274 lines
9.7 KiB
C
274 lines
9.7 KiB
C
/**
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* \file ctr_drbg.h
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*
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* \brief CTR_DRBG based on AES-256 (NIST SP 800-90)
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*
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* Copyright (C) 2006-2014, 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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#ifndef POLARSSL_CTR_DRBG_H
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#define POLARSSL_CTR_DRBG_H
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#include <string.h>
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#include "aes.h"
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#define POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED -0x0034 /**< The entropy source failed. */
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#define POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG -0x0036 /**< Too many random requested in single call. */
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#define POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG -0x0038 /**< Input too large (Entropy + additional). */
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#define POLARSSL_ERR_CTR_DRBG_FILE_IO_ERROR -0x003A /**< Read/write error in file. */
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#define CTR_DRBG_BLOCKSIZE 16 /**< Block size used by the cipher */
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#define CTR_DRBG_KEYSIZE 32 /**< Key size used by the cipher */
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#define CTR_DRBG_KEYBITS ( CTR_DRBG_KEYSIZE * 8 )
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#define CTR_DRBG_SEEDLEN ( CTR_DRBG_KEYSIZE + CTR_DRBG_BLOCKSIZE )
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/**< The seed length (counter + AES key) */
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/**
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* \name SECTION: Module settings
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*
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* The configuration options you can set for this module are in this section.
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* Either change them in config.h or define them on the compiler command line.
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* \{
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*/
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#if !defined(CTR_DRBG_ENTROPY_LEN)
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#if defined(POLARSSL_SHA512_C) && !defined(POLARSSL_ENTROPY_FORCE_SHA256)
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#define CTR_DRBG_ENTROPY_LEN 48 /**< Amount of entropy used per seed by default (48 with SHA-512, 32 with SHA-256) */
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#else
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#define CTR_DRBG_ENTROPY_LEN 32 /**< Amount of entropy used per seed by default (48 with SHA-512, 32 with SHA-256) */
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#endif
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#endif
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#if !defined(CTR_DRBG_RESEED_INTERVAL)
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#define CTR_DRBG_RESEED_INTERVAL 10000 /**< Interval before reseed is performed by default */
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#endif
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#if !defined(CTR_DRBG_MAX_INPUT)
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#define CTR_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */
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#endif
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#if !defined(CTR_DRBG_MAX_REQUEST)
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#define CTR_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */
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#endif
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#if !defined(CTR_DRBG_MAX_SEED_INPUT)
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#define CTR_DRBG_MAX_SEED_INPUT 384 /**< Maximum size of (re)seed buffer */
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#endif
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/* \} name SECTION: Module settings */
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#define CTR_DRBG_PR_OFF 0 /**< No prediction resistance */
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#define CTR_DRBG_PR_ON 1 /**< Prediction resistance enabled */
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* \brief CTR_DRBG context structure
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*/
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typedef struct
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{
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unsigned char counter[16]; /*!< counter (V) */
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int reseed_counter; /*!< reseed counter */
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int prediction_resistance; /*!< enable prediction resistance (Automatic
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reseed before every random generation) */
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size_t entropy_len; /*!< amount of entropy grabbed on each
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(re)seed */
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int reseed_interval; /*!< reseed interval */
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aes_context aes_ctx; /*!< AES context */
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/*
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* Callbacks (Entropy)
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*/
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int (*f_entropy)(void *, unsigned char *, size_t);
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void *p_entropy; /*!< context for the entropy function */
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}
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ctr_drbg_context;
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/**
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* \brief CTR_DRBG initialization
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*
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* Note: Personalization data can be provided in addition to the more generic
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* entropy source to make this instantiation as unique as possible.
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*
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* \param ctx CTR_DRBG context to be initialized
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* \param f_entropy Entropy callback (p_entropy, buffer to fill, buffer
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* length)
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* \param p_entropy Entropy context
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* \param custom Personalization data (Device specific identifiers)
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* (Can be NULL)
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* \param len Length of personalization data
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*
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* \return 0 if successful, or
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* POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED
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*/
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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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* \brief Clear CTR_CRBG context data
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*
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* \param ctx CTR_DRBG context to clear
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*/
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void ctr_drbg_free( ctr_drbg_context *ctx );
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/**
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* \brief Enable / disable prediction resistance (Default: Off)
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*
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* Note: If enabled, entropy is used for ctx->entropy_len before each call!
