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