drbg_lib.c
/*
* Copyright 2011-2018 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (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 <string.h>
#include <openssl/crypto.h>
#include <openssl/err.h>
#include <openssl/rand.h>
#include "rand_lcl.h"
#include "internal/thread_once.h"
#include "internal/rand_int.h"
/*
* Support framework for NIST SP 800-90A DRBG, AES-CTR mode.
* The RAND_DRBG is OpenSSL's pointer to an instance of the DRBG.
*
* The OpenSSL model is to have new and free functions, and that new
* does all initialization. That is not the NIST model, which has
* instantiation and un-instantiate, and re-use within a new/free
* lifecycle. (No doubt this comes from the desire to support hardware
* DRBG, where allocation of resources on something like an HSM is
* a much bigger deal than just re-setting an allocated resource.)
*/
/*
* THE THREE SHARED DRBGs
*
* There are three shared DRBGs (master, public and private), which are
* accessed concurrently by all threads.
*
* THE MASTER DRBG
*
* Not used directly by the application, only for reseeding the two other
* DRBGs. It reseeds itself by pulling either randomness from os entropy
* sources or by consuming randomnes which was added by RAND_add()
*/
static RAND_DRBG *drbg_master;
/*
* THE PUBLIC DRBG
*
* Used by default for generating random bytes using RAND_bytes().
*/
static RAND_DRBG *drbg_public;
/*
* THE PRIVATE DRBG
*
* Used by default for generating private keys using RAND_priv_bytes()
*/
static RAND_DRBG *drbg_private;
/*+
* DRBG HIERARCHY
*
* In addition there are DRBGs, which are not shared, but used only by a
* single thread at every time, for example the DRBGs which are owned by
* an SSL context. All DRBGs are organized in a hierarchical fashion
* with the <master> DRBG as root.
*
* This gives the following overall picture:
*
* <os entropy sources>
* |
* RAND_add() ==> <master> \
* / \ | shared DRBGs (with locking)
* <public> <private> /
* |
* <ssl> owned by an SSL context
*
* AUTOMATIC RESEEDING
*
* Before satisfying a generate request, a DRBG reseeds itself automatically,
* if one of the following two conditions holds:
*
* - the number of generate requests since the last reseeding exceeds a
* certain threshold, the so called |reseed_interval|. This behaviour
* can be disabled by setting the |reseed_interval| to 0.
*
* - the time elapsed since the last reseeding exceeds a certain time
* interval, the so called |reseed_time_interval|. This behaviour
* can be disabled by setting the |reseed_time_interval| to 0.
*
* MANUAL RESEEDING
*
* For the three shared DRBGs (and only for these) there is another way to
* reseed them manually by calling RAND_seed() (or RAND_add() with a positive
* |randomness| argument). This will immediately reseed the <master> DRBG.
* The <public> and <private> DRBG will detect this on their next generate
* call and reseed, pulling randomness from <master>.
*/
/* NIST SP 800-90A DRBG recommends the use of a personalization string. */
static const char ossl_pers_string[] = "OpenSSL NIST SP 800-90A DRBG";
static CRYPTO_ONCE rand_drbg_init = CRYPTO_ONCE_STATIC_INIT;
static RAND_DRBG *drbg_setup(RAND_DRBG *parent);
static void drbg_cleanup(RAND_DRBG *drbg);
/*
* Set/initialize |drbg| to be of type |nid|, with optional |flags|.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set(RAND_DRBG *drbg, int nid, unsigned int flags)
{
int ret = 1;
drbg->state = DRBG_UNINITIALISED;
drbg->flags = flags;
drbg->nid = nid;
switch (nid) {
default:
RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
return 0;
case 0:
/* Uninitialized; that's okay. */
return 1;
case NID_aes_128_ctr:
case NID_aes_192_ctr:
case NID_aes_256_ctr:
ret = drbg_ctr_init(drbg);
break;
}
if (ret == 0)
RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
return ret;
}
/*
* Allocate memory and initialize a new DRBG. The |parent|, if not
* NULL, will be used to auto-seed this RAND_DRBG as needed.
