OpenSSL测试-SM4

任务详情

使用OpenSSL编程对内容为"所有同学的8位学号（数字）"的文件进行加密解密，密钥要包含你的8位学号，提交代码和运行结果截图。（选做（10’））

• 编译：gcc -g sm4txtcode.c -o sm4_en_de_txt -L/usr/lib -lssl -lcrypto
  就像这样
  

• 运行：enout.txt是加密后的输出、deout.txt是解密后的输出、in.txt是输入、里面写的有学号
  

• 关于密钥：你不要急，密钥内嵌在代码里面，虽然不安全，但是这是测试。
  

• 操作环境ubuntu最新版（2023）

• 这里是源代码

点击查看代码

#include <openssl/evp.h>
#include <openssl/err.h>
#include <string.h>

#define BUF_SIZE 1024

int main(int argc, char *argv[]) {
    // 检查命令行参数
    if (argc != 4) {
        printf("Usage: %s <input file> <encrypted output file> <decrypted output file>\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    // 初始化 OpenSSL
    OpenSSL_add_all_algorithms();
    ERR_load_crypto_strings();

    // 设置加密上下文
    EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
    if (!ctx) {
        printf("Error creating context\n");
        exit(EXIT_FAILURE);
    }
    const EVP_CIPHER *cipher = EVP_sm4_ecb();
    unsigned char key[EVP_MAX_KEY_LENGTH] = {0};
    unsigned char iv[EVP_MAX_IV_LENGTH] = {0};
    char *student_id = "20201326"; // 用你自己的8位学号替换
    printf("学号%s\n",student_id);
    strncpy(key, student_id, 8);
    if (EVP_EncryptInit_ex(ctx, cipher, NULL, key, iv) != 1) {
        printf("Error setting up encryption context\n");
        exit(EXIT_FAILURE);
    }

    // 打开输入文件
    FILE *in_file = fopen(argv[1], "rb");
    if (!in_file) {
        printf("Error opening input file\n");
        exit(EXIT_FAILURE);
    }

    // 打开加密输出文件
    FILE *enc_file = fopen(argv[2], "wb");
    if (!enc_file) {
        printf("Error opening encrypted output file\n");
        exit(EXIT_FAILURE);
    }

    // 加密输入文件并写入加密输出文件
    unsigned char in_buf[BUF_SIZE] = {0};
    unsigned char enc_buf[BUF_SIZE + EVP_MAX_BLOCK_LENGTH] = {0};
    int num_bytes_read, enc_len;
    while ((num_bytes_read = fread(in_buf, sizeof(unsigned char), BUF_SIZE, in_file)) > 0) {
        if (EVP_EncryptUpdate(ctx, enc_buf, &enc_len, in_buf, num_bytes_read) != 1) {
            printf("Error encrypting data\n");
            exit(EXIT_FAILURE);
        }
        fwrite(enc_buf, sizeof(unsigned char), enc_len, enc_file);
    }
    if (num_bytes_read < 0) {
        printf("Error reading input file\n");
        exit(EXIT_FAILURE);
    }

    // 完成加密
    if (EVP_EncryptFinal_ex(ctx, enc_buf, &enc_len) != 1) {
        printf("Error finalizing encryption\n");
        exit(EXIT_FAILURE);
    }
    fwrite(enc_buf, sizeof(unsigned char), enc_len, enc_file);

    // 清理加密上下文
    EVP_CIPHER_CTX_free(ctx);

    // 关闭输入和输出文件
    fclose(in_file);
    fclose(enc_file);

    // 设置解密上下文
    ctx = EVP_CIPHER_CTX_new();
    if (!ctx) {
        printf("Error creating context\n");
        exit(EXIT_FAILURE);
    }
    if (EVP_DecryptInit_ex(ctx, cipher, NULL, key, iv) != 1) {
        printf("Error setting up decryption context\n");
        exit(EXIT_FAILURE);
    }

    // 打开加密输入文件
    enc_file = fopen(argv[2], "rb");
    if (!enc_file) {
        printf("Error opening encrypted input file\n");
        exit(EXIT_FAILURE);
    }

    // 打开解密输出文件
    FILE *dec_file = fopen(argv[3], "wb");
    if (!dec_file) {
        printf("Error opening decrypted output file\n");
        exit(EXIT_FAILURE);
    }

    // 解密加密输入文件并写入解密输出文件
    unsigned char dec_buf[BUF_SIZE + EVP_MAX_BLOCK_LENGTH] = {0};
    int dec_len;
    while ((num_bytes_read = fread(enc_buf, sizeof(unsigned char), BUF_SIZE + EVP_MAX_BLOCK_LENGTH, enc_file)) > 0) {
        if (EVP_DecryptUpdate(ctx, dec_buf, &dec_len, enc_buf, num_bytes_read) != 1) {
            printf("Error decrypting data\n");
            exit(EXIT_FAILURE);
        }
        fwrite(dec_buf, sizeof(unsigned char), dec_len, dec_file);
    }
    if (num_bytes_read < 0) {
        printf("Error reading encrypted input file\n");
        exit(EXIT_FAILURE);
    }

    // 完成解密
    if (EVP_DecryptFinal_ex(ctx, dec_buf, &dec_len) != 1) {
        printf("Error finalizing decryption\n");
        exit(EXIT_FAILURE);
    }
    fwrite(dec_buf, sizeof(unsigned char), dec_len, dec_file);

    // 清理解密上下文
    EVP_CIPHER_CTX_free(ctx);

    // 关闭输入和输出文件
    fclose(enc_file);
    fclose(dec_file);

    // 清理 OpenSSL
    EVP_cleanup();
    ERR_free_strings();

    return 0;
}