fips/rand/fips_drbg_lib.c - third_party/openssl - Git at Google

 /* fips/rand/fips_drbg_lib.c */
 /* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
  * project.
  */
 /* ====================================================================
  * Copyright (c) 2011 The OpenSSL Project.  All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in
  *    the documentation and/or other materials provided with the
  *    distribution.
  *
  * 3. All advertising materials mentioning features or use of this
  *    software must display the following acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
  *
  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
  *    endorse or promote products derived from this software without
  *    prior written permission. For written permission, please contact
  *    licensing@OpenSSL.org.
  *
  * 5. Products derived from this software may not be called "OpenSSL"
  *    nor may "OpenSSL" appear in their names without prior written
  *    permission of the OpenSSL Project.
  *
  * 6. Redistributions of any form whatsoever must retain the following
  *    acknowledgment:
  *    "This product includes software developed by the OpenSSL Project
  *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
  *
  * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
  * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  * OF THE POSSIBILITY OF SUCH DAMAGE.
  * ====================================================================
  */

 #define OPENSSL_FIPSAPI

 #include <string.h>
 #include <openssl/crypto.h>
 #include <openssl/evp.h>
 #include <openssl/aes.h>
 #include <openssl/err.h>
 #include <openssl/fips_rand.h>
 #include "fips_rand_lcl.h"

 /* Support framework for SP800-90 DRBGs */

 int FIPS_drbg_init(DRBG_CTX *dctx, int type, unsigned int flags)
 	{
 	int rv;
 	memset(dctx, 0, sizeof(DRBG_CTX));
 	dctx->status = DRBG_STATUS_UNINITIALISED;
 	dctx->flags = flags;
 	dctx->type = type;

 	rv = fips_drbg_hash_init(dctx);

 	if (rv == -2)
 		rv = fips_drbg_ctr_init(dctx);

 	if (rv <= 0)
 		{
 		if (rv == -2)
 			FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_UNSUPPORTED_DRBG_TYPE);
 		else
 			FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_ERROR_INITIALISING_DRBG);
 		}

 	return rv;
 	}

 DRBG_CTX *FIPS_drbg_new(int type, unsigned int flags)
 	{
 	int rv;
 	DRBG_CTX *dctx;
 	dctx = OPENSSL_malloc(sizeof(DRBG_CTX));
 	if (!dctx)
 		{
 		FIPSerr(FIPS_F_FIPS_DRBG_NEW, ERR_R_MALLOC_FAILURE);
 		return NULL;
 		}
 	if (type == 0)
 		return dctx;
 	rv = FIPS_drbg_init(dctx, type, flags);

 	if (FIPS_drbg_init(dctx, type, flags) <= 0)
 		{
 		OPENSSL_free(dctx);
 		return NULL;
 		}

 	return dctx;
 	}

 void FIPS_drbg_free(DRBG_CTX *dctx)
 	{
 	dctx->uninstantiate(dctx);
 	OPENSSL_cleanse(dctx, sizeof(DRBG_CTX));
 	OPENSSL_free(dctx);
 	}

 int FIPS_drbg_instantiate(DRBG_CTX *dctx,
 				const unsigned char *pers, size_t perslen)
 	{
 	size_t entlen, noncelen;

 #if 0
 	/* Put here so error script picks them up */
 	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE,
 				FIPS_R_PERSONALISATION_STRING_TOO_LONG);
 	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_IN_ERROR_STATE);
 	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ALREADY_INSTANTIATED);
 	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ERROR_RETRIEVING_ENTROPY);
 	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ERROR_RETRIEVING_NONCE);
 	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_INSTANTIATE_ERROR);
 #endif

 	int r = 0;

 	if (perslen > dctx->max_pers)
 		{
 		r = FIPS_R_PERSONALISATION_STRING_TOO_LONG;
 		goto end;
 		}

 	if (dctx->status != DRBG_STATUS_UNINITIALISED)
 		{
 		if (dctx->status == DRBG_STATUS_ERROR)
 			r = FIPS_R_IN_ERROR_STATE;
 		else
 			r = FIPS_R_ALREADY_INSTANTIATED;
 		goto end;
 		}

 	dctx->status = DRBG_STATUS_ERROR;

 	entlen = dctx->get_entropy(dctx, dctx->entropy, dctx->strength,
 				dctx->min_entropy, dctx->max_entropy);

 	if (entlen < dctx->min_entropy || entlen > dctx->max_entropy)
 		{
 		r = FIPS_R_ERROR_RETRIEVING_ENTROPY;
 		goto end;
 		}

 	if (dctx->max_nonce > 0)
 		{

 		noncelen = dctx->get_nonce(dctx, dctx->nonce,
 					dctx->strength / 2,
 					dctx->min_nonce, dctx->max_nonce);

 		if (noncelen < dctx->min_nonce || noncelen > dctx->max_nonce)
 			{
 			r = FIPS_R_ERROR_RETRIEVING_NONCE;
 			goto end;
 			}

