Generate HMAC SHA256 hash using key in C++

Question

I am looking for some function or a way that would return HMAC SHA256 hash in C++ using secret key. I have seen documentation of Crypto++ and OpenSSL but it does not accept an extra parameter of secret key for computation. Can someone help me by providing some info, code snippets or links.

Answer 1

You can use POCO library

Sample code:

class SHA256Engine : public Poco::Crypto::DigestEngine
{
public:
    enum
    {
        BLOCK_SIZE = 64,
        DIGEST_SIZE = 32
    };

    SHA256Engine()
            : DigestEngine("SHA256")
    {
    }

};


Poco::HMACEngine<SHA256Engine> hmac{secretKey};
hmac.update(string);

std::cout << "HMACE hex:" << Poco::DigestEngine::digestToHex(hmac.digest()) << std::endl;// lookout difest() calls reset ;)

Sample integration with POCO using cmake install:

mkdir build_poco/
cd build_poco/ && cmake -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=./install ../poco/

CMakeLists.txt

CMAKE_MINIMUM_REQUIRED(VERSION 3.8)
PROJECT(SamplePoco)

SET(CMAKE_CXX_STANDARD 14)

SET(SOURCE_FILES
        src/main.cpp
        )

SET(_IMPORT_PREFIX lib/build_poco/install)

INCLUDE(lib/build_poco/install/lib/cmake/Poco/PocoFoundationTargets.cmake)
INCLUDE(lib/build_poco/install/lib/cmake/Poco/PocoNetTargets.cmake)
INCLUDE(lib/build_poco/install/lib/cmake/Poco/PocoJSONTargets.cmake)
INCLUDE(lib/build_poco/install/lib/cmake/Poco/PocoXMLTargets.cmake)
INCLUDE(lib/build_poco/install/lib/cmake/Poco/PocoCryptoTargets.cmake)
INCLUDE(lib/build_poco/install/lib/cmake/Poco/PocoUtilTargets.cmake)
INCLUDE(lib/build_poco/install/lib/cmake/Poco/PocoNetSSLTargets.cmake)


ADD_EXECUTABLE(SamplePoco ${SOURCE_FILES})
TARGET_LINK_LIBRARIES(SamplePoco
        Poco::Foundation
        Poco::Crypto
        Poco::Util
        Poco::JSON
        Poco::NetSSL
        )
TARGET_INCLUDE_DIRECTORIES(SamplePoco PUBLIC src/)

Sample implementation used here: https://github.com/gelldur/abucoins-api-cpp