473 lines
14 KiB
C
473 lines
14 KiB
C
/*
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* HMAC_DRBG implementation (NIST SP 800-90)
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*
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* Copyright (C) 2014, Brainspark B.V.
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*
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* This file is part of PolarSSL (http://www.polarssl.org)
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* Lead Maintainer: Paul Bakker <polarssl_maintainer at polarssl.org>
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*
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* All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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/*
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* The NIST SP 800-90A DRBGs are described in the following publication.
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* http://csrc.nist.gov/publications/nistpubs/800-90A/SP800-90A.pdf
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* References below are based on rev. 1 (January 2012).
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*/
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#include "polarssl/config.h"
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#if defined(POLARSSL_HMAC_DRBG_C)
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#include "polarssl/hmac_drbg.h"
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#if defined(POLARSSL_FS_IO)
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#include <stdio.h>
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#endif
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/*
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* HMAC_DRBG update, using optional additional data (10.1.2.2)
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*/
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void hmac_drbg_update( hmac_drbg_context *ctx,
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const unsigned char *additional, size_t add_len )
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{
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size_t md_len = ctx->md_ctx.md_info->size;
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unsigned char rounds = ( additional != NULL && add_len != 0 ) ? 2 : 1;
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unsigned char sep[1];
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for( sep[0] = 0; sep[0] < rounds; sep[0]++ )
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{
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/* Step 1 or 4 */
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md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
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md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
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md_hmac_update( &ctx->md_ctx, sep, 1 );
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if( rounds == 2 )
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md_hmac_update( &ctx->md_ctx, additional, add_len );
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md_hmac_finish( &ctx->md_ctx, ctx->K );
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/* Step 2 or 5 */
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md_hmac_starts( &ctx->md_ctx, ctx->K, md_len );
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md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
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md_hmac_finish( &ctx->md_ctx, ctx->V );
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}
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}
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/*
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* Simplified HMAC_DRBG initialisation (for use with deterministic ECDSA)
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*/
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int hmac_drbg_init_buf( hmac_drbg_context *ctx,
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const md_info_t * md_info,
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const unsigned char *data, size_t data_len )
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{
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int ret;
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memset( ctx, 0, sizeof( hmac_drbg_context ) );
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if( ( ret = md_init_ctx( &ctx->md_ctx, md_info ) ) != 0 )
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return( ret );
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memset( ctx->V, 0x01, md_info->size );
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/* ctx->K is already 0 */
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hmac_drbg_update( ctx, data, data_len );
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return( 0 );
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}
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/*
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* HMAC_DRBG reseeding: 10.1.2.4 (arabic) + 9.2 (Roman)
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*/
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int hmac_drbg_reseed( hmac_drbg_context *ctx,
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const unsigned char *additional, size_t len )
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{
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unsigned char seed[POLARSSL_HMAC_DRBG_MAX_SEED_INPUT];
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size_t seedlen;
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/* III. Check input length */
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if( len > POLARSSL_HMAC_DRBG_MAX_INPUT ||
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ctx->entropy_len + len > POLARSSL_HMAC_DRBG_MAX_SEED_INPUT )
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{
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return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
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}
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memset( seed, 0, POLARSSL_HMAC_DRBG_MAX_SEED_INPUT );
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/* IV. Gather entropy_len bytes of entropy for the seed */
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if( ctx->f_entropy( ctx->p_entropy, seed, ctx->entropy_len ) != 0 )
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return( POLARSSL_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED );
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seedlen = ctx->entropy_len;
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/* 1. Concatenate entropy and additional data if any */
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if( additional != NULL && len != 0 )
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{
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memcpy( seed + seedlen, additional, len );
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seedlen += len;
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}
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/* 2. Update state */
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hmac_drbg_update( ctx, seed, seedlen );
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/* 3. Reset reseed_counter */
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ctx->reseed_counter = 1;
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/* 4. Done */
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return( 0 );
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}
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/*
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* HMAC_DRBG initialisation (10.1.2.3 + 9.1)
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*/
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int hmac_drbg_init( hmac_drbg_context *ctx,
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const md_info_t * md_info,
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int (*f_entropy)(void *, unsigned char *, size_t),
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void *p_entropy,
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const unsigned char *custom,
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size_t len )
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{
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int ret;
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size_t entropy_len;
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memset( ctx, 0, sizeof( hmac_drbg_context ) );
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if( ( ret = md_init_ctx( &ctx->md_ctx, md_info ) ) != 0 )
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return( ret );
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/* Set initial working state */
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memset( ctx->V, 0x01, md_info->size );
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/* ctx->K is already 0 */
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ctx->f_entropy = f_entropy;
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ctx->p_entropy = p_entropy;
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ctx->reseed_interval = POLARSSL_HMAC_DRBG_RESEED_INTERVAL;
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/*
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* See SP800-57 5.6.1 (p. 65-66) for the security strength provided by
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* each hash function, then according to SP800-90A rev1 10.1 table 2,
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* min_entropy_len (in bits) is security_strength.
