/**
* \file psa_crypto_storage.h
*
* \brief PSA cryptography module: Mbed TLS key storage
*/
/*
* Copyright (C) 2018, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* This file is part of mbed TLS (https://tls.mbed.org)
*/
#ifndef PSA_CRYPTO_STORAGE_H
#define PSA_CRYPTO_STORAGE_H
#ifdef __cplusplus
extern "C" {
#endif
/* Include the Mbed TLS configuration file, the way Mbed TLS does it
* in each of its header files. */
#if defined(MBEDTLS_CONFIG_FILE)
#include MBEDTLS_CONFIG_FILE
#else
#include "mbedtls/config.h"
#endif
#include "psa/crypto.h"
#include <stdint.h>
/* Limit the maximum key size to 30kB (just in case someone tries to
* inadvertently store an obscene amount of data) */
#define PSA_CRYPTO_MAX_STORAGE_SIZE ( 30 * 1024 )
/** The maximum permitted persistent slot number.
*
* In Mbed Crypto 0.1.0b:
* - Using the file backend, all key ids are ok except 0.
* - Using the ITS backend, all key ids are ok except 0xFFFFFF52
* (#PSA_CRYPTO_ITS_RANDOM_SEED_UID) for which the file contains the
* device's random seed (if this feature is enabled).
* - Only key ids from 1 to #PSA_KEY_SLOT_COUNT are actually used.
*
* Since we need to preserve the random seed, avoid using that key slot.
* Reserve a whole range of key slots just in case something else comes up.
*
* This limitation will probably become moot when we implement client
* separation for key storage.
*/
#define PSA_MAX_PERSISTENT_KEY_IDENTIFIER 0xfffeffff
/**
* \brief Checks if persistent data is stored for the given key slot number
*
* This function checks if any key data or metadata exists for the key slot in
* the persistent storage.
*
* \param key Persistent identifier to check.
*
* \retval 0
* No persistent data present for slot number
* \retval 1
* Persistent data present for slot number
*/
int psa_is_key_present_in_storage( const psa_key_file_id_t key );
/**
* \brief Format key data and metadata and save to a location for given key
* slot.
*
* This function formats the key data and metadata and saves it to a
* persistent storage backend. The storage location corresponding to the
* key slot must be empty, otherwise this function will fail. This function
* should be called after psa_import_key_into_slot() to ensure the
* persistent key is not saved into a storage location corresponding to an
* already occupied non-persistent key, as well as validating the key data.
*
*
* \param key Persistent identifier of the key to be stored. This
* should be an unoccupied storage location.
* \param type Key type (a \c PSA_KEY_TYPE_XXX value).
* \param[in] policy The key policy to save.
* \param[in] data Buffer containing the key data.
* \param data_length The number of bytes that make up the key data.
*
* \retval PSA_SUCCESS
* \retval PSA_ERROR_INSUFFICIENT_MEMORY
* \retval PSA_ERROR_INSUFFICIENT_STORAGE
* \retval PSA_ERROR_STORAGE_FAILURE
* \retval PSA_ERROR_ALREADY_EXISTS
*/
psa_status_t psa_save_persistent_key( const psa_key_file_id_t key,
const psa_key_type_t type,
const psa_key_policy_t *policy,
const uint8_t *data,
const size_t data_length );
/**
* \brief Parses key data and metadata and load persistent key for given
* key slot number.
*
* This function reads from a storage backend, parses the key data and
* metadata and writes them to the appropriate output parameters.
*
* Note: This function allocates a buffer and returns a pointer to it through
* the data parameter. psa_free_persistent_key_data() must be called after
* this function to zeroize and free this buffer, regardless of whether this
* function succeeds or fails.
*
* \param key Persistent identifier of the key to be loaded. This
* should be an occupied storage location.
* \param[out] type On success, the key type (a \c PSA_KEY_TYPE_XXX
* value).
* \param[out] policy On success, the key's policy.
* \param[out] data Pointer to an allocated key data buffer on return.
* \param[out] data_length The number of bytes that make up the key data.
*
* \retval PSA_SUCCESS
* \retval PSA_ERROR_INSUFFICIENT_MEMORY
* \retval PSA_ERROR_STORAGE_FAILURE
* \retval PSA_ERROR_DOES_NOT_EXIST
*/
psa_status_t psa_load_persistent_key( psa_key_file_id_t key,
psa_key_type_t *type,
psa_key_policy_t *policy,
uint8_t **data,
size_t *data_length );
/**
* \brief Remove persistent data for the given key slot number.
*
* \param key Persistent identifier of the key to remove
* from persistent storage.
*
* \retval PSA_SUCCESS
* The key was successfully removed,
* or the key did not exist.
* \retval PSA_ERROR_STORAGE_FAILURE
*/
psa_status_t psa_destroy_persistent_key( const psa_key_file_id_t key );
/**
* \brief Free the temporary buffer allocated by psa_load_persistent_key().
*
* This function must be called at some point after psa_load_persistent_key()
* to zeroize and free the memory allocated to the buffer in that function.
*
* \param key_data Buffer for the key data.
* \param key_data_length Size of the key data buffer.
*
*/
void psa_free_persistent_key_data( uint8_t *key_data, size_t key_data_length );
/**
* \brief Formats key data and metadata for persistent storage
*
* \param[in] data Buffer for the key data.
* \param data_length Length of the key data buffer.
* \param type Key type (a \c PSA_KEY_TYPE_XXX value).
* \param policy The key policy.
* \param[out] storage_data Output buffer for the formatted data.
*
*/
void psa_format_key_data_for_storage( const uint8_t *data,
const size_t data_length,
const psa_key_type_t type,
const psa_key_policy_t *policy,
uint8_t *storage_data );
/**
* \brief Parses persistent storage data into key data and metadata
*
* \param[in] storage_data Buffer for the storage data.
* \param storage_data_length Length of the storage data buffer
* \param[out] key_data On output, pointer to a newly allocated buffer
* containing the key data. This must be freed
* using psa_free_persistent_key_data()
* \param[out] key_data_length Length of the key data buffer
* \param[out] type Key type (a \c PSA_KEY_TYPE_XXX value).
* \param[out] policy The key policy.
*
* \retval PSA_SUCCESS
* \retval PSA_ERROR_INSUFFICIENT_STORAGE
* \retval PSA_ERROR_INSUFFICIENT_MEMORY
* \retval PSA_ERROR_STORAGE_FAILURE
*/
psa_status_t psa_parse_key_data_from_storage( const uint8_t *storage_data,
size_t storage_data_length,
uint8_t **key_data,
size_t *key_data_length,
psa_key_type_t *type,
psa_key_policy_t *policy );
#if defined(MBEDTLS_PSA_INJECT_ENTROPY)
/** Backend side of mbedtls_psa_inject_entropy().
*
* This function stores the supplied data into the entropy seed file.
*
* \retval #PSA_SUCCESS
* Success
* \retval #PSA_ERROR_STORAGE_FAILURE
* \retval #PSA_ERROR_INSUFFICIENT_STORAGE
* \retval #PSA_ERROR_NOT_PERMITTED
* The entropy seed file already exists.
*/
psa_status_t mbedtls_psa_storage_inject_entropy( const unsigned char *seed,
size_t seed_size );
#endif /* MBEDTLS_PSA_INJECT_ENTROPY */
#ifdef __cplusplus
}
#endif
#endif /* PSA_CRYPTO_STORAGE_H */