 		}
 	else
 		noncelen = 0;

 	if (!dctx->instantiate(dctx,
 				dctx->entropy, entlen,
 				dctx->nonce, noncelen,
 				pers, perslen))
 		{
 		r = FIPS_R_ERROR_INSTANTIATING_DRBG;
 		goto end;
 		}


 	dctx->status = DRBG_STATUS_READY;
 	dctx->reseed_counter = 1;

 	end:

 	OPENSSL_cleanse(dctx->entropy, sizeof(dctx->entropy));
 	OPENSSL_cleanse(dctx->nonce, sizeof(dctx->nonce));

 	if (dctx->status == DRBG_STATUS_READY)
 		return 1;

 	if (r && !(dctx->flags & DRBG_FLAG_NOERR))
 		FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, r);

 	return 0;

 	}

 int FIPS_drbg_reseed(DRBG_CTX *dctx,
 			const unsigned char *adin, size_t adinlen)
 	{
 	size_t entlen;
 	int r = 0;

 #if 0
 	FIPSerr(FIPS_F_FIPS_DRBG_RESEED, FIPS_R_NOT_INSTANTIATED);
 	FIPSerr(FIPS_F_FIPS_DRBG_RESEED, FIPS_R_ADDITIONAL_INPUT_TOO_LONG);
 #endif
 	if (dctx->status != DRBG_STATUS_READY
 		&& dctx->status != DRBG_STATUS_RESEED)
 		{
 		if (dctx->status == DRBG_STATUS_ERROR)
 			r = FIPS_R_IN_ERROR_STATE;
 		else if(dctx->status == DRBG_STATUS_UNINITIALISED)
 			r = FIPS_R_NOT_INSTANTIATED;
 		goto end;
 		}

 	if (!adin)
 		adinlen = 0;
 	else if (adinlen > dctx->max_adin)
 		{
 		r = FIPS_R_ADDITIONAL_INPUT_TOO_LONG;
 		goto end;
 		}

 	dctx->status = DRBG_STATUS_ERROR;

 	entlen = dctx->get_entropy(dctx, dctx->entropy, dctx->strength,
 				dctx->min_entropy, dctx->max_entropy);

 	if (entlen < dctx->min_entropy || entlen > dctx->max_entropy)
 		{
 		r = FIPS_R_ERROR_RETRIEVING_ENTROPY;
 		goto end;
 		}

 	if (!dctx->reseed(dctx, dctx->entropy, entlen, adin, adinlen))
 		goto end;

 	dctx->status = DRBG_STATUS_READY;
 	dctx->reseed_counter = 1;
 	end:
 	OPENSSL_cleanse(dctx->entropy, sizeof(dctx->entropy));

 	if (dctx->status == DRBG_STATUS_READY)
 		return 1;

 	if (r && !(dctx->flags & DRBG_FLAG_NOERR))
 		FIPSerr(FIPS_F_FIPS_DRBG_RESEED, r);

 	return 0;
 	}


 static int fips_drbg_generate_internal(DRBG_CTX *dctx,
 			unsigned char *out, size_t outlen,
 			int strength, int prediction_resistance,
 			const unsigned char *adin, size_t adinlen)
 	{
 	int r = 0;
 	if (outlen > dctx->max_request)
 		{
 		r = FIPS_R_REQUEST_TOO_LARGE_FOR_DRBG;
 		return 0;
 		}

 	if (strength > dctx->strength)
 		{
 		r = FIPS_R_INSUFFICIENT_SECURITY_STRENGTH;
 		goto end;
 		}

