library/hmac_drbg.c - security/mbedtls - Rivoreo Source Code Repositories

 /*
  *  HMAC_DRBG implementation (NIST SP 800-90)
  *
  *  Copyright (C) 2014, Brainspark B.V.
  *
  *  This file is part of PolarSSL (http://www.polarssl.org)
  *  Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
  *
  *  All rights reserved.
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by
  *  the Free Software Foundation; either version 2 of the License, or
  *  (at your option) any later version.
  *
  *  This program is distributed in the hope that it will be useful,
  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  *  GNU General Public License for more details.
  *
  *  You should have received a copy of the GNU General Public License along
  *  with this program; if not, write to the Free Software Foundation, Inc.,
  *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  */

 /*
  *  The NIST SP 800-90A DRBGs are described in the following publication.
  *  http://csrc.nist.gov/publications/nistpubs/800-90A/SP800-90A.pdf
  *  References below are based on rev. 1 (January 2012).
  */

 #include "polarssl/config.h"

 #if defined(POLARSSL_HMAC_DRBG_C)

 #include "polarssl/hmac_drbg.h"

 #if defined(POLARSSL_FS_IO)
 #include <stdio.h>
 #endif

 /*
  * HMAC_DRBG update, using optional additional data (10.1.2.2)
  */
 void hmac_drbg_update( hmac_drbg_context *ctx,
                        const unsigned char *additional, size_t add_len )
 {
     size_t md_len = ctx->md_ctx.md_info->size;
     unsigned char rounds = ( additional != NULL && add_len != 0 ) ? 2 : 1;
     unsigned char sep[1];

     for( sep[0] = 0; sep[0] < rounds; sep[0]++ )
     {
         /* Step 1 or 4 */
         md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
         md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
         md_hmac_update( &ctx->md_ctx, sep, 1 );
         if( rounds == 2 )
             md_hmac_update( &ctx->md_ctx, additional, add_len );
         md_hmac_finish( &ctx->md_ctx, ctx->K );

         /* Step 2 or 5 */
         md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
         md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
         md_hmac_finish( &ctx->md_ctx, ctx->V );
     }
 }

 /*
  * Simplified HMAC_DRBG initialisation (for use with deterministic ECDSA)
  */
 int hmac_drbg_init_buf( hmac_drbg_context *ctx,
                         const md_info_t * md_info,
                         const unsigned char *data, size_t data_len )
 {
     int ret;

     memset( ctx, 0, sizeof( hmac_drbg_context ) );

     if( ( ret = md_init_ctx( &ctx->md_ctx, md_info ) ) != 0 )
         return( ret );

     memset( ctx->V, 0x01, md_info->size );
     /* ctx->K is already 0 */

     hmac_drbg_update( ctx, data, data_len );

     return( 0 );
 }

 /*
  * HMAC_DRBG reseeding: 10.1.2.4 (arabic) + 9.2 (Roman)
  */
 int hmac_drbg_reseed( hmac_drbg_context *ctx,
                       const unsigned char *additional, size_t len )
 {
     unsigned char seed[POLARSSL_HMAC_DRBG_MAX_SEED_INPUT];
     size_t seedlen;

     /* III. Check input length */
     if( len > POLARSSL_HMAC_DRBG_MAX_INPUT ||
         ctx->entropy_len + len > POLARSSL_HMAC_DRBG_MAX_SEED_INPUT )
     {
         return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
     }

     memset( seed, 0, POLARSSL_HMAC_DRBG_MAX_SEED_INPUT );

     /* IV. Gather entropy_len bytes of entropy for the seed */
     if( ctx->f_entropy( ctx->p_entropy, seed, ctx->entropy_len ) != 0 )
         return( POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED );

     seedlen = ctx->entropy_len;

     /* 1. Concatenate entropy and additional data if any */
     if( additional != NULL && len != 0 )
     {
         memcpy( seed + seedlen, additional, len );
         seedlen += len;
     }

     /* 2. Update state */
     hmac_drbg_update( ctx, seed, seedlen );

     /* 3. Reset reseed_counter */
     ctx->reseed_counter = 1;

