1 /*
2  *  PSA crypto layer on top of Mbed TLS crypto
3  */
4 /*
5  *  Copyright The Mbed TLS Contributors
6  *  SPDX-License-Identifier: Apache-2.0
7  *
8  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
9  *  not use this file except in compliance with the License.
10  *  You may obtain a copy of the License at
11  *
12  *  http://www.apache.org/licenses/LICENSE-2.0
13  *
14  *  Unless required by applicable law or agreed to in writing, software
15  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
16  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
17  *  See the License for the specific language governing permissions and
18  *  limitations under the License.
19  */
20 
21 #include "common.h"
22 
23 #if defined(MBEDTLS_PSA_CRYPTO_C)
24 
25 #include "psa/crypto.h"
26 
27 #include "psa_crypto_core.h"
28 #include "psa_crypto_driver_wrappers.h"
29 #include "psa_crypto_slot_management.h"
30 #include "psa_crypto_storage.h"
31 #if defined(MBEDTLS_PSA_CRYPTO_SE_C)
32 #include "psa_crypto_se.h"
33 #endif
34 
35 #include <stdlib.h>
36 #include <string.h>
37 #if defined(MBEDTLS_PLATFORM_C)
38 #include "mbedtls/platform.h"
39 #else
40 #define mbedtls_calloc calloc
41 #define mbedtls_free   free
42 #endif
43 
44 #define ARRAY_LENGTH( array ) ( sizeof( array ) / sizeof( *( array ) ) )
45 
46 typedef struct
47 {
48     psa_key_slot_t key_slots[MBEDTLS_PSA_KEY_SLOT_COUNT];
49     unsigned key_slots_initialized : 1;
50 } psa_global_data_t;
51 
52 static psa_global_data_t global_data;
53 
psa_is_valid_key_id(mbedtls_svc_key_id_t key,int vendor_ok)54 int psa_is_valid_key_id( mbedtls_svc_key_id_t key, int vendor_ok )
55 {
56     psa_key_id_t key_id = MBEDTLS_SVC_KEY_ID_GET_KEY_ID( key );
57 
58     if( ( PSA_KEY_ID_USER_MIN <= key_id ) &&
59         ( key_id <= PSA_KEY_ID_USER_MAX ) )
60         return( 1 );
61 
62     if( vendor_ok &&
63         ( PSA_KEY_ID_VENDOR_MIN <= key_id ) &&
64         ( key_id <= PSA_KEY_ID_VENDOR_MAX ) )
65         return( 1 );
66 
67     return( 0 );
68 }
69 
70 /** Get the description in memory of a key given its identifier and lock it.
71  *
72  * The descriptions of volatile keys and loaded persistent keys are
73  * stored in key slots. This function returns a pointer to the key slot
74  * containing the description of a key given its identifier.
75  *
76  * The function searches the key slots containing the description of the key
77  * with \p key identifier. The function does only read accesses to the key
78  * slots. The function does not load any persistent key thus does not access
79  * any storage.
80  *
81  * For volatile key identifiers, only one key slot is queried as a volatile
82  * key with identifier key_id can only be stored in slot of index
83  * ( key_id - #PSA_KEY_ID_VOLATILE_MIN ).
84  *
85  * On success, the function locks the key slot. It is the responsibility of
86  * the caller to unlock the key slot when it does not access it anymore.
87  *
88  * \param key           Key identifier to query.
89  * \param[out] p_slot   On success, `*p_slot` contains a pointer to the
90  *                      key slot containing the description of the key
91  *                      identified by \p key.
92  *
93  * \retval #PSA_SUCCESS
94  *         The pointer to the key slot containing the description of the key
95  *         identified by \p key was returned.
96  * \retval #PSA_ERROR_INVALID_HANDLE
97  *         \p key is not a valid key identifier.
98  * \retval #PSA_ERROR_DOES_NOT_EXIST
99  *         There is no key with key identifier \p key in the key slots.
