linux cc++ 使用sm4加密字符串123456并使用加密后的值做base64输出给出加密解密的代码给出实现代码

以下是一个使用sm4加密字符串并进行base64输出的示例代码：

#include <iostream>
#include <openssl/evp.h>
#include <openssl/bio.h>
#include <openssl/buffer.h>
#include <openssl/err.h>
#include <openssl/ssl.h>
#include <openssl/sm4.h>
#include <string.h>

std::string base64_encode(const unsigned char* input, int length) {
    BIO* bmem, *b64;
    BUF_MEM* bptr;

    b64 = BIO_new(BIO_f_base64());
    bmem = BIO_new(BIO_s_mem());
    b64 = BIO_push(b64, bmem);
    BIO_set_flags(b64, BIO_FLAGS_BASE64_NO_NL);
    BIO_write(b64, input, length);
    BIO_flush(b64);
    BIO_get_mem_ptr(b64, &bptr);

    std::string output(bptr->data, bptr->length);
    BIO_free_all(b64);

    return output;
}

std::string base64_decode(const char* input, int length) {
    BIO* b64, *bmem;

    char* buffer = (char*)malloc(length);
    memset(buffer, 0, length);

    b64 = BIO_new(BIO_f_base64());
    bmem = BIO_new_mem_buf(input, length);
    bmem = BIO_push(b64, bmem);
    BIO_set_flags(bmem, BIO_FLAGS_BASE64_NO_NL);
    BIO_read(bmem, buffer, length);

    std::string output(buffer);
    free(buffer);
    BIO_free_all(bmem);

    return output;
}

std::string sm4_encrypt(const std::string& plaintext) {
    unsigned char key[16] = "0123456789ABCDEF";
    unsigned char iv[16] = "0123456789ABCDEF";
    unsigned char ciphertext[100];
    int ciphertext_len;

    EVP_CIPHER_CTX* ctx;
    ctx = EVP_CIPHER_CTX_new();
    EVP_EncryptInit_ex(ctx, EVP_sm4_ecb(), NULL, key, iv);
    EVP_EncryptUpdate(ctx, ciphertext, &ciphertext_len, (const unsigned char*)plaintext.c_str(), plaintext.length());
    EVP_EncryptFinal_ex(ctx, ciphertext + ciphertext_len, &ciphertext_len);
    EVP_CIPHER_CTX_free(ctx);

    std::string output = base64_encode(ciphertext, ciphertext_len);
    return output;
}

std::string sm4_decrypt(const std::string& ciphertext) {
    unsigned char key[16] = "0123456789ABCDEF";
    unsigned char iv[16] = "0123456789ABCDEF";
    unsigned char decryptedtext[100];
    int decryptedtext_len;

    std::string decoded_ciphertext = base64_decode(ciphertext.c_str(), ciphertext.length());

    EVP_CIPHER_CTX* ctx;
    ctx = EVP_CIPHER_CTX_new();
    EVP_DecryptInit_ex(ctx, EVP_sm4_ecb(), NULL, key, iv);
    EVP_DecryptUpdate(ctx, decryptedtext, &decryptedtext_len, (unsigned char*)decoded_ciphertext.c_str(), decoded_ciphertext.length());
    EVP_DecryptFinal_ex(ctx, decryptedtext + decryptedtext_len, &decryptedtext_len);
    EVP_CIPHER_CTX_free(ctx);

    std::string output((char*)decryptedtext);
    return output;
}

int main() {
    std::string plaintext = "123456";
    std::string encrypted_text = sm4_encrypt(plaintext);
    std::cout << "Encrypted Text: " << encrypted_text << std::endl;

    std::string decrypted_text = sm4_decrypt(encrypted_text);
    std::cout << "Decrypted Text: " << decrypted_text << std::endl;

    return 0;
}

请确保你的系统已经安装了OpenSSL库，并将源文件保存为sm4_example.cpp，然后使用以下命令进行编译：

g++ sm4_example.cpp -o sm4_example -lcrypto

运行编译后的可执行文件sm4_example，你将会得到加密后的字符串和解密后的字符串的输出