     /* 4. Done */
     return( 0 );
 }

 /*
  * HMAC_DRBG initialisation (10.1.2.3 + 9.1)
  */
 int hmac_drbg_init( hmac_drbg_context *ctx,
                     const md_info_t * md_info,
                     int (*f_entropy)(void *, unsigned char *, size_t),
                     void *p_entropy,
                     const unsigned char *custom,
                     size_t len )
 {
     int ret;
     size_t entropy_len;

     memset( ctx, 0, sizeof( hmac_drbg_context ) );

     if( ( ret = md_init_ctx( &ctx->md_ctx, md_info ) ) != 0 )
         return( ret );

     /* Set initial working state */
     memset( ctx->V, 0x01, md_info->size );
     /* ctx->K is already 0 */

     ctx->f_entropy = f_entropy;
     ctx->p_entropy = p_entropy;

     ctx->reseed_interval = POLARSSL_HMAC_DRBG_RESEED_INTERVAL;

     /*
      * See SP800-57 5.6.1 (p. 65-66) for the security strength provided by
      * each hash function, then according to SP800-90A rev1 10.1 table 2,
      * min_entropy_len (in bits) is security_strength.
      *
      * (This also matches the sizes used in the NIST test vectors.)
      */
     entropy_len = md_info->size <= 20 ? 16 : /* 160-bits hash -> 128 bits */
                   md_info->size <= 28 ? 24 : /* 224-bits hash -> 192 bits */
                                         32;  /* better (256+) -> 256 bits */

     /*
      * For initialisation, use more entropy to emulate a nonce
      * (Again, matches test vectors.)
      */
     ctx->entropy_len = entropy_len * 3 / 2;

     if( ( ret = hmac_drbg_reseed( ctx, custom, len ) ) != 0 )
         return( ret );

     ctx->entropy_len = entropy_len;

     return( 0 );
 }

 /*
  * Set prediction resistance
  */
 void hmac_drbg_set_prediction_resistance( hmac_drbg_context *ctx,
                                           int resistance )
 {
     ctx->prediction_resistance = resistance;
 }

 /*
  * Set entropy length grabbed for reseeds
  */
 void hmac_drbg_set_entropy_len( hmac_drbg_context *ctx, size_t len )
 {
     ctx->entropy_len = len;
 }

 /*
  * Set reseed interval
  */
 void hmac_drbg_set_reseed_interval( hmac_drbg_context *ctx, int interval )
 {
     ctx->reseed_interval = interval;
 }

 /*
  * HMAC_DRBG random function with optional additional data:
  * 10.1.2.5 (arabic) + 9.3 (Roman)
  */
 int hmac_drbg_random_with_add( void *p_rng,
                                unsigned char *output, size_t out_len,
                                const unsigned char *additional, size_t add_len )
 {
     int ret;
     hmac_drbg_context *ctx = (hmac_drbg_context *) p_rng;
     size_t md_len = md_get_size( ctx->md_ctx.md_info );
     size_t left = out_len;
     unsigned char *out = output;

     /* II. Check request length */
     if( out_len > POLARSSL_HMAC_DRBG_MAX_REQUEST )
         return( POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG );

     /* III. Check input length */
     if( add_len > POLARSSL_HMAC_DRBG_MAX_INPUT )
         return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );

     /* 1. (aka VII and IX) Check reseed counter and PR */
     if( ctx->f_entropy != NULL && /* For no-reseeding instances */
         ( ctx->prediction_resistance == POLARSSL_HMAC_DRBG_PR_ON ||
           ctx->reseed_counter > ctx->reseed_interval ) )
     {
         if( ( ret = hmac_drbg_reseed( ctx, additional, add_len ) ) != 0 )
             return( ret );

         add_len = 0; /* VII.4 */
     }

     /* 2. Use additional data if any */
     if( additional != NULL && add_len != 0 )
         hmac_drbg_update( ctx, additional, add_len );

     /* 3, 4, 5. Generate bytes */
     while( left != 0 )
     {
         size_t use_len = left > md_len ? md_len : left;

         md_hmac_reset( &ctx->md_ctx );
         md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
         md_hmac_finish( &ctx->md_ctx, ctx->V );

         memcpy( out, ctx->V, use_len );
         out += use_len;
         left -= use_len;
     }

     /* 6. Update */
     hmac_drbg_update( ctx, additional, add_len );

     /* 7. Update reseed counter */
     ctx->reseed_counter++;

     /* 8. Done */
     return( 0 );
 }

 /*
  * HMAC_DRBG random function
  */
 int hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len )
 {
     return( hmac_drbg_random_with_add( p_rng, output, out_len, NULL, 0 ) );
 }

