fuchsia / third_party / github.com / ARMmbed / mbedtls / dcba585f540bbb6be7ac5174e77c773d02d28884 / . / include / mbedtls / ctr_drbg.h

/** | |

* \file ctr_drbg.h | |

* | |

* \brief 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 | |

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

* The initial seeding grabs #MBEDTLS_CTR_DRBG_ENTROPY_LEN bytes of entropy. | |

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

* | |

* Based on NIST SP 800-90A §10.2.1 table 3 and NIST SP 800-57 part 1 table 2, | |

* here are the security strengths achieved in typical configuration: | |

* - 256 bits under the default configuration of the library, | |

* with #MBEDTLS_CTR_DRBG_ENTROPY_LEN set to 48 or more. | |

* - 256 bits if #MBEDTLS_CTR_DRBG_ENTROPY_LEN is set | |

* to 32 or more and the DRBG is initialized with an explicit | |

* nonce in the \c custom parameter to mbedtls_ctr_drbg_seed(). | |

* - 128 bits if #MBEDTLS_CTR_DRBG_ENTROPY_LEN is | |

* between 24 and 47 and the DRBG is not initialized with an explicit | |

* nonce (see mbedtls_ctr_drbg_seed()). | |

* | |

* Note that the value of #MBEDTLS_CTR_DRBG_ENTROPY_LEN defaults to: | |

* - \c 48 if the module \c MBEDTLS_SHA512_C is enabled and the symbol | |

* \c MBEDTLS_ENTROPY_FORCE_SHA256 is not enabled at compile time. | |

* This is the default configuration of the library. | |

* - \c 32 if the module \c MBEDTLS_SHA512_C is disabled at compile time. | |

* - \c 32 if \c MBEDTLS_ENTROPY_FORCE_SHA256 is enabled at compile time. | |

*/ | |

/* | |

* Copyright The Mbed TLS Contributors | |

* SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later | |

* | |

* This file is provided under the Apache License 2.0, or the | |

* GNU General Public License v2.0 or later. | |

* | |

* ********** | |

* Apache License 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. | |

* | |

* ********** | |

* | |

* ********** | |

* GNU General Public License v2.0 or later: | |

* | |

* This program is free software; you can redistribute it and/or modify | |

* it under the terms of the GNU General Public License as published by | |

* the Free Software Foundation; either version 2 of the License, or | |

* (at your option) any later version. | |

* | |

* This program is distributed in the hope that it will be useful, | |

* but WITHOUT ANY WARRANTY; without even the implied warranty of | |

* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |

* GNU General Public License for more details. | |

* | |

* You should have received a copy of the GNU General Public License along | |

* with this program; if not, write to the Free Software Foundation, Inc., | |

* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |

* | |

* ********** | |

*/ | |

#ifndef MBEDTLS_CTR_DRBG_H | |

#define MBEDTLS_CTR_DRBG_H | |

#if !defined(MBEDTLS_CONFIG_FILE) | |

#include "config.h" | |

#else | |

#include MBEDTLS_CONFIG_FILE | |

#endif | |

#include "aes.h" | |

#if defined(MBEDTLS_THREADING_C) | |

#include "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. */ | |

#define MBEDTLS_CTR_DRBG_KEYSIZE 32 /**< The key size used by the cipher. */ | |

#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 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 not set). | |

*/ | |

#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). | |

* | |

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

* to mbedtls_ctr_drbg_seed(). | |

*/ | |

#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 | |

/** | |

* \brief The CTR_DRBG context structure. | |

*/ | |

typedef struct | |

{ | |

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

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

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

resistance is enabled, that is | |

whether to systematically reseed before | |

each random generation. */ | |

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

seed or reseed operation. */ | |

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

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

/* | |

* Callbacks (Entropy) | |

*/ | |

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

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

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

#if defined(MBEDTLS_THREADING_C) | |

mbedtls_threading_mutex_t 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(). | |

* | |

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

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

* | |

* \note The _seed_material_ value passed to the derivation | |

* function in the CTR_DRBG Instantiate Process | |

* described in NIST SP 800-90A §10.2.1.3.2 | |

* is the concatenation of the string obtained from | |

* calling \p f_entropy and the \p custom string. | |

* The origin of the nonce depends on the value of | |

* the entropy length relative to the security strength. | |

* - If the entropy length is at least 1.5 times the | |

* security strength then the nonce is taken from the | |

* string obtained with \p f_entropy. | |

* - If the entropy length is less than the security | |

* strength, then the nonce is taken from \p custom. | |

* In this case, for compliance with SP 800-90A, | |

* you must pass a unique value of \p custom at | |

* each invocation. See SP 800-90A §8.6.7 for more | |

* details. | |

*/ | |

#if MBEDTLS_CTR_DRBG_ENTROPY_LEN < MBEDTLS_CTR_DRBG_KEYSIZE * 3 / 2 | |

/** \warning When #MBEDTLS_CTR_DRBG_ENTROPY_LEN is less than | |

* 48, to achieve a 256-bit security strength, | |

* you must pass a value of \p custom that is a nonce: | |

* this value must never be repeated in subsequent | |

* runs of the same application or on a different | |

* device. | |

*/ | |

#endif | |

/** | |

* \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. | |

* \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 | |

* 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, or | |

* #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 \p len must be at least | |

* 32 (in bytes) to achieve a 256-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. | |

*/ | |

void mbedtls_ctr_drbg_set_entropy_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. | |

* | |

* \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, or | |

* #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. | |

* | |

* \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_ret( mbedtls_ctr_drbg_context *ctx, | |

const unsigned char *additional, | |

size_t add_len ); | |

/** | |

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

* | |

* \warning This function cannot report errors. You should use | |

* mbedtls_ctr_drbg_update_ret() instead. | |

* | |

* \note If \p add_len is greater than | |

* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT, only the first | |

* #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT Bytes are used. | |

* The remaining Bytes are silently discarded. | |

* | |

* \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 data. This must be at | |

* most #MBEDTLS_CTR_DRBG_MAX_SEED_INPUT. | |

*/ | |

void 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. | |

* | |

* \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. | |

* | |

* | |

* \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 */ | |

/** | |

* \brief The CTR_DRBG checkup routine. | |

* | |

* \return \c 0 on success, or \c 1 on failure. | |

*/ | |

int mbedtls_ctr_drbg_self_test( int verbose ); | |

/* Internal functions (do not call directly) */ | |

int mbedtls_ctr_drbg_seed_entropy_len( mbedtls_ctr_drbg_context *, | |

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

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

#ifdef __cplusplus | |

} | |

#endif | |

#endif /* ctr_drbg.h */ |