crypto/rand/drbg_lib.c - third_party/openssl - Git at Google

 /*
  * Copyright 2011-2017 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"

 static RAND_DRBG rand_drbg; /* The default global DRBG. */
 static RAND_DRBG priv_drbg; /* The global private-key DRBG. */

 /*
  * 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.)
  */

 static CRYPTO_ONCE rand_init_drbg = CRYPTO_ONCE_STATIC_INIT;

 /*
  * Set/initialize |drbg| to be of type |nid|, with optional |flags|.
  * Return -2 if the type is not supported, 1 on success and -1 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 -2;
     case 0:
         /* Uninitialized; that's okay. */
         return 1;
     case NID_aes_128_ctr:
     case NID_aes_192_ctr:
     case NID_aes_256_ctr:
         ret = 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.
  */
 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->size = RANDOMNESS_NEEDED;
     drbg->fork_count = rand_fork_count;
     drbg->parent = parent;
     if (RAND_DRBG_set(drbg, type, flags) < 0)
         goto err;

     if (parent != NULL) {
         if (!RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_parent,
                                      drbg_release_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)
 {
     /* The global DRBG is free'd by rand_cleanup_drbg_int() */
     if (drbg == NULL || drbg == &rand_drbg)
         return;

     ctr_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.
  */
 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->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 (!ctr_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->reseed_counter = 1;

 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->state == DRBG_READY)
         return 1;
     return 0;
 }

 /*
  * Uninstantiate |drbg|. Must be instantiated before it can be used.
  */
 int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
 {
     int ret = ctr_uninstantiate(drbg);

     OPENSSL_cleanse(&drbg->ctr, sizeof(drbg->ctr));
     drbg->state = DRBG_UNINITIALISED;
     return ret;
 }

 /*
  * Mix in the specified data to reseed |drbg|.
  */
 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 (!ctr_reseed(drbg, entropy, entropylen, adin, adinlen))
         goto end;
     drbg->state = DRBG_READY;
     drbg->reseed_counter = 1;

 end:
     if (entropy != NULL && drbg->cleanup_entropy != NULL)
         drbg->cleanup_entropy(drbg, entropy, entropylen);
     if (drbg->state == DRBG_READY)
         return 1;
     return 0;
 }

 /*
  * 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|.
  */
 int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
                        int prediction_resistance,
                        const unsigned char *adin, size_t adinlen)
 {
     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;
         drbg->state = DRBG_RESEED;
     }

     if (drbg->reseed_counter >= drbg->reseed_interval)
         drbg->state = DRBG_RESEED;

     if (drbg->state == DRBG_RESEED || 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 (!ctr_generate(drbg, out, outlen, adin, adinlen)) {
         drbg->state = DRBG_ERROR;
         RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
         return 0;
     }

     if (drbg->reseed_counter >= drbg->reseed_interval)
         drbg->state = DRBG_RESEED;
     else
         drbg->reseed_counter++;
     return 1;
 }

 /*
  * Set the callbacks for entropy and nonce.  We currently don't use
  * the nonce; that's mainly for the KATs
  */
 int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
                             RAND_DRBG_get_entropy_fn cb_get_entropy,
                             RAND_DRBG_cleanup_entropy_fn cb_cleanup_entropy,
                             RAND_DRBG_get_nonce_fn cb_get_nonce,
                             RAND_DRBG_cleanup_nonce_fn cb_cleanup_nonce)
 {
     if (drbg->state != DRBG_UNINITIALISED)
         return 0;
     drbg->get_entropy = cb_get_entropy;
     drbg->cleanup_entropy = cb_cleanup_entropy;
     drbg->get_nonce = cb_get_nonce;
     drbg->cleanup_nonce = cb_cleanup_nonce;
     return 1;
 }

 /*
  * Set the reseed interval.
  */
 int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, int interval)
 {
     if (interval < 0 || interval > MAX_RESEED)
         return 0;
     drbg->reseed_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.
  */

