crypto/rand/rand_meth.c

   1 /*
   2  * Copyright 2011-2021 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <openssl/evp.h>
  11 #include <openssl/rand.h>
  12 #include "rand_local.h"
  13
  14 /* Implements the default OpenSSL RAND_add() method */
  15 static int drbg_add(const void *buf, int num, double randomness)
  16 {
  17     EVP_RAND_CTX *drbg = RAND_get0_primary(NULL);
  18
  19     if (drbg == NULL || num <= 0)
  20         return 0;
  21
  22     return EVP_RAND_reseed(drbg, 0, NULL, 0, buf, num);
  23 }
  24
  25 /* Implements the default OpenSSL RAND_seed() method */
  26 static int drbg_seed(const void *buf, int num)
  27 {
  28     return drbg_add(buf, num, num);
  29 }
  30
  31 /* Implements the default OpenSSL RAND_status() method */
  32 static int drbg_status(void)
  33 {
  34     EVP_RAND_CTX *drbg = RAND_get0_primary(NULL);
  35
  36     if (drbg == NULL)
  37         return 0;
  38
  39     return  EVP_RAND_get_state(drbg) == EVP_RAND_STATE_READY ? 1 : 0;
  40 }
  41
  42 /* Implements the default OpenSSL RAND_bytes() method */
  43 static int drbg_bytes(unsigned char *out, int count)
  44 {
  45     EVP_RAND_CTX *drbg = RAND_get0_public(NULL);
  46
  47     if (drbg == NULL)
  48         return 0;
  49
  50     return EVP_RAND_generate(drbg, out, count, 0, 0, NULL, 0);
  51 }
  52
  53 RAND_METHOD ossl_rand_meth = {
  54     drbg_seed,
  55     drbg_bytes,
  56     NULL,
  57     drbg_add,
  58     drbg_bytes,
  59     drbg_status
  60 };
  61
  62 RAND_METHOD *RAND_OpenSSL(void)
  63 {
  64 #ifndef FIPS_MODULE
  65     return &ossl_rand_meth;
  66 #else
  67     return NULL;
  68 #endif
  69 }