openssl/crypto/rand/drbg_lib.c
Dr. Matthias St. Pierre 5bc6bcf82d DRBG: implement a get_nonce() callback
Fixes #5849

In pull request #5503 a fallback was added which adds a random nonce of
security_strength/2 bits if no nonce callback is provided. This change raised
the entropy requirements form 256 to 384 bit, which can cause problems on some
platforms (e.g. VMS, see issue #5849).

The requirements for the nonce are given in section 8.6.7 of NIST SP 800-90Ar1:

  A nonce may be required in the construction of a seed during instantiation
  in order to provide a security cushion to block certain attacks.
  The nonce shall be either:

  a) A value with at least (security_strength/2) bits of entropy, or

  b) A value that is expected to repeat no more often than a
     (security_strength/2)-bit random string would be expected to repeat.

  Each nonce shall be unique to the cryptographic module in which instantiation
  is performed, but need not be secret. When used, the nonce shall be considered
  to be a critical security parameter.

This commit implements a nonce of type b) in order to lower the entropy
requirements during instantiation back to 256 bits.

The formulation "shall be unique to the cryptographic module" above implies
that the nonce needs to be unique among (with high probability) among all
DRBG instances in "space" and "time". We try to achieve this goal by creating a
nonce of the following form

    nonce = app-specific-data || high-resolution-utc-timestamp || counter

Where || denotes concatenation. The application specific data can be something
like the process or group id of the application. A utc timestamp is used because
it increases monotonically, provided the system time is synchronized. This approach
may not be perfect yet for a FIPS evaluation, but it should be good enough for the
moment.

This commit also harmonizes the implementation of the get_nonce() and the
get_additional_data() callbacks and moves the platform specific parts from
rand_lib.c into rand_unix.c, rand_win.c, and rand_vms.c.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5920)
2018-04-13 20:49:28 +02:00

1062 lines
30 KiB
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"
#include "internal/cryptlib_int.h"
/*
* Support framework for NIST SP 800-90A DRBG
*
* See manual page RAND_DRBG(7) for a general overview.
*
* 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 DRBG instances
*
* There are three shared DRBG instances: <master>, <public>, and <private>.
*/
/*
* 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 randomness which was added by RAND_add().
*
* The <master> DRBG is a global instance which is accessed concurrently by
* all threads. The necessary locking is managed automatically by its child
* DRBG instances during reseeding.
*/
static RAND_DRBG *master_drbg;
/*
* The <public> DRBG
*
* Used by default for generating random bytes using RAND_bytes().
*
* The <public> DRBG is thread-local, i.e., there is one instance per thread.
*/
static CRYPTO_THREAD_LOCAL public_drbg;
/*
* The <private> DRBG
*
* Used by default for generating private keys using RAND_priv_bytes()
*
* The <private> DRBG is thread-local, i.e., there is one instance per thread.
*/
static CRYPTO_THREAD_LOCAL private_drbg;
/* 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 int rand_drbg_type = RAND_DRBG_TYPE;
static unsigned int rand_drbg_flags = RAND_DRBG_FLAGS;
static unsigned int master_reseed_interval = MASTER_RESEED_INTERVAL;
static unsigned int slave_reseed_interval = SLAVE_RESEED_INTERVAL;
static time_t master_reseed_time_interval = MASTER_RESEED_TIME_INTERVAL;
static time_t slave_reseed_time_interval = SLAVE_RESEED_TIME_INTERVAL;
static RAND_DRBG *drbg_setup(RAND_DRBG *parent);
static RAND_DRBG *rand_drbg_new(int secure,
int type,
unsigned int flags,
RAND_DRBG *parent);
/*
* Set/initialize |drbg| to be of type |type|, with optional |flags|.
*
* If |type| and |flags| are zero, use the defaults
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set(RAND_DRBG *drbg, int type, unsigned int flags)
{
int ret = 1;
if (type == 0 && flags == 0) {
type = rand_drbg_type;
flags = rand_drbg_flags;
}
drbg->state = DRBG_UNINITIALISED;
drbg->flags = flags;
drbg->type = type;
switch (type) {
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;
}
/*
* Set/initialize default |type| and |flag| for new drbg instances.
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_defaults(int type, unsigned int flags)
{
int ret = 1;
switch (type) {
default:
RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_TYPE);
return 0;
case NID_aes_128_ctr:
case NID_aes_192_ctr:
case NID_aes_256_ctr:
break;
}
if ((flags & ~RAND_DRBG_USED_FLAGS) != 0) {
RANDerr(RAND_F_RAND_DRBG_SET_DEFAULTS, RAND_R_UNSUPPORTED_DRBG_FLAGS);
return 0;
}
rand_drbg_type = type;
rand_drbg_flags = flags;
return ret;
}
/*
* Allocate memory and initialize a new DRBG. The DRBG is allocated on
* the secure heap if |secure| is nonzero and the secure heap is enabled.
* The |parent|, if not NULL, will be used as random source for reseeding.
*
* Returns a pointer to the new DRBG instance on success, NULL on failure.
*/
static RAND_DRBG *rand_drbg_new(int secure,
int type,
unsigned int flags,
RAND_DRBG *parent)
{
RAND_DRBG *drbg = secure ?
OPENSSL_secure_zalloc(sizeof(*drbg)) : OPENSSL_zalloc(sizeof(*drbg));
if (drbg == NULL) {
RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
return NULL;
}
drbg->secure = secure && CRYPTO_secure_allocated(drbg);
drbg->fork_count = rand_fork_count;
drbg->parent = parent;
if (parent == NULL) {
drbg->get_entropy = rand_drbg_get_entropy;
drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
#ifndef RAND_DRBG_GET_RANDOM_NONCE
drbg->get_nonce = rand_drbg_get_nonce;
drbg->cleanup_nonce = rand_drbg_cleanup_nonce;
#endif
drbg->reseed_interval = master_reseed_interval;
drbg->reseed_time_interval = master_reseed_time_interval;
} else {
drbg->get_entropy = rand_drbg_get_entropy;
drbg->cleanup_entropy = rand_drbg_cleanup_entropy;
/*
* Do not provide nonce callbacks, the child DRBGs will
* obtain their nonce using random bits from the parent.
*/
drbg->reseed_interval = slave_reseed_interval;
drbg->reseed_time_interval = slave_reseed_time_interval;
}
if (RAND_DRBG_set(drbg, type, flags) == 0)
goto err;
if (parent != NULL) {
rand_drbg_lock(parent);
if (drbg->strength > parent->strength) {
/*
* We currently don't support the algorithm from NIST SP 800-90C
* 10.1.2 to use a weaker DRBG as source
*/
rand_drbg_unlock(parent);
RANDerr(RAND_F_RAND_DRBG_NEW, RAND_R_PARENT_STRENGTH_TOO_WEAK);
goto err;
}
rand_drbg_unlock(parent);
}
return drbg;
err:
if (drbg->secure)
OPENSSL_secure_free(drbg);
else
OPENSSL_free(drbg);
return NULL;
}
RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
{
return rand_drbg_new(0, type, flags, parent);
}
RAND_DRBG *RAND_DRBG_secure_new(int type, unsigned int flags, RAND_DRBG *parent)
{
return rand_drbg_new(1, type, flags, parent);
}
/*
* 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_THREAD_lock_free(drbg->lock);
CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
if (drbg->secure)
OPENSSL_secure_clear_free(drbg, sizeof(*drbg));
else
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;
size_t min_entropy = drbg->strength;
size_t min_entropylen = drbg->min_entropylen;
size_t max_entropylen = drbg->max_entropylen;
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;
/*
* NIST SP800-90Ar1 section 9.1 says you can combine getting the entropy
* and nonce in 1 call by increasing the entropy with 50% and increasing
* the minimum length to accomadate the length of the nonce.
* We do this in case a nonce is require and get_nonce is NULL.
*/
if (drbg->min_noncelen > 0 && drbg->get_nonce == NULL) {
min_entropy += drbg->strength / 2;
min_entropylen += drbg->min_noncelen;
max_entropylen += drbg->max_noncelen;
}
if (drbg->get_entropy != NULL)
