I am using openssl AES-CTR method for encryption/decryption with 128 bit key. encryption is fine but i am not able to get original input after decryption. i am testing 3GPP test vectors in linux environment in c. I am getting below output:
actual indata =
fd40a41d 370a1f65 74509568 7d47ba1d 36d2349e 23f64439 2c8ea9c4 9d40c132 71aff264 d0f24800
Enc indata =
75750d37 b4bba2a4 dedb3423 5bd68c66 45acdaac a48138a3 b0c471e2 a7041a57 6423d292 7287f0f5
decryption function is called
Dec indata =
c80f33a5 b884f2a4 489d2048 bc133a25 b9fad603 4c09f888 8ac7d546 1c359f1b f3c4ff3b b3bf19d1
Here after decryption output has to match to actual input data.But here i am unable to get proper output. can you please help in this regard.Thanks in advance.
#include <openssl/aes.h>
#include <openssl/rand.h>
#include <openssl/hmac.h>
#include <openssl/buffer.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <math.h>
#define u32 unsigned int
#define u8 unsigned char
#define MAX_SIZE 2048
#define BIT_SIZE 128
#define INPUT_LENGTH 40 /*set 3*/
struct ctr_state
{
unsigned char ivec[AES_BLOCK_SIZE];
unsigned int num;
unsigned char ecount[AES_BLOCK_SIZE];
};
AES_KEY key;
unsigned char indata[MAX_SIZE];
unsigned char outdata[MAX_SIZE];
unsigned char iv[AES_BLOCK_SIZE];
struct ctr_state state;
int init_ctr(struct ctr_state *state, const unsigned char iv[16])
{
/* aes_ctr128_encrypt requires 'num' and 'ecount' set to zero on the * first call. */
state->num = 0;
memset(state->ecount, 0, AES_BLOCK_SIZE);
/* Initialise counter in 'ivec' to 0 */
memset(state->ivec + 8, 0, 8);
/* Copy IV into 'ivec' */
memcpy(state->ivec, iv, 8);
}
void cipher_aes_128(const unsigned char *enckey, int count, int bearer, int dir, u8 *indata, int length )
{
int n,i,flag=1,n1,padbit,padded[16];
n=length/BIT_SIZE;
if(length%BIT_SIZE!=0)
{
flag=0;
n=n+1;
}
printf("\nn=%d\n",n);
iv[0] = (count >> 24) & 0xff ;
iv[1] = (count >> 16) & 0xff ;
iv[2] = (count >> 8) & 0xff;
iv[3] = count & 0xff;
iv[4] = htonl((( (bearer << 27) | ((dir & 0x1) << 26))));
iv[5] = iv[6]= iv[7] = 0;
//Initializing the encryption KEY
if (AES_set_encrypt_key(enckey, BIT_SIZE, &key) < 0)
{
printf(stderr, "Could not set decryption key.");
exit(1);
}
init_ctr(&state, iv);//Counter call
//Encrypting Blocks of 16 bytes and writing the output with ciphertext
for(i=0;i<n;i++)
{
AES_ctr128_encrypt(&indata[AES_BLOCK_SIZE*i], &outdata[AES_BLOCK_SIZE*i],AES_BLOCK_SIZE, &key, state.ivec, state.ecount, &state.num);
}
for(i=0;i<(AES_BLOCK_SIZE*n);i++)
{
indata[i] = outdata[i];
}
printf("\n");
}
void cipher_aes_128_decode(const unsigned char *enckey, int count, int bearer, int dir, u8 *indata, int length )
{
printf("\ndecryption function is called\n");
cipher_aes_128( enckey, count, bearer, dir, indata, length );
printf("\n");
}
int main(int argc, char *argv[])
{
/*Test data 3 */
u8 key1[16] = {
0x0a,0x8b,0x6b,0xd8,0xd9,0xb0,0x8b,0x08,
0xd6,0x4e,0x32,0xd1,0x81,0x77,0x77,0xfb
};
u8 count[4] ={0x54,0x4d,0x49,0xcd };
u32 tempCount = 0;
u8 bearer = 0x04;
u8 dir =0,i;
u32 length = 310 ;
u8 indata[INPUT_LENGTH] = {
0xfd,0x40,0xa4,0x1d,0x37,0x0a,0x1f,0x65,
0x74,0x50,0x95,0x68,0x7d,0x47,0xba,0x1d,
0x36,0xd2,0x34,0x9e,0x23,0xf6,0x44,0x39,
0x2c,0x8e,0xa9,0xc4,0x9d,0x40,0xc1,0x32,
0x71,0xaf,0xf2,0x64,0xd0,0xf2,0x48,0x00
};
tempCount = htonl((count[0] | (count[1] << 8) | count[2]<< 16 | count[3] << 24));
printf("actual indata =\n");
for(i=0;i<INPUT_LENGTH;i++)
{
if((i%4)==0)
printf(" ");
printf("%02x",indata[i]);
}
cipher_aes_128( key1, tempCount, bearer, dir, indata, length );
printf("Enc indata =\n");
for(i=0;i<INPUT_LENGTH;i++)
{
if((i%4)==0)
printf(" ");
printf("%02x",indata[i]);
}
cipher_aes_128_decode(key1,tempCount,bearer,dir,indata,length);
printf("\nDec indata =\n");
for(i=0;i<INPUT_LENGTH;i++)
{
if((i%4)==0)
printf(" ");
printf("%02x",indata[i]);
}
}
