123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512 |
- /**
- * \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 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 AES-256
- * and with #MBEDTLS_CTR_DRBG_ENTROPY_LEN set to 48 or more.
- * - 256 bits if AES-256 is used, #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 AES-256 is used but #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()).
- * - 128 bits if AES-128 is used (\c MBEDTLS_CTR_DRBG_USE_128_BIT_KEY enabled)
- * and #MBEDTLS_CTR_DRBG_ENTROPY_LEN is set to 24 or more (which is
- * always the case unless it is explicitly set to a different value
- * in config.h).
- *
- * 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 disabled 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 (C) 2006-2019, Arm Limited (or its affiliates), All Rights Reserved
- * 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.
- *
- * This file is part of Mbed TLS (https://tls.mbed.org)
- */
- #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. */
- #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 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
- /**
- * \brief The CTR_DRBG context structure.
- */
- typedef struct mbedtls_ctr_drbg_context
- {
- 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().
- *
- * \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
- * #MBEDTLS_CTR_DRBG_KEYSIZE * 3 / 2, to achieve the
- * maximum security strength permitted by CTR_DRBG,
- * 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.
- * \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 clears CTR_CRBG context data.
- *
- * \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.
- */
- 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.
- * \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.
- *
- * \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 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_DEPRECATED_REMOVED)
- #if defined(MBEDTLS_DEPRECATED_WARNING)
- #define MBEDTLS_DEPRECATED __attribute__((deprecated))
- #else
- #define MBEDTLS_DEPRECATED
- #endif
- /**
- * \brief This function updates the state of the CTR_DRBG context.
- *
- * \deprecated Superseded by mbedtls_ctr_drbg_update_ret()
- * in 2.16.0.
- *
- * \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.
- * \param add_len Length of \p additional data.
- */
- MBEDTLS_DEPRECATED void mbedtls_ctr_drbg_update(
- mbedtls_ctr_drbg_context *ctx,
- const unsigned char *additional,
- size_t add_len );
- #undef MBEDTLS_DEPRECATED
- #endif /* !MBEDTLS_DEPRECATED_REMOVED */
- #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 */
- /* 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 */
|