HMAC_DRBG documentation improvements clarifications
Improve the formatting and writing of the documentation based on what had been done for CTR_DRBG. Document the maximum size and nullability of some buffer parameters.
This commit is contained in:
Gilles Peskine
parent
ec51dd12fa
commit
74efcd2b71
1 changed files with 158 additions and 100 deletions
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@ -1,10 +1,14 @@
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/**
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* \file hmac_drbg.h
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*
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* \brief HMAC_DRBG (NIST SP 800-90A)
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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) 2006-2015, ARM Limited, All Rights Reserved
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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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@ -104,38 +108,50 @@ typedef struct mbedtls_hmac_drbg_context
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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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* Makes the context ready for mbedtls_hmac_drbg_seed(),
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* mbedtls_hmac_drbg_seed_buf() or
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* mbedtls_hmac_drbg_free().
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* \brief HMAC_DRBG context initialization.
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*
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* \param ctx HMAC_DRBG context to be initialized
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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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* Seed and setup entropy source for future reseeds.
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* \brief HMAC_DRBG initial seeding.
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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 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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* Set the initial seed and set up the entropy source for future reseeds.
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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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* \param p_entropy The entropy context to pass to \p f_entropy.
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* \param custom Personalization data, that is device-specific
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* identifiers. This can be NULL, in which case the
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* personalization data is empty regardless of the value
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* of \p len.
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* \param len The length of the personalization 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 * 3 / 2
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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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* \note The "security strength" as defined by NIST is set to:
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* 128 bits if md_alg is SHA-1,
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* 192 bits if md_alg is SHA-224,
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* 256 bits if md_alg is SHA-256 or higher.
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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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*
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* \return 0 if successful, or
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* MBEDTLS_ERR_MD_BAD_INPUT_DATA, or
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* MBEDTLS_ERR_MD_ALLOC_FAILED, or
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* MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED.
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* \return 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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@ -146,98 +162,131 @@ int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx,
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/**
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* \brief Initilisation of simpified HMAC_DRBG (never reseeds).
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* (For use with 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 entropy string and additional data
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* \param data_len Length of data in bytes
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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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* \return 0 if successful, or
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* MBEDTLS_ERR_MD_BAD_INPUT_DATA, or
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* MBEDTLS_ERR_MD_ALLOC_FAILED.
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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 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 Enable / disable prediction resistance (Default: Off)
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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 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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* \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 HMAC_DRBG context
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* \param resistance MBEDTLS_HMAC_DRBG_PR_ON or MBEDTLS_HMAC_DRBG_PR_OFF
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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 Set the amount of entropy grabbed on each reseed
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* (Default: given by the security strength, which
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* depends on the hash used, see \c mbedtls_hmac_drbg_init() )
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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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* \param ctx HMAC_DRBG context
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* \param len Amount of entropy to grab, in bytes
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* The default value is given by the security strength, which depends on the
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* hash used. See mbedtls_hmac_drbg_init().
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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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* (Default: MBEDTLS_HMAC_DRBG_RESEED_INTERVAL)
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* \brief Set the reseed interval.
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*
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* \param ctx HMAC_DRBG context
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* \param interval Reseed interval
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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 HMAC_DRBG update state
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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 HMAC_DRBG context
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* \param additional Additional data to update state with, or NULL
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* \param add_len Length of additional data, or 0
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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 \p 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 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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* \note Additional data is optional, pass NULL and 0 as second
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* third argument if no additional data is being used.
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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 HMAC_DRBG reseeding (extracts data from entropy source)
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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 HMAC_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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* \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 0 if successful, or
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* MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED
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* \return 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 HMAC_DRBG generate random with additional update input
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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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* Note: Automatically reseeds if reseed_counter is reached or PR is enabled.
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* \note The function automatically reseeds if the reseed counter is exceeded.
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*
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* \param p_rng HMAC_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 (can be 0)
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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 \p 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 0 if successful, or
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* MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or
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* MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG, or
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* MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG.
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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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@ -245,24 +294,28 @@ int mbedtls_hmac_drbg_random_with_add( void *p_rng,
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size_t add_len );
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/**
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* \brief HMAC_DRBG generate random
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* \brief This function uses HMAC_DRBG to generate random data.
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*
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* Note: Automatically reseeds if reseed_counter is reached or PR is enabled.
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* \note The function automatically reseeds if the reseed counter is exceeded.
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*
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* \param p_rng HMAC_DRBG context
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* \param output Buffer to fill
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* \param out_len Length of the buffer
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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 0 if successful, or
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* MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or
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* MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG
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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 HMAC_DRBG context to free.
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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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@ -273,17 +326,16 @@ void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx );
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#define MBEDTLS_DEPRECATED
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#endif
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/**
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* \brief HMAC_DRBG update state
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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 HMAC_DRBG context
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* \param additional Additional data to update state with, or NULL
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* \param add_len Length of additional data, or 0
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*
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* \note Additional data is optional, pass NULL and 0 as second
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* third argument if no additional data is being used.
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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 \p 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 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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@ -293,26 +345,31 @@ MBEDTLS_DEPRECATED void mbedtls_hmac_drbg_update(
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#if defined(MBEDTLS_FS_IO)
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/**
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* \brief Write a seed file
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* \brief This function writes a seed file.
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*
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* \param ctx HMAC_DRBG context
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* \param path Name of the file
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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 0 if successful, 1 on file error, or
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* MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED
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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 Read and update a seed file. Seed is added to this
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* instance
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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 HMAC_DRBG context
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* \param path Name of the file
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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 0 if successful, 1 on file error,
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* MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED or
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* MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG
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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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@ -320,9 +377,10 @@ int mbedtls_hmac_drbg_update_seed_file( mbedtls_hmac_drbg_context *ctx, const ch
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#if defined(MBEDTLS_SELF_TEST)
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/**
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* \brief Checkup routine
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* \brief The HMAC_DRBG Checkup routine.
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*
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* \return 0 if successful, or 1 if the test failed
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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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