1 /** 2 * \file hmac_drbg.h 3 * 4 * \brief HMAC_DRBG (NIST SP 800-90A) 5 * 6 * Copyright (C) 2006-2015, ARM Limited, All Rights Reserved 7 * SPDX-License-Identifier: Apache-2.0 8 * 9 * Licensed under the Apache License, Version 2.0 (the "License"); you may 10 * not use this file except in compliance with the License. 11 * You may obtain a copy of the License at 12 * 13 * http://www.apache.org/licenses/LICENSE-2.0 14 * 15 * Unless required by applicable law or agreed to in writing, software 16 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 17 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 18 * See the License for the specific language governing permissions and 19 * limitations under the License. 20 * 21 * This file is part of mbed TLS (https://tls.mbed.org) 22 */ 23 #ifndef MBEDTLS_HMAC_DRBG_H 24 #define MBEDTLS_HMAC_DRBG_H 25 26 #include "md.h" 27 28 #if defined(MBEDTLS_THREADING_C) 29 #include "mbedtls/threading.h" 30 #endif 31 32 /* 33 * Error codes 34 */ 35 #define MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG -0x0003 /**< Too many random requested in single call. */ 36 #define MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG -0x0005 /**< Input too large (Entropy + additional). */ 37 #define MBEDTLS_ERR_HMAC_DRBG_FILE_IO_ERROR -0x0007 /**< Read/write error in file. */ 38 #define MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED -0x0009 /**< The entropy source failed. */ 39 40 /** 41 * \name SECTION: Module settings 42 * 43 * The configuration options you can set for this module are in this section. 44 * Either change them in config.h or define them on the compiler command line. 45 * \{ 46 */ 47 48 #if !defined(MBEDTLS_HMAC_DRBG_RESEED_INTERVAL) 49 #define MBEDTLS_HMAC_DRBG_RESEED_INTERVAL 10000 /**< Interval before reseed is performed by default */ 50 #endif 51 52 #if !defined(MBEDTLS_HMAC_DRBG_MAX_INPUT) 53 #define MBEDTLS_HMAC_DRBG_MAX_INPUT 256 /**< Maximum number of additional input bytes */ 54 #endif 55 56 #if !defined(MBEDTLS_HMAC_DRBG_MAX_REQUEST) 57 #define MBEDTLS_HMAC_DRBG_MAX_REQUEST 1024 /**< Maximum number of requested bytes per call */ 58 #endif 59 60 #if !defined(MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT) 61 #define MBEDTLS_HMAC_DRBG_MAX_SEED_INPUT 384 /**< Maximum size of (re)seed buffer */ 62 #endif 63 64 /* \} name SECTION: Module settings */ 65 66 #define MBEDTLS_HMAC_DRBG_PR_OFF 0 /**< No prediction resistance */ 67 #define MBEDTLS_HMAC_DRBG_PR_ON 1 /**< Prediction resistance enabled */ 68 69 #ifdef __cplusplus 70 extern "C" { 71 #endif 72 73 /** 74 * HMAC_DRBG context. 75 */ 76 typedef struct 77 { 78 /* Working state: the key K is not stored explicitely, 79 * but is implied by the HMAC context */ 80 mbedtls_md_context_t md_ctx; /*!< HMAC context (inc. K) */ 81 unsigned char V[MBEDTLS_MD_MAX_SIZE]; /*!< V in the spec */ 82 int reseed_counter; /*!< reseed counter */ 83 84 /* Administrative state */ 85 size_t entropy_len; /*!< entropy bytes grabbed on each (re)seed */ 86 int prediction_resistance; /*!< enable prediction resistance (Automatic 87 reseed before every random generation) */ 88 int reseed_interval; /*!< reseed interval */ 89 90 /* Callbacks */ 91 int (*f_entropy)(void *, unsigned char *, size_t); /*!< entropy function */ 92 void *p_entropy; /*!