使用OpenSSL和C++生成sha256

Question

我正在寻找使用openssl和C++创建sha256的哈希.我知道在使用OpenSSL库的C++中生成SHA哈希的帖子类似,但我希望专门创建sha256.

更新:

似乎是包含路径的问题.即使我包含它也找不到任何OpenSSL函数

#include "openssl/sha.h"

我在构建中包含了路径

-I/opt/ssl/include/ -L/opt/ssl/lib/ -lcrypto 

Answer 1

我是这样做的:

void sha256_hash_string (unsigned char hash[SHA256_DIGEST_LENGTH], char outputBuffer[65])
{
    int i = 0;

    for(i = 0; i < SHA256_DIGEST_LENGTH; i++)
    {
        sprintf(outputBuffer + (i * 2), "%02x", hash[i]);
    }

    outputBuffer[64] = 0;
}


void sha256_string(char *string, char outputBuffer[65])
{
    unsigned char hash[SHA256_DIGEST_LENGTH];
    SHA256_CTX sha256;
    SHA256_Init(&sha256);
    SHA256_Update(&sha256, string, strlen(string));
    SHA256_Final(hash, &sha256);
    int i = 0;
    for(i = 0; i < SHA256_DIGEST_LENGTH; i++)
    {
        sprintf(outputBuffer + (i * 2), "%02x", hash[i]);
    }
    outputBuffer[64] = 0;
}

int sha256_file(char *path, char outputBuffer[65])
{
    FILE *file = fopen(path, "rb");
    if(!file) return -534;

    unsigned char hash[SHA256_DIGEST_LENGTH];
    SHA256_CTX sha256;
    SHA256_Init(&sha256);
    const int bufSize = 32768;
    unsigned char *buffer = malloc(bufSize);
    int bytesRead = 0;
    if(!buffer) return ENOMEM;
    while((bytesRead = fread(buffer, 1, bufSize, file)))
    {
        SHA256_Update(&sha256, buffer, bytesRead);
    }
    SHA256_Final(hash, &sha256);

    sha256_hash_string(hash, outputBuffer);
    fclose(file);
    free(buffer);
    return 0;
}

它被称为这样:

static unsigned char buffer[65];
sha256("string", buffer);
printf("%s\n", buffer);

Answer 2

以std为基础

#include <iostream>
#include <iomanip>
#include <sstream>
#include <string>

using namespace std;

#include <openssl/sha.h>
string sha256(const string str)
{
    unsigned char hash[SHA256_DIGEST_LENGTH];
    SHA256_CTX sha256;
    SHA256_Init(&sha256);
    SHA256_Update(&sha256, str.c_str(), str.size());
    SHA256_Final(hash, &sha256);
    stringstream ss;
    for(int i = 0; i < SHA256_DIGEST_LENGTH; i++)
    {
        ss << hex << setw(2) << setfill('0') << (int)hash[i];
    }
    return ss.str();
}

int main() {
    cout << sha256("1234567890_1") << endl;
    cout << sha256("1234567890_2") << endl;
    cout << sha256("1234567890_3") << endl;
    cout << sha256("1234567890_4") << endl;
    return 0;
}

Answer 3

使用OpenSSL的EVP接口(以下内容适用于OpenSSL 1.1):

#include <iomanip>
#include <iostream>
#include <sstream>
#include <string>
#include <openssl/evp.h>

bool computeHash(const std::string& unhashed, std::string& hashed)
{
    bool success = false;

    EVP_MD_CTX* context = EVP_MD_CTX_new();

    if(context != NULL)
    {
        if(EVP_DigestInit_ex(context, EVP_sha256(), NULL))
        {
            if(EVP_DigestUpdate(context, unhashed.c_str(), unhashed.length()))
            {
                unsigned char hash[EVP_MAX_MD_SIZE];
                unsigned int lengthOfHash = 0;

                if(EVP_DigestFinal_ex(context, hash, &lengthOfHash))
                {
                    std::stringstream ss;
                    for(unsigned int i = 0; i < lengthOfHash; ++i)
                    {
                        ss << std::hex << std::setw(2) << std::setfill('0') << (int)hash[i];
                    }

                    hashed = ss.str();
                    success = true;
                }
            }
        }