100  */
psa_get_and_lock_key_slot_in_memory(mbedtls_svc_key_id_t key,psa_key_slot_t ** p_slot)101 static psa_status_t psa_get_and_lock_key_slot_in_memory(
102     mbedtls_svc_key_id_t key, psa_key_slot_t **p_slot )
103 {
104     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
105     psa_key_id_t key_id = MBEDTLS_SVC_KEY_ID_GET_KEY_ID( key );
106     size_t slot_idx;
107     psa_key_slot_t *slot = NULL;
108 
109     if( psa_key_id_is_volatile( key_id ) )
110     {
111         slot = &global_data.key_slots[ key_id - PSA_KEY_ID_VOLATILE_MIN ];
112 
113         /*
114          * Check if both the PSA key identifier key_id and the owner
115          * identifier of key match those of the key slot.
116          *
117          * Note that, if the key slot is not occupied, its PSA key identifier
118          * is equal to zero. This is an invalid value for a PSA key identifier
119          * and thus cannot be equal to the valid PSA key identifier key_id.
120          */
121         status = mbedtls_svc_key_id_equal( key, slot->attr.id ) ?
122                  PSA_SUCCESS : PSA_ERROR_DOES_NOT_EXIST;
123     }
124     else
125     {
126         if ( !psa_is_valid_key_id( key, 1 ) )
127             return( PSA_ERROR_INVALID_HANDLE );
128 
129         for( slot_idx = 0; slot_idx < MBEDTLS_PSA_KEY_SLOT_COUNT; slot_idx++ )
130         {
131             slot = &global_data.key_slots[ slot_idx ];
132             if( mbedtls_svc_key_id_equal( key, slot->attr.id ) )
133                 break;
134         }
135         status = ( slot_idx < MBEDTLS_PSA_KEY_SLOT_COUNT ) ?
136                  PSA_SUCCESS : PSA_ERROR_DOES_NOT_EXIST;
137     }
138 
139     if( status == PSA_SUCCESS )
140     {
141         status = psa_lock_key_slot( slot );
142         if( status == PSA_SUCCESS )
143             *p_slot = slot;
144     }
145 
146     return( status );
147 }
148 
psa_initialize_key_slots(void)149 psa_status_t psa_initialize_key_slots( void )
150 {
151     /* Nothing to do: program startup and psa_wipe_all_key_slots() both
152      * guarantee that the key slots are initialized to all-zero, which
153      * means that all the key slots are in a valid, empty state. */
154     global_data.key_slots_initialized = 1;
155     return( PSA_SUCCESS );
156 }
157 
psa_wipe_all_key_slots(void)158 void psa_wipe_all_key_slots( void )
159 {
160     size_t slot_idx;
161 
162     for( slot_idx = 0; slot_idx < MBEDTLS_PSA_KEY_SLOT_COUNT; slot_idx++ )
163     {
164         psa_key_slot_t *slot = &global_data.key_slots[ slot_idx ];
165         slot->lock_count = 1;
166         (void) psa_wipe_key_slot( slot );
167     }
168     global_data.key_slots_initialized = 0;
169 }
170 
psa_get_empty_key_slot(psa_key_id_t * volatile_key_id,psa_key_slot_t ** p_slot)171 psa_status_t psa_get_empty_key_slot( psa_key_id_t *volatile_key_id,
172                                      psa_key_slot_t **p_slot )
173 {
174     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
175     size_t slot_idx;
176     psa_key_slot_t *selected_slot, *unlocked_persistent_key_slot;
177 
178     if( ! global_data.key_slots_initialized )
179     {
180         status = PSA_ERROR_BAD_STATE;
181         goto error;
182     }
183 
184     selected_slot = unlocked_persistent_key_slot = NULL;
185     for( slot_idx = 0; slot_idx < MBEDTLS_PSA_KEY_SLOT_COUNT; slot_idx++ )
186     {
187         psa_key_slot_t *slot = &global_data.key_slots[ slot_idx ];
188         if( ! psa_is_key_slot_occupied( slot ) )
189         {
190             selected_slot = slot;
191             break;
192         }
193 
194         if( ( unlocked_persistent_key_slot == NULL ) &&
195             ( ! PSA_KEY_LIFETIME_IS_VOLATILE( slot->attr.lifetime ) ) &&
196             ( ! psa_is_key_slot_locked( slot ) ) )
197             unlocked_persistent_key_slot = slot;
198     }
199 
200     /*
201      * If there is no unused key slot and there is at least one unlocked key
202      * slot containing the description of a persistent key, recycle the first
203      * such key slot we encountered. If we later need to operate on the
204      * persistent key we are evicting now, we will reload its description from
205      * storage.
206      */
207     if( ( selected_slot == NULL ) &&
208         ( unlocked_persistent_key_slot != NULL ) )
209     {
210         selected_slot = unlocked_persistent_key_slot;
211         selected_slot->lock_count = 1;
212         psa_wipe_key_slot( selected_slot );
213     }
214 
215     if( selected_slot != NULL )
216     {
217        status = psa_lock_key_slot( selected_slot );
218        if( status != PSA_SUCCESS )
219            goto error;
220 
221         *volatile_key_id = PSA_KEY_ID_VOLATILE_MIN +
222             ( (psa_key_id_t)( selected_slot - global_data.key_slots ) );
223         *p_slot = selected_slot;
224 
225         return( PSA_SUCCESS );
226     }
227     status = PSA_ERROR_INSUFFICIENT_MEMORY;
228 
229 error:
230     *p_slot = NULL;
231     *volatile_key_id = 0;
232 
233     return( status );
234 }
235 
236 #if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
psa_load_persistent_key_into_slot(psa_key_slot_t * slot)237 static psa_status_t psa_load_persistent_key_into_slot( psa_key_slot_t *slot )
238 {
239     psa_status_t status = PSA_SUCCESS;
240     uint8_t *key_data = NULL;
241     size_t key_data_length = 0;
242 
243     status = psa_load_persistent_key( &slot->attr,
244                                       &key_data, &key_data_length );
245     if( status != PSA_SUCCESS )
246         goto exit;
247 
248 #if defined(MBEDTLS_PSA_CRYPTO_SE_C)
249     /* Special handling is required for loading keys associated with a
250      * dynamically registered SE interface. */
251     const psa_drv_se_t *drv;
252     psa_drv_se_context_t *drv_context;
253     if( psa_get_se_driver( slot->attr.lifetime, &drv, &drv_context ) )
254     {
255         psa_se_key_data_storage_t *data;
256 
257         if( key_data_length != sizeof( *data ) )
258         {
259             status = PSA_ERROR_DATA_INVALID;
260             goto exit;
261         }
262         data = (psa_se_key_data_storage_t *) key_data;
263         status = psa_copy_key_material_into_slot(
264                      slot, data->slot_number, sizeof( data->slot_number ) );
265         goto exit;
266     }
267 #endif /* MBEDTLS_PSA_CRYPTO_SE_C */
268 
269     status = psa_copy_key_material_into_slot( slot, key_data, key_data_length );
270 
271 exit:
272     psa_free_persistent_key_data( key_data, key_data_length );
273     return( status );
274 }
275 #endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C */
276 
277 #if defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
278 
psa_load_builtin_key_into_slot(psa_key_slot_t * slot)279 static psa_status_t psa_load_builtin_key_into_slot( psa_key_slot_t *slot )
280 {
281     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
282     psa_key_attributes_t attributes = PSA_KEY_ATTRIBUTES_INIT;
283     psa_key_lifetime_t lifetime = PSA_KEY_LIFETIME_VOLATILE;
284     psa_drv_slot_number_t slot_number = 0;
285     size_t key_buffer_size = 0;
286     size_t key_buffer_length = 0;
287 
288     if( ! psa_key_id_is_builtin(
289             MBEDTLS_SVC_KEY_ID_GET_KEY_ID( slot->attr.id ) ) )
290     {
291         return( PSA_ERROR_DOES_NOT_EXIST );
292     }
293 
294     /* Check the platform function to see whether this key actually exists */
295     status = mbedtls_psa_platform_get_builtin_key(
296                 slot->attr.id, &lifetime, &slot_number );
297     if( status != PSA_SUCCESS )
298         return( status );
299 
300     /* Set required key attributes to ensure get_builtin_key can retrieve the
301      * full attributes. */
302     psa_set_key_id( &attributes, slot->attr.id );
303     psa_set_key_lifetime( &attributes, lifetime );
304 
305     /* Get the full key attributes from the driver in order to be able to
306      * calculate the required buffer size. */
307     status = psa_driver_wrapper_get_builtin_key(
308                 slot_number, &attributes,
309                 NULL, 0, NULL );
310     if( status != PSA_ERROR_BUFFER_TOO_SMALL )
311     {
312         /* Builtin keys cannot be defined by the attributes alone */
313         if( status == PSA_SUCCESS )
314             status = PSA_ERROR_CORRUPTION_DETECTED;
315         return( status );
316     }
317 
318     /* If the key should exist according to the platform, then ask the driver
319      * what its expected size is. */
320     status = psa_driver_wrapper_get_key_buffer_size( &attributes,
321                                                      &key_buffer_size );
322     if( status != PSA_SUCCESS )
323         return( status );
324 
325     /* Allocate a buffer of the required size and load the builtin key directly
326      * into the (now properly sized) slot buffer. */
327     status = psa_allocate_buffer_to_slot( slot, key_buffer_size );
328     if( status != PSA_SUCCESS )
329         return( status );
330 
331     status = psa_driver_wrapper_get_builtin_key(
332                 slot_number, &attributes,
333                 slot->key.data, slot->key.bytes, &key_buffer_length );
334     if( status != PSA_SUCCESS )
335         goto exit;
336 
337     /* Copy actual key length and core attributes into the slot on success */
338     slot->key.bytes = key_buffer_length;
339     slot->attr = attributes.core;
340 
341 exit:
342     if( status != PSA_SUCCESS )
343         psa_remove_key_data_from_memory( slot );
344     return( status );
345 }
346 #endif /* MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
347 
psa_get_and_lock_key_slot(mbedtls_svc_key_id_t key,psa_key_slot_t ** p_slot)348 psa_status_t psa_get_and_lock_key_slot( mbedtls_svc_key_id_t key,
349                                         psa_key_slot_t **p_slot )
350 {
351     psa_status_t status = PSA_ERROR_CORRUPTION_DETECTED;
352 
353     *p_slot = NULL;
354     if( ! global_data.key_slots_initialized )
355         return( PSA_ERROR_BAD_STATE );
356 
357     /*
358      * On success, the pointer to the slot is passed directly to the caller
359      * thus no need to unlock the key slot here.
360      */
361     status = psa_get_and_lock_key_slot_in_memory( key, p_slot );
362     if( status != PSA_ERROR_DOES_NOT_EXIST )
363         return( status );
364 
365     /* Loading keys from storage requires support for such a mechanism */
366 #if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) || \
367     defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
368     psa_key_id_t volatile_key_id;
369 
370     status = psa_get_empty_key_slot( &volatile_key_id, p_slot );
371     if( status != PSA_SUCCESS )
372         return( status );
373 
374     (*p_slot)->attr.id = key;
375     (*p_slot)->attr.lifetime = PSA_KEY_LIFETIME_PERSISTENT;
376 
377     status = PSA_ERROR_DOES_NOT_EXIST;
378 #if defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
379     /* Load keys in the 'builtin' range through their own interface */
380     status = psa_load_builtin_key_into_slot( *p_slot );
381 #endif /* MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
382 
383 #if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
384     if( status == PSA_ERROR_DOES_NOT_EXIST )
385         status = psa_load_persistent_key_into_slot( *p_slot );
386 #endif /* defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) */
387 
388     if( status != PSA_SUCCESS )
389     {
390         psa_wipe_key_slot( *p_slot );
391         if( status == PSA_ERROR_DOES_NOT_EXIST )
392             status = PSA_ERROR_INVALID_HANDLE;
393     }
394     else
395         /* Add implicit usage flags. */
396         psa_extend_key_usage_flags( &(*p_slot)->attr.policy.usage );
397 
398     return( status );
399 #else /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
400     return( PSA_ERROR_INVALID_HANDLE );
401 #endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
402 }
403 
psa_unlock_key_slot(psa_key_slot_t * slot)404 psa_status_t psa_unlock_key_slot( psa_key_slot_t *slot )
405 {
406     if( slot == NULL )
407         return( PSA_SUCCESS );
408 
409     if( slot->lock_count > 0 )
410     {
411         slot->lock_count--;
412         return( PSA_SUCCESS );
413     }
414 
415    /*
416     * As the return error code may not be handled in case of multiple errors,
417     * do our best to report if the lock counter is equal to zero. Assert with
418     * MBEDTLS_TEST_HOOK_TEST_ASSERT that the lock counter is strictly greater
419     * than zero: if the MBEDTLS_TEST_HOOKS configuration option is enabled and
420     * the function is called as part of the execution of a test suite, the
421     * execution of the test suite is stopped in error if the assertion fails.
