394 lines
15 KiB
C
394 lines
15 KiB
C
/**
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* \file psa_crypto_storage.h
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*
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* \brief PSA cryptography module: Mbed TLS key storage
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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_STORAGE_H
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#define PSA_CRYPTO_STORAGE_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include "psa/crypto.h"
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#include "psa/crypto_se_driver.h"
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#include <stdint.h>
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#include <string.h>
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/* Limit the maximum key size in storage. This should have no effect
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* since the key size is limited in memory. */
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#define PSA_CRYPTO_MAX_STORAGE_SIZE ( PSA_BITS_TO_BYTES( PSA_MAX_KEY_BITS ) )
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/* Sanity check: a file size must fit in 32 bits. Allow a generous
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* 64kB of metadata. */
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#if PSA_CRYPTO_MAX_STORAGE_SIZE > 0xffff0000
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#error PSA_CRYPTO_MAX_STORAGE_SIZE > 0xffff0000
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#endif
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/** The maximum permitted persistent slot number.
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*
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* In Mbed Crypto 0.1.0b:
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* - Using the file backend, all key ids are ok except 0.
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* - Using the ITS backend, all key ids are ok except 0xFFFFFF52
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* (#PSA_CRYPTO_ITS_RANDOM_SEED_UID) for which the file contains the
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* device's random seed (if this feature is enabled).
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* - Only key ids from 1 to #PSA_KEY_SLOT_COUNT are actually used.
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*
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* Since we need to preserve the random seed, avoid using that key slot.
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* Reserve a whole range of key slots just in case something else comes up.
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*
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* This limitation will probably become moot when we implement client
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* separation for key storage.
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*/
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#define PSA_MAX_PERSISTENT_KEY_IDENTIFIER PSA_KEY_ID_VENDOR_MAX
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/**
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* \brief Checks if persistent data is stored for the given key slot number
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*
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* This function checks if any key data or metadata exists for the key slot in
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* the persistent storage.
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*
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* \param key Persistent identifier to check.
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*
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* \retval 0
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* No persistent data present for slot number
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* \retval 1
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* Persistent data present for slot number
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*/
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int psa_is_key_present_in_storage( const mbedtls_svc_key_id_t key );
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/**
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* \brief Format key data and metadata and save to a location for given key
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* slot.
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*
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* This function formats the key data and metadata and saves it to a
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* persistent storage backend. The storage location corresponding to the
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* key slot must be empty, otherwise this function will fail. This function
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* should be called after loading the key into an internal slot to ensure the
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* persistent key is not saved into a storage location corresponding to an
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* already occupied non-persistent key, as well as ensuring the key data is
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* validated.
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*
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* Note: This function will only succeed for key buffers which are not
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* empty. If passed a NULL pointer or zero-length, the function will fail
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* with #PSA_ERROR_INVALID_ARGUMENT.
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*
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* \param[in] attr The attributes of the key to save.
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* The key identifier field in the attributes
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* determines the key's location.
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* \param[in] data Buffer containing the key data.
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* \param data_length The number of bytes that make up the key data.
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*
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* \retval #PSA_SUCCESS
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* \retval #PSA_ERROR_INVALID_ARGUMENT
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* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
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* \retval #PSA_ERROR_INSUFFICIENT_STORAGE
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* \retval #PSA_ERROR_STORAGE_FAILURE
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* \retval #PSA_ERROR_ALREADY_EXISTS
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*/
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psa_status_t psa_save_persistent_key( const psa_core_key_attributes_t *attr,
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const uint8_t *data,
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const size_t data_length );
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/**
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* \brief Parses key data and metadata and load persistent key for given
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* key slot number.
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*
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* This function reads from a storage backend, parses the key data and
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* metadata and writes them to the appropriate output parameters.
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*
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* Note: This function allocates a buffer and returns a pointer to it through
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* the data parameter. On successful return, the pointer is guaranteed to be
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* valid and the buffer contains at least one byte of data.
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* psa_free_persistent_key_data() must be called on the data buffer
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* afterwards to zeroize and free this buffer.
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*
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* \param[in,out] attr On input, the key identifier field identifies
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* the key to load. Other fields are ignored.
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* On success, the attribute structure contains
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* the key metadata that was loaded from storage.
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* \param[out] data Pointer to an allocated key data buffer on return.
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* \param[out] data_length The number of bytes that make up the key data.
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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_STORAGE_FAILURE
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* \retval #PSA_ERROR_DOES_NOT_EXIST
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*/
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psa_status_t psa_load_persistent_key( psa_core_key_attributes_t *attr,
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uint8_t **data,
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size_t *data_length );
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/**
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* \brief Remove persistent data for the given key slot number.
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*
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* \param key Persistent identifier of the key to remove
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* from persistent storage.