 	if (dctx->status == DRBG_STATUS_RESEED || prediction_resistance)
 		{
 		if (!FIPS_drbg_reseed(dctx, adin, adinlen))
 			{
 			r = FIPS_R_RESEED_ERROR;
 			goto end;
 			}
 		adin = NULL;
 		adinlen = 0;
 		}
 	if (dctx->status != DRBG_STATUS_READY)
 		{
 		if (dctx->status == DRBG_STATUS_ERROR)
 			r = FIPS_R_IN_ERROR_STATE;
 		else if(dctx->status == DRBG_STATUS_UNINITIALISED)
 			r = FIPS_R_NOT_INSTANTIATED;
 		goto end;
 		}
 	if (!dctx->generate(dctx, out, outlen, adin, adinlen))
 		{
 		r = FIPS_R_GENERATE_ERROR;
 		dctx->status = DRBG_STATUS_ERROR;
 		goto end;
 		}
 	if (dctx->reseed_counter >= dctx->reseed_interval)
 		dctx->status = DRBG_STATUS_RESEED;
 	else
 		dctx->reseed_counter++;

 	end:
 	if (r)
 		{
 		if (!(dctx->flags & DRBG_FLAG_NOERR))
 			FIPSerr(FIPS_F_FIPS_DRBG_GENERATE_INTERNAL, r);
 		return 0;
 		}

 	return 1;
 	}

 /* external generate function: incorporates continuous RNG test if not
  * in test mode.
  */

 int FIPS_drbg_generate(DRBG_CTX *dctx,
 			unsigned char *out, size_t outlen,
 			int strength, int prediction_resistance,
 			const unsigned char *adin, size_t adinlen)
 	{
 	unsigned char tmp[16], *pout;
 	size_t poutlen;
 	/* If test mode don't run continuous RNG test */
 	if (dctx->flags & DRBG_FLAG_TEST)
 		{
 		return fips_drbg_generate_internal(dctx, out, outlen,
 							strength,
 							prediction_resistance,
 							adin, adinlen);
 		}
 	/* If this is the first call generate block and save buffer */
 	if (!dctx->lb_valid)
 		{
 		if (!fips_drbg_generate_internal(dctx, dctx->lb, 16,
 						strength, prediction_resistance,
 						adin, adinlen))
 			return 0;
 		dctx->lb_valid = 1;
 		}

 	/* If request less that 16 bytes request 16 in temp buffer */

 	if (outlen < 16)
 		{
 		pout = tmp;
 		poutlen = 16;
 		}
 	else
 		{
 		pout = out;
 		poutlen = outlen;
 		}

 	/* Generate data */
 	if (!fips_drbg_generate_internal(dctx, pout, poutlen,
 						strength, prediction_resistance,
 						adin, adinlen))
 			return 0;
 	/* Compare to last block for continuous PRNG test */
 	if (!memcmp(pout, dctx->lb, 16))
 		{
 		FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, FIPS_R_DRBG_STUCK);
 		return 0;
 		}
 	/* Update last block */
 	memcpy(dctx->lb, pout, 16);
 	/* Copy to output buffer if needed */
 	if (outlen < 16)
 		memcpy(out, pout, outlen);

 	return 1;

 	}

 int FIPS_drbg_uninstantiate(DRBG_CTX *dctx)
 	{
 	int rv;
 	if (!dctx->uninstantiate)
 		return 1;
 	rv = dctx->uninstantiate(dctx);
 	/* Although we'd like to cleanse here we can't because we have to
 	 * test the uninstantiate really zeroes the data.
 	 */
 	memset(dctx, 0, sizeof(DRBG_CTX));
 	/* If method has problems uninstantiating, return error */
 	return rv;
 	}

 int FIPS_drbg_set_test_mode(DRBG_CTX *dctx,
 	size_t (*get_entropy)(DRBG_CTX *ctx, unsigned char *out,
 				int entropy, size_t min_len, size_t max_len),
 	size_t (*get_nonce)(DRBG_CTX *ctx, unsigned char *out,
 				int entropy, size_t min_len, size_t max_len))
 	{
 	if (dctx->status != DRBG_STATUS_UNINITIALISED)
 		return 0;
 	dctx->flags |= DRBG_FLAG_TEST;
 	dctx->get_entropy = get_entropy;
 	dctx->get_nonce = get_nonce;
 	return 1;
 	}

 void *FIPS_drbg_get_app_data(DRBG_CTX *dctx)
 	{
 	return dctx->app_data;
 	}

 void FIPS_drbg_set_app_data(DRBG_CTX *dctx, void *app_data)
 	{
 	dctx->app_data = app_data;
 	}

 size_t FIPS_drbg_get_blocklength(DRBG_CTX *dctx)
 	{
 	return dctx->blocklength;
 	}

