err_status_t
ctr_prng_get_octet_string(void *dest, uint32_t len) {
err_status_t status;
/*
* if we need to re-initialize the prng, do so now
*
* avoid 32-bit overflows by subtracting instead of adding
*/
if (ctr_prng.octet_count > MAX_PRNG_OUT_LEN - len) {
status = ctr_prng_init(ctr_prng.rand);
if (status)
return status;
}
ctr_prng.octet_count += len;
/*
* write prng output
*/
status = aes_icm_output(&ctr_prng.state, (uint8_t*)dest, len);
if (status)
return status;
return err_status_ok;
}
err_status_t
ctr_prng_get_octet_string(void *dest, int len) {
err_status_t status;
/*
* if we need to re-initialize the prng, do so now
*
* we cast to a 64-bit integer in order to avoid overflows
*/
if ((uint64_t) ctr_prng.octet_count + len > MAX_PRNG_OUT_LEN) {
status = ctr_prng_init(ctr_prng.rand);
if (status)
return status;
}
ctr_prng.octet_count += len;
/*
* write prng output
*/
status = aes_icm_output(&ctr_prng.state, dest, len);
if (status)
return status;
return err_status_ok;
}