1 /** 2 * \file psa/crypto_se_driver.h 3 * \brief PSA external cryptoprocessor driver module 4 * 5 * This header declares types and function signatures for cryptography 6 * drivers that access key material via opaque references. 7 * This is meant for cryptoprocessors that have a separate key storage from the 8 * space in which the PSA Crypto implementation runs, typically secure 9 * elements (SEs). 10 * 11 * This file is part of the PSA Crypto Driver HAL (hardware abstraction layer), 12 * containing functions for driver developers to implement to enable hardware 13 * to be called in a standardized way by a PSA Cryptography API 14 * implementation. The functions comprising the driver HAL, which driver 15 * authors implement, are not intended to be called by application developers. 16 */ 17 18 /* 19 * Copyright The Mbed TLS Contributors 20 * SPDX-License-Identifier: Apache-2.0 21 * 22 * Licensed under the Apache License, Version 2.0 (the "License"); you may 23 * not use this file except in compliance with the License. 24 * You may obtain a copy of the License at 25 * 26 * http://www.apache.org/licenses/LICENSE-2.0 27 * 28 * Unless required by applicable law or agreed to in writing, software 29 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 30 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 31 * See the License for the specific language governing permissions and 32 * limitations under the License. 33 */ 34 #ifndef PSA_CRYPTO_SE_DRIVER_H 35 #define PSA_CRYPTO_SE_DRIVER_H 36 #include "mbedtls/private_access.h" 37 38 #include "crypto_driver_common.h" 39 40 #ifdef __cplusplus 41 extern "C" { 42 #endif 43 44 /** \defgroup se_init Secure element driver initialization 45 */ 46 /**@{*/ 47 48 /** \brief Driver context structure 49 * 50 * Driver functions receive a pointer to this structure. 51 * Each registered driver has one instance of this structure. 52 * 53 * Implementations must include the fields specified here and 54 * may include other fields. 55 */ 56 typedef struct { 57 /** A read-only pointer to the driver's persistent data. 58 * 59 * Drivers typically use this persistent data to keep track of 60 * which slot numbers are available. This is only a guideline: 61 * drivers may use the persistent data for any purpose, keeping 62 * in mind the restrictions on when the persistent data is saved 63 * to storage: the persistent data is only saved after calling 64 * certain functions that receive a writable pointer to the 65 * persistent data. 66 * 67 * The core allocates a memory buffer for the persistent data. 68 * The pointer is guaranteed to be suitably aligned for any data type, 69 * like a pointer returned by `malloc` (but the core can use any 70 * method to allocate the buffer, not necessarily `malloc`). 71 * 72 * The size of this buffer is in the \c persistent_data_size field of 73 * this structure. 74 * 75 * Before the driver is initialized for the first time, the content of 76 * the persistent data is all-bits-zero. After a driver upgrade, if the 77 * size of the persistent data has increased, the original data is padded 78 * on the right with zeros; if the size has decreased, the original data 79 * is truncated to the new size. 80 * 81 * This pointer is to read-only data. Only a few driver functions are 82 * allowed to modify the persistent data. These functions receive a 83 * writable pointer. These functions are: 84 * - psa_drv_se_t::p_init 85 * - psa_drv_se_key_management_t::p_allocate 86 * - psa_drv_se_key_management_t::p_destroy 87 * 88 * The PSA Cryptography core saves the persistent data from one 89 * session to the next. It does this before returning from API functions 90 * that call a driver method that is allowed to modify the persistent 91 * data, specifically: 92 * - psa_crypto_init() causes a call to psa_drv_se_t::p_init, and may call 93 * psa_drv_se_key_management_t::p_destroy to complete an action 94 * that was interrupted by a power failure. 95 * - Key creation functions cause a call to 96 * psa_drv_se_key_management_t::p_allocate, and may cause a call to 97 * psa_drv_se_key_management_t::p_destroy in case an error occurs. 98 * - psa_destroy_key() causes a call to 99 * psa_drv_se_key_management_t::p_destroy. 100 */ 101 const void *const MBEDTLS_PRIVATE(persistent_data); 102 103 /** The size of \c persistent_data in bytes. 104 * 105 * This is always equal to the value of the `persistent_data_size` field 106 * of the ::psa_drv_se_t structure when the driver is registered. 107 */ 108 const size_t MBEDTLS_PRIVATE(persistent_data_size); 109 110 /** Driver transient data. 111 * 112 * The core initializes this value to 0 and does not read or modify it 113 * afterwards. The driver may store whatever it wants in this field. 114 */ 115 uintptr_t MBEDTLS_PRIVATE(transient_data); 116 } psa_drv_se_context_t; 117 118 /** \brief A driver initialization function. 119 * 120 * \param[in,out] drv_context The driver context structure. 121 * \param[in,out] persistent_data A pointer to the persistent data 122 * that allows writing. 123 * \param location The location value for which this driver 124 * is registered. The driver will be invoked 125 * for all keys whose lifetime is in this 126 * location. 127 * 128 * \retval #PSA_SUCCESS 129 * The driver is operational. 130 * The core will update the persistent data in storage. 131 * \return 132 * Any other return value prevents the driver from being used in 133 * this session. 134 * The core will NOT update the persistent data in storage. 135 */ 136 typedef psa_status_t (*psa_drv_se_init_t)(psa_drv_se_context_t *drv_context, 137 void *persistent_data, 138 psa_key_location_t location); 139 140 #if defined(__DOXYGEN_ONLY__) || !defined(MBEDTLS_PSA_CRYPTO_SE_C) 141 /* Mbed Crypto with secure element support enabled defines this type in 142 * crypto_types.h because it is also visible to applications through an 143 * implementation-specific extension. 144 * For the PSA Cryptography specification, this type is only visible 145 * via crypto_se_driver.h. */ 146 /** An internal designation of a key slot between the core part of the 147 * PSA Crypto implementation and the driver. The meaning of this value 148 * is driver-dependent. */ 149 typedef uint64_t psa_key_slot_number_t; 150 #endif /* __DOXYGEN_ONLY__ || !MBEDTLS_PSA_CRYPTO_SE_C */ 151 152 /**@}*/ 153 154 /** \defgroup se_mac Secure Element Message Authentication Codes 155 * Generation and authentication of Message Authentication Codes (MACs) using 156 * a secure element can be done either as a single function call (via the 157 * `psa_drv_se_mac_generate_t` or `psa_drv_se_mac_verify_t` functions), or in 158 * parts using the following sequence: 159 * - `psa_drv_se_mac_setup_t` 160 * - `psa_drv_se_mac_update_t` 161 * - `psa_drv_se_mac_update_t` 162 * - ... 163 * - `psa_drv_se_mac_finish_t` or `psa_drv_se_mac_finish_verify_t` 164 * 165 * If a previously started secure element MAC operation needs to be terminated, 166 * it should be done so by the `psa_drv_se_mac_abort_t`. Failure to do so may 167 * result in allocated resources not being freed or in other undefined 168 * behavior. 169 */ 170 /**@{*/ 171 /** \brief A function that starts a secure element MAC operation for a PSA 172 * Crypto Driver implementation 173 * 174 * \param[in,out] drv_context The driver context structure. 