*
* Returns a pointer to the new DRBG instance on success, NULL on failure.
*/
RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
{
RAND_DRBG *drbg = OPENSSL_zalloc(sizeof(*drbg));
if (drbg == NULL) {
RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
goto err;
}
drbg->fork_count = rand_fork_count;
drbg->parent = parent;
if (RAND_DRBG_set(drbg, type, flags) == 0)
goto err;
if (!RAND_DRBG_set_callbacks(drbg, rand_drbg_get_entropy,
rand_drbg_cleanup_entropy,
NULL, NULL))
goto err;
return drbg;
err:
OPENSSL_free(drbg);
return NULL;
}
/*
* Uninstantiate |drbg| and free all memory.
*/
void RAND_DRBG_free(RAND_DRBG *drbg)
{
if (drbg == NULL)
return;
if (drbg->meth != NULL)
drbg->meth->uninstantiate(drbg);
CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
OPENSSL_clear_free(drbg, sizeof(*drbg));
}
/*
* Instantiate |drbg|, after it has been initialized. Use |pers| and
* |perslen| as prediction-resistance input.
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_instantiate(RAND_DRBG *drbg,
const unsigned char *pers, size_t perslen)
{
unsigned char *nonce = NULL, *entropy = NULL;
size_t noncelen = 0, entropylen = 0;
if (perslen > drbg->max_perslen) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
RAND_R_PERSONALISATION_STRING_TOO_LONG);
goto end;
}
if (drbg->meth == NULL)
{
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
goto end;
}
if (drbg->state != DRBG_UNINITIALISED) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
: RAND_R_ALREADY_INSTANTIATED);
goto end;
}
drbg->state = DRBG_ERROR;
if (drbg->get_entropy != NULL)
entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
drbg->min_entropylen, drbg->max_entropylen);
if (entropylen < drbg->min_entropylen
|| entropylen > drbg->max_entropylen) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
goto end;
}
if (drbg->max_noncelen > 0 && drbg->get_nonce != NULL) {
noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
drbg->min_noncelen, drbg->max_noncelen);
if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
RAND_R_ERROR_RETRIEVING_NONCE);
goto end;
}
}
if (!drbg->meth->instantiate(drbg, entropy, entropylen,
nonce, noncelen, pers, perslen)) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
goto end;
}
drbg->state = DRBG_READY;
drbg->generate_counter = 0;
drbg->reseed_time = time(NULL);
if (drbg->reseed_counter > 0) {
if (drbg->parent == NULL)
drbg->reseed_counter++;
else
drbg->reseed_counter = drbg->parent->reseed_counter;
}
end:
if (entropy != NULL && drbg->cleanup_entropy != NULL)
drbg->cleanup_entropy(drbg, entropy, entropylen);
if (nonce != NULL && drbg->cleanup_nonce!= NULL )
drbg->cleanup_nonce(drbg, nonce, noncelen);
if (drbg->pool != NULL) {
if (drbg->state == DRBG_READY) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
RAND_R_ERROR_ENTROPY_POOL_WAS_IGNORED);
drbg->state = DRBG_ERROR;
}
RAND_POOL_free(drbg->pool);
drbg->pool = NULL;
}
if (drbg->state == DRBG_READY)
return 1;
return 0;
}
/*
* Uninstantiate |drbg|. Must be instantiated before it can be used.
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
{
if (drbg->meth == NULL)
{
RANDerr(RAND_F_RAND_DRBG_UNINSTANTIATE,
RAND_R_NO_DRBG_IMPLEMENTATION_SELECTED);
return 0;
}
/* Clear the entire drbg->ctr struct, then reset some important
* members of the drbg->ctr struct (e.g. keysize, df_ks) to their
* initial values.