 /*
  * Free an HMAC_DRBG context
  */
 void hmac_drbg_free( hmac_drbg_context *ctx )
 {
     if( ctx == NULL )
         return;

     md_free_ctx( &ctx->md_ctx );

     memset( ctx, 0, sizeof( hmac_drbg_context ) );
 }

 #if defined(POLARSSL_FS_IO)
 int hmac_drbg_write_seed_file( hmac_drbg_context *ctx, const char *path )
 {
     int ret = POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR;
     FILE *f;
     unsigned char buf[ POLARSSL_HMAC_DRBG_MAX_INPUT ];

     if( ( f = fopen( path, "wb" ) ) == NULL )
         return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR );

     if( ( ret = hmac_drbg_random( ctx, buf, sizeof( buf ) ) ) != 0 )
         goto exit;

     if( fwrite( buf, 1, sizeof( buf ), f ) != sizeof( buf ) )
     {
         ret = POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR;
         goto exit;
     }

     ret = 0;

 exit:
     fclose( f );
     return( ret );
 }

 int hmac_drbg_update_seed_file( hmac_drbg_context *ctx, const char *path )
 {
     FILE *f;
     size_t n;
     unsigned char buf[ POLARSSL_HMAC_DRBG_MAX_INPUT ];

     if( ( f = fopen( path, "rb" ) ) == NULL )
         return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR );

     fseek( f, 0, SEEK_END );
     n = (size_t) ftell( f );
     fseek( f, 0, SEEK_SET );

     if( n > POLARSSL_HMAC_DRBG_MAX_INPUT )
     {
         fclose( f );
         return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
     }

     if( fread( buf, 1, n, f ) != n )
     {
         fclose( f );
         return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR );
     }

     fclose( f );

     hmac_drbg_update( ctx, buf, n );

     return( hmac_drbg_write_seed_file( ctx, path ) );
 }
 #endif /* POLARSSL_FS_IO */


 #if defined(POLARSSL_SELF_TEST)

 #include <stdio.h>

 /*
  * Checkup routine
  */
 int hmac_drbg_self_test( int verbose )
 {

     if( verbose != 0 )
             printf( "\n" );

     return( 0 );
 }
 #endif /* POLARSSL_SELF_TEST */

 #endif /* POLARSSL_HMAC_DRBG_C */
	/*
	* HMAC_DRBG implementation (NIST SP 800-90)
	*
	* Copyright (C) 2014, Brainspark B.V.
	*
	* This file is part of PolarSSL (http://www.polarssl.org)
	* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
	*
	* All rights reserved.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	* GNU General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License along
	* with this program; if not, write to the Free Software Foundation, Inc.,
	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	*/

	/*
	* The NIST SP 800-90A DRBGs are described in the following publication.
	* http://csrc.nist.gov/publications/nistpubs/800-90A/SP800-90A.pdf
	* References below are based on rev. 1 (January 2012).
	*/

	#include "polarssl/config.h"

	#if defined(POLARSSL_HMAC_DRBG_C)

	#include "polarssl/hmac_drbg.h"

	#if defined(POLARSSL_FS_IO)
	#include <stdio.h>
	#endif

	/*
	* HMAC_DRBG update, using optional additional data (10.1.2.2)
	*/
	void hmac_drbg_update( hmac_drbg_context *ctx,
	const unsigned char *additional, size_t add_len )
	{
	size_t md_len = ctx->md_ctx.md_info->size;
	unsigned char rounds = ( additional != NULL && add_len != 0 ) ? 2 : 1;
	unsigned char sep[1];

	for( sep[0] = 0; sep[0] < rounds; sep[0]++ )
	{
	/* Step 1 or 4 */
	md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
	md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
	md_hmac_update( &ctx->md_ctx, sep, 1 );
	if( rounds == 2 )
	md_hmac_update( &ctx->md_ctx, additional, add_len );
	md_hmac_finish( &ctx->md_ctx, ctx->K );

	/* Step 2 or 5 */
	md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
	md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
	md_hmac_finish( &ctx->md_ctx, ctx->V );
	}
	}