< context for the entropy function */ 93 94 #if defined(MBEDTLS_THREADING_C) 95 mbedtls_threading_mutex_t mutex; 96 #endif 97 } mbedtls_hmac_drbg_context; 98 99 /** 100 * \brief HMAC_DRBG context initialization 101 * Makes the context ready for mbedtls_hmac_drbg_seed(), 102 * mbedtls_hmac_drbg_seed_buf() or 103 * mbedtls_hmac_drbg_free(). 104 * 105 * \param ctx HMAC_DRBG context to be initialized 106 */ 107 void mbedtls_hmac_drbg_init( mbedtls_hmac_drbg_context *ctx ); 108 109 /** 110 * \brief HMAC_DRBG initial seeding 111 * Seed and setup entropy source for future reseeds. 112 * 113 * \param ctx HMAC_DRBG context to be seeded 114 * \param md_info MD algorithm to use for HMAC_DRBG 115 * \param f_entropy Entropy callback (p_entropy, buffer to fill, buffer 116 * length) 117 * \param p_entropy Entropy context 118 * \param custom Personalization data (Device specific identifiers) 119 * (Can be NULL) 120 * \param len Length of personalization data 121 * 122 * \note The "security strength" as defined by NIST is set to: 123 * 128 bits if md_alg is SHA-1, 124 * 192 bits if md_alg is SHA-224, 125 * 256 bits if md_alg is SHA-256 or higher. 126 * Note that SHA-256 is just as efficient as SHA-224. 127 * 128 * \return 0 if successful, or 129 * MBEDTLS_ERR_MD_BAD_INPUT_DATA, or 130 * MBEDTLS_ERR_MD_ALLOC_FAILED, or 131 * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED. 132 */ 133 int mbedtls_hmac_drbg_seed( mbedtls_hmac_drbg_context *ctx, 134 const mbedtls_md_info_t * md_info, 135 int (*f_entropy)(void *, unsigned char *, size_t), 136 void *p_entropy, 137 const unsigned char *custom, 138 size_t len ); 139 140 /** 141 * \brief Initilisation of simpified HMAC_DRBG (never reseeds). 142 * (For use with deterministic ECDSA.) 143 * 144 * \param ctx HMAC_DRBG context to be initialised 145 * \param md_info MD algorithm to use for HMAC_DRBG 146 * \param data Concatenation of entropy string and additional data 147 * \param data_len Length of data in bytes 148 * 149 * \return 0 if successful, or 150 * MBEDTLS_ERR_MD_BAD_INPUT_DATA, or 151 * MBEDTLS_ERR_MD_ALLOC_FAILED. 152 */ 153 int mbedtls_hmac_drbg_seed_buf( mbedtls_hmac_drbg_context *ctx, 154 const mbedtls_md_info_t * md_info, 155 const unsigned char *data, size_t data_len ); 156 157 /** 158 * \brief Enable / disable prediction resistance (Default: Off) 159 * 160 * Note: If enabled, entropy is used for ctx->entropy_len before each call! 161 * Only use this if you have ample supply of good entropy! 162 * 163 * \param ctx HMAC_DRBG context 164 * \param resistance MBEDTLS_HMAC_DRBG_PR_ON or MBEDTLS_HMAC_DRBG_PR_OFF 165 */ 166 void mbedtls_hmac_drbg_set_prediction_resistance( mbedtls_hmac_drbg_context *ctx, 167 int resistance ); 168 169 /** 170 * \brief Set the amount of entropy grabbed on each reseed 171 * (Default: given by the security strength, which 172 * depends on the hash used, see \c mbedtls_hmac_drbg_init() ) 173 * 174 * \param ctx HMAC_DRBG context 175 * \param len Amount of entropy to grab, in bytes 176 */ 177 void mbedtls_hmac_drbg_set_entropy_len( mbedtls_hmac_drbg_context *ctx, 178 size_t len ); 179 180 /** 181 * \brief Set the reseed interval 182 * (Default: MBEDTLS_HMAC_DRBG_RESEED_INTERVAL) 183 * 184 * \param ctx HMAC_DRBG context 185 * \param interval Reseed interval 186 */ 187 void mbedtls_hmac_drbg_set_reseed_interval( mbedtls_hmac_drbg_context *ctx, 188 int interval ); 189 190 /** 191 * \brief HMAC_DRBG update state 192 * 193 * \param ctx HMAC_DRBG context 194 * \param additional Additional data to