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*
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* \retval #PSA_SUCCESS
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* The key was successfully removed,
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* or the key did not exist.
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* \retval #PSA_ERROR_STORAGE_FAILURE
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*/
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psa_status_t psa_destroy_persistent_key( const mbedtls_svc_key_id_t key );
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/**
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* \brief Free the temporary buffer allocated by psa_load_persistent_key().
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*
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* This function must be called at some point after psa_load_persistent_key()
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* to zeroize and free the memory allocated to the buffer in that function.
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*
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* \param key_data Buffer for the key data.
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* \param key_data_length Size of the key data buffer.
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*
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*/
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void psa_free_persistent_key_data( uint8_t *key_data, size_t key_data_length );
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/**
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* \brief Formats key data and metadata for persistent storage
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*
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* \param[in] data Buffer containing the key data.
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* \param data_length Length of the key data buffer.
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* \param[in] attr The core attributes of the key.
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* \param[out] storage_data Output buffer for the formatted data.
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*
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*/
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void psa_format_key_data_for_storage( const uint8_t *data,
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const size_t data_length,
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const psa_core_key_attributes_t *attr,
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uint8_t *storage_data );
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/**
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* \brief Parses persistent storage data into key data and metadata
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*
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* \param[in] storage_data Buffer for the storage data.
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* \param storage_data_length Length of the storage data buffer
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* \param[out] key_data On output, pointer to a newly allocated buffer
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* containing the key data. This must be freed
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* using psa_free_persistent_key_data()
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* \param[out] key_data_length Length of the key data buffer
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* \param[out] attr On success, the attribute structure is filled
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* with the loaded key metadata.
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*
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* \retval #PSA_SUCCESS
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* \retval #PSA_ERROR_INSUFFICIENT_STORAGE
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* \retval #PSA_ERROR_INSUFFICIENT_MEMORY
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* \retval #PSA_ERROR_STORAGE_FAILURE
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*/
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psa_status_t psa_parse_key_data_from_storage( const uint8_t *storage_data,
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size_t storage_data_length,
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uint8_t **key_data,
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size_t *key_data_length,
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psa_core_key_attributes_t *attr );
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#if defined(MBEDTLS_PSA_CRYPTO_SE_C)
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/** This symbol is defined if transaction support is required. */
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#define PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS
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#endif
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#if defined(PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS)
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/** The type of transaction that is in progress.
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*/
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/* This is an integer type rather than an enum for two reasons: to support
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* unknown values when loading a transaction file, and to ensure that the
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* type has a known size.
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*/
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typedef uint16_t psa_crypto_transaction_type_t;
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/** No transaction is in progress.
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*
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* This has the value 0, so zero-initialization sets a transaction's type to
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* this value.
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*/
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#define PSA_CRYPTO_TRANSACTION_NONE ( (psa_crypto_transaction_type_t) 0x0000 )
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/** A key creation transaction.
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*
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* This is only used for keys in an external cryptoprocessor (secure element).
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* Keys in RAM or in internal storage are created atomically in storage
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* (simple file creation), so they do not need a transaction mechanism.
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*/
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#define PSA_CRYPTO_TRANSACTION_CREATE_KEY ( (psa_crypto_transaction_type_t) 0x0001 )
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/** A key destruction transaction.
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*
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* This is only used for keys in an external cryptoprocessor (secure element).
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* Keys in RAM or in internal storage are destroyed atomically in storage
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* (simple file deletion), so they do not need a transaction mechanism.
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*/
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#define PSA_CRYPTO_TRANSACTION_DESTROY_KEY ( (psa_crypto_transaction_type_t) 0x0002 )
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/** Transaction data.
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*
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* This type is designed to be serialized by writing the memory representation
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* and reading it back on the same device.
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*
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* \note The transaction mechanism is designed for a single active transaction
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* at a time. The transaction object is #psa_crypto_transaction.
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*
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* \note If an API call starts a transaction, it must complete this transaction
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* before returning to the application.
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*
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* The lifetime of a transaction is the following (note that only one
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* transaction may be active at a time):
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*
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* -# Call psa_crypto_prepare_transaction() to initialize the transaction
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* object in memory and declare the type of transaction that is starting.
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* -# Fill in the type-specific fields of #psa_crypto_transaction.
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* -# Call psa_crypto_save_transaction() to start the transaction. This
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* saves the transaction data to internal storage.
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* -# Perform the work of the transaction by modifying files, contacting
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* external entities, or whatever needs doing. Note that the transaction
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* may be interrupted by a power failure, so you need to have a way
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* recover from interruptions either by undoing what has been done
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* so far or by resuming where you left off.
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* -# If there are intermediate stages in the transaction, update
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* the fields of #psa_crypto_transaction and call
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* psa_crypto_save_transaction() again when each stage is reached.
