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+/**
+ * \file psa/crypto_se_driver.h
+ * \brief PSA external cryptoprocessor driver module
+ *
+ * This header declares types and function signatures for cryptography
+ * drivers that access key material via opaque references.
+ * This is meant for cryptoprocessors that have a separate key storage from the
+ * space in which the PSA Crypto implementation runs, typically secure
+ * elements (SEs).
+ *
+ * This file is part of the PSA Crypto Driver HAL (hardware abstraction layer),
+ * containing functions for driver developers to implement to enable hardware
+ * to be called in a standardized way by a PSA Cryptography API
+ * implementation. The functions comprising the driver HAL, which driver
+ * authors implement, are not intended to be called by application developers.
+ */
+
+/*
+ * Copyright The Mbed TLS Contributors
+ * 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.
+ */
+#ifndef PSA_CRYPTO_SE_DRIVER_H
+#define PSA_CRYPTO_SE_DRIVER_H
+
+#include "crypto_driver_common.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** \defgroup se_init Secure element driver initialization
+ */
+/**@{*/
+
+/** \brief Driver context structure
+ *
+ * Driver functions receive a pointer to this structure.
+ * Each registered driver has one instance of this structure.
+ *
+ * Implementations must include the fields specified here and
+ * may include other fields.
+ */
+typedef struct {
+ /** A read-only pointer to the driver's persistent data.
+ *
+ * Drivers typically use this persistent data to keep track of
+ * which slot numbers are available. This is only a guideline:
+ * drivers may use the persistent data for any purpose, keeping
+ * in mind the restrictions on when the persistent data is saved
+ * to storage: the persistent data is only saved after calling
+ * certain functions that receive a writable pointer to the
+ * persistent data.
+ *
+ * The core allocates a memory buffer for the persistent data.
+ * The pointer is guaranteed to be suitably aligned for any data type,
+ * like a pointer returned by `malloc` (but the core can use any
+ * method to allocate the buffer, not necessarily `malloc`).
+ *
+ * The size of this buffer is in the \c persistent_data_size field of
+ * this structure.
+ *
+ * Before the driver is initialized for the first time, the content of
+ * the persistent data is all-bits-zero. After a driver upgrade, if the
+ * size of the persistent data has increased, the original data is padded
+ * on the right with zeros; if the size has decreased, the original data
+ * is truncated to the new size.
+ *
+ * This pointer is to read-only data. Only a few driver functions are
+ * allowed to modify the persistent data. These functions receive a
+ * writable pointer. These functions are:
+ * - psa_drv_se_t::p_init
+ * - psa_drv_se_key_management_t::p_allocate
+ * - psa_drv_se_key_management_t::p_destroy
+ *
+ * The PSA Cryptography core saves the persistent data from one
+ * session to the next. It does this before returning from API functions
+ * that call a driver method that is allowed to modify the persistent
+ * data, specifically:
+ * - psa_crypto_init() causes a call to psa_drv_se_t::p_init, and may call
+ * psa_drv_se_key_management_t::p_destroy to complete an action
+ * that was interrupted by a power failure.
+ * - Key creation functions cause a call to
+ * psa_drv_se_key_management_t::p_allocate, and may cause a call to
+ * psa_drv_se_key_management_t::p_destroy in case an error occurs.
+ * - psa_destroy_key() causes a call to
+ * psa_drv_se_key_management_t::p_destroy.
+ */
+ const void *const persistent_data;
+
+ /** The size of \c persistent_data in bytes.
+ *
+ * This is always equal to the value of the `persistent_data_size` field
+ * of the ::psa_drv_se_t structure when the driver is registered.
+ */
+ const size_t persistent_data_size;
+
+ /** Driver transient data.
+ *
+ * The core initializes this value to 0 and does not read or modify it
+ * afterwards. The driver may store whatever it wants in this field.
+ */
+ uintptr_t transient_data;
+} psa_drv_se_context_t;
+
+/** \brief A driver initialization function.
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in,out] persistent_data A pointer to the persistent data
+ * that allows writing.