175 * \param[in,out] op_context A structure that will contain the 176 * hardware-specific MAC context 177 * \param[in] key_slot The slot of the key to be used for the 178 * operation 179 * \param[in] algorithm The algorithm to be used to underly the MAC 180 * operation 181 * 182 * \retval #PSA_SUCCESS 183 * Success. 184 */ 185 typedef psa_status_t (*psa_drv_se_mac_setup_t)(psa_drv_se_context_t *drv_context, 186 void *op_context, 187 psa_key_slot_number_t key_slot, 188 psa_algorithm_t algorithm); 189 190 /** \brief A function that continues a previously started secure element MAC 191 * operation 192 * 193 * \param[in,out] op_context A hardware-specific structure for the 194 * previously-established MAC operation to be 195 * updated 196 * \param[in] p_input A buffer containing the message to be appended 197 * to the MAC operation 198 * \param[in] input_length The size in bytes of the input message buffer 199 */ 200 typedef psa_status_t (*psa_drv_se_mac_update_t)(void *op_context, 201 const uint8_t *p_input, 202 size_t input_length); 203 204 /** \brief a function that completes a previously started secure element MAC 205 * operation by returning the resulting MAC. 206 * 207 * \param[in,out] op_context A hardware-specific structure for the 208 * previously started MAC operation to be 209 * finished 210 * \param[out] p_mac A buffer where the generated MAC will be 211 * placed 212 * \param[in] mac_size The size in bytes of the buffer that has been 213 * allocated for the `output` buffer 214 * \param[out] p_mac_length After completion, will contain the number of 215 * bytes placed in the `p_mac` buffer 216 * 217 * \retval #PSA_SUCCESS 218 * Success. 219 */ 220 typedef psa_status_t (*psa_drv_se_mac_finish_t)(void *op_context, 221 uint8_t *p_mac, 222 size_t mac_size, 223 size_t *p_mac_length); 224 225 /** \brief A function that completes a previously started secure element MAC 226 * operation by comparing the resulting MAC against a provided value 227 * 228 * \param[in,out] op_context A hardware-specific structure for the previously 229 * started MAC operation to be finished 230 * \param[in] p_mac The MAC value against which the resulting MAC 231 * will be compared against 232 * \param[in] mac_length The size in bytes of the value stored in `p_mac` 233 * 234 * \retval #PSA_SUCCESS 235 * The operation completed successfully and the MACs matched each 236 * other 237 * \retval #PSA_ERROR_INVALID_SIGNATURE 238 * The operation completed successfully, but the calculated MAC did 239 * not match the provided MAC 240 */ 241 typedef psa_status_t (*psa_drv_se_mac_finish_verify_t)(void *op_context, 242 const uint8_t *p_mac, 243 size_t mac_length); 244 245 /** \brief A function that aborts a previous started secure element MAC 246 * operation 247 * 248 * \param[in,out] op_context A hardware-specific structure for the previously 249 * started MAC operation to be aborted 250 */ 251 typedef psa_status_t (*psa_drv_se_mac_abort_t)(void *op_context); 252 253 /** \brief A function that performs a secure element MAC operation in one 254 * command and returns the calculated MAC 255 * 256 * \param[in,out] drv_context The driver context structure. 257 * \param[in] p_input A buffer containing the message to be MACed 258 * \param[in] input_length The size in bytes of `p_input` 259 * \param[in] key_slot The slot of the key to be used 260 * \param[in] alg The algorithm to be used to underlie the MAC 261 * operation 262 * \param[out] p_mac A buffer where the generated MAC will be 263 * placed 264 * \param[in] mac_size The size in bytes of the `p_mac` buffer 265 * \param[out] p_mac_length After completion, will contain the number of 266 * bytes placed in the `output` buffer 267 * 268 * \retval #PSA_SUCCESS 269 * Success. 270 */ 271 typedef psa_status_t (*psa_drv_se_mac_generate_t)(psa_drv_se_context_t *drv_context, 272 const uint8_t *p_input, 273 size_t input_length, 274 psa_key_slot_number_t key_slot, 275 psa_algorithm_t alg, 276 uint8_t *p_mac, 277 size_t mac_size, 278 size_t *p_mac_length); 279 280 /** \brief A function that performs a secure element MAC operation in one 281 * command and compares the resulting MAC against a provided value 282 * 283 * \param[in,out] drv_context The driver context structure. 284 * \param[in] p_input A buffer containing the message to be MACed 285 * \param[in] input_length The size in bytes of `input` 286 * \param[in] key_slot The slot of the key to be used 287 * \param[in] alg The algorithm to be used to underlie the MAC 288 * operation 289 * \param[in] p_mac The MAC value against which the resulting MAC will 290 * be compared against 291 * \param[in] mac_length The size in bytes of `mac` 292 * 293 * \retval #PSA_SUCCESS 294 * The operation completed successfully and the MACs matched each 295 * other 296 * \retval #PSA_ERROR_INVALID_SIGNATURE 297 * The operation completed successfully, but the calculated MAC did 298 * not match the provided MAC 299 */ 300 typedef psa_status_t (*psa_drv_se_mac_verify_t)(psa_drv_se_context_t *drv_context, 301 const uint8_t *p_input, 302 size_t input_length, 303 psa_key_slot_number_t key_slot, 304 psa_algorithm_t alg, 305 const uint8_t *p_mac, 306 size_t mac_length); 307 308 /** \brief A struct containing all of the function pointers needed to 309 * perform secure element MAC operations 310 * 311 * PSA Crypto API implementations should populate the table as appropriate 312 * upon startup. 313 * 314 * If one of the functions is not implemented (such as 315 * `psa_drv_se_mac_generate_t`), it should be set to NULL. 316 * 317 * Driver implementers should ensure that they implement all of the functions 318 * that make sense for their hardware, and that they provide a full solution 319 * (for example, if they support `p_setup`, they should also support 320 * `p_update` and at least one of `p_finish` or `p_finish_verify`). 321 * 322 */ 323 typedef struct { 324 /**The size in bytes of the hardware-specific secure element MAC context 325 * structure 326 */ 327 size_t MBEDTLS_PRIVATE(context_size); 328 /** Function that performs a MAC setup operation 329 */ 330 psa_drv_se_mac_setup_t MBEDTLS_PRIVATE(p_setup); 331 /** Function that performs a MAC update operation 332 */ 333 psa_drv_se_mac_update_t MBEDTLS_PRIVATE(p_update); 334 /** Function that completes a MAC operation 335 */ 336 psa_drv_se_mac_finish_t MBEDTLS_PRIVATE(p_finish); 337 /** Function that completes a MAC operation with a verify check 338 */ 339 psa_drv_se_mac_finish_verify_t MBEDTLS_PRIVATE(p_finish_verify); 340 /** Function that aborts a previously started MAC operation 341 */ 342 psa_drv_se_mac_abort_t MBEDTLS_PRIVATE(p_abort); 343 /** Function that performs a MAC operation in one call 344 */ 345 psa_drv_se_mac_generate_t MBEDTLS_PRIVATE(p_mac); 346 /** Function that performs a MAC and verify operation in one call 347 */ 348 psa_drv_se_mac_verify_t MBEDTLS_PRIVATE(p_mac_verify); 349 } psa_drv_se_mac_t; 350 /**@}*/ 351 352 /** \defgroup se_cipher Secure Element Symmetric Ciphers 353 * 354 * Encryption and Decryption using secure element keys in block modes other 355 * than ECB must be done in multiple parts, using the following flow: 356 * - `psa_drv_se_cipher_setup_t` 357 * - `psa_drv_se_cipher_set_iv_t` (optional depending upon block mode) 358 * - `psa_drv_se_cipher_update_t` 359 * - `psa_drv_se_cipher_update_t` 360 * - ... 361 * - `psa_drv_se_cipher_finish_t` 362 * 363 * If a previously started secure element Cipher operation needs to be 364 * terminated, it should be done so by the `psa_drv_se_cipher_abort_t`. Failure 365 * to do so may result in allocated resources not being freed or in other 366 * undefined behavior. 