1 /** 2 * \file psa/crypto_types.h 3 * 4 * \brief PSA cryptography module: type aliases. 5 * 6 * \note This file may not be included directly. Applications must 7 * include psa/crypto.h. Drivers must include the appropriate driver 8 * header file. 9 * 10 * This file contains portable definitions of integral types for properties 11 * of cryptographic keys, designations of cryptographic algorithms, and 12 * error codes returned by the library. 13 * 14 * This header file does not declare any function. 15 */ 16 /* 17 * Copyright The Mbed TLS Contributors 18 * SPDX-License-Identifier: Apache-2.0 19 * 20 * Licensed under the Apache License, Version 2.0 (the "License"); you may 21 * not use this file except in compliance with the License. 22 * You may obtain a copy of the License at 23 * 24 * http://www.apache.org/licenses/LICENSE-2.0 25 * 26 * Unless required by applicable law or agreed to in writing, software 27 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 28 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 29 * See the License for the specific language governing permissions and 30 * limitations under the License. 31 */ 32 33 #ifndef PSA_CRYPTO_TYPES_H 34 #define PSA_CRYPTO_TYPES_H 35 36 #include "crypto_platform.h" 37 38 /* If MBEDTLS_PSA_CRYPTO_C is defined, make sure MBEDTLS_PSA_CRYPTO_CLIENT 39 * is defined as well to include all PSA code. 40 */ 41 #if defined(MBEDTLS_PSA_CRYPTO_C) 42 #define MBEDTLS_PSA_CRYPTO_CLIENT 43 #endif /* MBEDTLS_PSA_CRYPTO_C */ 44 45 #include <stdint.h> 46 47 /** \defgroup error Error codes 48 * @{ 49 */ 50 51 /** 52 * \brief Function return status. 53 * 54 * This is either #PSA_SUCCESS (which is zero), indicating success, 55 * or a small negative value indicating that an error occurred. Errors are 56 * encoded as one of the \c PSA_ERROR_xxx values defined here. */ 57 /* If #PSA_SUCCESS is already defined, it means that #psa_status_t 58 * is also defined in an external header, so prevent its multiple 59 * definition. 60 */ 61 #ifndef PSA_SUCCESS 62 typedef int32_t psa_status_t; 63 #endif 64 65 /**@}*/ 66 67 /** \defgroup crypto_types Key and algorithm types 68 * @{ 69 */ 70 71 /** \brief Encoding of a key type. 72 */ 73 typedef uint16_t psa_key_type_t; 74 75 /** The type of PSA elliptic curve family identifiers. 76 * 77 * The curve identifier is required to create an ECC key using the 78 * PSA_KEY_TYPE_ECC_KEY_PAIR() or PSA_KEY_TYPE_ECC_PUBLIC_KEY() 79 * macros. 80 * 81 * Values defined by this standard will never be in the range 0x80-0xff. 82 * Vendors who define additional families must use an encoding in this range. 83 */ 84 typedef uint8_t psa_ecc_family_t; 85 86 /** The type of PSA Diffie-Hellman group family identifiers. 87 * 88 * The group identifier is required to create an Diffie-Hellman key using the 89 * PSA_KEY_TYPE_DH_KEY_PAIR() or PSA_KEY_TYPE_DH_PUBLIC_KEY() 90 * macros. 91 * 92 * Values defined by this standard will never be in the range 0x80-0xff. 93 * Vendors who define additional families must use an encoding in this range. 94 */ 95 typedef uint8_t psa_dh_family_t; 96 97 /** \brief Encoding of a cryptographic algorithm. 98 * 99 * For algorithms that can be applied to multiple key types, this type 100 * does not encode the key type. For example, for symmetric ciphers 101 * based on a block cipher, #psa_algorithm_t encodes the block cipher 102 * mode and the padding mode while the block cipher itself is encoded 103 * via #psa_key_type_t. 104 */ 105 typedef uint32_t psa_algorithm_t; 106 107 /**@}*/ 108 109 /** \defgroup key_lifetimes Key lifetimes 110 * @{ 111 */ 112 113 /** Encoding of key lifetimes. 114 * 115 * The lifetime of a key indicates where it is stored and what system actions 116 * may create and destroy it. 117 * 118 * Lifetime values have the following structure: 119 * - Bits 0-7 (#PSA_KEY_LIFETIME_GET_PERSISTENCE(\c lifetime)): 120 * persistence level. This value indicates what device management 121 * actions can cause it to be destroyed. In particular, it indicates 122 * whether the key is _volatile_ or _persistent_. 