	/*
	* Simplified HMAC_DRBG initialisation (for use with deterministic ECDSA)
	*/
	int hmac_drbg_init_buf( hmac_drbg_context *ctx,
	const md_info_t * md_info,
	const unsigned char *data, size_t data_len )
	{
	int ret;

	memset( ctx, 0, sizeof( hmac_drbg_context ) );

	if( ( ret = md_init_ctx( &ctx->md_ctx, md_info ) ) != 0 )
	return( ret );

	memset( ctx->V, 0x01, md_info->size );
	/* ctx->K is already 0 */

	hmac_drbg_update( ctx, data, data_len );

	return( 0 );
	}

	/*
	* HMAC_DRBG reseeding: 10.1.2.4 (arabic) + 9.2 (Roman)
	*/
	int hmac_drbg_reseed( hmac_drbg_context *ctx,
	const unsigned char *additional, size_t len )
	{
	unsigned char seed[POLARSSL_HMAC_DRBG_MAX_SEED_INPUT];
	size_t seedlen;

	/* III. Check input length */
	if( len > POLARSSL_HMAC_DRBG_MAX_INPUT \|\|
	ctx->entropy_len + len > POLARSSL_HMAC_DRBG_MAX_SEED_INPUT )
	{
	return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
	}

	memset( seed, 0, POLARSSL_HMAC_DRBG_MAX_SEED_INPUT );

	/* IV. Gather entropy_len bytes of entropy for the seed */
	if( ctx->f_entropy( ctx->p_entropy, seed, ctx->entropy_len ) != 0 )
	return( POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED );

	seedlen = ctx->entropy_len;

	/* 1. Concatenate entropy and additional data if any */
	if( additional != NULL && len != 0 )
	{
	memcpy( seed + seedlen, additional, len );
	seedlen += len;
	}

	/* 2. Update state */
	hmac_drbg_update( ctx, seed, seedlen );

	/* 3. Reset reseed_counter */
	ctx->reseed_counter = 1;

	/* 4. Done */
	return( 0 );
	}

	/*
	* HMAC_DRBG initialisation (10.1.2.3 + 9.1)
	*/
	int hmac_drbg_init( hmac_drbg_context *ctx,
	const md_info_t * md_info,
	int (f_entropy)(void , unsigned char *, size_t),
	void *p_entropy,
	const unsigned char *custom,
	size_t len )
	{
	int ret;
	size_t entropy_len;

	memset( ctx, 0, sizeof( hmac_drbg_context ) );

	if( ( ret = md_init_ctx( &ctx->md_ctx, md_info ) ) != 0 )
	return( ret );

	/* Set initial working state */
	memset( ctx->V, 0x01, md_info->size );
	/* ctx->K is already 0 */

	ctx->f_entropy = f_entropy;
	ctx->p_entropy = p_entropy;

	ctx->reseed_interval = POLARSSL_HMAC_DRBG_RESEED_INTERVAL;

	/*
	* See SP800-57 5.6.1 (p. 65-66) for the security strength provided by
	* each hash function, then according to SP800-90A rev1 10.1 table 2,
	* min_entropy_len (in bits) is security_strength.
	*
	* (This also matches the sizes used in the NIST test vectors.)
	*/
	entropy_len = md_info->size <= 20 ? 16 : /* 160-bits hash -> 128 bits */
	md_info->size <= 28 ? 24 : /* 224-bits hash -> 192 bits */
	32; /* better (256+) -> 256 bits */

	/*
	* For initialisation, use more entropy to emulate a nonce
	* (Again, matches test vectors.)
	*/
	ctx->entropy_len = entropy_len * 3 / 2;

	if( ( ret = hmac_drbg_reseed( ctx, custom, len ) ) != 0 )
	return( ret );

	ctx->entropy_len = entropy_len;

	return( 0 );
	}

	/*
	* Set prediction resistance
	*/
	void hmac_drbg_set_prediction_resistance( hmac_drbg_context *ctx,
	int resistance )
	{
	ctx->prediction_resistance = resistance;
	}

	/*
	* Set entropy length grabbed for reseeds
	*/
	void hmac_drbg_set_entropy_len( hmac_drbg_context *ctx, size_t len )
	{
	ctx->entropy_len = len;
	}

	/*
	* Set reseed interval
	*/
	void hmac_drbg_set_reseed_interval( hmac_drbg_context *ctx, int interval )
	{
	ctx->reseed_interval = interval;
	}