 int FIPS_drbg_get_strength(DRBG_CTX *dctx)
 	{
 	return dctx->strength;
 	}
	/* fips/rand/fips_drbg_lib.c */
	/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
	* project.
	*/
	/* ====================================================================
	* Copyright (c) 2011 The OpenSSL Project. All rights reserved.
	*
	* Redistribution and use in source and binary forms, with or without
	* modification, are permitted provided that the following conditions
	* are met:
	*
	* 1. Redistributions of source code must retain the above copyright
	* notice, this list of conditions and the following disclaimer.
	*
	* 2. Redistributions in binary form must reproduce the above copyright
	* notice, this list of conditions and the following disclaimer in
	* the documentation and/or other materials provided with the
	* distribution.
	*
	* 3. All advertising materials mentioning features or use of this
	* software must display the following acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
	*
	* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
	* endorse or promote products derived from this software without
	* prior written permission. For written permission, please contact
	* licensing@OpenSSL.org.
	*
	* 5. Products derived from this software may not be called "OpenSSL"
	* nor may "OpenSSL" appear in their names without prior written
	* permission of the OpenSSL Project.
	*
	* 6. Redistributions of any form whatsoever must retain the following
	* acknowledgment:
	* "This product includes software developed by the OpenSSL Project
	* for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
	*
	* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
	* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
	* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
	* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
	* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
	* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
	* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
	* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
	* OF THE POSSIBILITY OF SUCH DAMAGE.
	* ====================================================================
	*/

	#define OPENSSL_FIPSAPI

	#include <string.h>
	#include <openssl/crypto.h>
	#include <openssl/evp.h>
	#include <openssl/aes.h>
	#include <openssl/err.h>
	#include <openssl/fips_rand.h>
	#include "fips_rand_lcl.h"

	/* Support framework for SP800-90 DRBGs */

	int FIPS_drbg_init(DRBG_CTX *dctx, int type, unsigned int flags)
	{
	int rv;
	memset(dctx, 0, sizeof(DRBG_CTX));
	dctx->status = DRBG_STATUS_UNINITIALISED;
	dctx->flags = flags;
	dctx->type = type;

	rv = fips_drbg_hash_init(dctx);

	if (rv == -2)
	rv = fips_drbg_ctr_init(dctx);

	if (rv <= 0)
	{
	if (rv == -2)
	FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_UNSUPPORTED_DRBG_TYPE);
	else
	FIPSerr(FIPS_F_FIPS_DRBG_INIT, FIPS_R_ERROR_INITIALISING_DRBG);
	}

	return rv;
	}

	DRBG_CTX *FIPS_drbg_new(int type, unsigned int flags)
	{
	int rv;
	DRBG_CTX *dctx;
	dctx = OPENSSL_malloc(sizeof(DRBG_CTX));
	if (!dctx)
	{
	FIPSerr(FIPS_F_FIPS_DRBG_NEW, ERR_R_MALLOC_FAILURE);
	return NULL;
	}
	if (type == 0)
	return dctx;
	rv = FIPS_drbg_init(dctx, type, flags);

	if (FIPS_drbg_init(dctx, type, flags) <= 0)
	{
	OPENSSL_free(dctx);
	return NULL;
	}

	return dctx;
	}

	void FIPS_drbg_free(DRBG_CTX *dctx)
	{
	dctx->uninstantiate(dctx);
	OPENSSL_cleanse(dctx, sizeof(DRBG_CTX));
	OPENSSL_free(dctx);
	}

	int FIPS_drbg_instantiate(DRBG_CTX *dctx,
	const unsigned char *pers, size_t perslen)
	{
	size_t entlen, noncelen;

	#if 0
	/* Put here so error script picks them up */
	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE,
	FIPS_R_PERSONALISATION_STRING_TOO_LONG);
	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_IN_ERROR_STATE);
	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ALREADY_INSTANTIATED);
	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ERROR_RETRIEVING_ENTROPY);
	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_ERROR_RETRIEVING_NONCE);
	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, FIPS_R_INSTANTIATE_ERROR);
	#endif

	int r = 0;

	if (perslen > dctx->max_pers)
	{
	r = FIPS_R_PERSONALISATION_STRING_TOO_LONG;
	goto end;
	}

	if (dctx->status != DRBG_STATUS_UNINITIALISED)
	{
	if (dctx->status == DRBG_STATUS_ERROR)
	r = FIPS_R_IN_ERROR_STATE;
	else
	r = FIPS_R_ALREADY_INSTANTIATED;
	goto end;
	}

