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