diff --git a/Chaos/Hash/Hasher.hpp b/Chaos/Hash/Hasher.hpp
index 796c02f..778bea5 100644
--- a/Chaos/Hash/Hasher.hpp
+++ b/Chaos/Hash/Hasher.hpp
@@ -1,42 +1,19 @@
 #ifndef CHAOS_HASH_HASHER_HPP
 #define CHAOS_HASH_HASHER_HPP
 
+#include <cstdint>
+
+#include "Hash.hpp"
+
 namespace Chaos::Hash
 {
 
 template<typename T>
-class Hasher
+concept Hasher = requires(T hasher, uint8_t * begin, uint8_t * end)
 {
-public:
-    void Reset()
-    {
-        Impl().Reset();
-    }
-
-    template<typename InputIt>
-    void Update(InputIt begin, InputIt end)
-    {
-        Impl().Update(begin, end);
-    }
-
-    auto Finish()
-    {
-        return Impl().Finish();
-    }
-
-protected:
-    Hasher() = default;
-
-private:
-    const T & Impl() const
-    {
-        return static_cast<const T &>(*this);
-    }
-
-    T & Impl()
-    {
-        return static_cast<T &>(*this);
-    }
+    hasher.Reset();
+    hasher.Update(begin, end);
+    { hasher.Finish() } -> Hash;
 };
 
 } // namespace Chaos::Hash
diff --git a/Chaos/Hash/Md4.hpp b/Chaos/Hash/Md4.hpp
index d6528d5..e78dec3 100644
--- a/Chaos/Hash/Md4.hpp
+++ b/Chaos/Hash/Md4.hpp
@@ -163,7 +163,7 @@ struct Md4Hash
 
 static_assert(Hash<Md4Hash>);
 
-class Md4Hasher : public Hasher<Md4Hasher>
+class Md4Hasher
 {
 public:
     using HashType = Md4Hash;
@@ -304,6 +304,8 @@ private:
     }
 };
 
+static_assert(Hasher<Md4Hasher>);
+
 } // namespace Chaos::Hash::Md4
 
 #endif // CHAOS_HASH_MD4_HPP
diff --git a/Chaos/Hash/Md5.hpp b/Chaos/Hash/Md5.hpp
index ecdb288..cb1be91 100644
--- a/Chaos/Hash/Md5.hpp
+++ b/Chaos/Hash/Md5.hpp
@@ -187,7 +187,7 @@ struct Md5Hash
 
 static_assert(Hash<Md5Hash>);
 
-class Md5Hasher : public Hasher<Md5Hasher>
+class Md5Hasher
 {
 public:
     using HashType = Md5Hash;
@@ -328,6 +328,8 @@ private:
     }
 };
 
+static_assert(Hasher<Md5Hasher>);
+
 } // namespace Chaos::Hash::Md5
 
 #endif // CHAOS_HASH_MD5_HPP
diff --git a/Chaos/Hash/Sha1.hpp b/Chaos/Hash/Sha1.hpp
index ee99e83..ad743d8 100644
--- a/Chaos/Hash/Sha1.hpp
+++ b/Chaos/Hash/Sha1.hpp
@@ -157,7 +157,7 @@ struct Sha1Hash
 
 static_assert(Hash<Sha1Hash>);
 
-class Sha1Hasher : public Hasher<Sha1Hasher>
+class Sha1Hasher
 {
 public:
     using HashType = Sha1Hash;
@@ -298,6 +298,8 @@ private:
     }
 };
 
+static_assert(Hasher<Sha1Hasher>);
+
 } // namespace Chaos::Hash::Sha1
 
 #endif // CHAOS_HASH_SHA1_HPP
diff --git a/Chaos/Mac/Hmac.hpp b/Chaos/Mac/Hmac.hpp
index 125bb3a..82ecc7e 100644
--- a/Chaos/Mac/Hmac.hpp
+++ b/Chaos/Mac/Hmac.hpp
@@ -3,7 +3,6 @@
 
 #include <array>
 #include <cstdint>
-#include <type_traits>
 
 #include "Hash/Hasher.hpp"
 #include "Service/ChaosException.hpp"
@@ -11,8 +10,7 @@
 namespace Chaos::Mac::Hmac
 {
 
-template<typename HasherImpl,
-         typename = std::enable_if_t<std::is_base_of_v<Hash::Hasher<HasherImpl>, HasherImpl>>>
+template<Hash::Hasher HasherImpl>
 class Hmac
 {
 public: