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 /* Make sure the Mbed TLS configuration is visible. */
37 #include "mbedtls/build_info.h"
38 /* Define the MBEDTLS_PRIVATE macro. */
39 #include "mbedtls/private_access.h"
40 
41 #if defined(MBEDTLS_PSA_CRYPTO_PLATFORM_FILE)
42 #include MBEDTLS_PSA_CRYPTO_PLATFORM_FILE
43 #else
44 #include "crypto_platform.h"
45 #endif
46 
47 #include <stdint.h>
48 
49 /** \defgroup error Error codes
50  * @{
51  */
52 
53 /**
54  * \brief Function return status.
55  *
56  * This is either #PSA_SUCCESS (which is zero), indicating success,
57  * or a small negative value indicating that an error occurred. Errors are
58  * encoded as one of the \c PSA_ERROR_xxx values defined here. */
59 /* If #PSA_SUCCESS is already defined, it means that #psa_status_t
60  * is also defined in an external header, so prevent its multiple
61  * definition.
62  */
63 #ifndef PSA_SUCCESS
64 typedef int32_t psa_status_t;
65 #endif
66 
67 /**@}*/
68 
69 /** \defgroup crypto_types Key and algorithm types
70  * @{
71  */
72 
73 /** \brief Encoding of a key type.
74  *
75  * Values of this type are generally constructed by macros called
76  * `PSA_KEY_TYPE_xxx`.
77  *
78  * \note Values of this type are encoded in the persistent key store.
79  *       Any changes to existing values will require bumping the storage
80  *       format version and providing a translation when reading the old
81  *       format.
82  */
83 typedef uint16_t psa_key_type_t;
84 
85 /** The type of PSA elliptic curve family identifiers.
86  *
87  * Values of this type are generally constructed by macros called
88  * `PSA_ECC_FAMILY_xxx`.
89  *
90  * The curve identifier is required to create an ECC key using the
91  * PSA_KEY_TYPE_ECC_KEY_PAIR() or PSA_KEY_TYPE_ECC_PUBLIC_KEY()
92  * macros.
93  *
94  * Values defined by this standard will never be in the range 0x80-0xff.
95  * Vendors who define additional families must use an encoding in this range.
96  *
97  * \note Values of this type are encoded in the persistent key store.
98  *       Any changes to existing values will require bumping the storage
99  *       format version and providing a translation when reading the old
100  *       format.
101  */
102 typedef uint8_t psa_ecc_family_t;
103 
104 /** The type of PSA Diffie-Hellman group family identifiers.
105  *
106  * Values of this type are generally constructed by macros called
107  * `PSA_DH_FAMILY_xxx`.
108  *
109  * The group identifier is required to create a Diffie-Hellman key using the
110  * PSA_KEY_TYPE_DH_KEY_PAIR() or PSA_KEY_TYPE_DH_PUBLIC_KEY()
111  * macros.
112  *
113  * Values defined by this standard will never be in the range 0x80-0xff.
114  * Vendors who define additional families must use an encoding in this range.
115  *
116  * \note Values of this type are encoded in the persistent key store.
117  *       Any changes to existing values will require bumping the storage
118  *       format version and providing a translation when reading the old
119  *       format.
120  */
121 typedef uint8_t psa_dh_family_t;
122 
123 /** \brief Encoding of a cryptographic algorithm.
124  *
125  * Values of this type are generally constructed by macros called
126  * `PSA_ALG_xxx`.
127  *
128  * For algorithms that can be applied to multiple key types, this type
129  * does not encode the key type. For example, for symmetric ciphers
130  * based on a block cipher, #psa_algorithm_t encodes the block cipher
131  * mode and the padding mode while the block cipher itself is encoded
132  * via #psa_key_type_t.
133  *
134  * \note Values of this type are encoded in the persistent key store.
135  *       Any changes to existing values will require bumping the storage
136  *       format version and providing a translation when reading the old
137  *       format.
138  */
139 typedef uint32_t psa_algorithm_t;
140 
141 /**@}*/
142 
143 /** \defgroup key_lifetimes Key lifetimes
144  * @{
145  */
146 
147 /** Encoding of key lifetimes.
148  *
149  * The lifetime of a key indicates where it is stored and what system actions
150  * may create and destroy it.
151  *
152  * Lifetime values have the following structure:
153  * - Bits 0-7 (#PSA_KEY_LIFETIME_GET_PERSISTENCE(\c lifetime)):
154  *   persistence level. This value indicates what device management
155  *   actions can cause it to be destroyed. In particular, it indicates
156  *   whether the key is _volatile_ or _persistent_.
157  *   See ::psa_key_persistence_t for more information.
158  * - Bits 8-31 (#PSA_KEY_LIFETIME_GET_LOCATION(\c lifetime)):
159  *   location indicator. This value indicates which part of the system
160  *   has access to the key material and can perform operations using the key.
161  *   See ::psa_key_location_t for more information.
162  *
163  * Volatile keys are automatically destroyed when the application instance
164  * terminates or on a power reset of the device. Persistent keys are
165  * preserved until the application explicitly destroys them or until an
166  * integration-specific device management event occurs (for example,
167  * a factory reset).
168  *
169  * Persistent keys have a key identifier of type #mbedtls_svc_key_id_t.
170  * This identifier remains valid throughout the lifetime of the key,
171  * even if the application instance that created the key terminates.
172  * The application can call psa_open_key() to open a persistent key that
173  * it created previously.
174  *
175  * The default lifetime of a key is #PSA_KEY_LIFETIME_VOLATILE. The lifetime
176  * #PSA_KEY_LIFETIME_PERSISTENT is supported if persistent storage is
177  * available. Other lifetime values may be supported depending on the
178  * library configuration.
179  *
180  * Values of this type are generally constructed by macros called
181  * `PSA_KEY_LIFETIME_xxx`.
182  *
183  * \note Values of this type are encoded in the persistent key store.
184  *       Any changes to existing values will require bumping the storage
185  *       format version and providing a translation when reading the old
186  *       format.
187  */
188 typedef uint32_t psa_key_lifetime_t;
189 
190 /** Encoding of key persistence levels.
191  *
192  * What distinguishes different persistence levels is what device management
193  * events may cause keys to be destroyed. _Volatile_ keys are destroyed
194  * by a power reset. Persistent keys may be destroyed by events such as
195  * a transfer of ownership or a factory reset. What management events
196  * actually affect persistent keys at different levels is outside the
197  * scope of the PSA Cryptography specification.
198  *
199  * The PSA Cryptography specification defines the following values of
200  * persistence levels:
201  * - \c 0 = #PSA_KEY_PERSISTENCE_VOLATILE: volatile key.
202  *   A volatile key is automatically destroyed by the implementation when
203  *   the application instance terminates. In particular, a volatile key
204  *   is automatically destroyed on a power reset of the device.
205  * - \c 1 = #PSA_KEY_PERSISTENCE_DEFAULT:
206  *   persistent key with a default lifetime.
207  * - \c 2-254: currently not supported by Mbed TLS.
208  * - \c 255 = #PSA_KEY_PERSISTENCE_READ_ONLY:
209  *   read-only or write-once key.
210  *   A key with this persistence level cannot be destroyed.
211  *   Mbed TLS does not currently offer a way to create such keys, but
212  *   integrations of Mbed TLS can use it for built-in keys that the
213  *   application cannot modify (for example, a hardware unique key (HUK)).
214  *
215  * \note Key persistence levels are 8-bit values. Key management
216  *       interfaces operate on lifetimes (type ::psa_key_lifetime_t) which
217  *       encode the persistence as the lower 8 bits of a 32-bit value.
218  *
219  * \note Values of this type are encoded in the persistent key store.
220  *       Any changes to existing values will require bumping the storage
221  *       format version and providing a translation when reading the old
222  *       format.
223  */
224 typedef uint8_t psa_key_persistence_t;
225 
226 /** Encoding of key location indicators.
227  *
228  * If an integration of Mbed TLS can make calls to external
229  * cryptoprocessors such as secure elements, the location of a key
230  * indicates which secure element performs the operations on the key.
231  * Depending on the design of the secure element, the key
232  * material may be stored either in the secure element, or
233  * in wrapped (encrypted) form alongside the key metadata in the
234  * primary local storage.
235  *
236  * The PSA Cryptography API specification defines the following values of
237  * location indicators:
238  * - \c 0: primary local storage.
239  *   This location is always available.
240  *   The primary local storage is typically the same storage area that
241  *   contains the key metadata.
242  * - \c 1: primary secure element.
243  *   Integrations of Mbed TLS should support this value if there is a secure
244  *   element attached to the operating environment.
245  *   As a guideline, secure elements may provide higher resistance against
246  *   side channel and physical attacks than the primary local storage, but may
247  *   have restrictions on supported key types, sizes, policies and operations
248  *   and may have different performance characteristics.
249  * - \c 2-0x7fffff: other locations defined by a PSA specification.
250  *   The PSA Cryptography API does not currently assign any meaning to these
251  *   locations, but future versions of that specification or other PSA
252  *   specifications may do so.
253  * - \c 0x800000-0xffffff: vendor-defined locations.
254  *   No PSA specification will assign a meaning to locations in this range.
255  *
256  * \note Key location indicators are 24-bit values. Key management
257  *       interfaces operate on lifetimes (type ::psa_key_lifetime_t) which
258  *       encode the location as the upper 24 bits of a 32-bit value.
259  *
260  * \note Values of this type are encoded in the persistent key store.
261  *       Any changes to existing values will require bumping the storage
262  *       format version and providing a translation when reading the old
263  *       format.
264  */
265 typedef uint32_t psa_key_location_t;
266 
267 /** Encoding of identifiers of persistent keys.
268  *
269  * - Applications may freely choose key identifiers in the range
270  *   #PSA_KEY_ID_USER_MIN to #PSA_KEY_ID_USER_MAX.
271  * - The implementation may define additional key identifiers in the range
272  *   #PSA_KEY_ID_VENDOR_MIN to #PSA_KEY_ID_VENDOR_MAX.
273  * - 0 is reserved as an invalid key identifier.
274  * - Key identifiers outside these ranges are reserved for future use.
275  *
276  * \note Values of this type are encoded in the persistent key store.
277  *       Any changes to how values are allocated must require careful
278  *       consideration to allow backward compatibility.
279  */
280 typedef uint32_t psa_key_id_t;
281 
282 /** Encoding of key identifiers as seen inside the PSA Crypto implementation.
283  *
284  * When PSA Crypto is built as a library inside an application, this type
285  * is identical to #psa_key_id_t. When PSA Crypto is built as a service
286  * that can store keys on behalf of multiple clients, this type
287  * encodes the #psa_key_id_t value seen by each client application as
288  * well as extra information that identifies the client that owns
289  * the key.
290  *
291  * \note Values of this type are encoded in the persistent key store.
292  *       Any changes to existing values will require bumping the storage
293  *       format version and providing a translation when reading the old
294  *       format.
295  */
296 #if !defined(MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER)
297 typedef psa_key_id_t mbedtls_svc_key_id_t;
298 
299 #else /* MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER */
300 /* Implementation-specific: The Mbed Cryptography library can be built as
301  * part of a multi-client service that exposes the PSA Cryptography API in each
302  * client and encodes the client identity in the key identifier argument of
303  * functions such as psa_open_key().
304  */
305 typedef struct {
306     psa_key_id_t MBEDTLS_PRIVATE(key_id);
307     mbedtls_key_owner_id_t MBEDTLS_PRIVATE(owner);
308 } mbedtls_svc_key_id_t;
309 
310 #endif /* !MBEDTLS_PSA_CRYPTO_KEY_ID_ENCODES_OWNER */
311 
312 /**@}*/
313 
314 /** \defgroup policy Key policies
315  * @{
316  */
317 
318 /** \brief Encoding of permitted usage on a key.
319  *
320  * Values of this type are generally constructed as bitwise-ors of macros
321  * called `PSA_KEY_USAGE_xxx`.
322  *
323  * \note Values of this type are encoded in the persistent key store.
324  *       Any changes to existing values will require bumping the storage
325  *       format version and providing a translation when reading the old
326  *       format.
327  */
328 typedef uint32_t psa_key_usage_t;
329 
330 /**@}*/
331 
332 /** \defgroup attributes Key attributes
333  * @{
334  */
335 
336 /** The type of a structure containing key attributes.
337  *
338  * This is an opaque structure that can represent the metadata of a key
339  * object. Metadata that can be stored in attributes includes:
340  * - The location of the key in storage, indicated by its key identifier
341  *   and its lifetime.
342  * - The key's policy, comprising usage flags and a specification of
343  *   the permitted algorithm(s).
344  * - Information about the key itself: the key type and its size.
345  * - Additional implementation-defined attributes.
346  *
347  * The actual key material is not considered an attribute of a key.
348  * Key attributes do not contain information that is generally considered
349  * highly confidential.
350  *
351  * An attribute structure works like a simple data structure where each function
352  * `psa_set_key_xxx` sets a field and the corresponding function
353  * `psa_get_key_xxx` retrieves the value of the corresponding field.
354  * However, a future version of the library  may report values that are
355  * equivalent to the original one, but have a different encoding. Invalid
356  * values may be mapped to different, also invalid values.