 /*
  * Creates a global DRBG with default settings.
  * Returns 1 on success, 0 on failure
  */
 static int setup_drbg(RAND_DRBG *drbg)
 {
     int ret = 1;

     drbg->lock = CRYPTO_THREAD_lock_new();
     ret &= drbg->lock != NULL;
     drbg->size = RANDOMNESS_NEEDED;
     drbg->secure = CRYPTO_secure_malloc_initialized();
     /* If you change these parameters, see RANDOMNESS_NEEDED */
     ret &= RAND_DRBG_set(drbg,
                          NID_aes_128_ctr, RAND_DRBG_FLAG_CTR_USE_DF) == 1;
     ret &= RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_system,
                                    drbg_release_entropy, NULL, NULL) == 1;
     ret &= RAND_DRBG_instantiate(drbg, NULL, 0) == 1;
     return ret;
 }

 /*
  * Initialize the global DRBGs on first use.
  * Returns 1 on success, 0 on failure.
  */
 DEFINE_RUN_ONCE_STATIC(do_rand_init_drbg)
 {
     int ret = 1;

     ret &= setup_drbg(&rand_drbg);
     ret &= setup_drbg(&priv_drbg);

     return ret;
 }

 /* Clean up a DRBG and free it */
 static void free_drbg(RAND_DRBG *drbg)
 {
     CRYPTO_THREAD_lock_free(drbg->lock);
     RAND_DRBG_uninstantiate(drbg);
 }

 /* Clean up the global DRBGs before exit */
 void rand_cleanup_drbg_int(void)
 {
     free_drbg(&rand_drbg);
     free_drbg(&priv_drbg);
 }

 static int drbg_bytes(unsigned char *out, int count)
 {
     int ret = 0;
     size_t chunk;
     RAND_DRBG *drbg = RAND_DRBG_get0_global();

     if (drbg == NULL)
         return 0;

     CRYPTO_THREAD_write_lock(drbg->lock);
     if (drbg->state == DRBG_UNINITIALISED)
         goto err;

     for ( ; count > 0; count -= chunk, out += chunk) {
         chunk = count;
         if (chunk > drbg->max_request)
             chunk = drbg->max_request;
         ret = RAND_DRBG_generate(drbg, out, chunk, 0, NULL, 0);
         if (!ret)
             goto err;
     }
     ret = 1;

 err:
     CRYPTO_THREAD_unlock(drbg->lock);
     return ret;
 }

 static int drbg_add(const void *buf, int num, double randomness)
 {
     unsigned char *in = (unsigned char *)buf;
     unsigned char *out, *end;

     CRYPTO_THREAD_write_lock(rand_bytes.lock);
     out = &rand_bytes.buff[rand_bytes.curr];
     end = &rand_bytes.buff[rand_bytes.size];

     /* Copy whatever fits into the end of the buffer. */
     for ( ; --num >= 0 && out < end; rand_bytes.curr++)
         *out++ = *in++;

     /* XOR any the leftover. */
     while (num > 0) {
         for (out = rand_bytes.buff; --num >= 0 && out < end; )
             *out++ ^= *in++;
     }

     CRYPTO_THREAD_unlock(rand_bytes.lock);
     return 1;
 }

 static int drbg_seed(const void *buf, int num)
 {
     return drbg_add(buf, num, num);
 }

 static int drbg_status(void)
 {
     int ret;
     RAND_DRBG *drbg = RAND_DRBG_get0_global();

     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 global public DRBG.
  * Returns pointer to the DRBG on success, NULL on failure.
  */
 RAND_DRBG *RAND_DRBG_get0_global(void)
 {
     if (!RUN_ONCE(&rand_init_drbg, do_rand_init_drbg))
         return NULL;

     return &rand_drbg;
 }

 /*
  * Get the global private DRBG.
  * Returns pointer to the DRBG on success, NULL on failure.
  */
 RAND_DRBG *RAND_DRBG_get0_priv_global(void)
 {
     if (!RUN_ONCE(&rand_init_drbg, do_rand_init_drbg))
         return NULL;

     return &priv_drbg;
 }

 RAND_METHOD rand_meth = {
     drbg_seed,
     drbg_bytes,
     NULL,
     drbg_add,
     drbg_bytes,
     drbg_status
 };

