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/*
* Copyright 2019 The OpenSSL Project Authors. All Rights Reserved.
* Copyright (c) 2019, Oracle and/or its affiliates. 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
*/
/*
* Implementation of the FIPS 140-2 section 4.9.2 Conditional Tests.
*/
#include <string.h>
#include <openssl/evp.h>
#include "crypto/rand.h"
#include "internal/thread_once.h"
#include "internal/cryptlib.h"
#include "rand_local.h"
typedef struct crng_test_global_st {
unsigned char crngt_prev[EVP_MAX_MD_SIZE];
RAND_POOL *crngt_pool;
} CRNG_TEST_GLOBAL;
int (*crngt_get_entropy)(OPENSSL_CTX *, RAND_POOL *, unsigned char *,
unsigned char *, unsigned int *)
= &rand_crngt_get_entropy_cb;
static void rand_crng_ossl_ctx_free(void *vcrngt_glob)
{
CRNG_TEST_GLOBAL *crngt_glob = vcrngt_glob;
rand_pool_free(crngt_glob->crngt_pool);
OPENSSL_free(crngt_glob);
}
static void *rand_crng_ossl_ctx_new(OPENSSL_CTX *ctx)
{
unsigned char buf[CRNGT_BUFSIZ];
CRNG_TEST_GLOBAL *crngt_glob = OPENSSL_zalloc(sizeof(*crngt_glob));
if (crngt_glob == NULL)
return NULL;
if ((crngt_glob->crngt_pool
= rand_pool_new(0, 1, CRNGT_BUFSIZ, CRNGT_BUFSIZ)) == NULL) {
OPENSSL_free(crngt_glob);
return NULL;
}
if (crngt_get_entropy(ctx, crngt_glob->crngt_pool, buf,
crngt_glob->crngt_prev, NULL)) {
OPENSSL_cleanse(buf, sizeof(buf));
return crngt_glob;
}
rand_pool_free(crngt_glob->crngt_pool);
OPENSSL_free(crngt_glob);
return NULL;
}
static const OPENSSL_CTX_METHOD rand_crng_ossl_ctx_method = {
rand_crng_ossl_ctx_new,
rand_crng_ossl_ctx_free,
};
int rand_crngt_get_entropy_cb(OPENSSL_CTX *ctx,
RAND_POOL *pool,
unsigned char *buf,
unsigned char *md,
unsigned int *md_size)
{
int r;
size_t n;
unsigned char *p;
if (pool == NULL)
return 0;
n = rand_pool_acquire_entropy(pool);
if (n >= CRNGT_BUFSIZ) {
EVP_MD *fmd = EVP_MD_fetch(ctx, "SHA256", "");
if (fmd == NULL)
return 0;
p = rand_pool_detach(pool);
r = EVP_Digest(p, CRNGT_BUFSIZ, md, md_size, fmd, NULL);
if (r != 0)
memcpy(buf, p, CRNGT_BUFSIZ);
rand_pool_reattach(pool, p);
EVP_MD_free(fmd);
return r;
}
return 0;
}
size_t rand_crngt_get_entropy(RAND_DRBG *drbg,
unsigned char **pout,
int entropy, size_t min_len, size_t max_len,
int prediction_resistance)
{
unsigned char buf[CRNGT_BUFSIZ], md[EVP_MAX_MD_SIZE];
unsigned int sz;
RAND_POOL *pool;
size_t q, r = 0, s, t = 0;
int attempts = 3;
CRNG_TEST_GLOBAL *crngt_glob
= openssl_ctx_get_data(drbg->libctx, OPENSSL_CTX_RAND_CRNGT_INDEX,
&rand_crng_ossl_ctx_method);
if (crngt_glob == NULL)
return 0;
if ((pool = rand_pool_new(entropy, 1, min_len, max_len)) == NULL)
return 0;
while ((q = rand_pool_bytes_needed(pool, 1)) > 0 && attempts-- > 0) {
s = q > sizeof(buf) ? sizeof(buf) : q;
if (!crngt_get_entropy(drbg->libctx, crngt_glob->crngt_pool, buf, md,
&sz)
|| memcmp(crngt_glob->crngt_prev, md, sz) == 0
|| !rand_pool_add(pool, buf, s, s * 8))
goto err;
memcpy(crngt_glob->crngt_prev, md, sz);
t += s;
attempts++;
}
r = t;
*pout = rand_pool_detach(pool);
err:
OPENSSL_cleanse(buf, sizeof(buf));
rand_pool_free(pool);
return r;
}
void rand_crngt_cleanup_entropy(RAND_DRBG *drbg,
unsigned char *out, size_t outlen)
{
OPENSSL_secure_clear_free(out, outlen);
}
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