357  *
358  * An attribute structure may contain references to auxiliary resources,
359  * for example pointers to allocated memory or indirect references to
360  * pre-calculated values. In order to free such resources, the application
361  * must call psa_reset_key_attributes(). As an exception, calling
362  * psa_reset_key_attributes() on an attribute structure is optional if
363  * the structure has only been modified by the following functions
364  * since it was initialized or last reset with psa_reset_key_attributes():
365  * - psa_set_key_id()
366  * - psa_set_key_lifetime()
367  * - psa_set_key_type()
368  * - psa_set_key_bits()
369  * - psa_set_key_usage_flags()
370  * - psa_set_key_algorithm()
371  *
372  * Before calling any function on a key attribute structure, the application
373  * must initialize it by any of the following means:
374  * - Set the structure to all-bits-zero, for example:
375  *   \code
376  *   psa_key_attributes_t attributes;
377  *   memset(&attributes, 0, sizeof(attributes));
378  *   \endcode
379  * - Initialize the structure to logical zero values, for example:
380  *   \code
381  *   psa_key_attributes_t attributes = {0};
382  *   \endcode
383  * - Initialize the structure to the initializer #PSA_KEY_ATTRIBUTES_INIT,
384  *   for example:
385  *   \code
386  *   psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
387  *   \endcode
388  * - Assign the result of the function psa_key_attributes_init()
389  *   to the structure, for example:
390  *   \code
391  *   psa_key_attributes_t attributes;
392  *   attributes = psa_key_attributes_init();
393  *   \endcode
394  *
395  * A freshly initialized attribute structure contains the following
396  * values:
397  *
398  * - lifetime: #PSA_KEY_LIFETIME_VOLATILE.
399  * - key identifier: 0 (which is not a valid key identifier).
400  * - type: \c 0 (meaning that the type is unspecified).
401  * - key size: \c 0 (meaning that the size is unspecified).
402  * - usage flags: \c 0 (which allows no usage except exporting a public key).
403  * - algorithm: \c 0 (which allows no cryptographic usage, but allows
404  *   exporting).
405  *
406  * A typical sequence to create a key is as follows:
407  * -# Create and initialize an attribute structure.
408  * -# If the key is persistent, call psa_set_key_id().
409  *    Also call psa_set_key_lifetime() to place the key in a non-default
410  *    location.
411  * -# Set the key policy with psa_set_key_usage_flags() and
412  *    psa_set_key_algorithm().
413  * -# Set the key type with psa_set_key_type().
414  *    Skip this step if copying an existing key with psa_copy_key().
415  * -# When generating a random key with psa_generate_key() or deriving a key
416  *    with psa_key_derivation_output_key(), set the desired key size with
417  *    psa_set_key_bits().
418  * -# Call a key creation function: psa_import_key(), psa_generate_key(),
419  *    psa_key_derivation_output_key() or psa_copy_key(). This function reads
420  *    the attribute structure, creates a key with these attributes, and
421  *    outputs a key identifier to the newly created key.
422  * -# The attribute structure is now no longer necessary.
423  *    You may call psa_reset_key_attributes(), although this is optional
424  *    with the workflow presented here because the attributes currently
425  *    defined in this specification do not require any additional resources
426  *    beyond the structure itself.
427  *
428  * A typical sequence to query a key's attributes is as follows:
429  * -# Call psa_get_key_attributes().
430  * -# Call `psa_get_key_xxx` functions to retrieve the attribute(s) that
431  *    you are interested in.
432  * -# Call psa_reset_key_attributes() to free any resources that may be
433  *    used by the attribute structure.
434  *
435  * Once a key has been created, it is impossible to change its attributes.
436  */
437 typedef struct psa_key_attributes_s psa_key_attributes_t;
438 
439 
440 #ifndef __DOXYGEN_ONLY__
441 #if defined(MBEDTLS_PSA_CRYPTO_SE_C)
442 /* Mbed Crypto defines this type in crypto_types.h because it is also
443  * visible to applications through an implementation-specific extension.
444  * For the PSA Cryptography specification, this type is only visible
445  * via crypto_se_driver.h. */
446 typedef uint64_t psa_key_slot_number_t;
447 #endif /* MBEDTLS_PSA_CRYPTO_SE_C */
448 #endif /* !__DOXYGEN_ONLY__ */
449 
450 /**@}*/
451 
452 /** \defgroup derivation Key derivation
453  * @{
454  */
455 
456 /** \brief Encoding of the step of a key derivation.
457  *
458  * Values of this type are generally constructed by macros called
459  * `PSA_KEY_DERIVATION_INPUT_xxx`.
460  */
461 typedef uint16_t psa_key_derivation_step_t;
462 
463 /**@}*/
464 
465 #endif /* PSA_CRYPTO_TYPES_H */
466