Hai
this is the openssl shell command i'm using to decrypt a binary file...
openssl enc -d -K
3834373532303435333730323834383132373330393233343531323330383839 -iv
36363333383630393433313132323031 -aes-256-cbc-in final2.bin -out test.zip
As my target doesnot support openssl commd i was asked to write decryption
code using some API's and create a binary ...so I decided to write it using
AES API's
Here is my code please tell me where I went wrong...thanks in advance.
int main()
{
unsigned long lSize;
FILE * inFile;
FILE * outFile;
size_t n,m;
char * pTemp;
char * buffer;
const AES_KEY *key;
inFile = fopen("SB2.bin", "rb");
outFile = fopen("finalPackResult", "wb+");
unsigned char uKey[]=
"3834373532303435333730323834383132373330393233343531323330383839";
unsigned char iv[] = "36363333383630393433313132323031";
/* Larger key length will make the program very slower
* in AES CBC mode encryption/decryption for more info check
* http://www.mail-archive.com/openssl-...@openssl.org/msg23863/aes.pod
*/
int keyLength = sizeof(uKey);
int ivLength = sizeof(iv);
printf("key length:%d.\n",keyLength);
printf("Initialisation vector length:%d.\n",ivLength);
/* get file size and allocate memory to buffer */
fseek (inFile , 0,SEEK_END);
lSize = ftell (inFile);
rewind (inFile);
printf("File size is: %ld.\n",lSize);
unsigned char pInBuff[lSize];
unsigned char pOutBuff[lSize];
/* Allocate memory */
memset(pInBuff,0,lSize * sizeof(char));
memset(pOutBuff,0,lSize * sizeof(char));
buffer = (char *)malloc(sizeof(char)*lSize);
/* Read the input signature package which contains
* encrypted data. The AES encryption technique
* with CBC mode is followed
*/
if ((n = fread (pInBuff, 1, lSize, inFile)) == -1)
{
printf ("read error");
return -1;
}
printf("Data read from input binary is :%d\n", n);
if (n == 0)
{
printf ("Data read error from input file.\n");
return -1;
}
printf("LINE :%d.\n",__LINE__);
/* The AES_cbc_encrypt() function implements the Cipher Block Chaining
(CBC)
* mode of operation. It encrypts or decrypts B<in> using the key
schedule
* B<schedule> and places the result in B<out>. The value of B<length>
is
* the length of B<in> in bytes
*/
AES_set_decrypt_key(uKey, 8*sizeof(uKey), &key);
printf("LINE :%d.\n",__LINE__);
AES_cbc_encrypt(pInBuff, pOutBuff, lSize, key, iv, AES_DECRYPT);
printf("LINE :%d.\n",__LINE__);
pTemp = AES_options();
printf("AES function to which pointed:%s.\n", pTemp);
/* Write decrypted data into a file */
if((m=fwrite(pOutBuff, 1, lSize, outFile)) == -1)
{
printf ("Write error.\n");
}
if(m != n)
{
printf("Didn't write the data properly.%dbytes info missed",n-m);
}
printf("size of data written is:%d.\n",m);
return 0;
}
--
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