 RAND_METHOD *RAND_OpenSSL(void)
 {
     return &rand_meth;
 }
	/*
	* Copyright 2011-2017 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"

	static RAND_DRBG rand_drbg; /* The default global DRBG. */
	static RAND_DRBG priv_drbg; /* The global private-key DRBG. */

	/*
	* 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.)
	*/

	static CRYPTO_ONCE rand_init_drbg = CRYPTO_ONCE_STATIC_INIT;

	/*
	* Set/initialize \|drbg\| to be of type \|nid\|, with optional \|flags\|.
	* Return -2 if the type is not supported, 1 on success and -1 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 -2;
	case 0:
	/* Uninitialized; that's okay. */
	return 1;
	case NID_aes_128_ctr:
	case NID_aes_192_ctr:
	case NID_aes_256_ctr:
	ret = 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.
	*/
	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->size = RANDOMNESS_NEEDED;
	drbg->fork_count = rand_fork_count;
	drbg->parent = parent;
	if (RAND_DRBG_set(drbg, type, flags) < 0)
	goto err;

	if (parent != NULL) {
	if (!RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_parent,
	drbg_release_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)
	{
	/* The global DRBG is free'd by rand_cleanup_drbg_int() */
	if (drbg == NULL \|\| drbg == &rand_drbg)
	return;

	ctr_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.
	*/
	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->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 (!ctr_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->reseed_counter = 1;

	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->state == DRBG_READY)
	return 1;
	return 0;
	}

	/*
	* Uninstantiate \|drbg\|. Must be instantiated before it can be used.
	*/
	int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
	{
	int ret = ctr_uninstantiate(drbg);

	OPENSSL_cleanse(&drbg->ctr, sizeof(drbg->ctr));
	drbg->state = DRBG_UNINITIALISED;
	return ret;
	}

	/*
	* Mix in the specified data to reseed \|drbg\|.
	*/
	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 (!ctr_reseed(drbg, entropy, entropylen, adin, adinlen))
	goto end;
	drbg->state = DRBG_READY;
	drbg->reseed_counter = 1;

	end:
	if (entropy != NULL && drbg->cleanup_entropy != NULL)
	drbg->cleanup_entropy(drbg, entropy, entropylen);
	if (drbg->state == DRBG_READY)
	return 1;
	return 0;
	}

	/*
	* 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\|.
	*/
	int RAND_DRBG_generate(RAND_DRBG drbg, unsigned char out, size_t outlen,
	int prediction_resistance,
	const unsigned char *adin, size_t adinlen)
	{
	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;
	drbg->state = DRBG_RESEED;
	}

	if (drbg->reseed_counter >= drbg->reseed_interval)
	drbg->state = DRBG_RESEED;

	if (drbg->state == DRBG_RESEED \|\| 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 (!ctr_generate(drbg, out, outlen, adin, adinlen)) {
	drbg->state = DRBG_ERROR;
	RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
	return 0;
	}

	if (drbg->reseed_counter >= drbg->reseed_interval)
	drbg->state = DRBG_RESEED;
	else
	drbg->reseed_counter++;
	return 1;
	}

	/*
	* Set the callbacks for entropy and nonce. We currently don't use
	* the nonce; that's mainly for the KATs
	*/
	int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
	RAND_DRBG_get_entropy_fn cb_get_entropy,
	RAND_DRBG_cleanup_entropy_fn cb_cleanup_entropy,
	RAND_DRBG_get_nonce_fn cb_get_nonce,
	RAND_DRBG_cleanup_nonce_fn cb_cleanup_nonce)
	{
	if (drbg->state != DRBG_UNINITIALISED)
	return 0;
	drbg->get_entropy = cb_get_entropy;
	drbg->cleanup_entropy = cb_cleanup_entropy;
	drbg->get_nonce = cb_get_nonce;
	drbg->cleanup_nonce = cb_cleanup_nonce;
	return 1;
	}

	/*
	* Set the reseed interval.
	*/
	int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, int interval)
	{
	if (interval < 0 \|\| interval > MAX_RESEED)
	return 0;
	drbg->reseed_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.
	*/

