异或加密
解密方式是进行第二次加密后自动解密
#define BUF_SIZE (16384)    //16k
/**************************************************************
功能描述: 加密实现
输入参数: 
---------------------------------------------------------------
修改作者: 
修改日期: 
修改说明:新增
***************************************************************/
void log_encrypt(char *data, int dataLen, const char *key)
{
    int n = 0;
    //对data的每一个字符和key进行按位异或
    for(n = 0; n < dataLen; n++)
    {
        *data = *data ^ 0x09;
        data++;
    }
}
/**************************************************************
功能描述: log文件加密
输入参数: 
---------------------------------------------------------------
修改作者: 
修改日期: 
修改说明:新增
***************************************************************/
unsigned int log_encryptFile(char *srcFileName)
{
    char *key = "google";
    int  srcFd = -1;
    int  dstFd = -1;
    char *tmpBuf = NULL;
    int  tmpLen = 0;
    int  writLen = 0;
    log_printf("start: CountFile build date: %s, [%s, %d]\n", __DATE__, __FUNCTION__, __LINE__);
    if (!srcFileName)
    {
        log_printf("srcFileName err![%s, %d]\n", __FUNCTION__, __LINE__);
        return EXIT_FAILURE;
    }
    srcFd = open(srcFileName, O_RDWR);
    log_printf("srcFileName:[%s] fd:[%d]\n", srcFileName, srcFd);
    if (srcFd < 0)
    {
        log_printf("open src file failed! [err:%d:%s]\n", errno, strerror(errno));
        return EXIT_FAILURE;
    }
    log_printf("file size:[%d]\n", lseek(srcFd, 0, SEEK_END));
    lseek(srcFd, 0, SEEK_SET);
    tmpBuf = (char *)malloc(BUF_SIZE);
    if (!tmpBuf)
    {
        log_printf("malloc buf failed! [err:%d:%s]\n", errno, strerror(errno));
        close(srcFd);
        return EXIT_FAILURE;
    }
    while((tmpLen = read(srcFd, tmpBuf, BUF_SIZE)) > 0)
    {
        //加密数据
        log_encrypt(tmpBuf, tmpLen, key);
        //指针会到此包开始处
        lseek(srcFd, -tmpLen, SEEK_CUR);
        //写文件
        writLen = write(srcFd, tmpBuf, tmpLen);
        if (writLen < 0)
        {
            log_printf("write err,Error: %s\n", strerror(errno));
        }
    }
    close(srcFd);
    free(tmpBuf);
    log_printf("end: ok: [%s, %d]\n", __FUNCTION__, __LINE__);
    return EXIT_SUCCESS;
}
 
AES加密
AES的算法时间复杂度最低,256K时间如下:
 
