pigweed / third_party / github / ARMmbed / mbedtls / c936bbb15a5fb5a50b6e17360fa9dd41270406f7 / . / include / mbedtls / ctr_drbg.h

/** | |

* \file ctr_drbg.h | |

* | |

* \brief This file contains definitions and functions for the | |

* CTR_DRBG pseudorandom generator. | |

* | |

* CTR_DRBG is a standardized way of building a PRNG from a block-cipher | |

* in counter mode operation, as defined in <em>NIST SP 800-90A: | |

* Recommendation for Random Number Generation Using Deterministic Random | |

* Bit Generators</em>. | |

* | |

* The Mbed TLS implementation of CTR_DRBG uses AES-256 (default) or AES-128 | |

* (if \c MBEDTLS_CTR_DRBG_USE_128_BIT_KEY is enabled at compile time) | |

* as the underlying block cipher, with a derivation function. | |

* | |

* The security strength as defined in NIST SP 800-90A is | |

* 128 bits when AES-128 is used (\c MBEDTLS_CTR_DRBG_USE_128_BIT_KEY enabled) | |

* and 256 bits otherwise, provided that #MBEDTLS_CTR_DRBG_ENTROPY_LEN is | |

* kept at its default value (and not overridden in mbedtls_config.h) and that the | |

* DRBG instance is set up with default parameters. | |

* See the documentation of mbedtls_ctr_drbg_seed() for more | |

* information. | |

*/ | |

/* | |

* 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_CTR_DRBG_H | |

#define MBEDTLS_CTR_DRBG_H | |

#include "mbedtls/private_access.h" | |

#include "mbedtls/build_info.h" | |

#include "mbedtls/aes.h" | |

#if defined(MBEDTLS_THREADING_C) | |

#include "mbedtls/threading.h" | |

#endif | |

#define MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED -0x0034 /**< The entropy source failed. */ | |

#define MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG -0x0036 /**< The requested random buffer length is too big. */ | |

#define MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG -0x0038 /**< The input (entropy + additional data) is too large. */ | |

#define MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR -0x003A /**< Read or write error in file. */ | |

#define MBEDTLS_CTR_DRBG_BLOCKSIZE 16 /**< The block size used by the cipher. */ | |

#if defined(MBEDTLS_CTR_DRBG_USE_128_BIT_KEY) | |

#define MBEDTLS_CTR_DRBG_KEYSIZE 16 | |

/**< The key size in bytes used by the cipher. | |

* | |

* Compile-time choice: 16 bytes (128 bits) | |

* because #MBEDTLS_CTR_DRBG_USE_128_BIT_KEY is enabled. | |

*/ | |

#else | |

#define MBEDTLS_CTR_DRBG_KEYSIZE 32 | |

/**< The key size in bytes used by the cipher. | |

* | |

* Compile-time choice: 32 bytes (256 bits) | |

* because \c MBEDTLS_CTR_DRBG_USE_128_BIT_KEY is disabled. | |

*/ | |

#endif | |

#define MBEDTLS_CTR_DRBG_KEYBITS ( MBEDTLS_CTR_DRBG_KEYSIZE * 8 ) /**< The key size for the DRBG operation, in bits. */ | |

#define MBEDTLS_CTR_DRBG_SEEDLEN ( MBEDTLS_CTR_DRBG_KEYSIZE + MBEDTLS_CTR_DRBG_BLOCKSIZE ) /**< The seed length, calculated as (counter + AES key). */ | |

/** | |

* \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 using the compiler command | |