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*
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* (This also matches the sizes used in the NIST test vectors.)
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*/
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entropy_len = md_info->size <= 20 ? 16 : /* 160-bits hash -> 128 bits */
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md_info->size <= 28 ? 24 : /* 224-bits hash -> 192 bits */
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32; /* better (256+) -> 256 bits */
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/*
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* For initialisation, use more entropy to emulate a nonce
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* (Again, matches test vectors.)
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*/
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ctx->entropy_len = entropy_len * 3 / 2;
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if( ( ret = hmac_drbg_reseed( ctx, custom, len ) ) != 0 )
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return( ret );
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ctx->entropy_len = entropy_len;
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return( 0 );
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}
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/*
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* Set prediction resistance
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*/
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void hmac_drbg_set_prediction_resistance( hmac_drbg_context *ctx,
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int resistance )
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{
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ctx->prediction_resistance = resistance;
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}
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/*
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* Set entropy length grabbed for reseeds
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*/
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void hmac_drbg_set_entropy_len( hmac_drbg_context *ctx, size_t len )
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{
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ctx->entropy_len = len;
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}
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/*
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* Set reseed interval
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*/
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void hmac_drbg_set_reseed_interval( hmac_drbg_context *ctx, int interval )
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{
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ctx->reseed_interval = interval;
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}
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/*
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* HMAC_DRBG random function with optional additional data:
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* 10.1.2.5 (arabic) + 9.3 (Roman)
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*/
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int hmac_drbg_random_with_add( void *p_rng,
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unsigned char *output, size_t out_len,
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const unsigned char *additional, size_t add_len )
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{
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int ret;
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hmac_drbg_context *ctx = (hmac_drbg_context *) p_rng;
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size_t md_len = md_get_size( ctx->md_ctx.md_info );
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size_t left = out_len;
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unsigned char *out = output;
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/* II. Check request length */
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if( out_len > POLARSSL_HMAC_DRBG_MAX_REQUEST )
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return( POLARSSL_ERR_HMAC_DRBG_REQUEST_TOO_BIG );
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/* III. Check input length */
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if( add_len > POLARSSL_HMAC_DRBG_MAX_INPUT )
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return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
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/* 1. (aka VII and IX) Check reseed counter and PR */
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if( ctx->f_entropy != NULL && /* For no-reseeding instances */
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( ctx->prediction_resistance == POLARSSL_HMAC_DRBG_PR_ON ||
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ctx->reseed_counter > ctx->reseed_interval ) )
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{
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if( ( ret = hmac_drbg_reseed( ctx, additional, add_len ) ) != 0 )
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return( ret );
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add_len = 0; /* VII.4 */
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}
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/* 2. Use additional data if any */
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if( additional != NULL && add_len != 0 )
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hmac_drbg_update( ctx, additional, add_len );
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/* 3, 4, 5. Generate bytes */
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while( left != 0 )
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{
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size_t use_len = left > md_len ? md_len : left;
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md_hmac_reset( &ctx->md_ctx );
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md_hmac_update( &ctx->md_ctx, ctx->V, md_len );
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md_hmac_finish( &ctx->md_ctx, ctx->V );
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memcpy( out, ctx->V, use_len );
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out += use_len;
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left -= use_len;
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}
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/* 6. Update */
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hmac_drbg_update( ctx, additional, add_len );
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/* 7. Update reseed counter */