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* Only use this if you have ample supply of good entropy!
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*
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* \param ctx CTR_DRBG context
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* \param resistance CTR_DRBG_PR_ON or CTR_DRBG_PR_OFF
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*/
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void ctr_drbg_set_prediction_resistance( ctr_drbg_context *ctx,
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int resistance );
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/**
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* \brief Set the amount of entropy grabbed on each (re)seed
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* (Default: CTR_DRBG_ENTROPY_LEN)
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*
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* \param ctx CTR_DRBG context
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* \param len Amount of entropy to grab
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*/
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void ctr_drbg_set_entropy_len( ctr_drbg_context *ctx,
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size_t len );
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/**
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* \brief Set the reseed interval
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* (Default: CTR_DRBG_RESEED_INTERVAL)
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*
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* \param ctx CTR_DRBG context
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* \param interval Reseed interval
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*/
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void ctr_drbg_set_reseed_interval( ctr_drbg_context *ctx,
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int interval );
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/**
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* \brief CTR_DRBG reseeding (extracts data from entropy source)
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*
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* \param ctx CTR_DRBG context
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* \param additional Additional data to add to state (Can be NULL)
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* \param len Length of additional data
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*
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* \return 0 if successful, or
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* POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED
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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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* \brief CTR_DRBG update state
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*
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* \param ctx CTR_DRBG context
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* \param additional Additional data to update state with
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* \param add_len Length of additional data
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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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* \brief CTR_DRBG generate random with additional update input
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*
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* Note: Automatically reseeds if reseed_counter is reached.
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*
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* \param p_rng CTR_DRBG context
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* \param output Buffer to fill
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* \param output_len Length of the buffer
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* \param additional Additional data to update with (Can be NULL)
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* \param add_len Length of additional data
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*
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* \return 0 if successful, or
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* POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED, or
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* POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG
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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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* \brief CTR_DRBG generate random
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*
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* Note: Automatically reseeds if reseed_counter is reached.
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*
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* \param p_rng CTR_DRBG context
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* \param output Buffer to fill
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* \param output_len Length of the buffer
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*
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* \return 0 if successful, or
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* POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED, or
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* POLARSSL_ERR_CTR_DRBG_REQUEST_TOO_BIG
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*/
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int ctr_drbg_random( void *p_rng,
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unsigned char *output, size_t output_len );
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#if defined(POLARSSL_FS_IO)
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/**
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* \brief Write a seed file
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*
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* \param ctx CTR_DRBG context
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* \param path Name of the file
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*
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* \return 0 if successful,
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* POLARSSL_ERR_CTR_DRBG_FILE_IO_ERROR on file error, or
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* POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED
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*/
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int ctr_drbg_write_seed_file( ctr_drbg_context *ctx, const char *path );
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/**
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* \brief Read and update a seed file. Seed is added to this
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* instance
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*
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* \param ctx CTR_DRBG context
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* \param path Name of the file
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*
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* \return 0 if successful,
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* POLARSSL_ERR_CTR_DRBG_FILE_IO_ERROR on file error,
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* POLARSSL_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or
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* POLARSSL_ERR_CTR_DRBG_INPUT_TOO_BIG
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*/
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int ctr_drbg_update_seed_file( ctr_drbg_context *ctx, const char *path );
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#endif /* POLARSSL_FS_IO */
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/**
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* \brief Checkup routine
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*
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* \return 0 if successful, or 1 if the test failed
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*/
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int ctr_drbg_self_test( int verbose );
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/* Internal functions (do not call directly) */
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int ctr_drbg_init_entropy_len( ctr_drbg_context *,
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int (*)(void *, unsigned char *, size_t), void *,
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const unsigned char *, size_t, size_t );
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#ifdef __cplusplus
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}
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#endif
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#endif /* ctr_drbg.h */
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