update state with, or NULL 195 * \param add_len Length of additional data, or 0 196 * 197 * \note Additional data is optional, pass NULL and 0 as second 198 * third argument if no additional data is being used. 199 */ 200 void mbedtls_hmac_drbg_update( mbedtls_hmac_drbg_context *ctx, 201 const unsigned char *additional, size_t add_len ); 202 203 /** 204 * \brief HMAC_DRBG reseeding (extracts data from entropy source) 205 * 206 * \param ctx HMAC_DRBG context 207 * \param additional Additional data to add to state (Can be NULL) 208 * \param len Length of additional data 209 * 210 * \return 0 if successful, or 211 * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED 212 */ 213 int mbedtls_hmac_drbg_reseed( mbedtls_hmac_drbg_context *ctx, 214 const unsigned char *additional, size_t len ); 215 216 /** 217 * \brief HMAC_DRBG generate random with additional update input 218 * 219 * Note: Automatically reseeds if reseed_counter is reached or PR is enabled. 220 * 221 * \param p_rng HMAC_DRBG context 222 * \param output Buffer to fill 223 * \param output_len Length of the buffer 224 * \param additional Additional data to update with (can be NULL) 225 * \param add_len Length of additional data (can be 0) 226 * 227 * \return 0 if successful, or 228 * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or 229 * MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG, or 230 * MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG. 231 */ 232 int mbedtls_hmac_drbg_random_with_add( void *p_rng, 233 unsigned char *output, size_t output_len, 234 const unsigned char *additional, 235 size_t add_len ); 236 237 /** 238 * \brief HMAC_DRBG generate random 239 * 240 * Note: Automatically reseeds if reseed_counter is reached or PR is enabled. 241 * 242 * \param p_rng HMAC_DRBG context 243 * \param output Buffer to fill 244 * \param out_len Length of the buffer 245 * 246 * \return 0 if successful, or 247 * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED, or 248 * MBEDTLS_ERR_HMAC_DRBG_REQUEST_TOO_BIG 249 */ 250 int mbedtls_hmac_drbg_random( void *p_rng, unsigned char *output, size_t out_len ); 251 252 /** 253 * \brief Free an HMAC_DRBG context 254 * 255 * \param ctx HMAC_DRBG context to free. 256 */ 257 void mbedtls_hmac_drbg_free( mbedtls_hmac_drbg_context *ctx ); 258 259 #if defined(MBEDTLS_FS_IO) 260 /** 261 * \brief Write a seed file 262 * 263 * \param ctx HMAC_DRBG context 264 * \param path Name of the file 265 * 266 * \return 0 if successful, 1 on file error, or 267 * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED 268 */ 269 int mbedtls_hmac_drbg_write_seed_file( mbedtls_hmac_drbg_context *ctx, const char *path ); 270 271 /** 272 * \brief Read and update a seed file. Seed is added to this 273 * instance 274 * 275 * \param ctx HMAC_DRBG context 276 * \param path Name of the file 277 * 278 * \return 0 if successful, 1 on file error, 279 * MBEDTLS_ERR_HMAC_DRBG_ENTROPY_SOURCE_FAILED or 280 * MBEDTLS_ERR_HMAC_DRBG_INPUT_TOO_BIG 281 */ 282 int mbedtls_hmac_drbg_update_seed_file( mbedtls_hmac_drbg_context *ctx, const char *path ); 283 #endif /* MBEDTLS_FS_IO */ 284 285 286 #if defined(MBEDTLS_SELF_TEST) 287 /** 288 * \brief Checkup routine 289 * 290 * \return 0 if successful, or 1 if the test failed 291 */ 292 int mbedtls_hmac_drbg_self_test( int verbose ); 293 #endif 294 295 #ifdef __cplusplus 296 } 297 #endif 298 299 #endif /* hmac_drbg.h */ 300
