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使用openssl C進行AES（aes-cbc-128，aes-cbc-192，aes-cbc-256）加密/解密

[英]AES (aes-cbc-128, aes-cbc-192, aes-cbc-256) encryption/decryption with openssl C

 原文  2013-08-09 18:03:59  6   2    c/ openssl/ aes

問題描述

我只想用openSSL測試這三種模式的AES：128,192和256密鑰長度，但我的解密文本與我的輸入不同，我不知道為什么。 此外，當我傳遞一個巨大的輸入長度（比方說1024字節）時，我的程序顯示core dumped ...我的輸入總是相同但不重要，至少現在。 下面是代碼： 

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

int main(int argc, char **argv)
{
    int i;
    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];
    memset(aes_key, 0, sizeof(aes_key));
    if (!RAND_bytes(aes_key, keylength))
    {
        exit(-1);
    }
    aes_key[keylength-1] = '\0';

    int inputslength;
    printf("Give an input's length:\n");
    scanf("%d", &inputslength);

    /* generate input with a given length */
    unsigned char aes_input[inputslength+1];
    memset(aes_input, '0', sizeof(aes_input));
    aes_input[inputslength] = '\0';

    /*printf("original:\t");
    for(i=0; i<inputslength; i++)
    {
        printf("%c ", aes_input[i]);
    }
    printf("\n");*/

    /* init vector */
    unsigned char iv[AES_BLOCK_SIZE];
    if (!RAND_bytes(iv, AES_BLOCK_SIZE))
    {
        exit(-1);
    }

    //printf("AES_BLOCK_SIZE = %d\n", AES_BLOCK_SIZE); // aes block size is 16 bytes = 128 bits
    AES_KEY enc_key, dec_key;
    unsigned char enc_out[AES_BLOCK_SIZE];
    unsigned char dec_out[AES_BLOCK_SIZE];

    // so i can do with this aes-cbc-128 aes-cbc-192 aes-cbc-256
    AES_set_encrypt_key(aes_key, keylength, &enc_key);
    AES_cbc_encrypt(aes_input, enc_out, inputslength, &enc_key, iv, AES_ENCRYPT);

    AES_set_decrypt_key(aes_key, keylength, &dec_key);
    AES_decrypt(enc_out, dec_out, &dec_key);

    printf("original:\t");
    for(i=0;*(aes_input+i)!=0x00;i++)
        printf("%X ",*(aes_input+i));
    printf("\nencrypted:\t");

    for(i=0;*(enc_out+i)!=0x00;i++)
        printf("%X ",*(enc_out+i));

    printf("\ndecrypted:\t");
    for(i=0;*(dec_out+i)!=0x00;i++)
        printf("%X ",*(dec_out+i));
    printf("\n");

    /*printf("\n\noriginal:\t");
    for(i=0; i<inputslength; i++)
    {
        printf("%x ", dec_out[i]);
    }
    printf("\n");*/


    return 0;
}

編輯：

當我將輸出大小更改為inputslength而不是AES_BLOCK_SIZE我得到了結果： 

Give a key length [only 128 or 192 or 256!]:
128
Give an input's length:
5
original:       30 30 30 30 30 
encrypted:      94 56 50 7E 19 B2 1C CE 20 23 4A E7 10 AF DB E3 30 30 30 30 30 
decrypted:      E1 5F F4 3D E8 8D 91 19 CD 3E 22 1E AF 1C 8F 5A 94 56 50 7E 19 B2 1C CE 20 23 4A E7 10 AF DB E3 30 30 30 30 30

因此，有可能是出現大小和iv大小的問題嗎？ 它們的尺寸應該是多少（對於AES-CBC-128，AES-CBC-192，AES-CBC-256）？

2 個解決方案

解決方案1
 28 已采納  2013-08-10 03:04:52

看一下代碼的這個修改版本。 請注意以下事項：

  1. 添加了hex_print（次要）
  2. 添加了適當的密鑰緩沖區大小（中）。
  3. 添加了適當的輸出加密緩沖區大小（必須是塊大小倍數，如果原始源緩沖區是精確的塊大小倍數，則仍需要一個完整的填充塊（有關詳細信息，請參閱PKCS 5填充）。
  4. 相同的IV用於加密和解密。
  5. 最后，奇，因為它看起來AES_cbc_encrypt()是用於加密和解密（見呼叫的最后一個參數）。

源代碼 

#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);

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

    // 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_cbc_encrypt(aes_input, enc_out, inputslength, &enc_key, iv_enc, AES_ENCRYPT);

    AES_set_decrypt_key(aes_key, keylength, &dec_key);
    AES_cbc_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;
}

