBegin, outEnd, inBegin, inEnd);
+    { decryptor.DecryptBlock(block) } -> std::same_as<typename T::Block>;
+    { decryptor.GetBlockSize() } -> std::unsigned_integral;
 };
 
 } // namespace Chaos::Cipher::Block
diff --git a/Chaos/Cipher/Block/Des/DesCrypt.hpp b/Chaos/Cipher/Block/Des/DesCrypt.hpp
index b6d72db..de6119f 100644
--- a/Chaos/Cipher/Block/Des/DesCrypt.hpp
+++ b/Chaos/Cipher/Block/Des/DesCrypt.hpp
@@ -281,7 +281,7 @@ public:
 
     static_assert(Chaos::Cipher::Block::Encryptor<Encryptor>);
 
-    class Decryptor : public Chaos::Cipher::Block::Decryptor<Decryptor>
+    class Decryptor
     {
     public:
         using Block = DesCrypt::Block;
@@ -327,6 +327,8 @@ public:
         Inner_::KeySchedule Schedule_;
     };
 
+    static_assert(Chaos::Cipher::Block::Decryptor<Decryptor>);
+
 private:
     using BlockHalf = uint32_t;
     using RawBlockArray = Service::SeArray<uint8_t, 8>;
diff --git a/ChaosTests/Cipher/Block/Des/DesCryptTests.cpp b/ChaosTests/Cipher/Block/Des/DesCryptTests.cpp
index d525671..7d9b86b 100644
--- a/ChaosTests/Cipher/Block/Des/DesCryptTests.cpp
+++ b/ChaosTests/Cipher/Block/Des/DesCryptTests.cpp
@@ -529,9 +529,9 @@ TEST(DesCryptTests, EncryptUInt64BlockGenericTest)
     ASSERT_EQ(expected, EncryptUInt64BlockGeneric(enc, data));
 }
 
-template<typename Impl, typename InputIt>
-static std::vector<uint8_t> DecryptThroughBase(const Decryptor<Impl> & dec,
-                                               InputIt begin, InputIt end)
+template<Decryptor DecryptorImpl, typename InputIt>
+static std::vector<uint8_t> DecryptGeneric(const DecryptorImpl & dec,
+                                           InputIt begin, InputIt end)
 {
     std::vector<uint8_t> result;
     result.resize(dec.GetBlockSize(), 0);
@@ -540,7 +540,7 @@ static std::vector<uint8_t> DecryptThroughBase(const Decryptor<Impl> & dec,
     return result;
 }
 
-TEST(DesCryptTests, DecryptThroughBaseTest)
+TEST(DesCryptTests, DecryptGenericTest)
 {
     std::array<uint8_t, DesCrypt::KeySize> key = { 0x13, 0x34, 0x57, 0x79, 0x9b, 0xbc, 0xdf, 0xf1 };
 
@@ -550,16 +550,16 @@ TEST(DesCryptTests, DecryptThroughBaseTest)
     DesCrypt::Key desKey(key.begin(), key.end());
     DesCrypt::Decryptor dec(desKey);
 
-    ASSERT_EQ(expected, DecryptThroughBase(dec, data.begin(), data.end()));
+    ASSERT_EQ(expected, DecryptGeneric(dec, data.begin(), data.end()));
 }
 
-template<typename Impl>
-static uint64_t DecryptUInt64BlockThroughBase(const Decryptor<Impl> & dec, uint64_t block)
+template<Decryptor DecryptorImpl>
+static uint64_t DecryptUInt64BlockGeneric(const DecryptorImpl & dec, uint64_t block)
 {
     return dec.DecryptBlock(block);
 }
 
-TEST(DesCryptTests, DecryptUInt64BlockThroughBaseTest)
+TEST(DesCryptTests, DecryptUInt64BlockGenericTest)
 {
     std::array<uint8_t, DesCrypt::KeySize> key = { 0x13, 0x34, 0x57, 0x79, 0x9b, 0xbc, 0xdf, 0xf1 };
 
@@ -569,5 +569,5 @@ TEST(DesCryptTests, DecryptUInt64BlockThroughBaseTest)
     DesCrypt::Key desKey(key.begin(), key.end());
     DesCrypt::Decryptor dec(desKey);
 
-    ASSERT_EQ(expected, DecryptUInt64BlockThroughBase(dec, data));
+    ASSERT_EQ(expected, DecryptUInt64BlockGeneric(dec, data));
 }