+ * \param location The location value for which this driver
+ * is registered. The driver will be invoked
+ * for all keys whose lifetime is in this
+ * location.
+ *
+ * \retval #PSA_SUCCESS
+ * The driver is operational.
+ * The core will update the persistent data in storage.
+ * \return
+ * Any other return value prevents the driver from being used in
+ * this session.
+ * The core will NOT update the persistent data in storage.
+ */
+typedef psa_status_t (*psa_drv_se_init_t)(psa_drv_se_context_t *drv_context,
+ void *persistent_data,
+ psa_key_location_t location);
+
+#if defined(__DOXYGEN_ONLY__) || !defined(MBEDTLS_PSA_CRYPTO_SE_C)
+/* Mbed Crypto with secure element support enabled defines this type in
+ * crypto_types.h because it is also visible to applications through an
+ * implementation-specific extension.
+ * For the PSA Cryptography specification, this type is only visible
+ * via crypto_se_driver.h. */
+/** An internal designation of a key slot between the core part of the
+ * PSA Crypto implementation and the driver. The meaning of this value
+ * is driver-dependent. */
+typedef uint64_t psa_key_slot_number_t;
+#endif /* __DOXYGEN_ONLY__ || !MBEDTLS_PSA_CRYPTO_SE_C */
+
+/**@}*/
+
+/** \defgroup se_mac Secure Element Message Authentication Codes
+ * Generation and authentication of Message Authentication Codes (MACs) using
+ * a secure element can be done either as a single function call (via the
+ * `psa_drv_se_mac_generate_t` or `psa_drv_se_mac_verify_t` functions), or in
+ * parts using the following sequence:
+ * - `psa_drv_se_mac_setup_t`
+ * - `psa_drv_se_mac_update_t`
+ * - `psa_drv_se_mac_update_t`
+ * - ...
+ * - `psa_drv_se_mac_finish_t` or `psa_drv_se_mac_finish_verify_t`
+ *
+ * If a previously started secure element MAC operation needs to be terminated,
+ * it should be done so by the `psa_drv_se_mac_abort_t`. Failure to do so may
+ * result in allocated resources not being freed or in other undefined
+ * behavior.
+ */
+/**@{*/
+/** \brief A function that starts a secure element MAC operation for a PSA
+ * Crypto Driver implementation
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in,out] op_context A structure that will contain the
+ * hardware-specific MAC context
+ * \param[in] key_slot The slot of the key to be used for the
+ * operation
+ * \param[in] algorithm The algorithm to be used to underly the MAC
+ * operation
+ *
+ * \retval #PSA_SUCCESS
+ * Success.
+ */
+typedef psa_status_t (*psa_drv_se_mac_setup_t)(psa_drv_se_context_t *drv_context,
+ void *op_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t algorithm);
+
+/** \brief A function that continues a previously started secure element MAC
+ * operation
+ *
+ * \param[in,out] op_context A hardware-specific structure for the
+ * previously-established MAC operation to be
+ * updated
+ * \param[in] p_input A buffer containing the message to be appended
+ * to the MAC operation
+ * \param[in] input_length The size in bytes of the input message buffer
+ */
+typedef psa_status_t (*psa_drv_se_mac_update_t)(void *op_context,
+ const uint8_t *p_input,
+ size_t input_length);
+
+/** \brief a function that completes a previously started secure element MAC
+ * operation by returning the resulting MAC.
+ *
+ * \param[in,out] op_context A hardware-specific structure for the
+ * previously started MAC operation to be
+ * finished
+ * \param[out] p_mac A buffer where the generated MAC will be
+ * placed
+ * \param[in] mac_size The size in bytes of the buffer that has been
+ * allocated for the `output` buffer
+ * \param[out] p_mac_length After completion, will contain the number of
+ * bytes placed in the `p_mac` buffer
+ *
+ * \retval #PSA_SUCCESS
+ * Success.
