(Ilya, great implementation. I modified it to cache the expanded key with great ease :) )

Buf size, number of null characters in your encrypted text and number of characters in printf output would be a very straightforward hint here.

#include
#include
#include “aes256.h”

#define DUMP(s, i, buf, sz) {printf(s); \
for (i = 0; i < (sz);i++) \
printf(”%02x “, buf[i]); \
printf(”\n”);}

int main (int argc, char *argv[])
{
aes256_context ctx;
uint8_t key[32];
uint8_t buf[16], i;

/* put a test vector */
//for (i = 0; i < sizeof(buf);i++) buf[i] = i * 16 + i;
//for (i = 0; i < sizeof(key);i++) key[i] = i;

strcpy(key,”My Key”);
strcpy(buf,”Blah Blah”);

DUMP(”txt: “, i, buf, sizeof(buf));
DUMP(”key: “, i, key, sizeof(key));

printf(”Initial KEY: %s\n”,key);
printf(”Initial BUF: %s\n”,buf);
printf(”—\n”);

aes256_init(&ctx, key);
aes256_encrypt_ecb(&ctx, buf);

printf(”Enc BUF: %s\n”,buf);

DUMP(”enc: “, i, buf, sizeof(buf));
printf(”tst: 8e a2 b7 ca 51 67 45 bf ea fc 49 90 4b 49 60 89\n”);

aes256_init(&ctx, key);
aes256_decrypt_ecb(&ctx, buf);
DUMP(”dec: “, i, buf, sizeof(buf));
printf(”Dec KEY: %s\n”,key);
printf(”Dec BUF: %s\n”,buf);

aes256_done(&ctx);

return 0;
} /* main */

/* put a test vector */
//for (i = 0; i < sizeof(buf);i++) buf[i] = i * 16 + i;
//for (i = 0; i aes_demo
txt: 42 6c 61 68 20 42 6c 61 68 00 cc cc cc cc cc cc
key: 4d 79 20 4b 65 79 00 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
cc cc cc cc cc cc cc
Initial KEY: My Key
Initial BUF: Blah Blah
—
Enc BUF: ^¥sεΓ%.┼0oHsë╘3╢╠╠╠╠╠╠╠╠My Key <—– Opps!
enc: 5e 9d 73 ee e2 25 2e c5 30 6f 48 73 89 d4 33 b6
tst: 8e a2 b7 ca 51 67 45 bf ea fc 49 90 4b 49 60 89
dec: 42 6c 61 68 20 42 6c 61 68 00 cc cc cc cc cc cc
Dec KEY: My Key
Dec BUF: Blah Blah

Note that the Key is appended unencrypted to the encrypted buffer.

To encrypt several blocks, I was looking for a simple XTS implementation. I have found the Gladman’s, but it seems very difficult to adapt it to work with your code.
Do you know a simpler implementation of XTS ?

Just wondering how the aes_addRoundKey_cpy fits into the standard?

This doesn’t appear in any of the docs I’ve read, but it appears to be (from what I can ascertain) to be the expanded key round, which helps avoid an extra lookup table.

But, I am trying to fix the failed attempt at porting this to AES-128 and I can’t figure out how I should change that. I tried the obvious of changing it to:


void aes_addRoundKey_cpy(uint8_t *buf, uint8_t *key, uint8_t *cpk)
{
register uint8_t i = 8;

} /* aes_addRoundKey_cpy */


but it either wasn’t right, or there’s more to it. (I have changed the number of rounds to 10) but debugging encryption algorithms tends to be a little difficult!

Any pointers in the right direction would be greatly appreciated!

Thanks in advance,
Michael (yes, the same one as before)