	/*
	* HMAC_DRBG random function with optional additional data:
	* 10.1.2.5 (arabic) + 9.3 (Roman)
	*/
	int hmac_drbg_random_with_add( void *p_rng,
	unsigned char *output, size_t out_len,
	const unsigned char *additional, size_t add_len )
	{
	int ret;
	hmac_drbg_context ctx = (hmac_drbg_context ) p_rng;
	size_t md_len = md_get_size( ctx->md_ctx.md_info );
	size_t left = out_len;
	unsigned char *out = output;

	/* II. Check request length */
	if( out_len > POLARSSL_HMAC_DRBG_MAX_REQUEST )
	return( POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG );

	/* III. Check input length */
	if( add_len > POLARSSL_HMAC_DRBG_MAX_INPUT )
	return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );

	/* 1. (aka VII and IX) Check reseed counter and PR */
	if( ctx->f_entropy != NULL && /* For no-reseeding instances */
	( ctx->prediction_resistance == POLARSSL_HMAC_DRBG_PR_ON \|\|
	ctx->reseed_counter > ctx->reseed_interval ) )
	{
	if( ( ret = hmac_drbg_reseed( ctx, additional, add_len ) ) != 0 )
	return( ret );

	add_len = 0; /* VII.4 */
	}

	/* 2. Use additional data if any */
	if( additional != NULL && add_len != 0 )
	hmac_drbg_update( ctx, additional, add_len );

	/* 3, 4, 5. Generate bytes */
	while( left != 0 )
	{
	size_t use_len = left > md_len ? md_len : left;

	md_hmac_reset( &ctx->md_ctx );
	md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
	md_hmac_finish( &ctx->md_ctx, ctx->V );

	memcpy( out, ctx->V, use_len );
	out += use_len;
	left -= use_len;
	}

	/* 6. Update */
	hmac_drbg_update( ctx, additional, add_len );

	/* 7. Update reseed counter */
	ctx->reseed_counter++;

	/* 8. Done */
	return( 0 );
	}

	/*
	* HMAC_DRBG random function
	*/
	int hmac_drbg_random( void p_rng, unsigned char output, size_t out_len )
	{
	return( hmac_drbg_random_with_add( p_rng, output, out_len, NULL, 0 ) );
	}

	/*
	* Free an HMAC_DRBG context
	*/
	void hmac_drbg_free( hmac_drbg_context *ctx )
	{
	if( ctx == NULL )
	return;

	md_free_ctx( &ctx->md_ctx );

	memset( ctx, 0, sizeof( hmac_drbg_context ) );
	}

	#if defined(POLARSSL_FS_IO)
	int hmac_drbg_write_seed_file( hmac_drbg_context ctx, const char path )
	{
	int ret = POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR;
	FILE *f;
	unsigned char buf[ POLARSSL_HMAC_DRBG_MAX_INPUT ];

	if( ( f = fopen( path, "wb" ) ) == NULL )
	return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR );

	if( ( ret = hmac_drbg_random( ctx, buf, sizeof( buf ) ) ) != 0 )
	goto exit;

	if( fwrite( buf, 1, sizeof( buf ), f ) != sizeof( buf ) )
	{
	ret = POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR;
	goto exit;
	}

	ret = 0;

	exit:
	fclose( f );
	return( ret );
	}

	int hmac_drbg_update_seed_file( hmac_drbg_context ctx, const char path )
	{
	FILE *f;
	size_t n;
	unsigned char buf[ POLARSSL_HMAC_DRBG_MAX_INPUT ];

	if( ( f = fopen( path, "rb" ) ) == NULL )
	return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR );

	fseek( f, 0, SEEK_END );
	n = (size_t) ftell( f );
	fseek( f, 0, SEEK_SET );

	if( n > POLARSSL_HMAC_DRBG_MAX_INPUT )
	{
	fclose( f );
	return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
	}

	if( fread( buf, 1, n, f ) != n )
	{
	fclose( f );
	return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR );
	}

	fclose( f );

	hmac_drbg_update( ctx, buf, n );

	return( hmac_drbg_write_seed_file( ctx, path ) );
	}
	#endif /* POLARSSL_FS_IO */


	#if defined(POLARSSL_SELF_TEST)

	#include <stdio.h>

	/*
	* Checkup routine
	*/
	int hmac_drbg_self_test( int verbose )
	{

	if( verbose != 0 )
	printf( "\n" );

	return( 0 );
	}
	#endif /* POLARSSL_SELF_TEST */

	#endif /* POLARSSL_HMAC_DRBG_C */