entropylen = drbg->get_entropy(drbg, &entropy, min_entropy,
min_entropylen, max_entropylen, 0);
if (entropylen < min_entropylen
|| entropylen > max_entropylen) {
RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
goto end;
}
if (drbg->min_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->type, 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,
int prediction_resistance)
{
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,
prediction_resistance);
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, 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, prediction_resistance)) {
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.
*
* Setting the callbacks is allowed only if the drbg has not been
* initialized yet. Otherwise, the operation will fail.
*
* Returns 1 on success, 0 on failure.
*/
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;
}
/*
* Set the default values for reseed (time) intervals of new DRBG instances
*
* The default values can be set independently for master DRBG instances
* (without a parent) and slave DRBG instances (with parent).
*
* Returns 1 on success, 0 on failure.
*/
int RAND_DRBG_set_reseed_defaults(
unsigned int _master_reseed_interval,
unsigned int _slave_reseed_interval,
time_t _master_reseed_time_interval,
time_t _slave_reseed_time_interval
)
{
if (_master_reseed_interval > MAX_RESEED_INTERVAL
|| _slave_reseed_interval > MAX_RESEED_INTERVAL)
return 0;
if (_master_reseed_time_interval > MAX_RESEED_TIME_INTERVAL
|| _slave_reseed_time_interval > MAX_RESEED_TIME_INTERVAL)
return 0;
master_reseed_interval = _master_reseed_interval;
slave_reseed_interval = _slave_reseed_interval;
master_reseed_time_interval = _master_reseed_time_interval;
slave_reseed_time_interval = _slave_reseed_time_interval;
return 1;
}
/*
* Locks the given drbg. Locking a drbg which does not have locking
* enabled is considered a successful no-op.
*
* Returns 1 on success, 0 on failure.
*/
int rand_drbg_lock(RAND_DRBG *drbg)
{
if (drbg->lock != NULL)
return CRYPTO_THREAD_write_lock(drbg->lock);
return 1;
}
/*
* Unlocks the given drbg. Unlocking a drbg which does not have locking
* enabled is considered a successful no-op.
*
* Returns 1 on success, 0 on failure.
*/
int rand_drbg_unlock(RAND_DRBG *drbg)
{
if (drbg->lock != NULL)
return CRYPTO_THREAD_unlock(drbg->lock);
return 1;
}
/*
* Enables locking for the given drbg
*
* Locking can only be enabled if the random generator
* is in the uninitialized state.
*
* Returns 1 on success, 0 on failure.
*/
int rand_drbg_enable_locking(RAND_DRBG *drbg)
{
if (drbg->state != DRBG_UNINITIALISED) {
RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
RAND_R_DRBG_ALREADY_INITIALIZED);
return 0;
}
if (drbg->lock == NULL) {
if (drbg->parent != NULL && drbg->parent->lock == NULL) {
RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
RAND_R_PARENT_LOCKING_NOT_ENABLED);
return 0;
}
drbg->lock = CRYPTO_THREAD_lock_new();
if (drbg->lock == NULL) {
RANDerr(RAND_F_RAND_DRBG_ENABLE_LOCKING,
RAND_R_FAILED_TO_CREATE_LOCK);
return 0;
}
}
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 = RAND_DRBG_secure_new(rand_drbg_type, rand_drbg_flags, parent);
if (drbg == NULL)
return NULL;
/* Only the master DRBG needs to have a lock */
if (parent == NULL && rand_drbg_enable_locking(drbg) == 0)
goto err;
/* 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:
RAND_DRBG_free(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)
{
int ret = 1;
/*
* ensure that libcrypto is initialized, otherwise the
* DRBG locks are not cleaned up properly
*/
if (!OPENSSL_init_crypto(0, NULL))
return 0;
ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
master_drbg = drbg_setup(NULL);
ret &= CRYPTO_THREAD_init_local(&private_drbg, NULL);
ret &= CRYPTO_THREAD_init_local(&public_drbg, NULL);
if (master_drbg == NULL || ret == 0)
return 0;
return 1;
}
/* Clean up the global DRBGs before exit */
void rand_drbg_cleanup_int(void)
{
RAND_DRBG_free(master_drbg);
master_drbg = NULL;
CRYPTO_THREAD_cleanup_local(&private_drbg);
CRYPTO_THREAD_cleanup_local(&public_drbg);
}
void drbg_delete_thread_state()
{
RAND_DRBG *drbg;
drbg = CRYPTO_THREAD_get_local(&public_drbg);
RAND_DRBG_free(drbg);
drbg = CRYPTO_THREAD_get_local(&private_drbg);
RAND_DRBG_free(drbg);
}
/* 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;
ret = RAND_DRBG_bytes(drbg, out, count);
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;
}
rand_drbg_lock(drbg);
ret = rand_drbg_restart(drbg, buf,
(size_t)(unsigned int)num,
(size_t)(8*randomness));
rand_drbg_unlock(drbg);
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;
rand_drbg_lock(drbg);
ret = drbg->state == DRBG_READY ? 1 : 0;
rand_drbg_unlock(drbg);
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 master_drbg;
}
/*
* Get the public DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*/
RAND_DRBG *RAND_DRBG_get0_public(void)
{
RAND_DRBG *drbg;
if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
return NULL;
drbg = CRYPTO_THREAD_get_local(&public_drbg);
if (drbg == NULL) {
ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
drbg = drbg_setup(master_drbg);
CRYPTO_THREAD_set_local(&public_drbg, drbg);
}
return drbg;
}
/*
* Get the private DRBG.
* Returns pointer to the DRBG on success, NULL on failure.
*/
RAND_DRBG *RAND_DRBG_get0_private(void)
{
RAND_DRBG *drbg;
if (!RUN_ONCE(&rand_drbg_init, do_rand_drbg_init))
return NULL;
drbg = CRYPTO_THREAD_get_local(&private_drbg);
if (drbg == NULL) {
ossl_init_thread_start(OPENSSL_INIT_THREAD_RAND);
drbg = drbg_setup(master_drbg);
CRYPTO_THREAD_set_local(&private_drbg, drbg);
}
return drbg;
}
RAND_METHOD rand_meth = {
drbg_seed,
drbg_bytes,
NULL,
drbg_add,
drbg_bytes,
drbg_status
};
RAND_METHOD *RAND_OpenSSL(void)
{
return &rand_meth;
}