 
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#define BLOCK_SIZE 16
#define KEY_BIT 256
#define IV_SIZE BLOCK_SIZE
#define KEY_SIZE (KEY_BIT/8)
#define JIEMI_SWITCH		1	//解密开关
// Generate IV
unsigned char iv[IV_SIZE] = {0x00,0x01,0x02,0x03,0x04,0x05,0x06,0x07,0x08,0x09,0x0a,0x0b,0x0c,0x0d,0x0e,0x0f};
void file_encrypt(char* filename) {
    FILE* fp = fopen(filename, "rb");
    FILE* outfp = fopen("encrypted.tmp", "wb");
    if(fp == NULL) {
        printf("Can't open file.\n");
        return;
    }
    // Generate key
    unsigned char key[KEY_SIZE];
    SHA256((unsigned char*)"google", strlen("google"), key);
    EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
    if(EVP_EncryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv) != 1) {
        printf("Failed to initialize encryption.\n");
        return;
    }
    unsigned char data_block[BLOCK_SIZE];
    unsigned char encrypt_block[BLOCK_SIZE + EVP_MAX_BLOCK_LENGTH];
    int out_len;
    fseek(fp, 0, SEEK_END);
    long file_size = ftell(fp);
    fseek(fp, 0, SEEK_SET);
    unsigned char* buffer = (unsigned char*)malloc(file_size + EVP_MAX_BLOCK_LENGTH);
    fread(buffer, 1, file_size, fp);
    for(long i = 0; i < file_size; i += BLOCK_SIZE) {
        memcpy(data_block, buffer + i, BLOCK_SIZE);
        if(i + BLOCK_SIZE > file_size) {
            for(int j = file_size % BLOCK_SIZE; j < BLOCK_SIZE; ++j)
                data_block[j] = BLOCK_SIZE - (file_size % BLOCK_SIZE);
        }
        if(EVP_EncryptUpdate(ctx, encrypt_block, &out_len, data_block, BLOCK_SIZE) != 1) {
            printf("Failed to encrypt block.\n");
            return;
        }
        fwrite(encrypt_block, 1, out_len, outfp);
    }
    if(EVP_EncryptFinal_ex(ctx, encrypt_block, &out_len) != 1) {
        printf("Failed to finish encryption.\n");
        return;
    }
    fwrite(encrypt_block, 1, out_len, outfp);
    free(buffer);
    fclose(fp);
    fclose(outfp);
    rename("encrypted.tmp", filename);
    EVP_CIPHER_CTX_free(ctx);
}
void file_decrypt(char* filename) {
    FILE* fp = fopen(filename, "rb");
    FILE* outfp = fopen("decrypted.tmp", "wb");
    if(fp == NULL) {
        printf("Can't open file.\n");
        return;
    }
    // Generate key
    unsigned char key[KEY_SIZE];
    SHA256((unsigned char*)"google", strlen("google"), key);
    EVP_CIPHER_CTX *ctx = EVP_CIPHER_CTX_new();
    if(EVP_DecryptInit_ex(ctx, EVP_aes_256_cbc(), NULL, key, iv) != 1) {
        printf("Failed to initialize decryption.\n");
        return;
    }
    unsigned char data_block[BLOCK_SIZE];
    unsigned char decrypt_block[BLOCK_SIZE + EVP_MAX_BLOCK_LENGTH];
    int out_len;
    fseek(fp, 0, SEEK_END);
    long file_size = ftell(fp);
    fseek(fp, 0, SEEK_SET);
    unsigned char* buffer = (unsigned char*)malloc(file_size + EVP_MAX_BLOCK_LENGTH);
    fread(buffer, 1, file_size, fp);
    for(long i = 0; i < file_size; i += BLOCK_SIZE) {
        memcpy(data_block, buffer + i, BLOCK_SIZE);
        if(EVP_DecryptUpdate(ctx, decrypt_block, &out_len, data_block, BLOCK_SIZE) != 1) {
            printf("Failed to decrypt block.\n");
            return;
        }
        fwrite(decrypt_block, 1, out_len, outfp);
    }
    if(EVP_DecryptFinal_ex(ctx, decrypt_block, &out_len) != 1) {
        printf("Failed to finish decryption.\n");
        return;
    }
    fwrite(decrypt_block, 1, out_len, outfp);
    free(buffer);
    fclose(fp);
    fclose(outfp);
    rename("decrypted.tmp", filename);
    EVP_CIPHER_CTX_free(ctx);
}
int main(int argc, char **argv) {
    if(argc != 2) {
        printf("Usage: %s <file>\n", argv[0]);
        return 1;
    }
    char *srcFileName = argv[1];
#if JIEMI_SWITCH
    file_encrypt(srcFileName);
    printf("加密成功\n");
#else
    file_decrypt(srcFileName);
    printf("解密成功\n");
#endif
    return 0;
}
 
简单加密
它只是对输入文件进行简单的异或加密操作,使用一个字符串作为密钥
 时间复杂度较高,对257K的文件加密,要33s
 
/**************************************************************
修改作者:wangjj
修改日期:9/25/2023
修改说明:新增
***************************************************************/
unsigned int log_encryptFile(char *srcFileName)
{
    char *key = "hualaixiaofang";
    int keyLen = strlen(key);
    int ch;
    int i = 0;
    log_printf("encrytFile begin [%s,%d\n]", __FUNCTION__, __LINE__);
    if (!srcFileName || !key)
    {
        log_printf("param err! error:%s [%s,%d]\n", strerror(errno), __FUNCTION__, __LINE__);
        return EXIT_FAILURE;
    }	
    FILE *file = fopen(srcFileName, "rb+");
    if (file == NULL)
    {
        log_printf("open file failed!!, error:%s [%s,%d]\n", strerror(errno), __FUNCTION__, __LINE__);
        return EXIT_FAILURE;
    }
    while ((ch = fgetc(file)) != EOF)
    {
        // 对每个字符和key的对应字符进行加密操作
        ch = ch + key[i];
        
        // 将加密后的字符写回文件
        fseek(file, -1, SEEK_CUR);
        fputc(ch, file);
        
        // 更新key的位置
        i = (i + 1) % keyLen;
    }
    log_printf("encrytFile end [%s,%d\n]", __FUNCTION__, __LINE__);
    fclose(file);
}
 
编译方式
gcc -o decrypt_program_jiemi AES_encrypt.c -lcrypto
