	/*
	* Creates a global DRBG with default settings.
	* Returns 1 on success, 0 on failure
	*/
	static int setup_drbg(RAND_DRBG *drbg)
	{
	int ret = 1;

	drbg->lock = CRYPTO_THREAD_lock_new();
	ret &= drbg->lock != NULL;
	drbg->size = RANDOMNESS_NEEDED;
	drbg->secure = CRYPTO_secure_malloc_initialized();
	/* If you change these parameters, see RANDOMNESS_NEEDED */
	ret &= RAND_DRBG_set(drbg,
	NID_aes_128_ctr, RAND_DRBG_FLAG_CTR_USE_DF) == 1;
	ret &= RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_system,
	drbg_release_entropy, NULL, NULL) == 1;
	ret &= RAND_DRBG_instantiate(drbg, NULL, 0) == 1;
	return ret;
	}

	/*
	* Initialize the global DRBGs on first use.
	* Returns 1 on success, 0 on failure.
	*/
	DEFINE_RUN_ONCE_STATIC(do_rand_init_drbg)
	{
	int ret = 1;

	ret &= setup_drbg(&rand_drbg);
	ret &= setup_drbg(&priv_drbg);

	return ret;
	}

	/* Clean up a DRBG and free it */
	static void free_drbg(RAND_DRBG *drbg)
	{
	CRYPTO_THREAD_lock_free(drbg->lock);
	RAND_DRBG_uninstantiate(drbg);
	}

	/* Clean up the global DRBGs before exit */
	void rand_cleanup_drbg_int(void)
	{
	free_drbg(&rand_drbg);
	free_drbg(&priv_drbg);
	}

	static int drbg_bytes(unsigned char *out, int count)
	{
	int ret = 0;
	size_t chunk;
	RAND_DRBG *drbg = RAND_DRBG_get0_global();

	if (drbg == NULL)
	return 0;

	CRYPTO_THREAD_write_lock(drbg->lock);
	if (drbg->state == DRBG_UNINITIALISED)
	goto err;

	for ( ; count > 0; count -= chunk, out += chunk) {
	chunk = count;
	if (chunk > drbg->max_request)
	chunk = drbg->max_request;
	ret = RAND_DRBG_generate(drbg, out, chunk, 0, NULL, 0);
	if (!ret)
	goto err;
	}
	ret = 1;

	err:
	CRYPTO_THREAD_unlock(drbg->lock);
	return ret;
	}

	static int drbg_add(const void *buf, int num, double randomness)
	{
	unsigned char in = (unsigned char )buf;
	unsigned char out, end;

	CRYPTO_THREAD_write_lock(rand_bytes.lock);
	out = &rand_bytes.buff[rand_bytes.curr];
	end = &rand_bytes.buff[rand_bytes.size];

	/* Copy whatever fits into the end of the buffer. */
	for ( ; --num >= 0 && out < end; rand_bytes.curr++)
	out++ = in++;

	/* XOR any the leftover. */
	while (num > 0) {
	for (out = rand_bytes.buff; --num >= 0 && out < end; )
	out++ ^= in++;
	}

	CRYPTO_THREAD_unlock(rand_bytes.lock);
	return 1;
	}

	static int drbg_seed(const void *buf, int num)
	{
	return drbg_add(buf, num, num);
	}

	static int drbg_status(void)
	{
	int ret;
	RAND_DRBG *drbg = RAND_DRBG_get0_global();

	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 global public DRBG.
	* Returns pointer to the DRBG on success, NULL on failure.
	*/
	RAND_DRBG *RAND_DRBG_get0_global(void)
	{
	if (!RUN_ONCE(&rand_init_drbg, do_rand_init_drbg))
	return NULL;

	return &rand_drbg;
	}

	/*
	* Get the global private DRBG.
	* Returns pointer to the DRBG on success, NULL on failure.
	*/
	RAND_DRBG *RAND_DRBG_get0_priv_global(void)
	{
	if (!RUN_ONCE(&rand_init_drbg, do_rand_init_drbg))
	return NULL;

	return &priv_drbg;
	}

	RAND_METHOD rand_meth = {
	drbg_seed,
	drbg_bytes,
	NULL,
	drbg_add,
	drbg_bytes,
	drbg_status
	};

	RAND_METHOD *RAND_OpenSSL(void)
	{
	return &rand_meth;
	}