493 lines
13 KiB
C
493 lines
13 KiB
C
/*
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* CTR_DRBG implementation based on AES-256 (NIST SP 800-90)
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*
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* Copyright (C) 2006-2011, 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 800-90 DRBGs are described in the following publucation.
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*
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* http://csrc.nist.gov/publications/nistpubs/800-90/SP800-90revised_March2007.pdf
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*/
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#include "polarssl/config.h"
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#if defined(POLARSSL_CTR_DRBG_C)
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#include "polarssl/ctr_drbg.h"
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int ctr_drbg_init( ctr_drbg_context *ctx,
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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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unsigned char key[CTR_DRBG_KEYSIZE];
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memset( ctx, 0, sizeof(ctr_drbg_context) );
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memset( key, 0, CTR_DRBG_KEYSIZE );
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ctx->f_entropy = f_entropy;
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ctx->p_entropy = p_entropy;
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ctx->entropy_len = CTR_DRBG_ENTROPY_LEN;
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ctx->reseed_interval = CTR_DRBG_RESEED_INTERVAL;
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/*
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* Initialize with an empty key
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*/
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aes_setkey_enc( &ctx->aes_ctx, key, CTR_DRBG_KEYBITS );
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if( ( ret = ctr_drbg_reseed( ctx, custom, len ) ) != 0 )
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return( ret );
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return( 0 );
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}
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void ctr_drbg_set_prediction_resistance( ctr_drbg_context *ctx, int resistance )
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{
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ctx->prediction_resistance = resistance;
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}
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void ctr_drbg_set_entropy_len( ctr_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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void ctr_drbg_set_reseed_interval( ctr_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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int block_cipher_df( unsigned char *output,
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const unsigned char *data, size_t data_len )
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{
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unsigned char buf[CTR_DRBG_MAX_SEED_INPUT + CTR_DRBG_BLOCKSIZE + 16];
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unsigned char tmp[CTR_DRBG_SEEDLEN];
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unsigned char key[CTR_DRBG_KEYSIZE];
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unsigned char chain[CTR_DRBG_BLOCKSIZE];
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unsigned char *p = buf, *iv;
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aes_context aes_ctx;
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int i, j, buf_len, use_len;
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memset( buf, 0, CTR_DRBG_MAX_SEED_INPUT + CTR_DRBG_BLOCKSIZE + 16 );
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/*
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* Construct IV (16 bytes) and S in buffer
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* IV = Counter (in 32-bits) padded to 16 with zeroes
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* S = Length input string (in 32-bits) || Length of output (in 32-bits) ||
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* data || 0x80
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* (Total is padded to a multiple of 16-bytes with zeroes)
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*/
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p = buf + CTR_DRBG_BLOCKSIZE;
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*p++ = ( data_len >> 24 ) & 0xff;
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*p++ = ( data_len >> 16 ) & 0xff;
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*p++ = ( data_len >> 8 ) & 0xff;
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*p++ = ( data_len ) & 0xff;
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p += 3;
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*p++ = CTR_DRBG_SEEDLEN;
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memcpy( p, data, data_len );
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p[data_len] = 0x80;
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buf_len = CTR_DRBG_BLOCKSIZE + 8 + data_len + 1;
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for( i = 0; i < CTR_DRBG_KEYSIZE; i++ )
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key[i] = i;
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aes_setkey_enc( &aes_ctx, key, CTR_DRBG_KEYBITS );
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/*
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* Reduce data to POLARSSL_CTR_DRBG_SEEDLEN bytes of data
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*/
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for( j = 0; j < CTR_DRBG_SEEDLEN; j += CTR_DRBG_BLOCKSIZE )
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{
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p = buf;
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memset( chain, 0, CTR_DRBG_BLOCKSIZE );
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use_len = buf_len;
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while( use_len > 0 )
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{
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for( i = 0; i < CTR_DRBG_BLOCKSIZE; i++ )
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chain[i] ^= p[i];
