openssl AES-CBC 加密解密问题 IV 如何保存下来。

[成都-狗蛋儿]

用户密码加密，解密我用到了 OPENSSL AES-CBC 加密模式。不管是加密还是解密，我的密钥都是固定的。但是我加密以后的iv是不是需要保存下来？因为我把加密后的数据进行解密，不能正确的解密，解密出来是乱码。

加密：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <openssl/aes.h>
 
int main(int argc, char** argv) {
    AES_KEY aes;
    unsigned char* key = "www.qqqqqqq.com ";        // AES_BLOCK_SIZE = 16
    unsigned char iv[AES_BLOCK_SIZE];        // init vector
    unsigned char* input_string;
    unsigned char* encrypt_string;
    unsigned int len;        // encrypt length (in multiple of AES_BLOCK_SIZE)
    unsigned int i;
 
    // check usage
    if (argc != 2) {
        fprintf(stderr, "%s <plain text>\n", argv[0]);
        exit(-1);
    }
 
    // set the encryption length
    len = 0;
    if ((strlen(argv[1]) + 1) % AES_BLOCK_SIZE == 0) {
        len = strlen(argv[1]) + 1;
    } else {
        len = ((strlen(argv[1]) + 1) / AES_BLOCK_SIZE + 1) * AES_BLOCK_SIZE;
    }
 
    // set the input string
    input_string = (unsigned char*)calloc(len, sizeof(unsigned char));
    if (input_string == NULL) {
        fprintf(stderr, "Unable to allocate memory for input_string\n");
        exit(-1);
    }
    strncpy((char*)input_string, argv[1], strlen(argv[1]));
 
    // Generate AES 128-bit key
    /*for (i=0; i<16; ++i) {
        key[i] = 32 + i;
    }*/
 
    // Set encryption key
    for (i=0; i<AES_BLOCK_SIZE; ++i) {
        iv[i] = 0;
    }
    if (AES_set_encrypt_key(key, 128, &aes) < 0) {
        fprintf(stderr, "Unable to set encryption key in AES\n");
        exit(-1);
    }
 
    // alloc encrypt_string
    encrypt_string = (unsigned char*)calloc(len, sizeof(unsigned char));    
    if (encrypt_string == NULL) {
        fprintf(stderr, "Unable to allocate memory for encrypt_string\n");
        exit(-1);
    }
    
    // encrypt (iv will change)
    AES_cbc_encrypt(input_string, encrypt_string, len, &aes, iv, AES_ENCRYPT);
    
    // print
    for (i=0; i<len; ++i) {
        printf("%X%X", (encrypt_string[i] >> 4) & 0xf, 
                encrypt_string[i] & 0xf);    
    }
    printf("\n");
 
    return 0;
}

解密：

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <openssl/aes.h>
 
int main(int argc, char** argv) {
    AES_KEY aes;
    unsigned char* key = "www.qqqqqqq.com ";        // AES_BLOCK_SIZE = 16
    unsigned char iv[AES_BLOCK_SIZE];        // init vector
    unsigned char* input_string;
    unsigned char* decrypt_string;
    unsigned int len;        // encrypt length (in multiple of AES_BLOCK_SIZE)
    unsigned int i;
 
    // check usage
    if (argc != 2) {
        fprintf(stderr, "%s <plain text>\n", argv[0]);
        exit(-1);
    }
 
    // set the encryption length
    len = 0;
    if ((strlen(argv[1]) + 1) % AES_BLOCK_SIZE == 0) {
        len = strlen(argv[1]) + 1;
    } else {
        len = ((strlen(argv[1]) + 1) / AES_BLOCK_SIZE + 1) * AES_BLOCK_SIZE;
    }
 
    // set the input string
    input_string = (unsigned char*)calloc(len, sizeof(unsigned char));
    if (input_string == NULL) {
        fprintf(stderr, "Unable to allocate memory for input_string\n");
        exit(-1);
    }
    strncpy((char*)input_string, argv[1], strlen(argv[1]));
 
    // alloc decrypt_string
    decrypt_string = (unsigned char*)calloc(len, sizeof(unsigned char));
    if (decrypt_string == NULL) {
        fprintf(stderr, "Unable to allocate memory for decrypt_string\n");
        exit(-1);
    }
 
    // Set decryption key
    for (i=0; i<AES_BLOCK_SIZE; ++i) {
        iv[i] = 0;
    }
    if (AES_set_decrypt_key(key, 128, &aes) < 0) {
        fprintf(stderr, "Unable to set decryption key in AES\n");
        exit(-1);
    }
 
    // decrypt
    AES_cbc_encrypt(input_string, decrypt_string, len, &aes, iv, 
            AES_DECRYPT);
 
    printf("%s", decrypt_string);
 	printf("\n");
    return 0;
}

[成都-狗蛋儿]

是不是 可以设置固定的 iv呢？

[赵4老师]

保存在大脑中以免被黑。

[muroachanf]

必须保存iv，否则解不出来了。