123 * See ::psa_key_persistence_t for more information. 124 * - Bits 8-31 (#PSA_KEY_LIFETIME_GET_LOCATION(\c lifetime)): 125 * location indicator. This value indicates which part of the system 126 * has access to the key material and can perform operations using the key. 127 * See ::psa_key_location_t for more information. 128 * 129 * Volatile keys are automatically destroyed when the application instance 130 * terminates or on a power reset of the device. Persistent keys are 131 * preserved until the application explicitly destroys them or until an 132 * integration-specific device management event occurs (for example, 133 * a factory reset). 134 * 135 * Persistent keys have a key identifier of type #mbedtls_svc_key_id_t. 136 * This identifier remains valid throughout the lifetime of the key, 137 * even if the application instance that created the key terminates. 138 * The application can call psa_open_key() to open a persistent key that 139 * it created previously. 140 * 141 * The default lifetime of a key is #PSA_KEY_LIFETIME_VOLATILE. The lifetime 142 * #PSA_KEY_LIFETIME_PERSISTENT is supported if persistent storage is 143 * available. Other lifetime values may be supported depending on the 144 * library configuration. 145 */ 146 typedef uint32_t psa_key_lifetime_t; 147 148 /** Encoding of key persistence levels. 149 * 150 * What distinguishes different persistence levels is what device management 151 * events may cause keys to be destroyed. _Volatile_ keys are destroyed 152 * by a power reset. Persistent keys may be destroyed by events such as 153 * a transfer of ownership or a factory reset. What management events 154 * actually affect persistent keys at different levels is outside the 155 * scope of the PSA Cryptography specification. 156 * 157 * The PSA Cryptography specification defines the following values of 158 * persistence levels: 159 * - \c 0 = #PSA_KEY_PERSISTENCE_VOLATILE: volatile key. 160 * A volatile key is automatically destroyed by the implementation when 161 * the application instance terminates. In particular, a volatile key 162 * is automatically destroyed on a power reset of the device. 163 * - \c 1 = #PSA_KEY_PERSISTENCE_DEFAULT: 164 * persistent key with a default lifetime. 165 * - \c 2-254: currently not supported by Mbed TLS. 166 * - \c 255 = #PSA_KEY_PERSISTENCE_READ_ONLY: 167 * read-only or write-once key. 168 * A key with this persistence level cannot be destroyed. 169 * Mbed TLS does not currently offer a way to create such keys, but 170 * integrations of Mbed TLS can use it for built-in keys that the 171 * application cannot modify (for example, a hardware unique key (HUK)). 172 * 173 * \note Key persistence levels are 8-bit values. Key management 174 * interfaces operate on lifetimes (type ::psa_key_lifetime_t) which 175 * encode the persistence as the lower 8 bits of a 32-bit value. 176 */ 177 typedef uint8_t psa_key_persistence_t; 178 179 /** Encoding of key location indicators. 180 * 181 * If an integration of Mbed TLS can make calls to external 182 * cryptoprocessors such as secure elements, the location of a key 183 * indicates which secure element performs the operations on the key. 184 * Depending on the design of the secure element, the key 185 * material may be stored either in the secure element, or 186 * in wrapped (encrypted) form alongside the key metadata in the 187 * primary local storage. 188 * 189 * The PSA Cryptography API specification defines the following values of 190 * location indicators: 191 * - \c 0: primary local storage. 192 * This location is always available. 193 * The primary local storage is typically the same storage area that 194 * contains the key metadata. 195 * - \c 1: primary secure element. 196 * Integrations of Mbed TLS should support this value if there is a secure 197 * element attached to the operating environment. 