422     */
423     MBEDTLS_TEST_HOOK_TEST_ASSERT( slot->lock_count > 0 );
424     return( PSA_ERROR_CORRUPTION_DETECTED );
425 }
426 
psa_validate_key_location(psa_key_lifetime_t lifetime,psa_se_drv_table_entry_t ** p_drv)427 psa_status_t psa_validate_key_location( psa_key_lifetime_t lifetime,
428                                         psa_se_drv_table_entry_t **p_drv )
429 {
430     if ( psa_key_lifetime_is_external( lifetime ) )
431     {
432 #if defined(MBEDTLS_PSA_CRYPTO_SE_C)
433         /* Check whether a driver is registered against this lifetime */
434         psa_se_drv_table_entry_t *driver = psa_get_se_driver_entry( lifetime );
435         if( driver != NULL )
436         {
437             if (p_drv != NULL)
438                 *p_drv = driver;
439             return( PSA_SUCCESS );
440         }
441 #else /* MBEDTLS_PSA_CRYPTO_SE_C */
442         (void) p_drv;
443 #endif /* MBEDTLS_PSA_CRYPTO_SE_C */
444 
445 #if defined(MBEDTLS_PSA_CRYPTO_DRIVERS)
446         /* Key location for external keys gets checked by the wrapper */
447         return( PSA_SUCCESS );
448 #else /* MBEDTLS_PSA_CRYPTO_DRIVERS */
449         /* No support for external lifetimes at all, or dynamic interface
450          * did not find driver for requested lifetime. */
451         return( PSA_ERROR_INVALID_ARGUMENT );
452 #endif /* MBEDTLS_PSA_CRYPTO_DRIVERS */
453     }
454     else
455         /* Local/internal keys are always valid */
456         return( PSA_SUCCESS );
457 }
458 
psa_validate_key_persistence(psa_key_lifetime_t lifetime)459 psa_status_t psa_validate_key_persistence( psa_key_lifetime_t lifetime )
460 {
461     if ( PSA_KEY_LIFETIME_IS_VOLATILE( lifetime ) )
462     {
463         /* Volatile keys are always supported */
464         return( PSA_SUCCESS );
465     }
466     else
467     {
468         /* Persistent keys require storage support */
469 #if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C)
470         if( PSA_KEY_LIFETIME_IS_READ_ONLY( lifetime ) )
471             return( PSA_ERROR_INVALID_ARGUMENT );
472         else
473             return( PSA_SUCCESS );
474 #else /* MBEDTLS_PSA_CRYPTO_STORAGE_C */
475         return( PSA_ERROR_NOT_SUPPORTED );
476 #endif /* !MBEDTLS_PSA_CRYPTO_STORAGE_C */
477     }
478 }
479 
psa_open_key(mbedtls_svc_key_id_t key,psa_key_handle_t * handle)480 psa_status_t psa_open_key( mbedtls_svc_key_id_t key, psa_key_handle_t *handle )
481 {
482 #if defined(MBEDTLS_PSA_CRYPTO_STORAGE_C) || \
483     defined(MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS)
484     psa_status_t status;
485     psa_key_slot_t *slot;
486 
487     status = psa_get_and_lock_key_slot( key, &slot );
488     if( status != PSA_SUCCESS )
489     {
490         *handle = PSA_KEY_HANDLE_INIT;
491         if( status == PSA_ERROR_INVALID_HANDLE )
492             status = PSA_ERROR_DOES_NOT_EXIST;
493 
494         return( status );
495     }
496 
497     *handle = key;
498 
499     return( psa_unlock_key_slot( slot ) );
