/*
* aes_icm_advance(...) refills the keystream_buffer and
* advances the block index of the sicm_context forward by one
*
* this is an internal, hopefully inlined function
*/
static void srtp_aes_icm_advance_ismacryp (srtp_aes_icm_ctx_t *c, uint8_t forIsmacryp)
{
/* fill buffer with new keystream */
v128_copy(&c->keystream_buffer, &c->counter);
srtp_aes_encrypt(&c->keystream_buffer, &c->expanded_key);
c->bytes_in_buffer = sizeof(v128_t);
debug_print(srtp_mod_aes_icm, "counter: %s",
v128_hex_string(&c->counter));
debug_print(srtp_mod_aes_icm, "ciphertext: %s",
v128_hex_string(&c->keystream_buffer));
/* clock counter forward */
if (forIsmacryp) {
uint32_t temp;
//alex's clock counter forward
temp = ntohl(c->counter.v32[3]);
++temp;
c->counter.v32[3] = htonl(temp);
} else {
if (!++(c->counter.v8[15])) {
++(c->counter.v8[14]);
}
}
}
/*
* aes_icm_advance(...) refills the keystream_buffer and
* advances the block index of the sicm_context forward by one
*
* this is an internal, hopefully inlined function
*/
static void srtp_aes_icm_advance (srtp_aes_icm_ctx_t *c)
{
/* fill buffer with new keystream */
v128_copy(&c->keystream_buffer, &c->counter);
srtp_aes_encrypt(&c->keystream_buffer, &c->expanded_key);
c->bytes_in_buffer = sizeof(v128_t);
debug_print(srtp_mod_aes_icm, "counter: %s",
v128_hex_string(&c->counter));
debug_print(srtp_mod_aes_icm, "ciphertext: %s",
v128_hex_string(&c->keystream_buffer));
/* clock counter forward */
if (!++(c->counter.v8[15])) {
++(c->counter.v8[14]);
}
}
