I'm having trouble using the AES_unwrap_key function. I have tried different things but it always returns 0 and the out buffer does not get written to.
I can wrap a key with the AES_wrap_key. Then I pass the wrapped key output to AES_unwrap_key and it is not able to unwrap it. This is regardless if I use the default IV (passing NULL to the function) or pass an explicit IV.See sample code below.
Has anybody seen this issue? Any help will be appreciated.
#include <aes.h>
int
main(int argc, char **argv)
{
int i;
int ret;
unsigned char wrappedKeyData[24];
unsigned char KEK[] = {0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E, 0x0F};
unsigned char keyData[] = {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF};
unsigned char IV[8] = {0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6, 0xA6};
AES_KEY wrp_key;
AES_set_encrypt_key(KEK, 128, &wrp_key);
/* wrapping */
ret = AES_wrap_key(&wrp_key, NULL, wrappedKeyData, keyData, 16);
printf("openssl wrapping returns %i\n", ret);
printf("wrapped keyData: ");
for (i = 0; i < ret; i++) {
printf ("%02x", wrappedKeyData[i]);
}
printf("\n");
/* unwrapping */
unsigned char keyDataOut[16];
ret = AES_unwrap_key(&wrp_key, NULL, keyDataOut, wrappedKeyData, 24);
printf("unwrapping openssl returns %i\n", ret);
printf("unwrapped keyData: ");
for (i = 0; i < 16; i++) {
printf ("%02x", keyDataOut[i]) ;
}
printf("\n");
return EXIT_SUCCESS;
}
