cbf6a1d651
It adds a bit a code for not much but that way we are such that a count overflow cannot occur. Signed-off-by: Ronald Cron <ronald.cron@arm.com>
233 lines
8.2 KiB
C
233 lines
8.2 KiB
C
/*
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* PSA crypto layer on top of Mbed TLS crypto
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*/
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/*
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* Copyright The Mbed TLS Contributors
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* SPDX-License-Identifier: Apache-2.0
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*
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* Licensed under the Apache License, Version 2.0 (the "License"); you may
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* not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef PSA_CRYPTO_SLOT_MANAGEMENT_H
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#define PSA_CRYPTO_SLOT_MANAGEMENT_H
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#include "psa/crypto.h"
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#include "psa_crypto_core.h"
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#include "psa_crypto_se.h"
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/* Number of key slots (plus one because 0 is not used).
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* The value is a compile-time constant for now, for simplicity. */
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#define PSA_KEY_SLOT_COUNT 32
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/** Range of volatile key identifiers.
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*
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* The last PSA_KEY_SLOT_COUNT identifiers of the implementation range
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* of key identifiers are reserved for volatile key identifiers.
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* A volatile key identifier is equal to #PSA_KEY_ID_VOLATILE_MIN plus the
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* index of the key slot containing the volatile key definition.
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*/
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/** The minimum value for a volatile key identifier.
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*/
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#define PSA_KEY_ID_VOLATILE_MIN ( PSA_KEY_ID_VENDOR_MAX - \
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PSA_KEY_SLOT_COUNT + 1 )
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/** The maximum value for a volatile key identifier.
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*/
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#define PSA_KEY_ID_VOLATILE_MAX PSA_KEY_ID_VENDOR_MAX
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/** Test whether a key identifier is a volatile key identifier.
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*
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* \param key_id Key identifier to test.
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*
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* \retval 1
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* The key identifier is a volatile key identifier.
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* \retval 0
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* The key identifier is not a volatile key identifier.
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*/
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static inline int psa_key_id_is_volatile( psa_key_id_t key_id )
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{
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return( ( key_id >= PSA_KEY_ID_VOLATILE_MIN ) &&
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( key_id <= PSA_KEY_ID_VOLATILE_MAX ) );
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}
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/** Retrieve the description of a key given its identifier.
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*
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* The descriptions of volatile keys and loaded persistent keys are
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* stored in key slots. This function returns a pointer to the key slot
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* containing the description of a key given its identifier.
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*
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* In case of a persistent key, the function loads the description of the key
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* into a key slot if not already done.
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*
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* On success, the access counter of the returned key slot is incremented by
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* one. It is the responsibility of the caller to call
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* psa_decrement_key_slot_access_count() when it does not access the slot
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* anymore.
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*
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* \param key Key identifier to query.
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* \param[out] p_slot On success, `*p_slot` contains a pointer to the
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* key slot containing the description of the key
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* identified by \p key.
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*
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* \retval #PSA_SUCCESS
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* The pointer to the key slot containing the description of the key
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* identified by \p key was returned. The key slot counter was
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* implemented.
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* \retval #PSA_ERROR_BAD_STATE
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* The library has not been initialized.
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* \retval #PSA_ERROR_INVALID_HANDLE
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* \p key is not a valid key identifier.
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* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
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* \p key is a persistent key identifier. The implementation does not
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* have sufficient resources to load the persistent key. This can be
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* due to a lack of empty key slot, or available memory.
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* \retval #PSA_ERROR_DOES_NOT_EXIST
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* There is no key with key identifier \p key.
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* \retval #PSA_ERROR_CORRUPTION_DETECTED
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* \retval #PSA_ERROR_STORAGE_FAILURE
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* \retval #PSA_ERROR_DATA_CORRUPT
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*/
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psa_status_t psa_get_key_slot( mbedtls_svc_key_id_t key,
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psa_key_slot_t **p_slot );
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/** Initialize the key slot structures.
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*
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* \retval #PSA_SUCCESS
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* Currently this function always succeeds.
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*/
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psa_status_t psa_initialize_key_slots( void );
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/** Delete all data from key slots in memory.
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*
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* This does not affect persistent storage. */
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void psa_wipe_all_key_slots( void );
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/** Find a free key slot.
