LibCrypto: Implement HMAC

Author: https://github.com/alimpfard
Commit: f2cd004d11
Pull-request: https://github.com/SerenityOS/serenity/pull/1661
Reviewed-by: https://github.com/Dexesttp
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/itamar8910

Libraries/LibCrypto/Cipher/Mode/CBC.h

@@ -26,6 +26,8 @@
 
 #pragma once
 
+#include <AK/String.h>
+#include <AK/StringBuilder.h>
 #include <LibCrypto/Cipher/Mode/Mode.h>
 
 namespace Crypto {
@@ -40,6 +42,14 @@ namespace Cipher {
         {
         }
 
+        virtual String class_name() const override
+        {
+            StringBuilder builder;
+            builder.append(this->cipher().class_name());
+            builder.append("_CBC");
+            return builder.build();
+        }
+
         virtual Optional<ByteBuffer> encrypt(const ByteBuffer& in, ByteBuffer& out, Optional<ByteBuffer> ivec = {}) override
         {
             auto length = in.size();