367 * 368 * In situations where a PSA Cryptographic API implementation is using a block 369 * mode not-supported by the underlying hardware or driver, it can construct 370 * the block mode itself, while calling the `psa_drv_se_cipher_ecb_t` function 371 * for the cipher operations. 372 */ 373 /**@{*/ 374 375 /** \brief A function that provides the cipher setup function for a 376 * secure element driver 377 * 378 * \param[in,out] drv_context The driver context structure. 379 * \param[in,out] op_context A structure that will contain the 380 * hardware-specific cipher context. 381 * \param[in] key_slot The slot of the key to be used for the 382 * operation 383 * \param[in] algorithm The algorithm to be used in the cipher 384 * operation 385 * \param[in] direction Indicates whether the operation is an encrypt 386 * or decrypt 387 * 388 * \retval #PSA_SUCCESS \emptydescription 389 * \retval #PSA_ERROR_NOT_SUPPORTED \emptydescription 390 */ 391 typedef psa_status_t (*psa_drv_se_cipher_setup_t)(psa_drv_se_context_t *drv_context, 392 void *op_context, 393 psa_key_slot_number_t key_slot, 394 psa_algorithm_t algorithm, 395 psa_encrypt_or_decrypt_t direction); 396 397 /** \brief A function that sets the initialization vector (if 398 * necessary) for a secure element cipher operation 399 * 400 * Rationale: The `psa_se_cipher_*` operation in the PSA Cryptographic API has 401 * two IV functions: one to set the IV, and one to generate it internally. The 402 * generate function is not necessary for the drivers to implement as the PSA 403 * Crypto implementation can do the generation using its RNG features. 404 * 405 * \param[in,out] op_context A structure that contains the previously set up 406 * hardware-specific cipher context 407 * \param[in] p_iv A buffer containing the initialization vector 408 * \param[in] iv_length The size (in bytes) of the `p_iv` buffer 409 * 410 * \retval #PSA_SUCCESS \emptydescription 411 */ 412 typedef psa_status_t (*psa_drv_se_cipher_set_iv_t)(void *op_context, 413 const uint8_t *p_iv, 414 size_t iv_length); 415 416 /** \brief A function that continues a previously started secure element cipher 417 * operation 418 * 419 * \param[in,out] op_context A hardware-specific structure for the 420 * previously started cipher operation 421 * \param[in] p_input A buffer containing the data to be 422 * encrypted/decrypted 423 * \param[in] input_size The size in bytes of the buffer pointed to 424 * by `p_input` 425 * \param[out] p_output The caller-allocated buffer where the 426 * output will be placed 427 * \param[in] output_size The allocated size in bytes of the 428 * `p_output` buffer 429 * \param[out] p_output_length After completion, will contain the number 430 * of bytes placed in the `p_output` buffer 431 * 432 * \retval #PSA_SUCCESS \emptydescription 433 */ 434 typedef psa_status_t (*psa_drv_se_cipher_update_t)(void *op_context, 435 const uint8_t *p_input, 436 size_t input_size, 437 uint8_t *p_output, 438 size_t output_size, 439 size_t *p_output_length); 440 441 /** \brief A function that completes a previously started secure element cipher 442 * operation 443 * 444 * \param[in,out] op_context A hardware-specific structure for the 445 * previously started cipher operation 446 * \param[out] p_output The caller-allocated buffer where the output 447 * will be placed 448 * \param[in] output_size The allocated size in bytes of the `p_output` 449 * buffer 450 * \param[out] p_output_length After completion, will contain the number of 451 * bytes placed in the `p_output` buffer 452 * 453 * \retval #PSA_SUCCESS \emptydescription 454 */ 455 typedef psa_status_t (*psa_drv_se_cipher_finish_t)(void *op_context, 456 uint8_t *p_output, 457 size_t output_size, 458 size_t *p_output_length); 459 460 /** \brief A function that aborts a previously started secure element cipher 461 * operation 462 * 463 * \param[in,out] op_context A hardware-specific structure for the 464 * previously started cipher operation 465 */ 466 typedef psa_status_t (*psa_drv_se_cipher_abort_t)(void *op_context); 467 468 /** \brief A function that performs the ECB block mode for secure element 469 * cipher operations 470 * 471 * Note: this function should only be used with implementations that do not 472 * provide a needed higher-level operation. 473 * 474 * \param[in,out] drv_context The driver context structure. 475 * \param[in] key_slot The slot of the key to be used for the operation 476 * \param[in] algorithm The algorithm to be used in the cipher operation 477 * \param[in] direction Indicates whether the operation is an encrypt or 478 * decrypt 479 * \param[in] p_input A buffer containing the data to be 480 * encrypted/decrypted 481 * \param[in] input_size The size in bytes of the buffer pointed to by 482 * `p_input` 483 * \param[out] p_output The caller-allocated buffer where the output 484 * will be placed 485 * \param[in] output_size The allocated size in bytes of the `p_output` 486 * buffer 487 * 488 * \retval #PSA_SUCCESS \emptydescription 489 * \retval #PSA_ERROR_NOT_SUPPORTED \emptydescription 490 */ 491 typedef psa_status_t (*psa_drv_se_cipher_ecb_t)(psa_drv_se_context_t *drv_context, 492 psa_key_slot_number_t key_slot, 493 psa_algorithm_t algorithm, 494 psa_encrypt_or_decrypt_t direction, 495 const uint8_t *p_input, 496 size_t input_size, 497 uint8_t *p_output, 498 size_t output_size); 499 500 /** 501 * \brief A struct containing all of the function pointers needed to implement 502 * cipher operations using secure elements. 503 * 504 * PSA Crypto API implementations should populate instances of the table as 505 * appropriate upon startup or at build time. 506 * 507 * If one of the functions is not implemented (such as 508 * `psa_drv_se_cipher_ecb_t`), it should be set to NULL. 509 */ 510 typedef struct { 511 /** The size in bytes of the hardware-specific secure element cipher 512 * context structure 513 */ 514 size_t MBEDTLS_PRIVATE(context_size); 515 /** Function that performs a cipher setup operation */ 516 psa_drv_se_cipher_setup_t MBEDTLS_PRIVATE(p_setup); 517 /** Function that sets a cipher IV (if necessary) */ 518 psa_drv_se_cipher_set_iv_t MBEDTLS_PRIVATE(p_set_iv); 519 /** Function that performs a cipher update operation */ 520 psa_drv_se_cipher_update_t MBEDTLS_PRIVATE(p_update); 521 /** Function that completes a cipher operation */ 522 psa_drv_se_cipher_finish_t MBEDTLS_PRIVATE(p_finish); 523 /** Function that aborts a cipher operation */ 524 psa_drv_se_cipher_abort_t MBEDTLS_PRIVATE(p_abort); 525 /** Function that performs ECB mode for a cipher operation 526 * (Danger: ECB mode should not be used directly by clients of the PSA 527 * Crypto Client API) 528 */ 529 psa_drv_se_cipher_ecb_t MBEDTLS_PRIVATE(p_ecb); 530 } psa_drv_se_cipher_t; 531 532 /**@}*/ 533 534 /** \defgroup se_asymmetric Secure Element Asymmetric Cryptography 535 * 536 * Since the amount of data that can (or should) be encrypted or signed using 537 * asymmetric keys is limited by the key size, asymmetric key operations using 538 * keys in a secure element must be done in single function calls. 539 */ 540 /**@{*/ 541 542 /** 543 * \brief A function that signs a hash or short message with a private key in 544 * a secure element 545 * 546 * \param[in,out] drv_context The driver context structure. 