416 lines
17 KiB
C
416 lines
17 KiB
C
/**
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* \file hmac_drbg.h
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*
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* \brief The HMAC_DRBG pseudorandom generator.
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*
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* This module implements the HMAC_DRBG pseudorandom generator described
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* in <em>NIST SP 800-90A: Recommendation for Random Number Generation Using
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* Deterministic Random Bit Generators</em>.
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*/
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/*
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* Copyright (C) 2006-2019, ARM Limited, All Rights Reserved
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of mbed TLS (https://tls.mbed.org)
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*/
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#ifndef MBEDTLS_HMAC_DRBG_H
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#define MBEDTLS_HMAC_DRBG_H
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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#include "md.h"
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#if defined(MBEDTLS_THREADING_C)
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#include "threading.h"
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#endif
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/*
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* Error codes
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*/
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#define MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG -0x0003 /**< Too many random requested in single call. */
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#define MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG -0x0005 /**< Input too large (Entropy + additional). */
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#define MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR -0x0007 /**< Read/write error in file. */
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#define MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED -0x0009 /**< The entropy source failed. */
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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(MBEDTLS_HMAC_DRBG_RESEED_INTERVAL)
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#define MBEDTLS_HMAC_DRBG_RESEED_INTERVAL 10000 /**< Interval before reseed is performed by default */
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#endif
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#if !defined(MBEDTLS_HMAC_DRBG_MAX_INPUT)
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#define MBEDTLS_HMAC_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */
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#endif
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#if !defined(MBEDTLS_HMAC_DRBG_MAX_REQUEST)
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#define MBEDTLS_HMAC_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */
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#endif
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#if !defined(MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT)
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#define MBEDTLS_HMAC_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 MBEDTLS_HMAC_DRBG_PR_OFF 0 /**< No prediction resistance */
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#define MBEDTLS_HMAC_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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* HMAC_DRBG context.
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*/
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typedef struct mbedtls_hmac_drbg_context
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{
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/* Working state: the key K is not stored explicitly,
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* but is implied by the HMAC context */
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mbedtls_md_context_t md_ctx; /*!< HMAC context (inc. K) */
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unsigned char V[MBEDTLS_MD_MAX_SIZE]; /*!< V in the spec */
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int reseed_counter; /*!< reseed counter */
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/* Administrative state */
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size_t entropy_len; /*!< entropy bytes grabbed on each (re)seed */
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int prediction_resistance; /*!< enable prediction resistance (Automatic
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reseed before every random generation) */
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int reseed_interval; /*!< reseed interval */
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/* Callbacks */
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int (*f_entropy)(void *, unsigned char *, size_t); /*!< entropy function */
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void *p_entropy; /*!< context for the entropy function */
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#if defined(MBEDTLS_THREADING_C)
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mbedtls_threading_mutex_t mutex;
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#endif
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} mbedtls_hmac_drbg_context;
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/**
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* \brief HMAC_DRBG context initialization.
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*
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* This function makes the context ready for mbedtls_hmac_drbg_seed(),
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* mbedtls_hmac_drbg_seed_buf() or mbedtls_hmac_drbg_free().
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*
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* \param ctx HMAC_DRBG context to be initialized.
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*/
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void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx );
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/**
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* \brief HMAC_DRBG initial seeding.
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*
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* Set the initial seed and set up the entropy source for future reseeds.
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*
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* A typical choice for the \p f_entropy and \p p_entropy parameters is
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* to use the entropy module:
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* - \p f_entropy is mbedtls_entropy_func();
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* - \p p_entropy is an instance of ::mbedtls_entropy_context initialized
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* with mbedtls_entropy_init() (which registers the platform's default
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* entropy sources).
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*
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* You can provide a personalization string in addition to the
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* entropy source, to make this instantiation as unique as possible.
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*
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* \note By default, the security strength as defined by NIST is:
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* - 128 bits if \p md_info is SHA-1;
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* - 192 bits if \p md_info is SHA-224;
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* - 256 bits if \p md_info is SHA-256, SHA-384 or SHA-512.
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* Note that SHA-256 is just as efficient as SHA-224.
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* The security strength can be reduced if a smaller
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* entropy length is set with
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* mbedtls_hmac_drbg_set_entropy_len().
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*
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* \note The default entropy length is the security strength
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* (converted from bits to bytes). You can override
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* it by calling mbedtls_hmac_drbg_set_entropy_len().
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*
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* \note During the initial seeding, this function calls
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* the entropy source to obtain a nonce
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* whose length is half the entropy length.