198 * As a guideline, secure elements may provide higher resistance against 199 * side channel and physical attacks than the primary local storage, but may 200 * have restrictions on supported key types, sizes, policies and operations 201 * and may have different performance characteristics. 202 * - \c 2-0x7fffff: other locations defined by a PSA specification. 203 * The PSA Cryptography API does not currently assign any meaning to these 204 * locations, but future versions of that specification or other PSA 205 * specifications may do so. 206 * - \c 0x800000-0xffffff: vendor-defined locations. 207 * No PSA specification will assign a meaning to locations in this range. 208 * 209 * \note Key location indicators are 24-bit values. Key management 210 * interfaces operate on lifetimes (type ::psa_key_lifetime_t) which 211 * encode the location as the upper 24 bits of a 32-bit value. 212 */ 213 typedef uint32_t psa_key_location_t; 214 215 /** Encoding of identifiers of persistent keys. 216 * 217 * - Applications may freely choose key identifiers in the range 218 * #PSA_KEY_ID_USER_MIN to #PSA_KEY_ID_USER_MAX. 219 * - The implementation may define additional key identifiers in the range 220 * #PSA_KEY_ID_VENDOR_MIN to #PSA_KEY_ID_VENDOR_MAX. 221 * - 0 is reserved as an invalid key identifier. 222 * - Key identifiers outside these ranges are reserved for future use. 223 */ 224 typedef uint32_t psa_key_id_t; 225 226 #if !defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER) 227 typedef psa_key_id_t mbedtls_svc_key_id_t; 228 229 #else /* MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER */ 230 /* Implementation-specific: The Mbed Cryptography library can be built as 231 * part of a multi-client service that exposes the PSA Cryptograpy API in each 232 * client and encodes the client identity in the key identifier argument of 233 * functions such as psa_open_key(). 234 */ 235 typedef struct 236 { 237 psa_key_id_t key_id; 238 mbedtls_key_owner_id_t owner; 239 } mbedtls_svc_key_id_t; 240 241 #endif /* !MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER */ 242 243 /**@}*/ 244 245 /** \defgroup policy Key policies 246 * @{ 247 */ 248 249 /** \brief Encoding of permitted usage on a key. */ 250 typedef uint32_t psa_key_usage_t; 251 252 /**@}*/ 253 254 /** \defgroup attributes Key attributes 255 * @{ 256 */ 257 258 /** The type of a structure containing key attributes. 259 * 260 * This is an opaque structure that can represent the metadata of a key 261 * object. Metadata that can be stored in attributes includes: 262 * - The location of the key in storage, indicated by its key identifier 263 * and its lifetime. 264 * - The key's policy, comprising usage flags and a specification of 265 * the permitted algorithm(s). 266 * - Information about the key itself: the key type and its size. 267 * - Additional implementation-defined attributes. 268 * 269 * The actual key material is not considered an attribute of a key. 270 * Key attributes do not contain information that is generally considered 271 * highly confidential. 272 * 273 * An attribute structure works like a simple data structure where each function 274 * `psa_set_key_xxx` sets a field and the corresponding function 275 * `psa_get_key_xxx` retrieves the value of the corresponding field. 276 * However, a future version of the library may report values that are 277 * equivalent to the original one, but have a different encoding. Invalid 278 * values may be mapped to different, also invalid values. 