547 * \param[in] key_slot Key slot of an asymmetric key pair 548 * \param[in] alg A signature algorithm that is compatible 549 * with the type of `key` 550 * \param[in] p_hash The hash to sign 551 * \param[in] hash_length Size of the `p_hash` buffer in bytes 552 * \param[out] p_signature Buffer where the signature is to be written 553 * \param[in] signature_size Size of the `p_signature` buffer in bytes 554 * \param[out] p_signature_length On success, the number of bytes 555 * that make up the returned signature value 556 * 557 * \retval #PSA_SUCCESS \emptydescription 558 */ 559 typedef psa_status_t (*psa_drv_se_asymmetric_sign_t)(psa_drv_se_context_t *drv_context, 560 psa_key_slot_number_t key_slot, 561 psa_algorithm_t alg, 562 const uint8_t *p_hash, 563 size_t hash_length, 564 uint8_t *p_signature, 565 size_t signature_size, 566 size_t *p_signature_length); 567 568 /** 569 * \brief A function that verifies the signature a hash or short message using 570 * an asymmetric public key in a secure element 571 * 572 * \param[in,out] drv_context The driver context structure. 573 * \param[in] key_slot Key slot of a public key or an asymmetric key 574 * pair 575 * \param[in] alg A signature algorithm that is compatible with 576 * the type of `key` 577 * \param[in] p_hash The hash whose signature is to be verified 578 * \param[in] hash_length Size of the `p_hash` buffer in bytes 579 * \param[in] p_signature Buffer containing the signature to verify 580 * \param[in] signature_length Size of the `p_signature` buffer in bytes 581 * 582 * \retval #PSA_SUCCESS 583 * The signature is valid. 584 */ 585 typedef psa_status_t (*psa_drv_se_asymmetric_verify_t)(psa_drv_se_context_t *drv_context, 586 psa_key_slot_number_t key_slot, 587 psa_algorithm_t alg, 588 const uint8_t *p_hash, 589 size_t hash_length, 590 const uint8_t *p_signature, 591 size_t signature_length); 592 593 /** 594 * \brief A function that encrypts a short message with an asymmetric public 595 * key in a secure element 596 * 597 * \param[in,out] drv_context The driver context structure. 598 * \param[in] key_slot Key slot of a public key or an asymmetric key 599 * pair 600 * \param[in] alg An asymmetric encryption algorithm that is 601 * compatible with the type of `key` 602 * \param[in] p_input The message to encrypt 603 * \param[in] input_length Size of the `p_input` buffer in bytes 604 * \param[in] p_salt A salt or label, if supported by the 605 * encryption algorithm 606 * If the algorithm does not support a 607 * salt, pass `NULL`. 608 * If the algorithm supports an optional 609 * salt and you do not want to pass a salt, 610 * pass `NULL`. 611 * For #PSA_ALG_RSA_PKCS1V15_CRYPT, no salt is 612 * supported. 613 * \param[in] salt_length Size of the `p_salt` buffer in bytes 614 * If `p_salt` is `NULL`, pass 0. 615 * \param[out] p_output Buffer where the encrypted message is to 616 * be written 617 * \param[in] output_size Size of the `p_output` buffer in bytes 618 * \param[out] p_output_length On success, the number of bytes that make up 619 * the returned output 620 * 621 * \retval #PSA_SUCCESS \emptydescription 622 */ 623 typedef psa_status_t (*psa_drv_se_asymmetric_encrypt_t)(psa_drv_se_context_t *drv_context, 624 psa_key_slot_number_t key_slot, 625 psa_algorithm_t alg, 626 const uint8_t *p_input, 627 size_t input_length, 628 const uint8_t *p_salt, 629 size_t salt_length, 630 uint8_t *p_output, 631 size_t output_size, 632 size_t *p_output_length); 633 634 /** 635 * \brief A function that decrypts a short message with an asymmetric private 636 * key in a secure element. 637 * 638 * \param[in,out] drv_context The driver context structure. 639 * \param[in] key_slot Key slot of an asymmetric key pair 640 * \param[in] alg An asymmetric encryption algorithm that is 641 * compatible with the type of `key` 642 * \param[in] p_input The message to decrypt 643 * \param[in] input_length Size of the `p_input` buffer in bytes 644 * \param[in] p_salt A salt or label, if supported by the 645 * encryption algorithm 646 * If the algorithm does not support a 647 * salt, pass `NULL`. 648 * If the algorithm supports an optional 649 * salt and you do not want to pass a salt, 650 * pass `NULL`. 651 * For #PSA_ALG_RSA_PKCS1V15_CRYPT, no salt is 652 * supported. 653 * \param[in] salt_length Size of the `p_salt` buffer in bytes 654 * If `p_salt` is `NULL`, pass 0. 655 * \param[out] p_output Buffer where the decrypted message is to 656 * be written 657 * \param[in] output_size Size of the `p_output` buffer in bytes 658 * \param[out] p_output_length On success, the number of bytes 659 * that make up the returned output 660 * 661 * \retval #PSA_SUCCESS \emptydescription 662 */ 663 typedef psa_status_t (*psa_drv_se_asymmetric_decrypt_t)(psa_drv_se_context_t *drv_context, 664 psa_key_slot_number_t key_slot, 665 psa_algorithm_t alg, 666 const uint8_t *p_input, 667 size_t input_length, 668 const uint8_t *p_salt, 669 size_t salt_length, 670 uint8_t *p_output, 671 size_t output_size, 672 size_t *p_output_length); 673 674 /** 675 * \brief A struct containing all of the function pointers needed to implement 676 * asymmetric cryptographic operations using secure elements. 677 * 678 * PSA Crypto API implementations should populate instances of the table as 679 * appropriate upon startup or at build time. 680 * 681 * If one of the functions is not implemented, it should be set to NULL. 682 */ 683 typedef struct { 684 /** Function that performs an asymmetric sign operation */ 685 psa_drv_se_asymmetric_sign_t MBEDTLS_PRIVATE(p_sign); 686 /** Function that performs an asymmetric verify operation */ 687 psa_drv_se_asymmetric_verify_t MBEDTLS_PRIVATE(p_verify); 688 /** Function that performs an asymmetric encrypt operation */ 689 psa_drv_se_asymmetric_encrypt_t MBEDTLS_PRIVATE(p_encrypt); 690 /** Function that performs an asymmetric decrypt operation */ 691 psa_drv_se_asymmetric_decrypt_t MBEDTLS_PRIVATE(p_decrypt); 692 } psa_drv_se_asymmetric_t; 693 694 /**@}*/ 695 696 /** \defgroup se_aead Secure Element Authenticated Encryption with Additional Data 697 * Authenticated Encryption with Additional Data (AEAD) operations with secure 698 * elements must be done in one function call. While this creates a burden for 699 * implementers as there must be sufficient space in memory for the entire 700 * message, it prevents decrypted data from being made available before the 701 * authentication operation is complete and the data is known to be authentic. 702 */ 703 /**@{*/ 704 705 /** \brief A function that performs a secure element authenticated encryption 706 * operation 707 * 708 * \param[in,out] drv_context The driver context structure. 709 * \param[in] key_slot Slot containing the key to use. 710 * \param[in] algorithm The AEAD algorithm to compute 711 * (\c PSA_ALG_XXX value such that 712 * #PSA_ALG_IS_AEAD(`alg`) is true) 713 * \param[in] p_nonce Nonce or IV to use 714 * \param[in] nonce_length Size of the `p_nonce` buffer in bytes 715 * \param[in] p_additional_data Additional data that will be 716 * authenticated but not encrypted 717 * \param[in] additional_data_length Size of `p_additional_data` in bytes 718 * \param[in] p_plaintext Data that will be authenticated and 719 * encrypted 720 * \param[in] plaintext_length Size of `p_plaintext` in bytes 721 * \param[out] p_ciphertext Output buffer for the authenticated and 722 * encrypted data. The additional data is 723 * not part of this output. For algorithms 724 * where the encrypted data and the 725 * authentication tag are defined as 726 * separate outputs, the authentication 727 * tag is appended to the encrypted data. 728 * \param[in] ciphertext_size Size of the `p_ciphertext` buffer in 729 * bytes 730 * \param[out] p_ciphertext_length On success, the size of the output in 731 * the `p_ciphertext` buffer 732 * 733 * \retval #PSA_SUCCESS 734 * Success. 