* line. | |

* \{ | |

*/ | |

/** \def MBEDTLS_CTR_DRBG_ENTROPY_LEN | |

* | |

* \brief The amount of entropy used per seed by default, in bytes. | |

*/ | |

#if !defined(MBEDTLS_CTR_DRBG_ENTROPY_LEN) | |

#if defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256) | |

/** This is 48 bytes because the entropy module uses SHA-512 | |

* (\c MBEDTLS_ENTROPY_FORCE_SHA256 is disabled). | |

*/ | |

#define MBEDTLS_CTR_DRBG_ENTROPY_LEN 48 | |

#else /* defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256) */ | |

/** This is 32 bytes because the entropy module uses SHA-256 | |

* (the SHA512 module is disabled or | |

* \c MBEDTLS_ENTROPY_FORCE_SHA256 is enabled). | |

*/ | |

#if !defined(MBEDTLS_CTR_DRBG_USE_128_BIT_KEY) | |

/** \warning To achieve a 256-bit security strength, you must pass a nonce | |

* to mbedtls_ctr_drbg_seed(). | |

*/ | |

#endif /* !defined(MBEDTLS_CTR_DRBG_USE_128_BIT_KEY) */ | |

#define MBEDTLS_CTR_DRBG_ENTROPY_LEN 32 | |

#endif /* defined(MBEDTLS_SHA512_C) && !defined(MBEDTLS_ENTROPY_FORCE_SHA256) */ | |

#endif /* !defined(MBEDTLS_CTR_DRBG_ENTROPY_LEN) */ | |

#if !defined(MBEDTLS_CTR_DRBG_RESEED_INTERVAL) | |

#define MBEDTLS_CTR_DRBG_RESEED_INTERVAL 10000 | |

/**< The interval before reseed is performed by default. */ | |

#endif | |

#if !defined(MBEDTLS_CTR_DRBG_MAX_INPUT) | |

#define MBEDTLS_CTR_DRBG_MAX_INPUT 256 | |

/**< The maximum number of additional input Bytes. */ | |

#endif | |

#if !defined(MBEDTLS_CTR_DRBG_MAX_REQUEST) | |

#define MBEDTLS_CTR_DRBG_MAX_REQUEST 1024 | |

/**< The maximum number of requested Bytes per call. */ | |

#endif | |

#if !defined(MBEDTLS_CTR_DRBG_MAX_SEED_INPUT) | |

#define MBEDTLS_CTR_DRBG_MAX_SEED_INPUT 384 | |

/**< The maximum size of seed or reseed buffer in bytes. */ | |

#endif | |

/* \} name SECTION: Module settings */ | |

#define MBEDTLS_CTR_DRBG_PR_OFF 0 | |

/**< Prediction resistance is disabled. */ | |

#define MBEDTLS_CTR_DRBG_PR_ON 1 | |

/**< Prediction resistance is enabled. */ | |

#ifdef __cplusplus | |

extern "C" { | |

#endif | |

#if MBEDTLS_CTR_DRBG_ENTROPY_LEN >= MBEDTLS_CTR_DRBG_KEYSIZE * 3 / 2 | |

/** The default length of the nonce read from the entropy source. | |

* | |

* This is \c 0 because a single read from the entropy source is sufficient | |

* to include a nonce. | |

* See the documentation of mbedtls_ctr_drbg_seed() for more information. | |

*/ | |

#define MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN 0 | |

#else | |

/** The default length of the nonce read from the entropy source. | |

* | |

* This is half of the default entropy length because a single read from | |

* the entropy source does not provide enough material to form a nonce. | |

* See the documentation of mbedtls_ctr_drbg_seed() for more information. | |

*/ | |

#define MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN ( MBEDTLS_CTR_DRBG_ENTROPY_LEN + 1 ) / 2 | |

#endif | |

/** | |

* \brief The CTR_DRBG context structure. | |

*/ | |

typedef struct mbedtls_ctr_drbg_context | |

{ | |

unsigned char MBEDTLS_PRIVATE(counter)[16]; /*!< The counter (V). */ | |

int MBEDTLS_PRIVATE(reseed_counter); /*!< The reseed counter. | |

* This is the number of requests that have | |

* been made since the last (re)seeding, | |

* minus one. | |

* Before the initial seeding, this field | |

* contains the amount of entropy in bytes | |

* to use as a nonce for the initial seeding, | |

* or -1 if no nonce length has been explicitly | |

* set (see mbedtls_ctr_drbg_set_nonce_len()). | |

*/ | |

int MBEDTLS_PRIVATE(prediction_resistance); /*!< This determines whether prediction | |

resistance is enabled, that is | |

whether to systematically reseed before | |

each random generation. */ | |

size_t MBEDTLS_PRIVATE(entropy_len); /*!< The amount of entropy grabbed on each | |

seed or reseed operation, in bytes. */ | |

int MBEDTLS_PRIVATE(reseed_interval); /*!< The reseed interval. | |

* This is the maximum number of requests | |

* that can be made between reseedings. */ | |

mbedtls_aes_context MBEDTLS_PRIVATE(aes_ctx); /*!< The AES context. */ | |

/* | |

* Callbacks (Entropy) | |

*/ | |

int (*MBEDTLS_PRIVATE(f_entropy))(void *, unsigned char *, size_t); | |

/*!< The entropy callback function. */ | |

void *MBEDTLS_PRIVATE(p_entropy); /*!< The context for the entropy function. */ | |

