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 */
15static 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 */
26static 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 */
32static 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 */
43static 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
53RAND_METHOD ossl_rand_meth = {
54    drbg_seed,
55    drbg_bytes,
56    NULL,
57    drbg_add,
58    drbg_bytes,
59    drbg_status
60};
61
62RAND_METHOD *RAND_OpenSSL(void)
63{
64    return &ossl_rand_meth;
65}
66