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mbedtls/include/mbedtls/hmac_drbg.h
Gilles Peskine d297157fe8 Move MBEDTLS_ERR_xxx Doxygen comments before the definition 
Now that descriptions of error codes no longer have to be on the same line
for the sake of generate_errors.pl, move them to their own line before the
definition. This aligns them with what we do for other definitions, and
means that we no longer need to have very long lines containing both the C
definition and the comment.

```
perl -i -pe 's~^(#define +MBEDTLS_ERR_\w+ +-\w+) */\*[*!]<(.*)\*/~/**$2*/\n$1~' include/mbedtls/*.h
```

This commit does not change the output of generate_errors.pl.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2021-08-02 22:51:03 +02:00

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