#if defined(MBEDTLS_THREADING_C) | |

/* Invariant: the mutex is initialized if and only if f_entropy != NULL. | |

* This means that the mutex is initialized during the initial seeding | |

* in mbedtls_ctr_drbg_seed() 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_ctr_drbg_context; | |

/** | |

* \brief This function initializes the CTR_DRBG context, | |

* and prepares it for mbedtls_ctr_drbg_seed() | |

* or mbedtls_ctr_drbg_free(). | |

* | |

* \note The reseed interval is | |

* #MBEDTLS_CTR_DRBG_RESEED_INTERVAL by default. | |

* You can override it by calling | |

* mbedtls_ctr_drbg_set_reseed_interval(). | |

* | |

* \param ctx The CTR_DRBG context to initialize. | |

*/ | |

void mbedtls_ctr_drbg_init( mbedtls_ctr_drbg_context *ctx ); | |

/** | |

* \brief This function seeds and sets up the CTR_DRBG | |

* 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). | |

* | |

* The entropy length is #MBEDTLS_CTR_DRBG_ENTROPY_LEN by default. | |

* You can override it by calling mbedtls_ctr_drbg_set_entropy_len(). | |

* | |

* The entropy nonce length is: | |

* - \c 0 if the entropy length is at least 3/2 times the entropy length, | |

* which guarantees that the security strength is the maximum permitted | |

* by the key size and entropy length according to NIST SP 800-90A Â§10.2.1; | |

* - Half the entropy length otherwise. | |

* You can override it by calling mbedtls_ctr_drbg_set_nonce_len(). | |

* With the default entropy length, the entropy nonce length is | |

* #MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN. | |

* | |

* You can provide a nonce and personalization string in addition to the | |

* entropy source, to make this instantiation as unique as possible. | |

* See SP 800-90A Â§8.6.7 for more details about nonces. | |

* | |

* The _seed_material_ value passed to the derivation function in | |

* the CTR_DRBG Instantiate Process described in NIST SP 800-90A Â§10.2.1.3.2 | |

* is the concatenation of the following strings: | |

* - A string obtained by calling \p f_entropy function for the entropy | |

* length. | |

*/ | |

#if MBEDTLS_CTR_DRBG_ENTROPY_NONCE_LEN == 0 | |

/** | |

* - If mbedtls_ctr_drbg_set_nonce_len() has been called, a string | |

* obtained by calling \p f_entropy function for the specified length. | |

*/ | |

#else | |

/** | |

* - A string obtained by calling \p f_entropy function for the entropy nonce | |

* length. If the entropy nonce length is \c 0, this function does not | |

* make a second call to \p f_entropy. | |

*/ | |

#endif | |

#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_ctr_drbg_random() | |

* from multiple threads. Other operations, including | |

* reseeding, are not thread-safe. | |

*/ | |

#endif /* MBEDTLS_THREADING_C */ | |

/** | |

* - The \p custom string. | |

* | |

* \note To achieve the nominal security strength permitted | |

* by CTR_DRBG, the entropy length must be: | |

* - at least 16 bytes for a 128-bit strength | |

* (maximum achievable strength when using AES-128); | |

* - at least 32 bytes for a 256-bit strength | |

* (maximum achievable strength when using AES-256). | |

* | |

* In addition, if you do not pass a nonce in \p custom, | |

* the sum of the entropy length | |

* and the entropy nonce length must be: | |

* - at least 24 bytes for a 128-bit strength | |

* (maximum achievable strength when using AES-128); | |

* - at least 48 bytes for a 256-bit strength | |

* (maximum achievable strength when using AES-256). | |

* | |

* \param ctx The CTR_DRBG context to seed. | |

* It must have been initialized with | |

* mbedtls_ctr_drbg_init(). | |

* After a successful call to mbedtls_ctr_drbg_seed(), | |

* you may not call mbedtls_ctr_drbg_seed() again on | |

* the same context unless you call | |

* mbedtls_ctr_drbg_free() and mbedtls_ctr_drbg_init() | |

* again first. | |

* After a failed call to mbedtls_ctr_drbg_seed(), | |

* you must call mbedtls_ctr_drbg_free(). | |

* \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 buffer size | |

* 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_CTR_DRBG_MAX_SEED_INPUT | |