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p += CTR_DRBG_BLOCKSIZE;
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use_len -= CTR_DRBG_BLOCKSIZE;
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aes_crypt_ecb( &aes_ctx, AES_ENCRYPT, chain, chain );
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}
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memcpy( tmp + j, chain, CTR_DRBG_BLOCKSIZE );
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/*
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* Update IV
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*/
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buf[3]++;
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}
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/*
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* Do final encryption with reduced data
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*/
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aes_setkey_enc( &aes_ctx, tmp, CTR_DRBG_KEYBITS );
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iv = tmp + CTR_DRBG_KEYSIZE;
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p = output;
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for( j = 0; j < CTR_DRBG_SEEDLEN; j += CTR_DRBG_BLOCKSIZE )
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{
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aes_crypt_ecb( &aes_ctx, AES_ENCRYPT, iv, iv );
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memcpy( p, iv, CTR_DRBG_BLOCKSIZE );
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p += CTR_DRBG_BLOCKSIZE;
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}
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return( 0 );
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}
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int ctr_drbg_update_internal( ctr_drbg_context *ctx,
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const unsigned char data[CTR_DRBG_SEEDLEN] )
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{
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unsigned char tmp[CTR_DRBG_SEEDLEN];
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unsigned char *p = tmp;
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int cb, i, j;
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memset( tmp, 0, CTR_DRBG_SEEDLEN );
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for( j = 0; j < CTR_DRBG_SEEDLEN; j += CTR_DRBG_BLOCKSIZE )
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{
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/*
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* Increase counter
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*/
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i = CTR_DRBG_BLOCKSIZE - 1;
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do {
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ctx->counter[i]++;
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cb = ctx->counter[i] == 0;
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} while( i-- && cb );
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/*
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* Crypt counter block
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*/
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aes_crypt_ecb( &ctx->aes_ctx, AES_ENCRYPT, ctx->counter, p );
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p += CTR_DRBG_BLOCKSIZE;
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}
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for( i = 0; i < CTR_DRBG_SEEDLEN; i++ )
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tmp[i] ^= data[i];
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/*
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* Update key and counter
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*/
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aes_setkey_enc( &ctx->aes_ctx, tmp, CTR_DRBG_KEYBITS );
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memcpy( ctx->counter, tmp + CTR_DRBG_KEYSIZE, CTR_DRBG_BLOCKSIZE );
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return( 0 );
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}
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void ctr_drbg_update( ctr_drbg_context *ctx,
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const unsigned char *additional, size_t add_len )
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{
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unsigned char add_input[CTR_DRBG_SEEDLEN];
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if( add_len > 0 )
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{
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block_cipher_df( add_input, additional, add_len );
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ctr_drbg_update_internal( ctx, add_input );
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}
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}
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int ctr_drbg_reseed( ctr_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[CTR_DRBG_MAX_SEED_INPUT];
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size_t seedlen = 0;
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if( ctx->entropy_len + len > CTR_DRBG_MAX_SEED_INPUT )
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return( POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG );
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memset( seed, 0, CTR_DRBG_MAX_SEED_INPUT );
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/*
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* Gather POLARSSL_CTR_DRBG_ENTROPYLEN bytes of entropy to seed state
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*/
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if( 0 != ctx->f_entropy( ctx->p_entropy, seed,
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ctx->entropy_len ) )
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{
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return( POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED );
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}
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seedlen += ctx->entropy_len;
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/*
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* Add additional data
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*/
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if( additional && len )