	dctx->status = DRBG_STATUS_ERROR;

	entlen = dctx->get_entropy(dctx, dctx->entropy, dctx->strength,
	dctx->min_entropy, dctx->max_entropy);

	if (entlen < dctx->min_entropy \|\| entlen > dctx->max_entropy)
	{
	r = FIPS_R_ERROR_RETRIEVING_ENTROPY;
	goto end;
	}

	if (dctx->max_nonce > 0)
	{

	noncelen = dctx->get_nonce(dctx, dctx->nonce,
	dctx->strength / 2,
	dctx->min_nonce, dctx->max_nonce);

	if (noncelen < dctx->min_nonce \|\| noncelen > dctx->max_nonce)
	{
	r = FIPS_R_ERROR_RETRIEVING_NONCE;
	goto end;
	}

	}
	else
	noncelen = 0;

	if (!dctx->instantiate(dctx,
	dctx->entropy, entlen,
	dctx->nonce, noncelen,
	pers, perslen))
	{
	r = FIPS_R_ERROR_INSTANTIATING_DRBG;
	goto end;
	}


	dctx->status = DRBG_STATUS_READY;
	dctx->reseed_counter = 1;

	end:

	OPENSSL_cleanse(dctx->entropy, sizeof(dctx->entropy));
	OPENSSL_cleanse(dctx->nonce, sizeof(dctx->nonce));

	if (dctx->status == DRBG_STATUS_READY)
	return 1;

	if (r && !(dctx->flags & DRBG_FLAG_NOERR))
	FIPSerr(FIPS_F_FIPS_DRBG_INSTANTIATE, r);

	return 0;

	}

	int FIPS_drbg_reseed(DRBG_CTX *dctx,
	const unsigned char *adin, size_t adinlen)
	{
	size_t entlen;
	int r = 0;

	#if 0
	FIPSerr(FIPS_F_FIPS_DRBG_RESEED, FIPS_R_NOT_INSTANTIATED);
	FIPSerr(FIPS_F_FIPS_DRBG_RESEED, FIPS_R_ADDITIONAL_INPUT_TOO_LONG);
	#endif
	if (dctx->status != DRBG_STATUS_READY
	&& dctx->status != DRBG_STATUS_RESEED)
	{
	if (dctx->status == DRBG_STATUS_ERROR)
	r = FIPS_R_IN_ERROR_STATE;
	else if(dctx->status == DRBG_STATUS_UNINITIALISED)
	r = FIPS_R_NOT_INSTANTIATED;
	goto end;
	}

	if (!adin)
	adinlen = 0;
	else if (adinlen > dctx->max_adin)
	{
	r = FIPS_R_ADDITIONAL_INPUT_TOO_LONG;
	goto end;
	}

	dctx->status = DRBG_STATUS_ERROR;

	entlen = dctx->get_entropy(dctx, dctx->entropy, dctx->strength,
	dctx->min_entropy, dctx->max_entropy);

	if (entlen < dctx->min_entropy \|\| entlen > dctx->max_entropy)
	{
	r = FIPS_R_ERROR_RETRIEVING_ENTROPY;
	goto end;
	}

	if (!dctx->reseed(dctx, dctx->entropy, entlen, adin, adinlen))
	goto end;

	dctx->status = DRBG_STATUS_READY;
	dctx->reseed_counter = 1;
	end:
	OPENSSL_cleanse(dctx->entropy, sizeof(dctx->entropy));

	if (dctx->status == DRBG_STATUS_READY)
	return 1;

	if (r && !(dctx->flags & DRBG_FLAG_NOERR))
	FIPSerr(FIPS_F_FIPS_DRBG_RESEED, r);

	return 0;
	}


	static int fips_drbg_generate_internal(DRBG_CTX *dctx,
	unsigned char *out, size_t outlen,
	int strength, int prediction_resistance,
	const unsigned char *adin, size_t adinlen)
	{
	int r = 0;
	if (outlen > dctx->max_request)
	{
	r = FIPS_R_REQUEST_TOO_LARGE_FOR_DRBG;
	return 0;
	}

	if (strength > dctx->strength)
	{
	r = FIPS_R_INSUFFICIENT_SECURITY_STRENGTH;
	goto end;
	}

