mac使用sha256算法,读取pem公钥文件的签名函数,c++实现
时间: 2024-05-04 22:20:13 浏览: 7
以下是使用 OpenSSL 库在 C++ 中实现读取 pem 公钥文件的 SHA256 签名函数的示例代码:
```cpp
#include <iostream>
#include <fstream>
#include <openssl/evp.h>
#include <openssl/pem.h>
#include <openssl/sha.h>
std::string sha256(const std::string& message, const std::string& publicKeyPath) {
// 读取公钥文件
std::ifstream publicKeyFile(publicKeyPath);
if (!publicKeyFile.is_open()) {
std::cerr << "Error: failed to open public key file." << std::endl;
return "";
}
std::string publicKeyStr((std::istreambuf_iterator<char>(publicKeyFile)), std::istreambuf_iterator<char>());
publicKeyFile.close();
// 转换公钥字符串为 EVP_PKEY 对象
BIO* publicKeyBio = BIO_new_mem_buf(publicKeyStr.c_str(), -1);
EVP_PKEY* publicKey = PEM_read_bio_PUBKEY(publicKeyBio, nullptr, nullptr, nullptr);
BIO_free(publicKeyBio);
if (!publicKey) {
std::cerr << "Error: failed to read public key." << std::endl;
return "";
}
// 计算 SHA256 摘要
EVP_MD_CTX* mdCtx = EVP_MD_CTX_new();
EVP_DigestInit(mdCtx, EVP_sha256());
EVP_DigestUpdate(mdCtx, message.c_str(), message.length());
unsigned char digest[SHA256_DIGEST_LENGTH];
unsigned int digestLen;
EVP_DigestFinal(mdCtx, digest, &digestLen);
EVP_MD_CTX_free(mdCtx);
// 使用公钥进行签名
size_t sigLen = EVP_PKEY_size(publicKey);
unsigned char* sig = new unsigned char[sigLen];
EVP_MD_CTX* sigCtx = EVP_MD_CTX_new();
EVP_SignInit(sigCtx, EVP_sha256());
EVP_SignUpdate(sigCtx, digest, digestLen);
int sigLenActual;
if (!EVP_SignFinal(sigCtx, sig, (unsigned int*)&sigLenActual, publicKey)) {
std::cerr << "Error: failed to sign message." << std::endl;
return "";
}
EVP_MD_CTX_free(sigCtx);
std::string signature((char*)sig, sigLenActual);
delete[] sig;
EVP_PKEY_free(publicKey);
return signature;
}
```
使用示例:
```cpp
std::string message = "Hello, World!";
std::string publicKeyPath = "/path/to/public/key.pem";
std::string signature = sha256(message, publicKeyPath);
std::cout << "Signature: " << signature << std::endl;
```
请注意,此示例仅适用于 RSA 公钥,如果您使用的是其他类型的公钥,请相应更改公钥读取和签名代码。