Viewing file:  rand_cpu_arm64.c (1.9 KB) -rw-r--r--
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/*
* Copyright 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_RDCPU
#include "crypto/arm_arch.h"
size_t OPENSSL_rndrrs_bytes(unsigned char *buf, size_t len);
static size_t get_hardware_random_value(unsigned char *buf, size_t len);
/*
* Acquire entropy using Arm-specific cpu instructions
*
* Uses the RNDRRS instruction. RNDR is never needed since
* RNDRRS will always be available if RNDR is an available
* instruction.
*
* 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_cpu(RAND_POOL *pool)
{
size_t bytes_needed;
unsigned char *buffer;
bytes_needed = ossl_rand_pool_bytes_needed(pool, 1 /*entropy_factor*/);
if (bytes_needed > 0) {
buffer = ossl_rand_pool_add_begin(pool, bytes_needed);
if (buffer != NULL) {
if (get_hardware_random_value(buffer, bytes_needed) == bytes_needed)
ossl_rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
else
ossl_rand_pool_add_end(pool, 0, 0);
}
}
return ossl_rand_pool_entropy_available(pool);
}
static size_t get_hardware_random_value(unsigned char *buf, size_t len)
{
/* Always use RNDRRS or nothing */
if (OPENSSL_armcap_P & ARMV8_RNG) {
if (OPENSSL_rndrrs_bytes(buf, len) != len)
return 0;
} else {
return 0;
}
return len;
}
#else
NON_EMPTY_TRANSLATION_UNIT
#endif /* OPENSSL_RAND_SEED_RDCPU */
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