+ */
+typedef psa_status_t (*psa_drv_se_mac_finish_t)(void *op_context,
+ uint8_t *p_mac,
+ size_t mac_size,
+ size_t *p_mac_length);
+
+/** \brief A function that completes a previously started secure element MAC
+ * operation by comparing the resulting MAC against a provided value
+ *
+ * \param[in,out] op_context A hardware-specific structure for the previously
+ * started MAC operation to be fiinished
+ * \param[in] p_mac The MAC value against which the resulting MAC
+ * will be compared against
+ * \param[in] mac_length The size in bytes of the value stored in `p_mac`
+ *
+ * \retval #PSA_SUCCESS
+ * The operation completed successfully and the MACs matched each
+ * other
+ * \retval #PSA_ERROR_INVALID_SIGNATURE
+ * The operation completed successfully, but the calculated MAC did
+ * not match the provided MAC
+ */
+typedef psa_status_t (*psa_drv_se_mac_finish_verify_t)(void *op_context,
+ const uint8_t *p_mac,
+ size_t mac_length);
+
+/** \brief A function that aborts a previous started secure element MAC
+ * operation
+ *
+ * \param[in,out] op_context A hardware-specific structure for the previously
+ * started MAC operation to be aborted
+ */
+typedef psa_status_t (*psa_drv_se_mac_abort_t)(void *op_context);
+
+/** \brief A function that performs a secure element MAC operation in one
+ * command and returns the calculated MAC
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] p_input A buffer containing the message to be MACed
+ * \param[in] input_length The size in bytes of `p_input`
+ * \param[in] key_slot The slot of the key to be used
+ * \param[in] alg The algorithm to be used to underlie the MAC
+ * operation
+ * \param[out] p_mac A buffer where the generated MAC will be
+ * placed
+ * \param[in] mac_size The size in bytes of the `p_mac` buffer
+ * \param[out] p_mac_length After completion, will contain the number of
+ * bytes placed in the `output` buffer
+ *
+ * \retval #PSA_SUCCESS
+ * Success.
+ */
+typedef psa_status_t (*psa_drv_se_mac_generate_t)(psa_drv_se_context_t *drv_context,
+ const uint8_t *p_input,
+ size_t input_length,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t alg,
+ uint8_t *p_mac,
+ size_t mac_size,
+ size_t *p_mac_length);
+
+/** \brief A function that performs a secure element MAC operation in one
+ * command and compares the resulting MAC against a provided value
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] p_input A buffer containing the message to be MACed
+ * \param[in] input_length The size in bytes of `input`
+ * \param[in] key_slot The slot of the key to be used
+ * \param[in] alg The algorithm to be used to underlie the MAC
+ * operation
+ * \param[in] p_mac The MAC value against which the resulting MAC will
+ * be compared against
+ * \param[in] mac_length The size in bytes of `mac`
+ *
+ * \retval #PSA_SUCCESS
+ * The operation completed successfully and the MACs matched each
+ * other
+ * \retval #PSA_ERROR_INVALID_SIGNATURE
+ * The operation completed successfully, but the calculated MAC did
+ * not match the provided MAC
+ */
+typedef psa_status_t (*psa_drv_se_mac_verify_t)(psa_drv_se_context_t *drv_context,
+ const uint8_t *p_input,
+ size_t input_length,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t alg,
+ const uint8_t *p_mac,
+ size_t mac_length);
+
+/** \brief A struct containing all of the function pointers needed to
+ * perform secure element MAC operations
+ *
+ * PSA Crypto API implementations should populate the table as appropriate
+ * upon startup.
+ *
+ * If one of the functions is not implemented (such as
+ * `psa_drv_se_mac_generate_t`), it should be set to NULL.
+ *
+ * Driver implementers should ensure that they implement all of the functions
+ * that make sense for their hardware, and that they provide a full solution
+ * (for example, if they support `p_setup`, they should also support
+ * `p_update` and at least one of `p_finish` or `p_finish_verify`).