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*
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* \param ctx HMAC_DRBG context to be seeded.
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* \param md_info MD algorithm to use for HMAC_DRBG.
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* \param f_entropy The entropy callback, taking as arguments the
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* \p p_entropy context, the buffer to fill, and the
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* length of the buffer.
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* \p f_entropy is always called with a length that is
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* less than or equal to the entropy length.
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* \param p_entropy The entropy context to pass to \p f_entropy.
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* \param custom The personalization string.
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* This can be \c NULL, in which case the personalization
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* string is empty regardless of the value of \p len.
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* \param len The length of the personalization string.
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* This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT
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* and also at most
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* #MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT - \p entropy_len * 3 / 2
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* where \p entropy_len is the entropy length
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* described above.
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*
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* \return \c 0 if successful.
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* \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info is
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* invalid.
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* \return #MBEDTLS_ERR_MD_ALLOC_FAILED if there was not enough
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* memory to allocate context data.
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* \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED
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* if the call to \p f_entropy failed.
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*/
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int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx,
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const mbedtls_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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* \brief Initilisation of simpified HMAC_DRBG (never reseeds).
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*
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* This function is meant for use in algorithms that need a pseudorandom
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* input such as deterministic ECDSA.
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*
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* \param ctx HMAC_DRBG context to be initialised.
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* \param md_info MD algorithm to use for HMAC_DRBG.
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* \param data Concatenation of the initial entropy string and
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* the additional data.
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* \param data_len Length of \p data in bytes.
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*
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* \return \c 0 if successful. or
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* \return #MBEDTLS_ERR_MD_BAD_INPUT_DATA if \p md_info is
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* invalid.
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* \return #MBEDTLS_ERR_MD_ALLOC_FAILED if there was not enough
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* memory to allocate context data.
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*/
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int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx,
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const mbedtls_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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* \brief This function turns prediction resistance on or off.
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* The default value is off.
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*
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* \note If enabled, entropy is gathered at the beginning of
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* every call to mbedtls_hmac_drbg_random_with_add()
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* or mbedtls_hmac_drbg_random().
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* Only use this if your entropy source has sufficient
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* throughput.
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*
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* \param ctx The HMAC_DRBG context.
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* \param resistance #MBEDTLS_HMAC_DRBG_PR_ON or #MBEDTLS_HMAC_DRBG_PR_OFF.
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*/
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void mbedtls_hmac_drbg_set_prediction_resistance( mbedtls_hmac_drbg_context *ctx,
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int resistance );
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/**
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* \brief This function sets the amount of entropy grabbed on each
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* seed or reseed.
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*
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* See the documentation of mbedtls_hmac_drbg_seed() for the default value.
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*
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* \param ctx The HMAC_DRBG context.
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* \param len The amount of entropy to grab, in bytes.
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*/
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void mbedtls_hmac_drbg_set_entropy_len( mbedtls_hmac_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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*
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* The reseed interval is the number of calls to mbedtls_hmac_drbg_random()
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* or mbedtls_hmac_drbg_random_with_add() after which the entropy function
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* is called again.
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*
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* The default value is #MBEDTLS_HMAC_DRBG_RESEED_INTERVAL.
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*
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* \param ctx The HMAC_DRBG context.
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* \param interval The reseed interval.
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*/
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void mbedtls_hmac_drbg_set_reseed_interval( mbedtls_hmac_drbg_context *ctx,
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int interval );
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/**
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* \brief This function updates the state of the HMAC_DRBG context.
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*
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* \param ctx The HMAC_DRBG context.
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* \param additional The data to update the state with.
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* If this is \c NULL, there is no additional data.
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* \param add_len Length of \p additional in bytes.
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* Unused if \p additional is \c NULL.
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*
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* \return \c 0 on success, or an error from the underlying
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* hash calculation.
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*/
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int mbedtls_hmac_drbg_update_ret( mbedtls_hmac_drbg_context *ctx,
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const unsigned char *additional, size_t add_len );
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/**
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* \brief This function reseeds the HMAC_DRBG context, that is
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* extracts data from the entropy source.
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*
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* \param ctx The HMAC_DRBG context.
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* \param additional Additional data to add to the state.
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* If this is \c NULL, there is no additional data
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* and \p len should be \c 0.
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* \param len The length of the additional data.
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* This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT
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* and also at most
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* #MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT - \p entropy_len
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* where \p entropy_len is the entropy length
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* (see mbedtls_hmac_drbg_set_entropy_len()).
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*
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* \return \c 0 if successful.