735 */ 736 typedef psa_status_t (*psa_drv_se_aead_encrypt_t)(psa_drv_se_context_t *drv_context, 737 psa_key_slot_number_t key_slot, 738 psa_algorithm_t algorithm, 739 const uint8_t *p_nonce, 740 size_t nonce_length, 741 const uint8_t *p_additional_data, 742 size_t additional_data_length, 743 const uint8_t *p_plaintext, 744 size_t plaintext_length, 745 uint8_t *p_ciphertext, 746 size_t ciphertext_size, 747 size_t *p_ciphertext_length); 748 749 /** A function that performs a secure element authenticated decryption operation 750 * 751 * \param[in,out] drv_context The driver context structure. 752 * \param[in] key_slot Slot containing the key to use 753 * \param[in] algorithm The AEAD algorithm to compute 754 * (\c PSA_ALG_XXX value such that 755 * #PSA_ALG_IS_AEAD(`alg`) is true) 756 * \param[in] p_nonce Nonce or IV to use 757 * \param[in] nonce_length Size of the `p_nonce` buffer in bytes 758 * \param[in] p_additional_data Additional data that has been 759 * authenticated but not encrypted 760 * \param[in] additional_data_length Size of `p_additional_data` in bytes 761 * \param[in] p_ciphertext Data that has been authenticated and 762 * encrypted. 763 * For algorithms where the encrypted data 764 * and the authentication tag are defined 765 * as separate inputs, the buffer must 766 * contain the encrypted data followed by 767 * the authentication tag. 768 * \param[in] ciphertext_length Size of `p_ciphertext` in bytes 769 * \param[out] p_plaintext Output buffer for the decrypted data 770 * \param[in] plaintext_size Size of the `p_plaintext` buffer in 771 * bytes 772 * \param[out] p_plaintext_length On success, the size of the output in 773 * the `p_plaintext` buffer 774 * 775 * \retval #PSA_SUCCESS 776 * Success. 777 */ 778 typedef psa_status_t (*psa_drv_se_aead_decrypt_t)(psa_drv_se_context_t *drv_context, 779 psa_key_slot_number_t key_slot, 780 psa_algorithm_t algorithm, 781 const uint8_t *p_nonce, 782 size_t nonce_length, 783 const uint8_t *p_additional_data, 784 size_t additional_data_length, 785 const uint8_t *p_ciphertext, 786 size_t ciphertext_length, 787 uint8_t *p_plaintext, 788 size_t plaintext_size, 789 size_t *p_plaintext_length); 790 791 /** 792 * \brief A struct containing all of the function pointers needed to implement 793 * secure element Authenticated Encryption with Additional Data operations 794 * 795 * PSA Crypto API implementations should populate instances of the table as 796 * appropriate upon startup. 797 * 798 * If one of the functions is not implemented, it should be set to NULL. 799 */ 800 typedef struct { 801 /** Function that performs the AEAD encrypt operation */ 802 psa_drv_se_aead_encrypt_t MBEDTLS_PRIVATE(p_encrypt); 803 /** Function that performs the AEAD decrypt operation */ 804 psa_drv_se_aead_decrypt_t MBEDTLS_PRIVATE(p_decrypt); 805 } psa_drv_se_aead_t; 806 /**@}*/ 807 808 /** \defgroup se_key_management Secure Element Key Management 809 * Currently, key management is limited to importing keys in the clear, 810 * destroying keys, and exporting keys in the clear. 811 * Whether a key may be exported is determined by the key policies in place 812 * on the key slot. 813 */ 814 /**@{*/ 815 816 /** An enumeration indicating how a key is created. 817 */ 818 typedef enum { 819 PSA_KEY_CREATION_IMPORT, /**< During psa_import_key() */ 820 PSA_KEY_CREATION_GENERATE, /**< During psa_generate_key() */ 821 PSA_KEY_CREATION_DERIVE, /**< During psa_key_derivation_output_key() */ 822 PSA_KEY_CREATION_COPY, /**< During psa_copy_key() */ 823 824 #ifndef __DOXYGEN_ONLY__ 825 /** A key is being registered with mbedtls_psa_register_se_key(). 826 * 827 * The core only passes this value to 828 * psa_drv_se_key_management_t::p_validate_slot_number, not to 829 * psa_drv_se_key_management_t::p_allocate. The call to 830 * `p_validate_slot_number` is not followed by any other call to the 831 * driver: the key is considered successfully registered if the call to 832 * `p_validate_slot_number` succeeds, or if `p_validate_slot_number` is 833 * null. 834 * 835 * With this creation method, the driver must return #PSA_SUCCESS if 836 * the given attributes are compatible with the existing key in the slot, 837 * and #PSA_ERROR_DOES_NOT_EXIST if the driver can determine that there 838 * is no key with the specified slot number. 839 * 840 * This is an Mbed Crypto extension. 841 */ 842 PSA_KEY_CREATION_REGISTER, 843 #endif 844 } psa_key_creation_method_t; 845 846 /** \brief A function that allocates a slot for a key. 847 * 848 * To create a key in a specific slot in a secure element, the core 849 * first calls this function to determine a valid slot number, 850 * then calls a function to create the key material in that slot. 851 * In nominal conditions (that is, if no error occurs), 852 * the effect of a call to a key creation function in the PSA Cryptography 853 * API with a lifetime that places the key in a secure element is the 854 * following: 855 * -# The core calls psa_drv_se_key_management_t::p_allocate 856 * (or in some implementations 857 * psa_drv_se_key_management_t::p_validate_slot_number). The driver 858 * selects (or validates) a suitable slot number given the key attributes 859 * and the state of the secure element. 860 * -# The core calls a key creation function in the driver. 861 * 862 * The key creation functions in the PSA Cryptography API are: 863 * - psa_import_key(), which causes 864 * a call to `p_allocate` with \p method = #PSA_KEY_CREATION_IMPORT 865 * then a call to psa_drv_se_key_management_t::p_import. 866 * - psa_generate_key(), which causes 867 * a call to `p_allocate` with \p method = #PSA_KEY_CREATION_GENERATE 868 * then a call to psa_drv_se_key_management_t::p_import. 869 * - psa_key_derivation_output_key(), which causes 870 * a call to `p_allocate` with \p method = #PSA_KEY_CREATION_DERIVE 871 * then a call to psa_drv_se_key_derivation_t::p_derive. 872 * - psa_copy_key(), which causes 873 * a call to `p_allocate` with \p method = #PSA_KEY_CREATION_COPY 874 * then a call to psa_drv_se_key_management_t::p_export. 875 * 876 * In case of errors, other behaviors are possible. 877 * - If the PSA Cryptography subsystem dies after the first step, 878 * for example because the device has lost power abruptly, 879 * the second step may never happen, or may happen after a reset 880 * and re-initialization. Alternatively, after a reset and 881 * re-initialization, the core may call 882 * psa_drv_se_key_management_t::p_destroy on the slot number that 883 * was allocated (or validated) instead of calling a key creation function. 884 * - If an error occurs, the core may call 885 * psa_drv_se_key_management_t::p_destroy on the slot number that 886 * was allocated (or validated) instead of calling a key creation function. 887 * 888 * Errors and system resets also have an impact on the driver's persistent 889 * data. If a reset happens before the overall key creation process is 890 * completed (before or after the second step above), it is unspecified 891 * whether the persistent data after the reset is identical to what it 892 * was before or after the call to `p_allocate` (or `p_validate_slot_number`). 893 * 894 * \param[in,out] drv_context The driver context structure. 