+ *
+ */
+typedef struct {
+ /**The size in bytes of the hardware-specific secure element MAC context
+ * structure
+ */
+ size_t context_size;
+ /** Function that performs a MAC setup operation
+ */
+ psa_drv_se_mac_setup_t p_setup;
+ /** Function that performs a MAC update operation
+ */
+ psa_drv_se_mac_update_t p_update;
+ /** Function that completes a MAC operation
+ */
+ psa_drv_se_mac_finish_t p_finish;
+ /** Function that completes a MAC operation with a verify check
+ */
+ psa_drv_se_mac_finish_verify_t p_finish_verify;
+ /** Function that aborts a previoustly started MAC operation
+ */
+ psa_drv_se_mac_abort_t p_abort;
+ /** Function that performs a MAC operation in one call
+ */
+ psa_drv_se_mac_generate_t p_mac;
+ /** Function that performs a MAC and verify operation in one call
+ */
+ psa_drv_se_mac_verify_t p_mac_verify;
+} psa_drv_se_mac_t;
+/**@}*/
+
+/** \defgroup se_cipher Secure Element Symmetric Ciphers
+ *
+ * Encryption and Decryption using secure element keys in block modes other
+ * than ECB must be done in multiple parts, using the following flow:
+ * - `psa_drv_se_cipher_setup_t`
+ * - `psa_drv_se_cipher_set_iv_t` (optional depending upon block mode)
+ * - `psa_drv_se_cipher_update_t`
+ * - `psa_drv_se_cipher_update_t`
+ * - ...
+ * - `psa_drv_se_cipher_finish_t`
+ *
+ * If a previously started secure element Cipher operation needs to be
+ * terminated, it should be done so by the `psa_drv_se_cipher_abort_t`. Failure
+ * to do so may result in allocated resources not being freed or in other
+ * undefined behavior.
+ *
+ * In situations where a PSA Cryptographic API implementation is using a block
+ * mode not-supported by the underlying hardware or driver, it can construct
+ * the block mode itself, while calling the `psa_drv_se_cipher_ecb_t` function
+ * for the cipher operations.
+ */
+/**@{*/
+
+/** \brief A function that provides the cipher setup function for a
+ * secure element driver
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in,out] op_context A structure that will contain the
+ * hardware-specific cipher context.
+ * \param[in] key_slot The slot of the key to be used for the
+ * operation
+ * \param[in] algorithm The algorithm to be used in the cipher
+ * operation
+ * \param[in] direction Indicates whether the operation is an encrypt
+ * or decrypt
+ *
+ * \retval #PSA_SUCCESS
+ * \retval #PSA_ERROR_NOT_SUPPORTED
+ */
+typedef psa_status_t (*psa_drv_se_cipher_setup_t)(psa_drv_se_context_t *drv_context,
+ void *op_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t algorithm,
+ psa_encrypt_or_decrypt_t direction);
+
+/** \brief A function that sets the initialization vector (if
+ * necessary) for an secure element cipher operation
+ *
+ * Rationale: The `psa_se_cipher_*` operation in the PSA Cryptographic API has
+ * two IV functions: one to set the IV, and one to generate it internally. The
+ * generate function is not necessary for the drivers to implement as the PSA
+ * Crypto implementation can do the generation using its RNG features.