500 
501 #else /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
502     (void) key;
503     *handle = PSA_KEY_HANDLE_INIT;
504     return( PSA_ERROR_NOT_SUPPORTED );
505 #endif /* MBEDTLS_PSA_CRYPTO_STORAGE_C || MBEDTLS_PSA_CRYPTO_BUILTIN_KEYS */
506 }
507 
psa_close_key(psa_key_handle_t handle)508 psa_status_t psa_close_key( psa_key_handle_t handle )
509 {
510     psa_status_t status;
511     psa_key_slot_t *slot;
512 
513     if( psa_key_handle_is_null( handle ) )
514         return( PSA_SUCCESS );
515 
516     status = psa_get_and_lock_key_slot_in_memory( handle, &slot );
517     if( status != PSA_SUCCESS )
518     {
519         if( status == PSA_ERROR_DOES_NOT_EXIST )
520             status = PSA_ERROR_INVALID_HANDLE;
521 
522         return( status );
523     }
524     if( slot->lock_count <= 1 )
525         return( psa_wipe_key_slot( slot ) );
526     else
527         return( psa_unlock_key_slot( slot ) );
528 }
529 
psa_purge_key(mbedtls_svc_key_id_t key)530 psa_status_t psa_purge_key( mbedtls_svc_key_id_t key )
531 {
532     psa_status_t status;
533     psa_key_slot_t *slot;
534 
535     status = psa_get_and_lock_key_slot_in_memory( key, &slot );
536     if( status != PSA_SUCCESS )
537         return( status );
538 
539     if( ( ! PSA_KEY_LIFETIME_IS_VOLATILE( slot->attr.lifetime ) ) &&
540         ( slot->lock_count <= 1 ) )
541         return( psa_wipe_key_slot( slot ) );
542     else
543         return( psa_unlock_key_slot( slot ) );
544 }
545 
mbedtls_psa_get_stats(mbedtls_psa_stats_t * stats)546 void mbedtls_psa_get_stats( mbedtls_psa_stats_t *stats )
547 {
548     size_t slot_idx;
549 
550     memset( stats, 0, sizeof( *stats ) );
551 
552     for( slot_idx = 0; slot_idx < MBEDTLS_PSA_KEY_SLOT_COUNT; slot_idx++ )
553     {
554         const psa_key_slot_t *slot = &global_data.key_slots[ slot_idx ];
555         if( psa_is_key_slot_locked( slot ) )
556         {
557             ++stats->locked_slots;
558         }
559         if( ! psa_is_key_slot_occupied( slot ) )
560         {
561             ++stats->empty_slots;
562             continue;
563         }
564         if( PSA_KEY_LIFETIME_IS_VOLATILE( slot->attr.lifetime ) )
565             ++stats->volatile_slots;
566         else
567         {
568             psa_key_id_t id = MBEDTLS_SVC_KEY_ID_GET_KEY_ID( slot->attr.id );
569             ++stats->persistent_slots;
570             if( id > stats->max_open_internal_key_id )
571                 stats->max_open_internal_key_id = id;
572         }
573         if( PSA_KEY_LIFETIME_GET_LOCATION( slot->attr.lifetime ) !=
574             PSA_KEY_LOCATION_LOCAL_STORAGE )
575         {
576             psa_key_id_t id = MBEDTLS_SVC_KEY_ID_GET_KEY_ID( slot->attr.id );
577             ++stats->external_slots;
578             if( id > stats->max_open_external_key_id )
579                 stats->max_open_external_key_id = id;
580         }
581     }
582 }
583 
584 #endif /* MBEDTLS_PSA_CRYPTO_C */
585