	if (dctx->status == DRBG_STATUS_RESEED \|\| prediction_resistance)
	{
	if (!FIPS_drbg_reseed(dctx, adin, adinlen))
	{
	r = FIPS_R_RESEED_ERROR;
	goto end;
	}
	adin = NULL;
	adinlen = 0;
	}
	if (dctx->status != DRBG_STATUS_READY)
	{
	if (dctx->status == DRBG_STATUS_ERROR)
	r = FIPS_R_IN_ERROR_STATE;
	else if(dctx->status == DRBG_STATUS_UNINITIALISED)
	r = FIPS_R_NOT_INSTANTIATED;
	goto end;
	}
	if (!dctx->generate(dctx, out, outlen, adin, adinlen))
	{
	r = FIPS_R_GENERATE_ERROR;
	dctx->status = DRBG_STATUS_ERROR;
	goto end;
	}
	if (dctx->reseed_counter >= dctx->reseed_interval)
	dctx->status = DRBG_STATUS_RESEED;
	else
	dctx->reseed_counter++;

	end:
	if (r)
	{
	if (!(dctx->flags & DRBG_FLAG_NOERR))
	FIPSerr(FIPS_F_FIPS_DRBG_GENERATE_INTERNAL, r);
	return 0;
	}

	return 1;
	}

	/* external generate function: incorporates continuous RNG test if not
	* in test mode.
	*/

	int FIPS_drbg_generate(DRBG_CTX *dctx,
	unsigned char *out, size_t outlen,
	int strength, int prediction_resistance,
	const unsigned char *adin, size_t adinlen)
	{
	unsigned char tmp[16], *pout;
	size_t poutlen;
	/* If test mode don't run continuous RNG test */
	if (dctx->flags & DRBG_FLAG_TEST)
	{
	return fips_drbg_generate_internal(dctx, out, outlen,
	strength,
	prediction_resistance,
	adin, adinlen);
	}
	/* If this is the first call generate block and save buffer */
	if (!dctx->lb_valid)
	{
	if (!fips_drbg_generate_internal(dctx, dctx->lb, 16,
	strength, prediction_resistance,
	adin, adinlen))
	return 0;
	dctx->lb_valid = 1;
	}

	/* If request less that 16 bytes request 16 in temp buffer */

	if (outlen < 16)
	{
	pout = tmp;
	poutlen = 16;
	}
	else
	{
	pout = out;
	poutlen = outlen;
	}

	/* Generate data */
	if (!fips_drbg_generate_internal(dctx, pout, poutlen,
	strength, prediction_resistance,
	adin, adinlen))
	return 0;
	/* Compare to last block for continuous PRNG test */
	if (!memcmp(pout, dctx->lb, 16))
	{
	FIPSerr(FIPS_F_FIPS_DRBG_GENERATE, FIPS_R_DRBG_STUCK);
	return 0;
	}
	/* Update last block */
	memcpy(dctx->lb, pout, 16);
	/* Copy to output buffer if needed */
	if (outlen < 16)
	memcpy(out, pout, outlen);

	return 1;

	}

	int FIPS_drbg_uninstantiate(DRBG_CTX *dctx)
	{
	int rv;
	if (!dctx->uninstantiate)
	return 1;
	rv = dctx->uninstantiate(dctx);
	/* Although we'd like to cleanse here we can't because we have to
	* test the uninstantiate really zeroes the data.
	*/
	memset(dctx, 0, sizeof(DRBG_CTX));
	/* If method has problems uninstantiating, return error */
	return rv;
	}

	int FIPS_drbg_set_test_mode(DRBG_CTX *dctx,
	size_t (get_entropy)(DRBG_CTX ctx, unsigned char *out,
	int entropy, size_t min_len, size_t max_len),
	size_t (get_nonce)(DRBG_CTX ctx, unsigned char *out,
	int entropy, size_t min_len, size_t max_len))
	{
	if (dctx->status != DRBG_STATUS_UNINITIALISED)
	return 0;
	dctx->flags \|= DRBG_FLAG_TEST;
	dctx->get_entropy = get_entropy;
	dctx->get_nonce = get_nonce;
	return 1;
	}

	void FIPS_drbg_get_app_data(DRBG_CTX dctx)
	{
	return dctx->app_data;
	}

	void FIPS_drbg_set_app_data(DRBG_CTX dctx, void app_data)
	{
	dctx->app_data = app_data;
	}

	size_t FIPS_drbg_get_blocklength(DRBG_CTX *dctx)
	{
	return dctx->blocklength;
	}

	int FIPS_drbg_get_strength(DRBG_CTX *dctx)
	{
	return dctx->strength;
	}