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*
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* This function returns a key slot that is available for use and is in its
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* ground state (all-bits-zero). On success, the access counter of the
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* returned key slot is incremented by one. It is the responsibility of the
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* caller to call psa_decrement_key_slot_access_count() when it does not access
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* the key slot anymore.
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*
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* \param[out] volatile_key_id On success, volatile key identifier
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* associated to the returned slot.
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* \param[out] p_slot On success, a pointer to the slot.
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*
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* \retval #PSA_SUCCESS
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* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
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* \retval #PSA_ERROR_BAD_STATE
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*/
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psa_status_t psa_get_empty_key_slot( psa_key_id_t *volatile_key_id,
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psa_key_slot_t **p_slot );
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/** Increment slot access counter.
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*
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* This function increments the slot access counter by one.
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*
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* \param[in] slot The key slot.
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*
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* \retval #PSA_SUCCESS
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The access count was incremented.
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* \retval #PSA_ERROR_CORRUPTION_DETECTED
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* The access count already reached its maximum value and was not
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* increased.
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*/
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static inline psa_status_t psa_increment_key_slot_access_count( psa_key_slot_t *slot )
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{
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if( slot->access_count >= SIZE_MAX )
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return( PSA_ERROR_CORRUPTION_DETECTED );
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slot->access_count++;
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return( PSA_SUCCESS );
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}
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/** Decrement slot access counter.
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*
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* This function decrements the slot access counter by one.
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*
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* \note To ease the handling of errors in retrieving a key slot
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* a NULL input pointer is valid, and the function returns
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* successfully without doing anything in that case.
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*
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* \param[in] slot The key slot.
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* \retval #PSA_SUCCESS
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* \p slot is NULL or the key slot access pointer has been
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* decremented successfully.
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* \retval #PSA_ERROR_CORRUPTION_DETECTED
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* The access counter was equal to 0.
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*
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*/
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psa_status_t psa_decrement_key_slot_access_count( psa_key_slot_t *slot );
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/** Test whether a lifetime designates a key in an external cryptoprocessor.
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*
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* \param lifetime The lifetime to test.
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*
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* \retval 1
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* The lifetime designates an external key. There should be a
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* registered driver for this lifetime, otherwise the key cannot
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* be created or manipulated.
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* \retval 0
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* The lifetime designates a key that is volatile or in internal
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* storage.
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*/
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static inline int psa_key_lifetime_is_external( psa_key_lifetime_t lifetime )
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{
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return( PSA_KEY_LIFETIME_GET_LOCATION( lifetime )
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!= PSA_KEY_LOCATION_LOCAL_STORAGE );
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}
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/** Validate a key's location.
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*
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* This function checks whether the key's attributes point to a location that
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* is known to the PSA Core, and returns the driver function table if the key
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* is to be found in an external location.
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*
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* \param[in] lifetime The key lifetime attribute.
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* \param[out] p_drv On success, when a key is located in external
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* storage, returns a pointer to the driver table
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* associated with the key's storage location.
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*
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* \retval #PSA_SUCCESS
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* \retval #PSA_ERROR_INVALID_ARGUMENT
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*/
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psa_status_t psa_validate_key_location( psa_key_lifetime_t lifetime,
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psa_se_drv_table_entry_t **p_drv );
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/** Validate the persistence of a key.
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*
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* \param[in] lifetime The key lifetime attribute.
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*
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* \retval #PSA_SUCCESS
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* \retval #PSA_ERROR_INVALID_ARGUMENT The key is persistent but persistent
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* keys are not supported.
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*/
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psa_status_t psa_validate_key_persistence( psa_key_lifetime_t lifetime );
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/** Validate a key identifier.
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*
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* \param[in] key The key identifier.
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* \param[in] vendor_ok Non-zero to indicate that key identifiers in the
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* vendor range are allowed, volatile key identifiers
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* excepted \c 0 otherwise.
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*
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* \retval #PSA_SUCCESS The identifier is valid.
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* \retval #PSA_ERROR_INVALID_ARGUMENT The key identifier is not valid.
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*/
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psa_status_t psa_validate_key_id( mbedtls_svc_key_id_t key, int vendor_ok );
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#endif /* PSA_CRYPTO_SLOT_MANAGEMENT_H */
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