LibCrypto: Introduce utility class for OpenSSL backed hashes

This abstract class allows implementing hashes backed by OpenSSL with
very few lines of code, see next commit.

Libraries/LibCrypto/Hash/OpenSSLHashFunction.h

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2024, Altomani Gianluca <[email protected]>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/ByteString.h>
+#include <AK/NonnullOwnPtr.h>
+#include <AK/Types.h>
+#include <LibCrypto/Hash/HashFunction.h>
+
+#include <openssl/evp.h>
+
+namespace Crypto::Hash {
+
+template<typename T, size_t BlockS, size_t DigestS, typename DigestT = Digest<DigestS>>
+class OpenSSLHashFunction : public HashFunction<BlockS, DigestS, DigestT> {
+    AK_MAKE_NONCOPYABLE(OpenSSLHashFunction);
+
+public:
+    using HashFunction<BlockS, DigestS, DigestT>::update;
+
+    static NonnullOwnPtr<T> create()
+    {
+        auto* context = EVP_MD_CTX_new();
+        return make<T>(context);
+    }
+
+    explicit OpenSSLHashFunction(EVP_MD const* type, EVP_MD_CTX* context)
+        : m_type(type)
+        , m_context(context)
+    {
+        OpenSSLHashFunction::reset();
+    }
+
+    virtual ~OpenSSLHashFunction() override
+    {
+        EVP_MD_CTX_free(m_context);
+    }
+
+    virtual ByteString class_name() const override = 0;
+
+    void update(u8 const* input, size_t length) override
+    {
+        VERIFY(EVP_DigestUpdate(m_context, input, length));
+    }
+
+    DigestT digest() override
+    {
+        DigestT digest;
+        VERIFY(EVP_DigestFinal_ex(m_context, digest.data, nullptr));
+        reset();
+        return digest;
+    }
+
+    DigestT peek() override
+    {
+        auto c = copy();
+        return c->digest();
+    }
+
+    void reset() override
+    {
+        VERIFY(EVP_DigestInit_ex(m_context, m_type, nullptr));
+    }
+
+    virtual NonnullOwnPtr<T> copy() const
+    {
+        auto context = create();
+        VERIFY(EVP_MD_CTX_copy_ex(context->m_context, m_context));
+        return context;
+    }
+
+    static DigestT hash(u8 const* data, size_t length)
+    {
+        auto md5 = create();
+        md5->update(data, length);
+        return md5->digest();
+    }
+
+    static DigestT hash(ByteBuffer const& buffer) { return hash(buffer.data(), buffer.size()); }
+    static DigestT hash(StringView buffer) { return hash((u8 const*)buffer.characters_without_null_termination(), buffer.length()); }
+
+private:
+    EVP_MD const* m_type;
+    EVP_MD_CTX* m_context;
+};
+
+}