*/
drbg->meth->uninstantiate(drbg);
return RAND_DRBG_set(drbg, drbg->nid, drbg->flags);
}
/*
* Reseed |drbg|, mixing in the specified data
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_reseed(RAND_DRBG *drbg,
const unsigned char *adin, size_t adinlen)
{
unsigned char *entropy = NULL;
size_t entropylen = 0;
if (drbg->state == DRBG_ERROR) {
RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
return 0;
}
if (drbg->state == DRBG_UNINITIALISED) {
RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
return 0;
}
if (adin == NULL)
adinlen = 0;
else if (adinlen > drbg->max_adinlen) {
RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
return 0;
}
drbg->state = DRBG_ERROR;
if (drbg->get_entropy != NULL)
entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
drbg->min_entropylen, drbg->max_entropylen);
if (entropylen < drbg->min_entropylen
|| entropylen > drbg->max_entropylen) {
RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
goto end;
}
if (!drbg->meth->reseed(drbg, entropy, entropylen, adin, adinlen))
goto end;
drbg->state = DRBG_READY;
drbg->generate_counter = 0;
drbg->reseed_time = time(NULL);
if (drbg->reseed_counter > 0) {
if (drbg->parent == NULL)
drbg->reseed_counter++;
else
drbg->reseed_counter = drbg->parent->reseed_counter;
}
end:
if (entropy != NULL && drbg->cleanup_entropy != NULL)
drbg->cleanup_entropy(drbg, entropy, entropylen);
if (drbg->state == DRBG_READY)
return 1;
return 0;
}
/*
* Restart |drbg|, using the specified entropy or additional input
*
* Tries its best to get the drbg instantiated by all means,
* regardless of its current state.
*
* Optionally, a |buffer| of |len| random bytes can be passed,
* which is assumed to contain at least |entropy| bits of entropy.
*
* If |entropy| > 0, the buffer content is used as entropy input.
*
* If |entropy| == 0, the buffer content is used as additional input
*
* Returns 1 on success, 0 on failure.
*
* This function is used internally only.
*/
int rand_drbg_restart(RAND_DRBG *drbg,
const unsigned char *buffer, size_t len, size_t entropy)
{
int reseeded = 0;
const unsigned char *adin = NULL;
size_t adinlen = 0;
if (drbg->pool != NULL) {
RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
RAND_POOL_free(drbg->pool);
drbg->pool = NULL;
}
if (buffer != NULL) {
if (entropy > 0) {
if (drbg->max_entropylen < len) {
RANDerr(RAND_F_RAND_DRBG_RESTART,
RAND_R_ENTROPY_INPUT_TOO_LONG);
return 0;
}
if (entropy > 8 * len) {
RANDerr(RAND_F_RAND_DRBG_RESTART, RAND_R_ENTROPY_OUT_OF_RANGE);
return 0;
}
/* will be picked up by the rand_drbg_get_entropy() callback */
drbg->pool = RAND_POOL_new(entropy, len, len);
if (drbg->pool == NULL)
return 0;
RAND_POOL_add(drbg->pool, buffer, len, entropy);
} else {
if (drbg->max_adinlen < len) {
RANDerr(RAND_F_RAND_DRBG_RESTART,
RAND_R_ADDITIONAL_INPUT_TOO_LONG);
return 0;
}
adin = buffer;
adinlen = len;
}
}
/* repair error state */
if (drbg->state == DRBG_ERROR)
RAND_DRBG_uninstantiate(drbg);
/* repair uninitialized state */
if (drbg->state == DRBG_UNINITIALISED) {
/* reinstantiate drbg */
RAND_DRBG_instantiate(drbg,
(const unsigned char *) ossl_pers_string,
sizeof(ossl_pers_string) - 1);
/* already reseeded. prevent second reseeding below */
reseeded = (drbg->state == DRBG_READY);
}
/* refresh current state if entropy or additional input has been provided */
if (drbg->state == DRBG_READY) {
if (adin != NULL) {
/*
* mix in additional input without reseeding
*
* Similar to RAND_DRBG_reseed(), but the provided additional
* data |adin| is mixed into the current state without pulling
* entropy from the trusted entropy source using get_entropy().
* This is not a reseeding in the strict sense of NIST SP 800-90A.
