我正在玩OpenSSL EVP例程以使用AES 128 cbc模式进行解密。OpenSSL上的EVP_DecryptFinal_ex错误
我使用在NIST站点指定的测试向量来测试我的程序。
该程序似乎在EVP_DecryptFinal_ex例程失败。
任何人都可以告诉我有什么问题吗?
另外我该如何做错误检查来找出这个例程失败的原因?
更新:
请检查下面的代码。我已经添加了加密和解密部分。加密作品。但是在解密过程中,虽然两个匹配的结果相同,但密码的十六进制值似乎是80字节,而不是预期的64字节(在NIST中提到),尽管解密工作并且解密文本与明文匹配! 有人可以澄清?
预期的密文值应为:
cipher: 0000 76 49 ab ac 81 19 b2 46 ce e9 8e 9b 12 e9 19 7d
0010 50 86 cb 9b 50 72 19 ee 95 db 11 3a 91 76 78 b2
0020 73 be d6 b8 e3 c1 74 3b 71 16 e6 9e 22 22 95 16
0030 3f f1 ca a1 68 1f ac 09 12 0e ca 30 75 86 e1 a7
这里是代码:
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <openssl/evp.h>
int AES_BLOCK_SIZE;
int main(int argc, char **argv)
{
EVP_CIPHER_CTX en;
EVP_CIPHER_CTX de;
EVP_CIPHER_CTX_init(&en);
EVP_CIPHER_CTX_init(&de);
const EVP_CIPHER *cipher_type;
unsigned char *mode;
unsigned char *passkey, *passiv, *plaintxt;
int vector_len = 0;
char *plain;
char *plaintext;
unsigned char *ciphertext;
int olen, len;
int i =0;
//NIST VALUES TO CHECK
unsigned char iv[] =
{ 0x00, 0x01, 0x02, 0x03,
0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b,
0x0c, 0x0d, 0x0e, 0x0f, 0 };
unsigned char key[] =
{ 0x2b, 0x7e, 0x15, 0x16,
0x28, 0xae, 0xd2, 0xa6,
0xab, 0xf7, 0x15, 0x88,
0x09, 0xcf, 0x4f, 0x3c , 0 };
unsigned char input[] =
{ 0x6b, 0xc1, 0xbe, 0xe2,
0x2e, 0x40, 0x9f, 0x96,
0xe9, 0x3d, 0x7e, 0x11,
0x73, 0x93, 0x17, 0x2a,
0xae, 0x2d, 0x8a, 0x57,
0x1e, 0x03, 0xac, 0x9c,
0x9e, 0xb7, 0x6f, 0xac,
0x45, 0xaf, 0x8e, 0x51,
0x30, 0xc8, 0x1c, 0x46,
0xa3, 0x5c, 0xe4, 0x11,
0xe5, 0xfb, 0xc1, 0x19,
0x1a, 0x0a, 0x52, 0xef,
0xf6, 0x9f, 0x24, 0x45,
0xdf, 0x4f, 0x9b, 0x17,
0xad, 0x2b, 0x41, 0x7b,
0xe6, 0x6c, 0x37, 0x10, 0 };
printf("AES ALGORITHM FOR 128 bit CBC MODE\n");
cipher_type = EVP_aes_128_cbc();
AES_BLOCK_SIZE = 128;
passkey = key;
passiv = iv;
plain = input;
printf("iv=");
for(i = 0; i < sizeof iv; i++){
printf("%02x", iv[i]);
}
printf("\n");
printf("key=");
for(i = 0; i < sizeof key; i++){
printf("%02x", key[i]);
}
printf("\n");
printf("Initializing AES ALGORITHM FOR CBC MODE..\n");
EVP_EncryptInit_ex(&en, cipher_type, NULL, passkey, passiv);
EVP_DecryptInit_ex(&de, cipher_type, NULL, passkey, passiv);
olen = len = strlen(input)+1;
printf("len value before aes_encrypt \"%d\"\n", len);
int c_len = len + AES_BLOCK_SIZE - 1;
int f_len = 0;
ciphertext = (unsigned char *)malloc(c_len);
if(!EVP_EncryptInit_ex(&en, NULL, NULL, NULL, NULL)){
