49 lines
1.4 KiB
C
49 lines
1.4 KiB
C
/*
|
|
* Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
|
|
*
|
|
* Licensed under the Apache License 2.0 (the "License"). You may not use
|
|
* this file except in compliance with the License. You can obtain a copy
|
|
* in the file LICENSE in the source distribution or at
|
|
* https://www.openssl.org/source/license.html
|
|
*/
|
|
|
|
#include "internal/cryptlib.h"
|
|
#include <openssl/opensslconf.h>
|
|
#include "crypto/rand_pool.h"
|
|
#include "prov/seeding.h"
|
|
|
|
#ifdef OPENSSL_RAND_SEED_RDTSC
|
|
/*
|
|
* IMPORTANT NOTE: It is not currently possible to use this code
|
|
* because we are not sure about the amount of randomness it provides.
|
|
* Some SP800-90B tests have been run, but there is internal skepticism.
|
|
* So for now this code is not used.
|
|
*/
|
|
# error "RDTSC enabled? Should not be possible!"
|
|
|
|
/*
|
|
* Acquire entropy from high-speed clock
|
|
*
|
|
* Since we get some randomness from the low-order bits of the
|
|
* high-speed clock, it can help.
|
|
*
|
|
* Returns the total entropy count, if it exceeds the requested
|
|
* entropy count. Otherwise, returns an entropy count of 0.
|
|
*/
|
|
size_t ossl_prov_acquire_entropy_from_tsc(RAND_POOL *pool)
|
|
{
|
|
unsigned char c;
|
|
int i;
|
|
|
|
if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
|
|
for (i = 0; i < TSC_READ_COUNT; i++) {
|
|
c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
|
|
ossl_rand_pool_add(pool, &c, 1, 4);
|
|
}
|
|
}
|
|
return ossl_rand_pool_entropy_available(pool);
|
|
}
|
|
#else
|
|
NON_EMPTY_TRANSLATION_UNIT
|
|
#endif
|