*/
drbg->meth->reseed(drbg, adin, adinlen, NULL, 0);
} else if (reseeded == 0) {
/* do a full reseeding if it has not been done yet above */
RAND_DRBG_reseed(drbg, NULL, 0);
}
}
/* check whether a given entropy pool was cleared properly during reseed */
if (drbg->pool != NULL) {
drbg->state = DRBG_ERROR;
RANDerr(RAND_F_RAND_DRBG_RESTART, ERR_R_INTERNAL_ERROR);
RAND_POOL_free(drbg->pool);
drbg->pool = NULL;
return 0;
}
return drbg->state == DRBG_READY;
}
/*
* Generate |outlen| bytes into the buffer at |out|. Reseed if we need
* to or if |prediction_resistance| is set. Additional input can be
* sent in |adin| and |adinlen|.
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success, 0 on failure.
*
*/
int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
int prediction_resistance,
const unsigned char *adin, size_t adinlen)
{
int reseed_required = 0;
if (drbg->state != DRBG_READY) {
/* try to recover from previous errors */
rand_drbg_restart(drbg, NULL, 0, 0);
if (drbg->state == DRBG_ERROR) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
return 0;
}
if (drbg->state == DRBG_UNINITIALISED) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
return 0;
}
}
if (outlen > drbg->max_request) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
return 0;
}
if (adinlen > drbg->max_adinlen) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
return 0;
}
if (drbg->fork_count != rand_fork_count) {
drbg->fork_count = rand_fork_count;
reseed_required = 1;
}
if (drbg->reseed_interval > 0) {
if (drbg->generate_counter >= drbg->reseed_interval)
reseed_required = 1;
}
if (drbg->reseed_time_interval > 0) {
time_t now = time(NULL);
if (now < drbg->reseed_time
|| now - drbg->reseed_time >= drbg->reseed_time_interval)
reseed_required = 1;
}
if (drbg->reseed_counter > 0 && drbg->parent != NULL) {
if (drbg->reseed_counter != drbg->parent->reseed_counter)
reseed_required = 1;
}
if (reseed_required || prediction_resistance) {
if (!RAND_DRBG_reseed(drbg, adin, adinlen)) {
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
return 0;
}
adin = NULL;
adinlen = 0;
}
if (!drbg->meth->generate(drbg, out, outlen, adin, adinlen)) {
drbg->state = DRBG_ERROR;
RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
return 0;
}
drbg->generate_counter++;
return 1;
}
/*
* Generates |outlen| random bytes and stores them in |out|. It will
* using the given |drbg| to generate the bytes.
*
* Requires that drbg->lock is already locked for write, if non-null.
*
* Returns 1 on success 0 on failure.
*/
int RAND_DRBG_bytes(RAND_DRBG *drbg, unsigned char *out, size_t outlen)
{
unsigned char *additional = NULL;
size_t additional_len;
size_t chunk;
size_t ret;
additional_len = rand_drbg_get_additional_data(&additional, drbg->max_adinlen);
for ( ; outlen > 0; outlen -= chunk, out += chunk) {
chunk = outlen;
if (chunk > drbg->max_request)
chunk = drbg->max_request;
ret = RAND_DRBG_generate(drbg, out, chunk, 0, additional, additional_len);
if (!ret)
goto err;
}
ret = 1;
err:
if (additional_len != 0)
OPENSSL_secure_clear_free(additional, additional_len);
return ret;
}
/*
* Set the RAND_DRBG callbacks for obtaining entropy and nonce.
*
* In the following, the signature and the semantics of the
* get_entropy() and cleanup_entropy() callbacks are explained.
*
* GET_ENTROPY
*
* size_t get_entropy(RAND_DRBG *ctx,
* unsigned char **pout,
* int entropy,
* size_t min_len, size_t max_len);
*
* This is a request to allocate and fill a buffer of size
* |min_len| <= size <= |max_len| (in bytes) which contains
* at least |entropy| bits of randomness. The buffer's address is
* to be returned in |*pout| and the number of collected
* randomness bytes (which may be less than the allocated size
* of the buffer) as return value.