895 * \param[in,out] persistent_data A pointer to the persistent data 896 * that allows writing. 897 * \param[in] attributes Attributes of the key. 898 * \param method The way in which the key is being created. 899 * \param[out] key_slot Slot where the key will be stored. 900 * This must be a valid slot for a key of the 901 * chosen type. It must be unoccupied. 902 * 903 * \retval #PSA_SUCCESS 904 * Success. 905 * The core will record \c *key_slot as the key slot where the key 906 * is stored and will update the persistent data in storage. 907 * \retval #PSA_ERROR_NOT_SUPPORTED \emptydescription 908 * \retval #PSA_ERROR_INSUFFICIENT_STORAGE \emptydescription 909 */ 910 typedef psa_status_t (*psa_drv_se_allocate_key_t)( 911 psa_drv_se_context_t *drv_context, 912 void *persistent_data, 913 const psa_key_attributes_t *attributes, 914 psa_key_creation_method_t method, 915 psa_key_slot_number_t *key_slot); 916 917 /** \brief A function that determines whether a slot number is valid 918 * for a key. 919 * 920 * To create a key in a specific slot in a secure element, the core 921 * first calls this function to validate the choice of slot number, 922 * then calls a function to create the key material in that slot. 923 * See the documentation of #psa_drv_se_allocate_key_t for more details. 924 * 925 * As of the PSA Cryptography API specification version 1.0, there is no way 926 * for applications to trigger a call to this function. However some 927 * implementations offer the capability to create or declare a key in 928 * a specific slot via implementation-specific means, generally for the 929 * sake of initial device provisioning or onboarding. Such a mechanism may 930 * be added to a future version of the PSA Cryptography API specification. 931 * 932 * This function may update the driver's persistent data through 933 * \p persistent_data. The core will save the updated persistent data at the 934 * end of the key creation process. See the description of 935 * ::psa_drv_se_allocate_key_t for more information. 936 * 937 * \param[in,out] drv_context The driver context structure. 938 * \param[in,out] persistent_data A pointer to the persistent data 939 * that allows writing. 940 * \param[in] attributes Attributes of the key. 941 * \param method The way in which the key is being created. 942 * \param[in] key_slot Slot where the key is to be stored. 943 * 944 * \retval #PSA_SUCCESS 945 * The given slot number is valid for a key with the given 946 * attributes. 947 * \retval #PSA_ERROR_INVALID_ARGUMENT 948 * The given slot number is not valid for a key with the 949 * given attributes. This includes the case where the slot 950 * number is not valid at all. 951 * \retval #PSA_ERROR_ALREADY_EXISTS 952 * There is already a key with the specified slot number. 953 * Drivers may choose to return this error from the key 954 * creation function instead. 955 */ 956 typedef psa_status_t (*psa_drv_se_validate_slot_number_t)( 957 psa_drv_se_context_t *drv_context, 958 void *persistent_data, 959 const psa_key_attributes_t *attributes, 960 psa_key_creation_method_t method, 961 psa_key_slot_number_t key_slot); 962 963 /** \brief A function that imports a key into a secure element in binary format 964 * 965 * This function can support any output from psa_export_key(). Refer to the 966 * documentation of psa_export_key() for the format for each key type. 967 * 968 * \param[in,out] drv_context The driver context structure. 969 * \param key_slot Slot where the key will be stored. 970 * This must be a valid slot for a key of the 971 * chosen type. It must be unoccupied. 972 * \param[in] attributes The key attributes, including the lifetime, 973 * the key type and the usage policy. 974 * Drivers should not access the key size stored 975 * in the attributes: it may not match the 976 * data passed in \p data. 977 * Drivers can call psa_get_key_lifetime(), 978 * psa_get_key_type(), 979 * psa_get_key_usage_flags() and 980 * psa_get_key_algorithm() to access this 981 * information. 982 * \param[in] data Buffer containing the key data. 983 * \param[in] data_length Size of the \p data buffer in bytes. 984 * \param[out] bits On success, the key size in bits. The driver 985 * must determine this value after parsing the 986 * key according to the key type. 987 * This value is not used if the function fails. 988 * 989 * \retval #PSA_SUCCESS 990 * Success. 991 */ 992 typedef psa_status_t (*psa_drv_se_import_key_t)( 993 psa_drv_se_context_t *drv_context, 994 psa_key_slot_number_t key_slot, 995 const psa_key_attributes_t *attributes, 996 const uint8_t *data, 997 size_t data_length, 998 size_t *bits); 999 1000 /** 1001 * \brief A function that destroys a secure element key and restore the slot to 1002 * its default state 1003 * 1004 * This function destroys the content of the key from a secure element. 1005 * Implementations shall make a best effort to ensure that any previous content 1006 * of the slot is unrecoverable. 1007 * 1008 * This function returns the specified slot to its default state. 1009 * 1010 * \param[in,out] drv_context The driver context structure. 1011 * \param[in,out] persistent_data A pointer to the persistent data 1012 * that allows writing. 1013 * \param key_slot The key slot to erase. 1014 * 1015 * \retval #PSA_SUCCESS 1016 * The slot's content, if any, has been erased. 1017 */ 1018 typedef psa_status_t (*psa_drv_se_destroy_key_t)( 1019 psa_drv_se_context_t *drv_context, 1020 void *persistent_data, 1021 psa_key_slot_number_t key_slot); 1022 1023 /** 1024 * \brief A function that exports a secure element key in binary format 1025 * 1026 * The output of this function can be passed to psa_import_key() to 1027 * create an equivalent object. 1028 * 1029 * If a key is created with `psa_import_key()` and then exported with 1030 * this function, it is not guaranteed that the resulting data is 1031 * identical: the implementation may choose a different representation 1032 * of the same key if the format permits it. 1033 * 1034 * This function should generate output in the same format that 1035 * `psa_export_key()` does. Refer to the 1036 * documentation of `psa_export_key()` for the format for each key type. 1037 * 1038 * \param[in,out] drv_context The driver context structure. 1039 * \param[in] key Slot whose content is to be exported. This must 1040 * be an occupied key slot. 1041 * \param[out] p_data Buffer where the key data is to be written. 1042 * \param[in] data_size Size of the `p_data` buffer in bytes. 1043 * \param[out] p_data_length On success, the number of bytes 1044 * that make up the key data. 1045 * 1046 * \retval #PSA_SUCCESS \emptydescription 1047 * \retval #PSA_ERROR_DOES_NOT_EXIST \emptydescription 1048 * \retval #PSA_ERROR_NOT_PERMITTED \emptydescription 1049 * \retval #PSA_ERROR_NOT_SUPPORTED \emptydescription 1050 * \retval #PSA_ERROR_COMMUNICATION_FAILURE \emptydescription 1051 * \retval #PSA_ERROR_HARDWARE_FAILURE \emptydescription 1052 * \retval #PSA_ERROR_CORRUPTION_DETECTED \emptydescription 1053 */ 1054 typedef psa_status_t (*psa_drv_se_export_key_t)(psa_drv_se_context_t *drv_context, 1055 psa_key_slot_number_t key, 1056 uint8_t *p_data, 1057 size_t data_size, 1058 size_t *p_data_length); 1059 1060 /** 1061 * \brief A function that generates a symmetric or asymmetric key on a secure 1062 * element 1063 * 1064 * If the key type \c type recorded in \p attributes 1065 * is asymmetric (#PSA_KEY_TYPE_IS_ASYMMETRIC(\c type) = 1), 1066 * the driver may export the public key at the time of generation, 1067 * in the format documented for psa_export_public_key() by writing it 1068 * to the \p pubkey buffer. 