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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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/*
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* Reduce to 384 bits
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*/
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block_cipher_df( seed, seed, seedlen );
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/*
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* Update state
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*/
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ctr_drbg_update_internal( ctx, seed );
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ctx->reseed_counter = 1;
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return( 0 );
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}
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int ctr_drbg_random_with_add( void *p_rng,
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unsigned char *output, size_t output_len,
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const unsigned char *additional, size_t add_len )
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{
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int ret = 0;
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ctr_drbg_context *ctx = (ctr_drbg_context *) p_rng;
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unsigned char add_input[CTR_DRBG_SEEDLEN];
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unsigned char *p = output;
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unsigned char tmp[CTR_DRBG_BLOCKSIZE];
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int cb, i;
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size_t use_len;
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if( output_len > CTR_DRBG_MAX_REQUEST )
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return( POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG );
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if( add_len > CTR_DRBG_MAX_INPUT )
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return( POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG );
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memset( add_input, 0, CTR_DRBG_SEEDLEN );
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if( ctx->reseed_counter > ctx->reseed_interval ||
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ctx->prediction_resistance )
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{
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if( ( ret = ctr_drbg_reseed( ctx, additional, add_len ) ) != 0 )
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return( ret );
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add_len = 0;
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}
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if( add_len > 0 )
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{
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block_cipher_df( add_input, additional, add_len );
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ctr_drbg_update_internal( ctx, add_input );
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}
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while( output_len > 0 )
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{
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/*
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* Increase counter
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*/
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i = CTR_DRBG_BLOCKSIZE - 1;
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do {
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ctx->counter[i]++;
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cb = ctx->counter[i] == 0;
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} while( i-- && cb );
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/*
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* Crypt counter block
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*/
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aes_crypt_ecb( &ctx->aes_ctx, AES_ENCRYPT, ctx->counter, tmp );
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use_len = (output_len > CTR_DRBG_BLOCKSIZE ) ? CTR_DRBG_BLOCKSIZE : output_len;
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/*
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* Copy random block to destination
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*/
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memcpy( p, tmp, use_len );
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p += use_len;
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output_len -= use_len;
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}
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ctr_drbg_update_internal( ctx, add_input );
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ctx->reseed_counter++;
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return( 0 );
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}
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int ctr_drbg_random( void *p_rng, unsigned char *output, size_t output_len )
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{
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return ctr_drbg_random_with_add( p_rng, output, output_len, NULL, 0 );
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}
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#if defined(POLARSSL_SELF_TEST)
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#include <stdio.h>
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unsigned char entropy_source_pr[96] =
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{ 0xc1, 0x80, 0x81, 0xa6, 0x5d, 0x44, 0x02, 0x16,
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0x19, 0xb3, 0xf1, 0x80, 0xb1, 0xc9, 0x20, 0x02,
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0x6a, 0x54, 0x6f, 0x0c, 0x70, 0x81, 0x49, 0x8b,
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0x6e, 0xa6, 0x62, 0x52, 0x6d, 0x51, 0xb1, 0xcb,
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0x58, 0x3b, 0xfa, 0xd5, 0x37, 0x5f, 0xfb, 0xc9,
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0xff, 0x46, 0xd2, 0x19, 0xc7, 0x22, 0x3e, 0x95,
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0x45, 0x9d, 0x82, 0xe1, 0xe7, 0x22, 0x9f, 0x63,
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0x31, 0x69, 0xd2, 0x6b, 0x57, 0x47, 0x4f, 0xa3,
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0x37, 0xc9, 0x98, 0x1c, 0x0b, 0xfb, 0x91, 0x31,