* - #MBEDTLS_CTR_DRBG_ENTROPY_LEN. | |

* | |

* \return \c 0 on success. | |

* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure. | |

*/ | |

int mbedtls_ctr_drbg_seed( mbedtls_ctr_drbg_context *ctx, | |

int (*f_entropy)(void *, unsigned char *, size_t), | |

void *p_entropy, | |

const unsigned char *custom, | |

size_t len ); | |

/** | |

* \brief This function resets CTR_DRBG context to the state immediately | |

* after initial call of mbedtls_ctr_drbg_init(). | |

* | |

* \param ctx The CTR_DRBG context to clear. | |

*/ | |

void mbedtls_ctr_drbg_free( mbedtls_ctr_drbg_context *ctx ); | |

/** | |

* \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_ctr_drbg_random_with_add() | |

* or mbedtls_ctr_drbg_random(). | |

* Only use this if your entropy source has sufficient | |

* throughput. | |

* | |

* \param ctx The CTR_DRBG context. | |

* \param resistance #MBEDTLS_CTR_DRBG_PR_ON or #MBEDTLS_CTR_DRBG_PR_OFF. | |

*/ | |

void mbedtls_ctr_drbg_set_prediction_resistance( mbedtls_ctr_drbg_context *ctx, | |

int resistance ); | |

/** | |

* \brief This function sets the amount of entropy grabbed on each | |

* seed or reseed. | |

* | |

* The default value is #MBEDTLS_CTR_DRBG_ENTROPY_LEN. | |

* | |

* \note The security strength of CTR_DRBG is bounded by the | |

* entropy length. Thus: | |

* - When using AES-256 | |

* (\c MBEDTLS_CTR_DRBG_USE_128_BIT_KEY is disabled, | |

* which is the default), | |

* \p len must be at least 32 (in bytes) | |

* to achieve a 256-bit strength. | |

* - When using AES-128 | |

* (\c MBEDTLS_CTR_DRBG_USE_128_BIT_KEY is enabled) | |

* \p len must be at least 16 (in bytes) | |

* to achieve a 128-bit strength. | |

* | |

* \param ctx The CTR_DRBG context. | |

* \param len The amount of entropy to grab, in bytes. | |

* This must be at most #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT | |

* and at most the maximum length accepted by the | |

* entropy function that is set in the context. | |

*/ | |

void mbedtls_ctr_drbg_set_entropy_len( mbedtls_ctr_drbg_context *ctx, | |

size_t len ); | |

/** | |

* \brief This function sets the amount of entropy grabbed | |

* as a nonce for the initial seeding. | |

* | |

* Call this function before calling mbedtls_ctr_drbg_seed() to read | |

* a nonce from the entropy source during the initial seeding. | |

* | |

* \param ctx The CTR_DRBG context. | |

* \param len The amount of entropy to grab for the nonce, in bytes. | |

* This must be at most #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT | |

* and at most the maximum length accepted by the | |

* entropy function that is set in the context. | |

* | |

* \return \c 0 on success. | |

* \return #MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG if \p len is | |

* more than #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT. | |

* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED | |

* if the initial seeding has already taken place. | |

*/ | |

int mbedtls_ctr_drbg_set_nonce_len( mbedtls_ctr_drbg_context *ctx, | |

size_t len ); | |

/** | |

* \brief This function sets the reseed interval. | |

* | |

* The reseed interval is the number of calls to mbedtls_ctr_drbg_random() | |

* or mbedtls_ctr_drbg_random_with_add() after which the entropy function | |

* is called again. | |

* | |

* The default value is #MBEDTLS_CTR_DRBG_RESEED_INTERVAL. | |

* | |

* \param ctx The CTR_DRBG context. | |

* \param interval The reseed interval. | |

*/ | |

void mbedtls_ctr_drbg_set_reseed_interval( mbedtls_ctr_drbg_context *ctx, | |

int interval ); | |

/** | |

* \brief This function reseeds the CTR_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 CTR_DRBG context. | |