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ctx->reseed_counter++;
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/* 8. Done */
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return( 0 );
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}
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/*
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* HMAC_DRBG random function
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*/
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int hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len )
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{
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return( hmac_drbg_random_with_add( p_rng, output, out_len, NULL, 0 ) );
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}
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/*
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* Free an HMAC_DRBG context
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*/
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void hmac_drbg_free( hmac_drbg_context *ctx )
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{
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if( ctx == NULL )
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return;
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md_free_ctx( &ctx->md_ctx );
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memset( ctx, 0, sizeof( hmac_drbg_context ) );
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}
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#if defined(POLARSSL_FS_IO)
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int hmac_drbg_write_seed_file( hmac_drbg_context *ctx, const char *path )
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{
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int ret;
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FILE *f;
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unsigned char buf[ POLARSSL_HMAC_DRBG_MAX_INPUT ];
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if( ( f = fopen( path, "wb" ) ) == NULL )
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return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR );
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if( ( ret = hmac_drbg_random( ctx, buf, sizeof( buf ) ) ) != 0 )
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goto exit;
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if( fwrite( buf, 1, sizeof( buf ), f ) != sizeof( buf ) )
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{
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ret = POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR; /* LCOV_EXCL_LINE */
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goto exit; /* LCOV_EXCL_LINE */
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}
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ret = 0;
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exit:
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fclose( f );
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return( ret );
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}
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int hmac_drbg_update_seed_file( hmac_drbg_context *ctx, const char *path )
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{
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FILE *f;
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size_t n;
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unsigned char buf[ POLARSSL_HMAC_DRBG_MAX_INPUT ];
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if( ( f = fopen( path, "rb" ) ) == NULL )
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return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR );
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fseek( f, 0, SEEK_END );
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n = (size_t) ftell( f );
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fseek( f, 0, SEEK_SET );
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if( n > POLARSSL_HMAC_DRBG_MAX_INPUT )
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{
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fclose( f );
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return( POLARSSL_ERR_HMAC_DRBG_INPUT_TOO_BIG );
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}
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if( fread( buf, 1, n, f ) != n )
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{
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fclose( f ); /* LCOV_EXCL_LINE */
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return( POLARSSL_ERR_HMAC_DRBG_FILE_IO_ERROR ); /* LCOV_EXCL_LINE */
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}
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fclose( f );
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hmac_drbg_update( ctx, buf, n );
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return( hmac_drbg_write_seed_file( ctx, path ) );
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}
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#endif /* POLARSSL_FS_IO */
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#if defined(POLARSSL_SELF_TEST)
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#include <stdio.h>
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#if !defined(POLARSSL_SHA1_C)
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/* Dummy checkup routine */
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int hmac_drbg_self_test( int verbose )
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{
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if( verbose != 0 )
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printf( "\n" );
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return( 0 );
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}
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#else
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#define OUTPUT_LEN 80
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/* From a NIST PR=true test vector */
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static unsigned char entropy_pr[] = {
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0xa0, 0xc9, 0xab, 0x58, 0xf1, 0xe2, 0xe5, 0xa4, 0xde, 0x3e, 0xbd, 0x4f,
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0xf7, 0x3e, 0x9c, 0x5b, 0x64, 0xef, 0xd8, 0xca, 0x02, 0x8c, 0xf8, 0x11,
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0x48, 0xa5, 0x84, 0xfe, 0x69, 0xab, 0x5a, 0xee, 0x42, 0xaa, 0x4d, 0x42,
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0x17, 0x60, 0x99, 0xd4, 0x5e, 0x13, 0x97, 0xdc, 0x40, 0x4d, 0x86, 0xa3,
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0x7b, 0xf5, 0x59, 0x54, 0x75, 0x69, 0x51, 0xe4 };
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static const unsigned char result_pr[OUTPUT_LEN] = {
