Generate HMAC SHA256 hash using key in C++
Solution 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
Solution 2
Following is a sample of function to generate SHA256-HMAC using Crypto++
#include <string>
#include <string_view>
#include <cryptopp/filters.h>
using CryptoPP::StringSink;
using CryptoPP::StringSource;
using CryptoPP::HashFilter;
#include <cryptopp/hmac.h>
using CryptoPP::HMAC;
#include <cryptopp/sha.h>
using CryptoPP::SHA256;
std::string CalcHmacSHA256(std::string_view decodedSecretKey, std::string_view request)
{
// Calculate HMAC
HMAC<SHA256> hmac(reinterpret_cast<CryptoPP::byte const*>(decodedSecretKey.data()), decodedSecretKey.size());
std::string calculated_hmac;
auto sink = std::make_unique<StringSink>(calculated_hmac);
auto filter = std::make_unique<HashFilter>(hmac, sink.get());
sink.release();
StringSource(reinterpret_cast<CryptoPP::byte const*>(request.data()), request.size(), true, filter.get()); // StringSource
filter.release();
return calculated_hmac;
}
#include <iostream>
int main() {
std::cout << CalcHmacSHA256("key", "data");
}
The source is CME iLink2 specification
Solution 3
For consistency, following is a sample of function to generate SHA256-HMAC using OpenSSL
#include <openssl/sha.h>
#include <openssl/hmac.h>
#include <string>
#include <string_view>
#include <array>
std::string CalcHmacSHA256(std::string_view decodedKey, std::string_view msg)
{
std::array<unsigned char, EVP_MAX_MD_SIZE> hash;
unsigned int hashLen;
HMAC(
EVP_sha256(),
decodedKey.data(),
static_cast<int>(decodedKey.size()),
reinterpret_cast<unsigned char const*>(msg.data()),
static_cast<int>(msg.size()),
hash.data(),
&hashLen
);
return std::string{reinterpret_cast<char const*>(hash.data()), hashLen};
}
For the record, I like Crypto++ better as in case of Crypto++ generated binary is smaller. The drawback is that Crypto++ does not have a CMake module.
RDoonds
Updated on June 13, 2022Comments
-
RDoonds about 2 years
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.
-
M.M over 3 yearsThe page you link to doesn't seem to use
make_unique
-
Dmytro Ovdiienko over 3 yearsOnce
HashFilter
object is created I callstd::unique_ptr::release
member function to release ownership fromunique_ptr
toHashFilter
. -
Dmytro Ovdiienko over 3 yearsRight, the CME version of this function does not use
std::unique_ptr
-
M.M over 3 yearsOK, that makes sense
-
Dmytro Ovdiienko over 3 yearsIt depends on boost library. It is neither good nor bad. Just it is.
-
Vincent Guyard about 2 yearsOn MacOS, I am getting error: Undefined symbols for architecture x86_64, "_EVP_sha256", "_HMAC", referenced from ...
-
Dmytro Ovdiienko about 2 years@VincentGuyard Did you pass
-lssl -lcrypto
keys to g++? -
Vincent Guyard about 2 yearsI could deal with this adding theses lines in my CMakeLists.txt: include_directories(/usr/local/opt/openssl@3/include) target_link_libraries(fillerchecker /usr/local/opt/openssl@3/lib/libcrypto.a)
-
Dmytro Ovdiienko about 2 yearsIn order to use openssl in the CMake project, you should use
find_package(OpenSSL REQUIRED)
and thenTARGET_LINK_LIBRARIES (${PROJECT_NAME} OpenSSL::Crypto)