*
* If the callback fails to acquire at least |entropy| bits of
* randomness, it shall return a buffer length of 0.
*
* CLEANUP_ENTROPY
*
* void cleanup_entropy(RAND_DRBG *ctx,
* unsigned char *out, size_t outlen);
*
* A request to clear and free the buffer allocated by get_entropy().
* The values |out| and |outlen| are expected to be the random buffer's
* address and length, as returned by the get_entropy() callback.
*
* GET_NONCE, CLEANUP_NONCE
*
* Signature and semantics of the get_nonce() and cleanup_nonce()
* callbacks are analogous to get_entropy() and cleanup_entropy().
* Currently, the nonce is used only for the known answer tests.
*/
int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
RAND_DRBG_get_entropy_fn get_entropy,
RAND_DRBG_cleanup_entropy_fn cleanup_entropy,
RAND_DRBG_get_nonce_fn get_nonce,
RAND_DRBG_cleanup_nonce_fn cleanup_nonce)
{
if (drbg->state != DRBG_UNINITIALISED)
return 0;
drbg->get_entropy = get_entropy;
drbg->cleanup_entropy = cleanup_entropy;
drbg->get_nonce = get_nonce;
drbg->cleanup_nonce = cleanup_nonce;
return 1;
}
/*
* Set the reseed interval.
*
* The drbg will reseed automatically whenever the number of generate
* requests exceeds the given reseed interval. If the reseed interval
* is 0, then this feature is disabled.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, unsigned int interval)
{
if (interval > MAX_RESEED_INTERVAL)
return 0;
drbg->reseed_interval = interval;
return 1;
}
/*
* Set the reseed time interval.
*
* The drbg will reseed automatically whenever the time elapsed since
* the last reseeding exceeds the given reseed time interval. For safety,
* a reseeding will also occur if the clock has been reset to a smaller
* value.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_reseed_time_interval(RAND_DRBG *drbg, time_t interval)
{
if (interval > MAX_RESEED_TIME_INTERVAL)
return 0;
drbg->reseed_time_interval = interval;
return 1;
}
/*
* Get and set the EXDATA
*/
int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
{
return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
}
void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
{
return CRYPTO_get_ex_data(&drbg->ex_data, idx);
}
/*
* The following functions provide a RAND_METHOD that works on the
* global DRBG. They lock.
*/
/*
* Allocates a new global DRBG on the secure heap (if enabled) and
* initializes it with default settings.
*
* Returns a pointer to the new DRBG instance on success, NULL on failure.
*/
static RAND_DRBG *drbg_setup(RAND_DRBG *parent)
{
RAND_DRBG *drbg;
drbg = OPENSSL_secure_zalloc(sizeof(RAND_DRBG));
if (drbg == NULL)
return NULL;
drbg->lock = CRYPTO_THREAD_lock_new();
if (drbg->lock == NULL) {
RANDerr(RAND_F_DRBG_SETUP, RAND_R_FAILED_TO_CREATE_LOCK);
goto err;
}
if (RAND_DRBG_set(drbg,
RAND_DRBG_NID, RAND_DRBG_FLAG_CTR_USE_DF) != 1)
goto err;
if (RAND_DRBG_set_callbacks(drbg, rand_drbg_get_entropy,
rand_drbg_cleanup_entropy, NULL, NULL) != 1)
goto err;
if (parent == NULL) {
drbg->reseed_interval = MASTER_RESEED_INTERVAL;
drbg->reseed_time_interval = MASTER_RESEED_TIME_INTERVAL;
} else {
drbg->parent = parent;
drbg->reseed_interval = SLAVE_RESEED_INTERVAL;
drbg->reseed_time_interval = SLAVE_RESEED_TIME_INTERVAL;
}
/* enable seed propagation */
drbg->reseed_counter = 1;
/*
* Ignore instantiation error so support just-in-time instantiation.
*
* The state of the drbg will be checked in RAND_DRBG_generate() and
* an automatic recovery is attempted.