測試輸出 

Give a key length [only 128 or 192 or 256!]:
128
Give an input's length:
10
original:   58 58 58 58 58 58 58 58 58 58 
encrypt:    A9 66 C5 24 A4 02 AB 96 08 65 F7 22 A5 FB BE 26 
decrypt:    58 58 58 58 58 58 58 58 58 58

第二次測試輸出 

Give a key length [only 128 or 192 or 256!]:
128
Give an input's length:
10
original:   58 58 58 58 58 58 58 58 58 58 
encrypt:    C2 47 6D B1 A1 68 29 53 55 74 C5 CC 3F 27 0A 3F 
decrypt:    58 58 58 58 58 58 58 58 58 58

我真誠地希望這會有所幫助。

解決方案2
 3  2013-08-10 18:49:02

@WhozCraig：非常感謝你的幫助！ 它向我解釋了很多！ 但還有一個問題。 我將靜態數組更改為動態數組。 當我這樣做時，發生了一些錯誤。 但是只有當我給出一個巨大的輸入大小時才會出現它們，看看valgrind輸出： http ： //pastie.org/private/bzofrrtgrlzr0doyb3g 。 只有當我傳遞一個巨大的輸入時，才會出現錯誤，當我傳遞一個小尺寸（如你的例子，10）時，它就可以了。 其他一切都很完美。 

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

    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 = (unsigned char*)malloc(sizeof(unsigned char) * (keylength/8));
    memset(aes_key, 0, keylength/8);
    RAND_bytes(aes_key, keylength/8);

    //  generate input with a given length
    unsigned char *aes_input = (unsigned char*)malloc(sizeof(unsigned char) * (inputslength));
    memset(aes_input, 'X', sizeof(aes_input));

    // init vectors
    unsigned char *iv_enc = (unsigned char*)malloc(sizeof(unsigned char) * (AES_BLOCK_SIZE));
    unsigned char *iv_dec = (unsigned char*)malloc(sizeof(unsigned char) * (AES_BLOCK_SIZE));
    // iv_dec == iv_enc
    RAND_bytes(iv_enc, AES_BLOCK_SIZE);
    memcpy(iv_dec, iv_enc, AES_BLOCK_SIZE);

    // buffers for encryption and decryption
    const size_t length = (((inputslength + AES_BLOCK_SIZE) / AES_BLOCK_SIZE) * AES_BLOCK_SIZE);
    unsigned char *enc_out = (unsigned char*)malloc(sizeof(unsigned char) * (length));
    unsigned char *dec_out = (unsigned char*)malloc(sizeof(unsigned char) * (inputslength));

    // so i can do with this aes-cbc-128 aes-cbc-192 aes-cbc-256
    AES_KEY encKey, decKey;
    AES_set_encrypt_key(aes_key, keylength, &encKey);
    AES_cbc_encrypt(aes_input, enc_out, inputslength, &encKey, iv_enc, AES_ENCRYPT);

    AES_set_decrypt_key(aes_key, keylength, &decKey);
    AES_cbc_encrypt(enc_out, dec_out, length, &decKey, 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));

    free(aes_key);
    aes_key = NULL;
    free(aes_input);
    aes_input = NULL;
    free(iv_enc);
    iv_enc = NULL;
    free(iv_dec);
    iv_dec = NULL;
    free(enc_out);
    enc_out = NULL;
    free(dec_out);
    dec_out = NULL;

    return 0;
}

編輯：

好吧，我發布的普通代碼出了問題，這是一個新的代碼，工作得很好，即使是大量的輸入。 干杯再次幫助我！:) 

#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 = (unsigned char*)malloc(sizeof(unsigned char) * (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 = (unsigned char*)malloc(sizeof(unsigned char) *inputslength);
    memset(aes_input, 'X', inputslength);

    /* init vector */
    unsigned char *iv_enc = (unsigned char*)malloc(sizeof(unsigned char) *AES_BLOCK_SIZE), *iv_dec = (unsigned char*)malloc(sizeof(unsigned char) *AES_BLOCK_SIZE);
    RAND_bytes(iv_enc, AES_BLOCK_SIZE);
    memcpy(iv_dec, iv_enc, AES_BLOCK_SIZE);

    // buffers for encryption and decryption
    const size_t encslength = ((inputslength + AES_BLOCK_SIZE) / AES_BLOCK_SIZE) * AES_BLOCK_SIZE;
    unsigned char *enc_out = (unsigned char*)malloc(sizeof(unsigned char) *encslength);
    unsigned char *dec_out = (unsigned char*)malloc(sizeof(unsigned char) *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_cbc_encrypt(aes_input, enc_out, inputslength, &enc_key, iv_enc, AES_ENCRYPT);

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

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

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

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

    // free memory here

    return 0;
}

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