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0x9a, 0x00, 0xa2, 0xd0, 0x0e, 0xd5, 0x9b, 0xfe, 0x31, 0xec, 0xb1, 0x39,
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0x9b, 0x60, 0x81, 0x48, 0xd1, 0x96, 0x9d, 0x25, 0x0d, 0x3c, 0x1e, 0x94,
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0x10, 0x10, 0x98, 0x12, 0x93, 0x25, 0xca, 0xb8, 0xfc, 0xcc, 0x2d, 0x54,
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0x73, 0x19, 0x70, 0xc0, 0x10, 0x7a, 0xa4, 0x89, 0x25, 0x19, 0x95, 0x5e,
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0x4b, 0xc6, 0x00, 0x1d, 0x7f, 0x4e, 0x6a, 0x2b, 0xf8, 0xa3, 0x01, 0xab,
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0x46, 0x05, 0x5c, 0x09, 0xa6, 0x71, 0x88, 0xf1, 0xa7, 0x40, 0xee, 0xf3,
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0xe1, 0x5c, 0x02, 0x9b, 0x44, 0xaf, 0x03, 0x44 };
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/* From a NIST PR=false test vector */
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static unsigned char entropy_nopr[] = {
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0x79, 0x34, 0x9b, 0xbf, 0x7c, 0xdd, 0xa5, 0x79, 0x95, 0x57, 0x86, 0x66,
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0x21, 0xc9, 0x13, 0x83, 0x11, 0x46, 0x73, 0x3a, 0xbf, 0x8c, 0x35, 0xc8,
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0xc7, 0x21, 0x5b, 0x5b, 0x96, 0xc4, 0x8e, 0x9b, 0x33, 0x8c, 0x74, 0xe3,
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0xe9, 0x9d, 0xfe, 0xdf };
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static const unsigned char result_nopr[OUTPUT_LEN] = {
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0xc6, 0xa1, 0x6a, 0xb8, 0xd4, 0x20, 0x70, 0x6f, 0x0f, 0x34, 0xab, 0x7f,
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0xec, 0x5a, 0xdc, 0xa9, 0xd8, 0xca, 0x3a, 0x13, 0x3e, 0x15, 0x9c, 0xa6,
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0xac, 0x43, 0xc6, 0xf8, 0xa2, 0xbe, 0x22, 0x83, 0x4a, 0x4c, 0x0a, 0x0a,
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0xff, 0xb1, 0x0d, 0x71, 0x94, 0xf1, 0xc1, 0xa5, 0xcf, 0x73, 0x22, 0xec,
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0x1a, 0xe0, 0x96, 0x4e, 0xd4, 0xbf, 0x12, 0x27, 0x46, 0xe0, 0x87, 0xfd,
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0xb5, 0xb3, 0xe9, 0x1b, 0x34, 0x93, 0xd5, 0xbb, 0x98, 0xfa, 0xed, 0x49,
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0xe8, 0x5f, 0x13, 0x0f, 0xc8, 0xa4, 0x59, 0xb7 };
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/* "Entropy" from buffer */
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static int test_offset;
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static int hmac_drbg_self_test_entropy( void *data,
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unsigned char *buf, size_t len )
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{
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const unsigned char *p = data;
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memcpy( buf, p + test_offset, len );
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test_offset += len;
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return( 0 );
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}
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#define CHK( c ) if( (c) != 0 ) \
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{ \
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if( verbose != 0 ) \
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printf( "failed\n" ); \
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return( 1 ); \
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}
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/*
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* Checkup routine for HMAC_DRBG with SHA-1
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*/
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int hmac_drbg_self_test( int verbose )
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{
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hmac_drbg_context ctx;
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unsigned char buf[OUTPUT_LEN];
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const md_info_t *md_info = md_info_from_type( POLARSSL_MD_SHA1 );
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/*
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* PR = True
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*/
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if( verbose != 0 )
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printf( " HMAC_DRBG (PR = True) : " );
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test_offset = 0;
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CHK( hmac_drbg_init( &ctx, md_info,
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hmac_drbg_self_test_entropy, entropy_pr,
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NULL, 0 ) );
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hmac_drbg_set_prediction_resistance( &ctx, POLARSSL_HMAC_DRBG_PR_ON );
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CHK( hmac_drbg_random( &ctx, buf, OUTPUT_LEN ) );
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CHK( hmac_drbg_random( &ctx, buf, OUTPUT_LEN ) );
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CHK( memcmp( buf, result_pr, OUTPUT_LEN ) );
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hmac_drbg_free( &ctx );
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if( verbose != 0 )
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printf( "passed\n" );
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/*
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* PR = False
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*/
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if( verbose != 0 )
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printf( " HMAC_DRBG (PR = False) : " );
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test_offset = 0;
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CHK( hmac_drbg_init( &ctx, md_info,
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hmac_drbg_self_test_entropy, entropy_nopr,
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NULL, 0 ) );
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CHK( hmac_drbg_reseed( &ctx, NULL, 0 ) );
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CHK( hmac_drbg_random( &ctx, buf, OUTPUT_LEN ) );
|
|
CHK( hmac_drbg_random( &ctx, buf, OUTPUT_LEN ) );
|
|
CHK( memcmp( buf, result_nopr, OUTPUT_LEN ) );
|
|
hmac_drbg_free( &ctx );
|
|
|
|
if( verbose != 0 )
|
|
printf( "passed\n" );
|
|
|
|
if( verbose != 0 )
|
|
printf( "\n" );
|
|
|
|
return( 0 );
|
|
}
|
|
#endif /* POLARSSL_SHA1_C */
|
|
#endif /* POLARSSL_SELF_TEST */
|
|
|
|
#endif /* POLARSSL_HMAC_DRBG_C */
|