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0x4d, 0x55, 0xb9, 0xe9, 0x1c, 0x5a, 0x5e, 0xe4,
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0x93, 0x92, 0xcf, 0xc5, 0x23, 0x12, 0xd5, 0x56,
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0x2c, 0x4a, 0x6e, 0xff, 0xdc, 0x10, 0xd0, 0x68 };
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unsigned char entropy_source_nopr[64] =
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{ 0x5a, 0x19, 0x4d, 0x5e, 0x2b, 0x31, 0x58, 0x14,
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0x54, 0xde, 0xf6, 0x75, 0xfb, 0x79, 0x58, 0xfe,
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0xc7, 0xdb, 0x87, 0x3e, 0x56, 0x89, 0xfc, 0x9d,
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0x03, 0x21, 0x7c, 0x68, 0xd8, 0x03, 0x38, 0x20,
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0xf9, 0xe6, 0x5e, 0x04, 0xd8, 0x56, 0xf3, 0xa9,
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0xc4, 0x4a, 0x4c, 0xbd, 0xc1, 0xd0, 0x08, 0x46,
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0xf5, 0x98, 0x3d, 0x77, 0x1c, 0x1b, 0x13, 0x7e,
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0x4e, 0x0f, 0x9d, 0x8e, 0xf4, 0x09, 0xf9, 0x2e };
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unsigned char nonce_pers_pr[16] =
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{ 0xd2, 0x54, 0xfc, 0xff, 0x02, 0x1e, 0x69, 0xd2,
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0x29, 0xc9, 0xcf, 0xad, 0x85, 0xfa, 0x48, 0x6c };
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unsigned char nonce_pers_nopr[16] =
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{ 0x1b, 0x54, 0xb8, 0xff, 0x06, 0x42, 0xbf, 0xf5,
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0x21, 0xf1, 0x5c, 0x1c, 0x0b, 0x66, 0x5f, 0x3f };
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unsigned char result_pr[16] =
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{ 0x34, 0x01, 0x16, 0x56, 0xb4, 0x29, 0x00, 0x8f,
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0x35, 0x63, 0xec, 0xb5, 0xf2, 0x59, 0x07, 0x23 };
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unsigned char result_nopr[16] =
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{ 0xa0, 0x54, 0x30, 0x3d, 0x8a, 0x7e, 0xa9, 0x88,
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0x9d, 0x90, 0x3e, 0x07, 0x7c, 0x6f, 0x21, 0x8f };
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int test_offset;
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int ctr_drbg_self_test_entropy( void *data, unsigned char *buf, size_t len )
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{
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unsigned char *p = data;
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memcpy( buf, p + test_offset, len );
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test_offset += 32;
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return( 0 );
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}
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/*
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* Checkup routine
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*/
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int ctr_drbg_self_test( int verbose )
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{
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ctr_drbg_context ctx;
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unsigned char buf[16];
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/*
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* Based on a NIST CTR_DRBG test vector (PR = True)
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*/
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if( verbose != 0 )
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printf( " CTR_DRBG (PR = TRUE) : " );
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test_offset = 0;
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if( ctr_drbg_init( &ctx, ctr_drbg_self_test_entropy, entropy_source_pr, nonce_pers_pr, 16 ) != 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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ctr_drbg_set_prediction_resistance( &ctx, CTR_DRBG_PR_ON );
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if( ctr_drbg_random( &ctx, buf, CTR_DRBG_BLOCKSIZE ) != 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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if( ctr_drbg_random( &ctx, buf, CTR_DRBG_BLOCKSIZE ) != 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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if( memcmp( buf, result_pr, CTR_DRBG_BLOCKSIZE ) != 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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if( verbose != 0 )
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printf( "passed\n" );
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/*
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* Based on a NIST CTR_DRBG test vector (PR = FALSE)
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*/
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if( verbose != 0 )
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printf( " CTR_DRBG (PR = FALSE): " );
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test_offset = 0;
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if( ctr_drbg_init( &ctx, ctr_drbg_self_test_entropy, entropy_source_nopr, nonce_pers_nopr, 16 ) != 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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if( ctr_drbg_random( &ctx, buf, 16 ) != 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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if( ctr_drbg_reseed( &ctx, NULL, 0 ) != 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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if( ctr_drbg_random( &ctx, buf, 16 ) != 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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if( memcmp( buf, result_nopr, 16 ) != 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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if( verbose != 0 )
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printf( "passed\n" );
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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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#endif
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#endif
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