c - AES (aes-ige-128, aes-ige-192, aes-ige-256) 加密/解密与 openssl C

Question

最近我终于(在 stackoverflow 的用户@WhozCraig 的帮助下)开始在 CBC 模式下使用 AES。现在，我想做完全相同的事情，但使用 AES IGE。我查看了 openssl-1.0.1e/test/igetest.c 并尝试构建我自己的测试。但是再一次，我对输入和输出的正确大小有疑问。其他一切都很好，因为我从我以前的代码中复制了它:AES (aes-cbc-128, aes-cbc-192, aes-cbc-256) encryption/decryption with openssl C .

现在，当我传递一个小于 32 的输入长度时，它说:

Give a key length [only 128 or 192 or 256!]:
256
Give an input's length:
3
aes_ige.c(88): OpenSSL internal error, assertion failed: (length%AES_BLOCK_SIZE) == 0
 (core dumped)

但是当长度大于32时，我也不确定是否一切正常:

Give a key length [only 128 or 192 or 256!]:
256
Give an input's length:
48
original:       58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 
encrypt:        A4 1F C4 E8 42 5E E5 62 1A B6 C1 47 D2 2F 8D 98 D0 0B 32 77 4E 36 84 25 15 5B BA 60 EA A9 64 D2 53 D1 98 78 83 21 90 90 74 44 C7 AA 3E AD 9B 26 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 
decrypt:        58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 58 

代码如下:

    #include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/aes.h>
#include <openssl/rand.h>

// a simple hex-print routine. could be modified to print 16 bytes-per-line
static void hex_print(const void* pv, size_t len)
{
    const unsigned char * p = (const unsigned char*)pv;
    if (NULL == pv)
        printf("NULL");
    else
    {
        size_t i = 0;
        for (; i<len;++i)
            printf("%02X ", *p++);
    }
    printf("\n");
}

// main entrypoint
int main(int argc, char **argv)
{
    int keylength;
    printf("Give a key length [only 128 or 192 or 256!]:\n");
    scanf("%d", &keylength);

    /* generate a key with a given length */
    unsigned char aes_key[keylength/8];
    memset(aes_key, 0, keylength/8);
    if (!RAND_bytes(aes_key, keylength/8))
        exit(-1);

    size_t inputslength = 0;
    printf("Give an input's length:\n");
    scanf("%lu", &inputslength);

    /* generate input with a given length */
    unsigned char aes_input[inputslength];
    memset(aes_input, 'X', inputslength);

    const size_t ivsize = AES_BLOCK_SIZE*2;

    /* init vector */
    unsigned char iv_enc[ivsize], iv_dec[ivsize];
    RAND_bytes(iv_enc, ivsize);
    memcpy(iv_dec, iv_enc, ivsize);

    // buffers for encryption and decryption
    const size_t encslength = (inputslength/AES_BLOCK_SIZE + 1) * AES_BLOCK_SIZE;//((inputslength + AES_BLOCK_SIZE) / AES_BLOCK_SIZE) * AES_BLOCK_SIZE;
    unsigned char enc_out[encslength];
    unsigned char dec_out[inputslength];
    memset(enc_out, 0, sizeof(enc_out));
    memset(dec_out, 0, sizeof(dec_out));

    AES_KEY enc_key, dec_key;
    AES_set_encrypt_key(aes_key, keylength, &enc_key);
    AES_set_decrypt_key(aes_key, keylength, &dec_key);

    AES_ige_encrypt(aes_input, enc_out, inputslength, &enc_key, iv_enc, AES_ENCRYPT);

    AES_ige_encrypt(enc_out, dec_out, encslength, &dec_key, iv_dec, AES_DECRYPT);

    printf("original:\t");
    hex_print(aes_input, sizeof(aes_input));

    printf("encrypt:\t");
    hex_print(enc_out, sizeof(enc_out));

    printf("decrypt:\t");
    hex_print(dec_out, sizeof(dec_out));

    return 0;
}

最后!成功了(希望如此)。但如果有人能说下面这段代码 100% 好，我将不胜感激；)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/aes.h>
#include <openssl/rand.h>

// a simple hex-print routine. could be modified to print 16 bytes-per-line
static void hex_print(const void* pv, size_t len)
{
    const unsigned char * p = (const unsigned char*)pv;
    if (NULL == pv)
        printf("NULL");
    else
    {
        size_t i = 0;
        for (; i<len;++i)
            printf("%02X ", *p++);
    }
    printf("\n");
}

// main entrypoint
int main(int argc, char **argv)
{
    int keylength = 256;
    //printf("Give a key length [only 128 or 192 or 256!]:\n");
    //scanf("%d", &keylength);

    /* generate a key with a given length */
    unsigned char aes_key[keylength/8];
    memset(aes_key, 0, keylength/8);
    if (!RAND_bytes(aes_key, keylength/8))
        exit(-1);

    size_t inputslength = 0;
    printf("Give an input's length:\n");
    scanf("%lu", &inputslength);

    /* generate input with a given length */
    unsigned char aes_input[inputslength];
    memset(aes_input, 'X', inputslength);

    const size_t ivsize = AES_BLOCK_SIZE*2;
    /* init vector */
    unsigned char iv_enc[ivsize], iv_dec[ivsize];
    RAND_bytes(iv_enc, ivsize);
    memcpy(iv_dec, iv_enc, ivsize);