*/
RAND_DRBG_instantiate(drbg,
(const unsigned char *) ossl_pers_string,
sizeof(ossl_pers_string) - 1);
return drbg;
err:
drbg_cleanup(drbg);
return NULL;
}
/*
* Initialize the global DRBGs on first use.
* Returns 1 on success, 0 on failure.
*/
DEFINE_RUN_ONCE_STATIC(do_rand_drbg_init)
{
/*
* ensure that libcrypto is initialized, otherwise the
* DRBG locks are not cleaned up properly
*/
if (!OPENSSL_init_crypto(0, NULL))
return 0;
drbg_master = drbg_setup(NULL);
drbg_public = drbg_setup(drbg_master);
drbg_private = drbg_setup(drbg_master);
if (drbg_master == NULL || drbg_public == NULL || drbg_private == NULL)
return 0;
return 1;
}
/* Cleans up the given global DRBG */
static void drbg_cleanup(RAND_DRBG *drbg)
{
if (drbg != NULL) {
RAND_DRBG_uninstantiate(drbg);
CRYPTO_THREAD_lock_free(drbg->lock);
OPENSSL_secure_clear_free(drbg, sizeof(RAND_DRBG));
}
}
/* Clean up the global DRBGs before exit */
void rand_drbg_cleanup_int(void)
{
drbg_cleanup(drbg_private);
drbg_cleanup(drbg_public);
drbg_cleanup(drbg_master);
drbg_private = drbg_public = drbg_master = NULL;
}
/* Implements the default OpenSSL RAND_bytes() method */
static int drbg_bytes(unsigned char *out, int count)
{
int ret;
RAND_DRBG *drbg = RAND_DRBG_get0_public();
if (drbg == NULL)
return 0;
CRYPTO_THREAD_write_lock(drbg->lock);
ret = RAND_DRBG_bytes(drbg, out, count);
CRYPTO_THREAD_unlock(drbg->lock);
return ret;
}
/* Implements the default OpenSSL RAND_add() method */
static int drbg_add(const void *buf, int num, double randomness)
{
int ret = 0;
RAND_DRBG *drbg = RAND_DRBG_get0_master();
if (drbg == NULL)
return 0;
if (num < 0 || randomness < 0.0)
return 0;
if (randomness > (double)drbg->max_entropylen) {
/*
* The purpose of this check is to bound |randomness| by a
* relatively small value in order to prevent an integer
* overflow when multiplying by 8 in the rand_drbg_restart()
* call below.
*/
return 0;
}
CRYPTO_THREAD_write_lock(drbg->lock);
ret = rand_drbg_restart(drbg, buf,
(size_t)(unsigned int)num,
(size_t)(8*randomness));
CRYPTO_THREAD_unlock(drbg->lock);
return ret;
}
/* Implements the default OpenSSL RAND_seed() method */
static int drbg_seed(const void *buf, int num)
{
return drbg_add(buf, num, num);
}
/* Implements the default OpenSSL RAND_status() method */
static int drbg_status(void)
{
int ret;
RAND_DRBG *drbg = RAND_DRBG_get0_master();
if (drbg == NULL)
return 0;
CRYPTO_THREAD_write_lock(drbg->lock);
ret = drbg->state == DRBG_READY ? 1 : 0;
CRYPTO_THREAD_unlock(drbg->lock);
return ret;
}
/*
* Get the master DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*
*/
RAND_DRBG *RAND_DRBG_get0_master(void)
{
if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
return NULL;
return drbg_master;
}
/*
* Get the public DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*/
RAND_DRBG *RAND_DRBG_get0_public(void)
{
if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
return NULL;
return drbg_public;
}
/*
* Get the private DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*/
RAND_DRBG *RAND_DRBG_get0_private(void)
{
if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
return NULL;
return drbg_private;
}
RAND_METHOD rand_meth = {
drbg_seed,
drbg_bytes,
NULL,
drbg_add,
drbg_bytes,
drbg_status
};
RAND_METHOD *RAND_OpenSSL(void)
{
return &rand_meth;
}
