在 C++ 中使用密钥生成 HMAC SHA256 哈希

Question

我正在寻找一些函数或方法 return 使用密钥在 C++ 中进行 HMAC SHA256 散列。我看过 Crypto++ 和 OpenSSL 的文档，但它不接受用于计算的额外密钥参数。谁能提供一些信息、代码片段或链接来帮助我。

Answer 1

HMAC 的 OpenSSL 文档，明确说明 'key' 作为上下文初始化的一部分的要求。

int HMAC_Init_ex(HMAC_CTX *ctx, const void *key, int key_len,
               const EVP_MD *md, ENGINE *impl);

HMAC() computes the message authentication code of the n bytes at d using the hash function evp_md and the key key which is key_len bytes long.

Answer 2

您可以使用POCO library

示例代码：

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 ;)

使用 cmake 安装与 POCO 集成的示例：

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/)

此处使用的示例实现：https://github.com/gelldur/abucoins-api-cpp

Answer 3

以下是使用 Crypto++ 生成 SHA256-HMAC 的函数示例

#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");
}

来源是CME iLink2 specification

Answer 4

为了保持一致性，以下是使用 OpenSSL 生成 SHA256-HMAC 的函数示例

#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};
}

郑重声明，我更喜欢 Crypto++，因为 Crypto++ 生成的二进制文件更小。缺点是Crypto++没有CMake模块。

Answer 5

您可以使用cpp-cryptlite生成HMAC SHA256哈希，以下是代码片段：

std::string src_str = "abcdefg";
std::string secret_key = "xxxxxx";  // this value is an example
boost::uint8_t digest[32];  // cryptlite::sha256::HASH_SIZE
cryptlite::hmac<cryptlite::sha256>::calc(src_str, secret_key, digest);
// and digest is the output hash

Answer 6

我不得不稍微修改@DmytroOvdiienko 的回答以获得十六进制输出：

#include <iomanip>

...

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
    );
    std::stringstream out;
    for (unsigned int i=0; i < hashLen; i++) {
        out << std::setfill('0') << std::setw(2) << std::right << std::hex << (int)hash.data()[i];
    }
    return out.str();
}

int main(int, char**) {
    std::string key = "ESiFg448MqOmhQyxbt6HEHHPnAA1OE8nX0o9ANIVMIvWLISQS0MivDrkZvnBxMEI";
    std::string msg = "foo";
    std::string_view key_view{key};
    std::string_view msg_view{msg};
    std::cout << CalcHmacSHA256(key_view, msg_view) << std::endl;
}

需要 <iomanip>、setfill、setw、right 来确保 single-digit 十六进制值以 0 为前缀。另一种方法是使用提升：

#include <boost/format.hpp>

...

        out << boost::format("%02x") % (int)hash.data()[i];

在 C++ 中使用密钥生成 HMAC SHA256 哈希

Generate HMAC SHA256 hash using key in C++

c++

sha256

hmac

使用 cmake 安装与 POCO 集成的示例：

CMakeLists.txt