279 * 280 * An attribute structure may contain references to auxiliary resources, 281 * for example pointers to allocated memory or indirect references to 282 * pre-calculated values. In order to free such resources, the application 283 * must call psa_reset_key_attributes(). As an exception, calling 284 * psa_reset_key_attributes() on an attribute structure is optional if 285 * the structure has only been modified by the following functions 286 * since it was initialized or last reset with psa_reset_key_attributes(): 287 * - psa_set_key_id() 288 * - psa_set_key_lifetime() 289 * - psa_set_key_type() 290 * - psa_set_key_bits() 291 * - psa_set_key_usage_flags() 292 * - psa_set_key_algorithm() 293 * 294 * Before calling any function on a key attribute structure, the application 295 * must initialize it by any of the following means: 296 * - Set the structure to all-bits-zero, for example: 297 * \code 298 * psa_key_attributes_t attributes; 299 * memset(&attributes, 0, sizeof(attributes)); 300 * \endcode 301 * - Initialize the structure to logical zero values, for example: 302 * \code 303 * psa_key_attributes_t attributes = {0}; 304 * \endcode 305 * - Initialize the structure to the initializer #PSA_KEY_ATTRIBUTES_INIT, 306 * for example: 307 * \code 308 * psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT; 309 * \endcode 310 * - Assign the result of the function psa_key_attributes_init() 311 * to the structure, for example: 312 * \code 313 * psa_key_attributes_t attributes; 314 * attributes = psa_key_attributes_init(); 315 * \endcode 316 * 317 * A freshly initialized attribute structure contains the following 318 * values: 319 * 320 * - lifetime: #PSA_KEY_LIFETIME_VOLATILE. 321 * - key identifier: 0 (which is not a valid key identifier). 322 * - type: \c 0 (meaning that the type is unspecified). 323 * - key size: \c 0 (meaning that the size is unspecified). 324 * - usage flags: \c 0 (which allows no usage except exporting a public key). 325 * - algorithm: \c 0 (which allows no cryptographic usage, but allows 326 * exporting). 327 * 328 * A typical sequence to create a key is as follows: 329 * -# Create and initialize an attribute structure. 330 * -# If the key is persistent, call psa_set_key_id(). 331 * Also call psa_set_key_lifetime() to place the key in a non-default 332 * location. 333 * -# Set the key policy with psa_set_key_usage_flags() and 334 * psa_set_key_algorithm(). 335 * -# Set the key type with psa_set_key_type(). 336 * Skip this step if copying an existing key with psa_copy_key(). 337 * -# When generating a random key with psa_generate_key() or deriving a key 338 * with psa_key_derivation_output_key(), set the desired key size with 339 * psa_set_key_bits(). 340 * -# Call a key creation function: psa_import_key(), psa_generate_key(), 341 * psa_key_derivation_output_key() or psa_copy_key(). This function reads 342 * the attribute structure, creates a key with these attributes, and 343 * outputs a key identifier to the newly created key. 344 * -# The attribute structure is now no longer necessary. 345 * You may call psa_reset_key_attributes(), although this is optional 346 * with the workflow presented here because the attributes currently 347 * defined in this specification do not require any additional resources 348 * beyond the structure itself. 349 * 350 * A typical sequence to query a key's attributes is as follows: 351 * -# Call psa_get_key_attributes(). 352 * -# Call `psa_get_key_xxx` functions to retrieve the attribute(s) that 353 * you are interested in. 354 * -# Call psa_reset_key_attributes() to free any resources that may be 355 * used by the attribute structure. 356 * 357 * Once a key has been created, it is impossible to change its attributes. 358 */ 359 typedef struct psa_key_attributes_s psa_key_attributes_t; 360 361 362 #ifndef __DOXYGEN_ONLY__ 363 #if defined(MBEDTLS_PSA_CRYPTO_SE_C) 364 /* Mbed Crypto defines this type in crypto_types.h because it is also 365 * visible to applications through an implementation-specific extension. 366 * For the PSA Cryptography specification, this type is only visible 367 * via crypto_se_driver.h. */ 368 typedef uint64_t psa_key_slot_number_t; 369 #endif /* MBEDTLS_PSA_CRYPTO_SE_C */ 370 #endif /* !__DOXYGEN_ONLY__ */ 371 372 /**@}*/ 373 374 /** \defgroup derivation Key derivation 375 * @{ 376 */ 377 378 /** \brief Encoding of the step of a key derivation. */ 379 typedef uint16_t psa_key_derivation_step_t; 380 381 /**@}*/ 382 383 #endif /* PSA_CRYPTO_TYPES_H */ 384