        EVP_MD_CTX_free(context);
    }

    return success;
}

int main(int, char**)
{
    std::string pw1 = "password1", pw1hashed;
    std::string pw2 = "password2", pw2hashed;
    std::string pw3 = "password3", pw3hashed;
    std::string pw4 = "password4", pw4hashed;

    hashPassword(pw1, pw1hashed);
    hashPassword(pw2, pw2hashed);
    hashPassword(pw3, pw3hashed);
    hashPassword(pw4, pw4hashed);

    std::cout << pw1hashed << std::endl;
    std::cout << pw2hashed << std::endl;
    std::cout << pw3hashed << std::endl;
    std::cout << pw4hashed << std::endl;

    return 0;
}

这种更高级别界面的优点是您只需要将EVP_sha256()调用与另一个摘要的功能交换出来,例如EVP_sha512(),使用不同的摘要.所以它增加了一些灵活性.

Answer 4

随着 OpenSSL 更新到 3.0，大多数解决方案将不起作用（因为 API 已弃用），建议使用这些EVP函数。下面的代码显示了我根据OpenSSL 官方文档对EVP的看法

该实现使用 pureC并经过验证Ubuntu 22.04

/**
 * Simple program to calculate message digest using openssl'l new EVP method
 *
 * Verified on Ubuntu 22.04 on Jan 29, 2023
 *
 * Install dependency:
 * sudo apt install make gcc libssl-dev -y
 *
 * To compile:
 * gcc sha256sum.c -o shasum.out -lcrypto
 *
 * To cross verify:
 * echo -n "Hello world" | sha256sum
 *
 * Author: Daniel Selvan D. <danilselvan@gmail.com>
 */

#include <stdio.h>
#include <string.h>

#include <openssl/evp.h>

// OpenSSL engine implementation
#define OPENSSL_ENGINE NULL

/**
 * Returns the SHA256 value of the input string
 *
 * @param string input string for which the hash to be calculated
 * @returns string (32 bytes) - SHA256 hash
 */
static const unsigned char *getShaSum(const unsigned char *string)
{
    EVP_MD_CTX *mdCtx = EVP_MD_CTX_new();
    unsigned char mdVal[EVP_MAX_MD_SIZE], *md;
    unsigned int mdLen, i;

    if (!EVP_DigestInit_ex(mdCtx, EVP_sha256(), OPENSSL_ENGINE))
    {
        printf("Message digest initialization failed.\n");
        EVP_MD_CTX_free(mdCtx);
        exit(EXIT_FAILURE);
    }

    // Hashes cnt bytes of data at d into the digest context mdCtx
    if (!EVP_DigestUpdate(mdCtx, string, strlen((const char *)string)))
    {
        printf("Message digest update failed.\n");
        EVP_MD_CTX_free(mdCtx);
        exit(EXIT_FAILURE);
    }

    if (!EVP_DigestFinal_ex(mdCtx, mdVal, &mdLen))
    {
        printf("Message digest finalization failed.\n");
        EVP_MD_CTX_free(mdCtx);
        exit(EXIT_FAILURE);
    }
    EVP_MD_CTX_free(mdCtx);

    printf("DEBUG: Digest is: ");
    for (i = 0; i < mdLen; i++)
        printf("%02x", mdVal[i]);
    printf("\n");

    md = mdVal;

    return md;
}

int main()
{
    // To calculate the hash of a file, read it and pass the pointer
    getShaSum("Hello world");

    exit(EXIT_SUCCESS);
}

这个更高级别接口的优点是您只需将调用替换EVP_sha256()为另一个摘要的函数，例如EVP_sha512()，使用不同的摘要。