1069 * This is optional, intended for secure elements that output the 1070 * public key at generation time and that cannot export the public key 1071 * later. Drivers that do not need this feature should leave 1072 * \p *pubkey_length set to 0 and should 1073 * implement the psa_drv_key_management_t::p_export_public function. 1074 * Some implementations do not support this feature, in which case 1075 * \p pubkey is \c NULL and \p pubkey_size is 0. 1076 * 1077 * \param[in,out] drv_context The driver context structure. 1078 * \param key_slot Slot where the key will be stored. 1079 * This must be a valid slot for a key of the 1080 * chosen type. It must be unoccupied. 1081 * \param[in] attributes The key attributes, including the lifetime, 1082 * the key type and size, and the usage policy. 1083 * Drivers can call psa_get_key_lifetime(), 1084 * psa_get_key_type(), psa_get_key_bits(), 1085 * psa_get_key_usage_flags() and 1086 * psa_get_key_algorithm() to access this 1087 * information. 1088 * \param[out] pubkey A buffer where the driver can write the 1089 * public key, when generating an asymmetric 1090 * key pair. 1091 * This is \c NULL when generating a symmetric 1092 * key or if the core does not support 1093 * exporting the public key at generation time. 1094 * \param pubkey_size The size of the `pubkey` buffer in bytes. 1095 * This is 0 when generating a symmetric 1096 * key or if the core does not support 1097 * exporting the public key at generation time. 1098 * \param[out] pubkey_length On entry, this is always 0. 1099 * On success, the number of bytes written to 1100 * \p pubkey. If this is 0 or unchanged on return, 1101 * the core will not read the \p pubkey buffer, 1102 * and will instead call the driver's 1103 * psa_drv_key_management_t::p_export_public 1104 * function to export the public key when needed. 1105 */ 1106 typedef psa_status_t (*psa_drv_se_generate_key_t)( 1107 psa_drv_se_context_t *drv_context, 1108 psa_key_slot_number_t key_slot, 1109 const psa_key_attributes_t *attributes, 1110 uint8_t *pubkey, size_t pubkey_size, size_t *pubkey_length); 1111 1112 /** 1113 * \brief A struct containing all of the function pointers needed to for secure 1114 * element key management 1115 * 1116 * PSA Crypto API implementations should populate instances of the table as 1117 * appropriate upon startup or at build time. 1118 * 1119 * If one of the functions is not implemented, it should be set to NULL. 1120 */ 1121 typedef struct { 1122 /** Function that allocates a slot for a key. */ 1123 psa_drv_se_allocate_key_t MBEDTLS_PRIVATE(p_allocate); 1124 /** Function that checks the validity of a slot for a key. */ 1125 psa_drv_se_validate_slot_number_t MBEDTLS_PRIVATE(p_validate_slot_number); 1126 /** Function that performs a key import operation */ 1127 psa_drv_se_import_key_t MBEDTLS_PRIVATE(p_import); 1128 /** Function that performs a generation */ 1129 psa_drv_se_generate_key_t MBEDTLS_PRIVATE(p_generate); 1130 /** Function that performs a key destroy operation */ 1131 psa_drv_se_destroy_key_t MBEDTLS_PRIVATE(p_destroy); 1132 /** Function that performs a key export operation */ 1133 psa_drv_se_export_key_t MBEDTLS_PRIVATE(p_export); 1134 /** Function that performs a public key export operation */ 1135 psa_drv_se_export_key_t MBEDTLS_PRIVATE(p_export_public); 1136 } psa_drv_se_key_management_t; 1137 1138 /**@}*/ 1139 1140 /** \defgroup driver_derivation Secure Element Key Derivation and Agreement 1141 * Key derivation is the process of generating new key material using an 1142 * existing key and additional parameters, iterating through a basic 1143 * cryptographic function, such as a hash. 1144 * Key agreement is a part of cryptographic protocols that allows two parties 1145 * to agree on the same key value, but starting from different original key 1146 * material. 1147 * The flows are similar, and the PSA Crypto Driver Model uses the same functions 1148 * for both of the flows. 1149 * 1150 * There are two different final functions for the flows, 1151 * `psa_drv_se_key_derivation_derive` and `psa_drv_se_key_derivation_export`. 1152 * `psa_drv_se_key_derivation_derive` is used when the key material should be 1153 * placed in a slot on the hardware and not exposed to the caller. 1154 * `psa_drv_se_key_derivation_export` is used when the key material should be 1155 * returned to the PSA Cryptographic API implementation. 1156 * 1157 * Different key derivation algorithms require a different number of inputs. 1158 * Instead of having an API that takes as input variable length arrays, which 1159 * can be problematic to manage on embedded platforms, the inputs are passed 1160 * to the driver via a function, `psa_drv_se_key_derivation_collateral`, that 1161 * is called multiple times with different `collateral_id`s. Thus, for a key 1162 * derivation algorithm that required 3 parameter inputs, the flow would look 1163 * something like: 1164 * ~~~~~~~~~~~~~{.c} 1165 * psa_drv_se_key_derivation_setup(kdf_algorithm, source_key, dest_key_size_bytes); 1166 * psa_drv_se_key_derivation_collateral(kdf_algorithm_collateral_id_0, 1167 * p_collateral_0, 1168 * collateral_0_size); 1169 * psa_drv_se_key_derivation_collateral(kdf_algorithm_collateral_id_1, 1170 * p_collateral_1, 1171 * collateral_1_size); 1172 * psa_drv_se_key_derivation_collateral(kdf_algorithm_collateral_id_2, 1173 * p_collateral_2, 1174 * collateral_2_size); 1175 * psa_drv_se_key_derivation_derive(); 1176 * ~~~~~~~~~~~~~ 1177 * 1178 * key agreement example: 1179 * ~~~~~~~~~~~~~{.c} 1180 * psa_drv_se_key_derivation_setup(alg, source_key. dest_key_size_bytes); 1181 * psa_drv_se_key_derivation_collateral(DHE_PUBKEY, p_pubkey, pubkey_size); 1182 * psa_drv_se_key_derivation_export(p_session_key, 1183 * session_key_size, 1184 * &session_key_length); 1185 * ~~~~~~~~~~~~~ 1186 */ 1187 /**@{*/ 1188 1189 /** \brief A function that Sets up a secure element key derivation operation by 1190 * specifying the algorithm and the source key sot 1191 * 1192 * \param[in,out] drv_context The driver context structure. 1193 * \param[in,out] op_context A hardware-specific structure containing any 1194 * context information for the implementation 1195 * \param[in] kdf_alg The algorithm to be used for the key derivation 1196 * \param[in] source_key The key to be used as the source material for 1197 * the key derivation 1198 * 1199 * \retval #PSA_SUCCESS \emptydescription 1200 */ 1201 typedef psa_status_t (*psa_drv_se_key_derivation_setup_t)(psa_drv_se_context_t *drv_context, 1202 void *op_context, 1203 psa_algorithm_t kdf_alg, 1204 psa_key_slot_number_t source_key); 1205 1206 /** \brief A function that provides collateral (parameters) needed for a secure 1207 * element key derivation or key agreement operation 1208 * 1209 * Since many key derivation algorithms require multiple parameters, it is 1210 * expected that this function may be called multiple times for the same 1211 * operation, each with a different algorithm-specific `collateral_id` 1212 * 1213 * \param[in,out] op_context A hardware-specific structure containing any 1214 * context information for the implementation 1215 * \param[in] collateral_id An ID for the collateral being provided 1216 * \param[in] p_collateral A buffer containing the collateral data 1217 * \param[in] collateral_size The size in bytes of the collateral 1218 * 1219 * \retval #PSA_SUCCESS \emptydescription 1220 */ 1221 typedef psa_status_t (*psa_drv_se_key_derivation_collateral_t)(void *op_context, 1222 uint32_t collateral_id, 1223 const uint8_t *p_collateral, 1224 size_t collateral_size); 1225 1226 /** \brief A function that performs the final secure element key derivation 1227 * step and place the generated key material in a slot 1228 * 1229 * \param[in,out] op_context A hardware-specific structure containing any 1230 * context information for the implementation 1231 * \param[in] dest_key The slot where the generated key material 1232 * should be placed 1233 * 1234 * \retval #PSA_SUCCESS \emptydescription 1235 */ 1236 typedef psa_status_t (*psa_drv_se_key_derivation_derive_t)(void *op_context, 1237 psa_key_slot_number_t dest_key); 1238 1239 /** \brief A function that performs the final step of a secure element key 1240 * agreement and place the generated key material in a buffer 1241 * 1242 * \param[out] p_output Buffer in which to place the generated key 1243 * material 1244 * \param[in] output_size The size in bytes of `p_output` 1245 * \param[out] p_output_length Upon success, contains the number of bytes of 1246 * key material placed in `p_output` 1247 * 1248 * \retval #PSA_SUCCESS \emptydescription 1249 */ 1250 typedef psa_status_t (*psa_drv_se_key_derivation_export_t)(void *op_context, 1251 uint8_t *p_output, 1252 size_t output_size, 1253 size_t *p_output_length); 1254 1255 /** 1256 * \brief A struct containing all of the function pointers needed to for secure 1257 * element key derivation and agreement 1258 * 1259 * PSA Crypto API implementations should populate instances of the table as 1260 * appropriate upon startup. 1261 * 1262 * If one of the functions is not implemented, it should be set to NULL. 1263 */ 1264 typedef struct { 1265 /** The driver-specific size of the key derivation context */ 1266 size_t MBEDTLS_PRIVATE(context_size); 1267 /** Function that performs a key derivation setup */ 1268 psa_drv_se_key_derivation_setup_t MBEDTLS_PRIVATE(p_setup); 1269 /** Function that sets key derivation collateral */ 1270 psa_drv_se_key_derivation_collateral_t MBEDTLS_PRIVATE(p_collateral); 1271 /** Function that performs a final key derivation step */ 1272 psa_drv_se_key_derivation_derive_t MBEDTLS_PRIVATE(p_derive); 1273 /** Function that performs a final key derivation or agreement and 1274 * exports the key */ 1275 psa_drv_se_key_derivation_export_t MBEDTLS_PRIVATE(p_export); 1276 } psa_drv_se_key_derivation_t; 1277 1278 /**@}*/ 1279 1280 /** \defgroup se_registration Secure element driver registration 1281 */ 1282 /**@{*/ 1283 1284 /** A structure containing pointers to all the entry points of a 1285 * secure element driver. 1286 * 1287 * Future versions of this specification may add extra substructures at 1288 * the end of this structure. 1289 */ 1290 typedef struct { 1291 /** The version of the driver HAL that this driver implements. 1292 * This is a protection against loading driver binaries built against 1293 * a different version of this specification. 1294 * Use #PSA_DRV_SE_HAL_VERSION. 1295 */ 1296 uint32_t MBEDTLS_PRIVATE(hal_version); 1297 1298 /** The size of the driver's persistent data in bytes. 1299 * 1300 * This can be 0 if the driver does not need persistent data. 1301 * 1302 * See the documentation of psa_drv_se_context_t::persistent_data 1303 * for more information about why and how a driver can use 1304 * persistent data. 1305 */ 1306 size_t MBEDTLS_PRIVATE(persistent_data_size); 1307 1308 /** The driver initialization function. 1309 * 1310 * This function is called once during the initialization of the 1311 * PSA Cryptography subsystem, before any other function of the 1312 * driver is called. If this function returns a failure status, 1313 * the driver will be unusable, at least until the next system reset. 1314 * 1315 * If this field is \c NULL, it is equivalent to a function that does 1316 * nothing and returns #PSA_SUCCESS. 1317 */ 1318 psa_drv_se_init_t MBEDTLS_PRIVATE(p_init); 1319 1320 const psa_drv_se_key_management_t *MBEDTLS_PRIVATE(key_management); 1321 const psa_drv_se_mac_t *MBEDTLS_PRIVATE(mac); 1322 const psa_drv_se_cipher_t *MBEDTLS_PRIVATE(cipher); 1323 const psa_drv_se_aead_t *MBEDTLS_PRIVATE(aead); 1324 const psa_drv_se_asymmetric_t *MBEDTLS_PRIVATE(asymmetric); 1325 const psa_drv_se_key_derivation_t *MBEDTLS_PRIVATE(derivation); 1326 } psa_drv_se_t; 1327 1328 /** The current version of the secure element driver HAL. 1329 */ 1330 /* 0.0.0 patchlevel 5 */ 1331 #define PSA_DRV_SE_HAL_VERSION 0x00000005 1332 1333 /** Register an external cryptoprocessor (secure element) driver. 1334 * 1335 * This function is only intended to be used by driver code, not by 1336 * application code. In implementations with separation between the 1337 * PSA cryptography module and applications, this function should 1338 * only be available to callers that run in the same memory space as 1339 * the cryptography module, and should not be exposed to applications 1340 * running in a different memory space. 1341 * 1342 * This function may be called before psa_crypto_init(). It is 1343 * implementation-defined whether this function may be called 1344 * after psa_crypto_init(). 1345 * 1346 * \note Implementations store metadata about keys including the lifetime 1347 * value, which contains the driver's location indicator. Therefore, 1348 * from one instantiation of the PSA Cryptography 1349 * library to the next one, if there is a key in storage with a certain 1350 * lifetime value, you must always register the same driver (or an 1351 * updated version that communicates with the same secure element) 1352 * with the same location value. 1353 * 1354 * \param location The location value through which this driver will 1355 * be exposed to applications. 1356 * This driver will be used for all keys such that 1357 * `location == #PSA_KEY_LIFETIME_GET_LOCATION( lifetime )`. 1358 * The value #PSA_KEY_LOCATION_LOCAL_STORAGE is reserved 1359 * and may not be used for drivers. Implementations 1360 * may reserve other values. 1361 * \param[in] methods The method table of the driver. This structure must 1362 * remain valid for as long as the cryptography 1363 * module keeps running. It is typically a global 1364 * constant. 1365 * 1366 * \return #PSA_SUCCESS 1367 * The driver was successfully registered. Applications can now 1368 * use \p location to access keys through the methods passed to 1369 * this function. 1370 * \return #PSA_ERROR_BAD_STATE 1371 * This function was called after the initialization of the 1372 * cryptography module, and this implementation does not support 1373 * driver registration at this stage. 1374 * \return #PSA_ERROR_ALREADY_EXISTS 1375 * There is already a registered driver for this value of \p location. 1376 * \return #PSA_ERROR_INVALID_ARGUMENT 1377 * \p location is a reserved value. 1378 * \return #PSA_ERROR_NOT_SUPPORTED 1379 * `methods->hal_version` is not supported by this implementation. 1380 * \return #PSA_ERROR_INSUFFICIENT_MEMORY 1381 * \return #PSA_ERROR_NOT_PERMITTED 1382 * \return #PSA_ERROR_STORAGE_FAILURE 1383 * \return #PSA_ERROR_DATA_CORRUPT 1384 */ 1385 psa_status_t psa_register_se_driver( 1386 psa_key_location_t location, 1387 const psa_drv_se_t *methods); 1388 1389 /**@}*/ 1390 1391 #ifdef __cplusplus 1392 } 1393 #endif 1394 1395 #endif /* PSA_CRYPTO_SE_DRIVER_H */ 1396