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* \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED
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* if a call to the entropy function failed.
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*/
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int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx,
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const unsigned char *additional, size_t len );
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/**
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* \brief This function updates an HMAC_DRBG instance with additional
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* data and uses it to generate random data.
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*
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* This function automatically reseeds if the reseed counter is exceeded
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* or prediction resistance is enabled.
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*
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* \param p_rng The HMAC_DRBG context. This must be a pointer to a
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* #mbedtls_hmac_drbg_context structure.
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* \param output The buffer to fill.
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* \param output_len The length of the buffer in bytes.
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* This must be at most #MBEDTLS_HMAC_DRBG_MAX_REQUEST.
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* \param additional Additional data to update with.
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* If this is \c NULL, there is no additional data
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* and \p add_len should be \c 0.
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* \param add_len The length of the additional data.
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* This must be at most #MBEDTLS_HMAC_DRBG_MAX_INPUT.
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*
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* \return \c 0 if successful.
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* \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED
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* if a call to the entropy source failed.
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* \return #MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG if
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* \p output_len > #MBEDTLS_HMAC_DRBG_MAX_REQUEST.
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* \return #MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG if
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* \p add_len > #MBEDTLS_HMAC_DRBG_MAX_INPUT.
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*/
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int mbedtls_hmac_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,
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size_t add_len );
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/**
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* \brief This function uses HMAC_DRBG to generate random data.
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*
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* This function automatically reseeds if the reseed counter is exceeded
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* or prediction resistance is enabled.
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*
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* \param p_rng The HMAC_DRBG context. This must be a pointer to a
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* #mbedtls_hmac_drbg_context structure.
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* \param output The buffer to fill.
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* \param out_len The length of the buffer in bytes.
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* This must be at most #MBEDTLS_HMAC_DRBG_MAX_REQUEST.
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*
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* \return \c 0 if successful.
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* \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED
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* if a call to the entropy source failed.
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* \return #MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG if
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* \p out_len > #MBEDTLS_HMAC_DRBG_MAX_REQUEST.
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*/
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int mbedtls_hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len );
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/**
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* \brief Free an HMAC_DRBG context
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*
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* \param ctx The HMAC_DRBG context to free.
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*/
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void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx );
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#if ! defined(MBEDTLS_DEPRECATED_REMOVED)
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#if defined(MBEDTLS_DEPRECATED_WARNING)
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#define MBEDTLS_DEPRECATED __attribute__((deprecated))
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#else
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#define MBEDTLS_DEPRECATED
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#endif
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/**
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* \brief This function updates the state of the HMAC_DRBG context.
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*
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* \deprecated Superseded by mbedtls_hmac_drbg_update_ret()
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* in 2.16.0.
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*
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* \param ctx The HMAC_DRBG context.
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* \param additional The data to update the state with.
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* If this is \c NULL, there is no additional data.
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* \param add_len Length of \p additional in bytes.
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* Unused if \p additional is \c NULL.
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*/
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MBEDTLS_DEPRECATED void mbedtls_hmac_drbg_update(
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mbedtls_hmac_drbg_context *ctx,
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const unsigned char *additional, size_t add_len );
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#undef MBEDTLS_DEPRECATED
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#endif /* !MBEDTLS_DEPRECATED_REMOVED */
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#if defined(MBEDTLS_FS_IO)
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/**
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* \brief This function writes a seed file.
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*
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* \param ctx The HMAC_DRBG context.
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* \param path The name of the file.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR on file error.
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* \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED on reseed
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* failure.
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*/
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int mbedtls_hmac_drbg_write_seed_file( mbedtls_hmac_drbg_context *ctx, const char *path );
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/**
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* \brief This function reads and updates a seed file. The seed
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* is added to this instance.
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*
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* \param ctx The HMAC_DRBG context.
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* \param path The name of the file.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR on file error.
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* \return #MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED on
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* reseed failure.
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* \return #MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG if the existing
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* seed file is too large.
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*/
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int mbedtls_hmac_drbg_update_seed_file( mbedtls_hmac_drbg_context *ctx, const char *path );
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#endif /* MBEDTLS_FS_IO */
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#if defined(MBEDTLS_SELF_TEST)
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/**
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* \brief The HMAC_DRBG Checkup routine.
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*
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* \return \c 0 if successful.
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* \return \c 1 if the test failed.
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*/
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int mbedtls_hmac_drbg_self_test( int verbose );
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#endif
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#ifdef __cplusplus
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}
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#endif
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#endif /* hmac_drbg.h */
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