    // buffers for encryption and decryption
    const size_t encslength = ((inputslength + AES_BLOCK_SIZE) / AES_BLOCK_SIZE) * AES_BLOCK_SIZE;
    unsigned char enc_out[encslength];
    unsigned char dec_out[inputslength];
    memset(enc_out, 0, sizeof(enc_out));
    memset(dec_out, 0, sizeof(dec_out));

    // so i can do with this aes-cbc-128 aes-cbc-192 aes-cbc-256
    AES_KEY enc_key, dec_key;
    AES_set_encrypt_key(aes_key, keylength, &enc_key);
    AES_ige_encrypt(aes_input, enc_out, encslength, &enc_key, iv_enc, AES_ENCRYPT);

    AES_set_decrypt_key(aes_key, keylength, &dec_key);
    AES_ige_encrypt(enc_out, dec_out, encslength, &dec_key, iv_dec, AES_DECRYPT);

    printf("original:\t");
    hex_print(aes_input, sizeof(aes_input));

    printf("encrypt:\t");
    hex_print(enc_out, sizeof(enc_out));

    printf("decrypt:\t");
    hex_print(dec_out, sizeof(dec_out));

    return 0;
}

我只改变了这个:

AES_ige_encrypt(aes_input, enc_out, **inputslength**, &enc_key, iv_enc, AES_ENCRYPT);

进入那个:

AES_ige_encrypt(aes_input, enc_out, **encslength**, &enc_key, iv_enc, AES_ENCRYPT);

正确吗？

编辑 No.2 ;)

好吧，伙计们，做了另一个例子，根据你的建议在输入中添加了一些填充。希望现在没事吧？

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/aes.h>
#include <openssl/rand.h>

// a simple hex-print routine. could be modified to print 16 bytes-per-line
static void hex_print(const void* pv, size_t len)
{
    const unsigned char * p = (const unsigned char*)pv;
    if (NULL == pv)
        printf("NULL");
    else
    {
        size_t i = 0;
        for (; i<len;++i)
            printf("%02X ", *p++);
    }
    printf("\n");
}

// main entrypoint
int main(int argc, char **argv)
{
    int keylength = 256;
    //printf("Give a key length [only 128 or 192 or 256!]:\n");
    //scanf("%d", &keylength);

    /* generate a key with a given length */
    unsigned char aes_key[keylength/8];
    memset(aes_key, 0, keylength/8);
    if (!RAND_bytes(aes_key, keylength/8))
        exit(-1);

    size_t inputslength = 0;
    printf("Give an input's length:\n");
    scanf("%lu", &inputslength);

    /* generate input with a given length */
    unsigned char aes_input[inputslength];
    memset(aes_input, 'X', inputslength);

    const size_t ivsize = AES_BLOCK_SIZE*2;
    /* init vector */
    unsigned char iv_enc[ivsize], iv_dec[ivsize];
    RAND_bytes(iv_enc, ivsize);
    memcpy(iv_dec, iv_enc, ivsize);

    // buffers for encryption and decryption
    const size_t encslength = ((inputslength + AES_BLOCK_SIZE) / AES_BLOCK_SIZE) * AES_BLOCK_SIZE;

    unsigned char paddedinput[encslength];
    memset(paddedinput, 0, encslength);
    memcpy(paddedinput, aes_input, inputslength);

    unsigned char enc_out[encslength];
    unsigned char dec_out[inputslength];
    memset(enc_out, 0, sizeof(enc_out));
    memset(dec_out, 0, sizeof(dec_out));

    AES_KEY enc_key, dec_key;
    AES_set_encrypt_key(aes_key, keylength, &enc_key);
    AES_ige_encrypt(paddedinput, enc_out, encslength, &enc_key, iv_enc, AES_ENCRYPT);

    AES_set_decrypt_key(aes_key, keylength, &dec_key);
    AES_ige_encrypt(enc_out, dec_out, encslength, &dec_key, iv_dec, AES_DECRYPT);

    printf("original:\t");
    hex_print(aes_input, sizeof(aes_input));

    printf("encrypt:\t");
    hex_print(enc_out, sizeof(enc_out));

    printf("decrypt:\t");
    hex_print(dec_out, sizeof(dec_out));

    return 0;
}

Answer 1

错误消息说明了一切。

aes_ige.c(88): OpenSSL internal error, assertion failed: (length%AES_BLOCK_SIZE) == 0

这基本上是一个运行时检查(断言)，由于提供给函数的无效输入而失败 AES_ige_encrypt() 出现在源代码中 line 88 of aes_ige.c .

OPENSSL_assert((length%AES_BLOCK_SIZE) == 0);

断言主要检查是否 length (传递给函数的第三个参数)是 AES_BLOCK_SIZE 的整数倍 。如果是，则继续执行，否则程序停止并打印有关断言失败的警告。

1. 因此确保传递给的数据大小AES_ige_encrypt() 是 AES_BLOCK_SIZE 的倍数.

2. 如果数据大小不是整数倍，则追加 NUL 字节，使总大小最接近 AES_BLOCK_SIZE 的倍数.

3. 此外，始终将“整数倍数- AES_BLOCK_SIZE ”值作为 length 传递 参数到 AES_ige_encrypt() .