printf("ERROR in EVP_EncryptInit_ex \n");
return NULL;
}
if(!EVP_EncryptUpdate(&en, ciphertext, &c_len, plain, len)){
printf("ERROR in EVP_EncryptUpdate \n");
return NULL;
}
printf("strlen value of ciphertext after update \"%d\"\n", strlen(ciphertext));
if(!EVP_EncryptFinal_ex(&en, ciphertext+c_len, &f_len)){
printf("ERROR in EVP_EncryptFinal_ex \n");
return NULL;
}
printf("strlen value of ciphertext after final \"%d\"\n", strlen(ciphertext));
EVP_CIPHER_CTX_cleanup(&en);
len = c_len + f_len;
printf("len value after aes_encrypt \"%d\"\n", len);
len = strlen(ciphertext);
printf("strlen value of ciphertext after aes_encrypt \"%d\"\n", len);
int p_len = len;
f_len = 0;
plaintext = (unsigned char *)malloc(p_len);
//memset(plaintext,0,sizeof(plaintext));
if(!EVP_DecryptInit_ex(&de, NULL, NULL, NULL, NULL)){
printf("ERROR in EVP_DecryptInit_ex \n");
return NULL;
}
EVP_CIPHER_CTX_set_padding(&de, 0);
if(!EVP_DecryptUpdate(&de, plaintext, &p_len, ciphertext, len)){
printf("ERROR in EVP_DecryptUpdate\n");
return NULL;
}
if(!EVP_DecryptFinal_ex(&de, plaintext+p_len, &f_len)){
printf("ERROR in EVP_DecryptFinal_ex\n");
return NULL;
}
EVP_CIPHER_CTX_cleanup(&de);
len = p_len + f_len;
printf("Decrypted value = %s\n", plaintext);
printf("len value after aes_decrypt \"%d\"\n", len);
if (strncmp(plaintext, input, olen))
printf("FAIL: enc/dec failed for \"%s\"\n", input);
else
printf("OK: enc/dec ok for \"%s\"\n", plaintext); // \"%s\"\n
printf("OK: ciphertext is \"%s\"\n", ciphertext); // \"%s\"\n
printf("\n");
unsigned char *s3 = ciphertext;
printf("s3 =\n");
int nc = 0;
while(*s3 != '\0'){
printf("%02x", *s3);
s3++;
nC++;
if(nc == 16){
printf("\n");
nc = 0;
}
}
printf("\n");
//printf("nc = %d\n", nc);
free(ciphertext);
free(plaintext);
return 0;
}
填充标准错误导致我行:改用EVPerr(EVP_F_EVP_DECRYPTFINAL_EX,EVP_R_WRONG_FINAL_BLOCK_LENGTH);如果我设置填充如上(零)我得到的错误是:EVPerr(EVP_F_EVP_DECRYPTFINAL_EX, EVP_R_DATA_NOT_MULTIPLE_OF_BLOCK_LENGTH);但如何纠正这一点?在解密程序中我没有提到块长度还是应该? – pimmling 2011-04-15 07:38:24
但根据你的解释没有填充设置,因此我不需要设置填充功能,仍然解密应该正常工作?我编辑了代码。你可以请现在检查? – pimmling 2011-04-15 12:51:28
@pimmling:EVP_R_WRONG_FINAL_BLOCK_LENGTH表示它正在寻找填充但没有找到它,所以你解决了这个问题。现在你看到的是AES数据长度必须是16个字节。您不使用以空字符结尾的字符串。你正在处理二进制数据。在所有事情结束时取消空终止符。不要使用strlen(),因为它不是以空字符结尾的字符串。在你的情况下使用sizeof()。只需给解密器一次16个字节,它就可以工作,并且您必须弄清楚如何将更大的数据块分成16个字节的块。 – indiv 2011-04-15 15:03:46