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* -# When the transaction is over, call psa_crypto_stop_transaction() to
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* remove the transaction data in storage and in memory.
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*
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* If the system crashes while a transaction is in progress, psa_crypto_init()
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* calls psa_crypto_load_transaction() and takes care of completing or
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* rewinding the transaction. This is done in psa_crypto_recover_transaction()
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* in psa_crypto.c. If you add a new type of transaction, be
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* sure to add code for it in psa_crypto_recover_transaction().
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*/
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typedef union
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{
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/* Each element of this union must have the following properties
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* to facilitate serialization and deserialization:
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*
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* - The element is a struct.
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* - The first field of the struct is `psa_crypto_transaction_type_t type`.
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* - Elements of the struct are arranged such a way that there is
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* no padding.
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*/
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struct psa_crypto_transaction_unknown_s
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{
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psa_crypto_transaction_type_t type;
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uint16_t unused1;
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uint32_t unused2;
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uint64_t unused3;
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uint64_t unused4;
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} unknown;
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/* ::type is #PSA_CRYPTO_TRANSACTION_CREATE_KEY or
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* #PSA_CRYPTO_TRANSACTION_DESTROY_KEY. */
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struct psa_crypto_transaction_key_s
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{
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psa_crypto_transaction_type_t type;
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uint16_t unused1;
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psa_key_lifetime_t lifetime;
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psa_key_slot_number_t slot;
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mbedtls_svc_key_id_t id;
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} key;
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} psa_crypto_transaction_t;
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/** The single active transaction.
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*/
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extern psa_crypto_transaction_t psa_crypto_transaction;
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/** Prepare for a transaction.
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*
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* There must not be an ongoing transaction.
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*
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* \param type The type of transaction to start.
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*/
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static inline void psa_crypto_prepare_transaction(
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psa_crypto_transaction_type_t type )
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{
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psa_crypto_transaction.unknown.type = type;
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}
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/** Save the transaction data to storage.
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*
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* You may call this function multiple times during a transaction to
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* atomically update the transaction state.
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*
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* \retval #PSA_SUCCESS
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* \retval #PSA_ERROR_INSUFFICIENT_STORAGE
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* \retval #PSA_ERROR_STORAGE_FAILURE
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*/
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psa_status_t psa_crypto_save_transaction( void );
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/** Load the transaction data from storage, if any.
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*
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* This function is meant to be called from psa_crypto_init() to recover
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* in case a transaction was interrupted by a system crash.
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*
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* \retval #PSA_SUCCESS
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* The data about the ongoing transaction has been loaded to
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* #psa_crypto_transaction.
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* \retval #PSA_ERROR_DOES_NOT_EXIST
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* There is no ongoing transaction.
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* \retval #PSA_ERROR_STORAGE_FAILURE
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*/
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psa_status_t psa_crypto_load_transaction( void );
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/** Indicate that the current transaction is finished.
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*
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* Call this function at the very end of transaction processing.
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* This function does not "commit" or "abort" the transaction: the storage
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* subsystem has no concept of "commit" and "abort", just saving and
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* removing the transaction information in storage.
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*
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* This function erases the transaction data in storage (if any) and
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* resets the transaction data in memory.
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*
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* \retval #PSA_SUCCESS
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* There was transaction data in storage.
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* \retval #PSA_ERROR_DOES_NOT_EXIST
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* There was no transaction data in storage.
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* \retval #PSA_ERROR_STORAGE_FAILURE
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* It was impossible to determine whether there was transaction data
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* in storage, or the transaction data could not be erased.
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*/
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psa_status_t psa_crypto_stop_transaction( void );
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/** The ITS file identifier for the transaction data.
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*
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* 0xffffffNN = special file; 0x74 = 't' for transaction.
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*/
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#define PSA_CRYPTO_ITS_TRANSACTION_UID ( (psa_key_id_t) 0xffffff74 )
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#endif /* PSA_CRYPTO_STORAGE_HAS_TRANSACTIONS */
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#if defined(MBEDTLS_PSA_INJECT_ENTROPY)
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/** Backend side of mbedtls_psa_inject_entropy().
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*
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* This function stores the supplied data into the entropy seed file.
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*
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* \retval #PSA_SUCCESS
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* Success
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* \retval #PSA_ERROR_STORAGE_FAILURE
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* \retval #PSA_ERROR_INSUFFICIENT_STORAGE
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* \retval #PSA_ERROR_NOT_PERMITTED
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* The entropy seed file already exists.
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*/
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psa_status_t mbedtls_psa_storage_inject_entropy( const unsigned char *seed,
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size_t seed_size );
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#endif /* MBEDTLS_PSA_INJECT_ENTROPY */
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#ifdef __cplusplus
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}
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#endif
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#endif /* PSA_CRYPTO_STORAGE_H */
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