* \param additional Additional data to add to the state. Can be \c NULL. | |

* \param len The length of the additional data. | |

* This must be less than | |

* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT - \c entropy_len | |

* where \c entropy_len is the entropy length | |

* configured for the context. | |

* | |

* \return \c 0 on success. | |

* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on failure. | |

*/ | |

int mbedtls_ctr_drbg_reseed( mbedtls_ctr_drbg_context *ctx, | |

const unsigned char *additional, size_t len ); | |

/** | |

* \brief This function updates the state of the CTR_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 CTR_DRBG context. | |

* \param additional The data to update the state with. This must not be | |

* \c NULL unless \p add_len is \c 0. | |

* \param add_len Length of \p additional in bytes. This must be at | |

* most #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT. | |

* | |

* \return \c 0 on success. | |

* \return #MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG if | |

* \p add_len is more than | |

* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT. | |

* \return An error from the underlying AES cipher on failure. | |

*/ | |

int mbedtls_ctr_drbg_update( mbedtls_ctr_drbg_context *ctx, | |

const unsigned char *additional, | |

size_t add_len ); | |

/** | |

* \brief This function updates a CTR_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 CTR_DRBG context. This must be a pointer to a | |

* #mbedtls_ctr_drbg_context structure. | |

* \param output The buffer to fill. | |

* \param output_len The length of the buffer in bytes. | |

* \param additional Additional data to update. Can be \c NULL, in which | |

* case the additional data is empty regardless of | |

* the value of \p add_len. | |

* \param add_len The length of the additional data | |

* if \p additional is not \c NULL. | |

* This must be less than #MBEDTLS_CTR_DRBG_MAX_INPUT | |

* and less than | |

* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT - \c entropy_len | |

* where \c entropy_len is the entropy length | |

* configured for the context. | |

* | |

* \return \c 0 on success. | |

* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or | |

* #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure. | |

*/ | |

int mbedtls_ctr_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 CTR_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 CTR_DRBG context. This must be a pointer to a | |

* #mbedtls_ctr_drbg_context structure. | |

* \param output The buffer to fill. | |

* \param output_len The length of the buffer in bytes. | |

* | |

* \return \c 0 on success. | |

* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED or | |

* #MBEDTLS_ERR_CTR_DRBG_REQUEST_TOO_BIG on failure. | |

*/ | |

int mbedtls_ctr_drbg_random( void *p_rng, | |

unsigned char *output, size_t output_len ); | |

#if defined(MBEDTLS_FS_IO) | |

/** | |

* \brief This function writes a seed file. | |

* | |

* \param ctx The CTR_DRBG context. | |

* \param path The name of the file. | |

* | |

* \return \c 0 on success. | |

* \return #MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error. | |

* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on reseed | |

* failure. | |

*/ | |

int mbedtls_ctr_drbg_write_seed_file( mbedtls_ctr_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 CTR_DRBG context. | |

* \param path The name of the file. | |

* | |

* \return \c 0 on success. | |

* \return #MBEDTLS_ERR_CTR_DRBG_FILE_IO_ERROR on file error. | |

* \return #MBEDTLS_ERR_CTR_DRBG_ENTROPY_SOURCE_FAILED on | |

* reseed failure. | |

* \return #MBEDTLS_ERR_CTR_DRBG_INPUT_TOO_BIG if the existing | |

* seed file is too large. | |

*/ | |

int mbedtls_ctr_drbg_update_seed_file( mbedtls_ctr_drbg_context *ctx, const char *path ); | |

#endif /* MBEDTLS_FS_IO */ | |

#if defined(MBEDTLS_SELF_TEST) | |

/** | |

* \brief The CTR_DRBG checkup routine. | |

* | |

* \return \c 0 on success. | |

* \return \c 1 on failure. | |

*/ | |

int mbedtls_ctr_drbg_self_test( int verbose ); | |

#endif /* MBEDTLS_SELF_TEST */ | |

#ifdef __cplusplus | |

} | |

#endif | |

#endif /* ctr_drbg.h */ |