+ *
+ * \param[in,out] op_context A structure that contains the previously set up
+ * hardware-specific cipher context
+ * \param[in] p_iv A buffer containing the initialization vector
+ * \param[in] iv_length The size (in bytes) of the `p_iv` buffer
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_cipher_set_iv_t)(void *op_context,
+ const uint8_t *p_iv,
+ size_t iv_length);
+
+/** \brief A function that continues a previously started secure element cipher
+ * operation
+ *
+ * \param[in,out] op_context A hardware-specific structure for the
+ * previously started cipher operation
+ * \param[in] p_input A buffer containing the data to be
+ * encrypted/decrypted
+ * \param[in] input_size The size in bytes of the buffer pointed to
+ * by `p_input`
+ * \param[out] p_output The caller-allocated buffer where the
+ * output will be placed
+ * \param[in] output_size The allocated size in bytes of the
+ * `p_output` buffer
+ * \param[out] p_output_length After completion, will contain the number
+ * of bytes placed in the `p_output` buffer
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_cipher_update_t)(void *op_context,
+ const uint8_t *p_input,
+ size_t input_size,
+ uint8_t *p_output,
+ size_t output_size,
+ size_t *p_output_length);
+
+/** \brief A function that completes a previously started secure element cipher
+ * operation
+ *
+ * \param[in,out] op_context A hardware-specific structure for the
+ * previously started cipher operation
+ * \param[out] p_output The caller-allocated buffer where the output
+ * will be placed
+ * \param[in] output_size The allocated size in bytes of the `p_output`
+ * buffer
+ * \param[out] p_output_length After completion, will contain the number of
+ * bytes placed in the `p_output` buffer
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_cipher_finish_t)(void *op_context,
+ uint8_t *p_output,
+ size_t output_size,
+ size_t *p_output_length);
+
+/** \brief A function that aborts a previously started secure element cipher
+ * operation
+ *
+ * \param[in,out] op_context A hardware-specific structure for the
+ * previously started cipher operation
+ */
+typedef psa_status_t (*psa_drv_se_cipher_abort_t)(void *op_context);
+
+/** \brief A function that performs the ECB block mode for secure element
+ * cipher operations
+ *
+ * Note: this function should only be used with implementations that do not
+ * provide a needed higher-level operation.
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] key_slot The slot of the key to be used for the operation
+ * \param[in] algorithm The algorithm to be used in the cipher operation
+ * \param[in] direction Indicates whether the operation is an encrypt or
+ * decrypt
+ * \param[in] p_input A buffer containing the data to be
+ * encrypted/decrypted
+ * \param[in] input_size The size in bytes of the buffer pointed to by
+ * `p_input`
+ * \param[out] p_output The caller-allocated buffer where the output
+ * will be placed
+ * \param[in] output_size The allocated size in bytes of the `p_output`
+ * buffer
+ *
+ * \retval #PSA_SUCCESS
+ * \retval #PSA_ERROR_NOT_SUPPORTED
+ */
+typedef psa_status_t (*psa_drv_se_cipher_ecb_t)(psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t algorithm,
+ psa_encrypt_or_decrypt_t direction,
+ const uint8_t *p_input,
+ size_t input_size,
+ uint8_t *p_output,
+ size_t output_size);
+
+/**
+ * \brief A struct containing all of the function pointers needed to implement
+ * cipher operations using secure elements.
+ *
+ * PSA Crypto API implementations should populate instances of the table as
+ * appropriate upon startup or at build time.
+ *
+ * If one of the functions is not implemented (such as
+ * `psa_drv_se_cipher_ecb_t`), it should be set to NULL.
+ */
+typedef struct {
+ /** The size in bytes of the hardware-specific secure element cipher
+ * context structure
+ */
+ size_t context_size;
+ /** Function that performs a cipher setup operation */
+ psa_drv_se_cipher_setup_t p_setup;
+ /** Function that sets a cipher IV (if necessary) */
+ psa_drv_se_cipher_set_iv_t p_set_iv;
+ /** Function that performs a cipher update operation */
+ psa_drv_se_cipher_update_t p_update;
+ /** Function that completes a cipher operation */
+ psa_drv_se_cipher_finish_t p_finish;
+ /** Function that aborts a cipher operation */
+ psa_drv_se_cipher_abort_t p_abort;
+ /** Function that performs ECB mode for a cipher operation
+ * (Danger: ECB mode should not be used directly by clients of the PSA
+ * Crypto Client API)
+ */
+ psa_drv_se_cipher_ecb_t p_ecb;
+} psa_drv_se_cipher_t;
+
+/**@}*/
+
+/** \defgroup se_asymmetric Secure Element Asymmetric Cryptography
+ *
+ * Since the amount of data that can (or should) be encrypted or signed using
+ * asymmetric keys is limited by the key size, asymmetric key operations using
+ * keys in a secure element must be done in single function calls.
+ */
+/**@{*/
+
+/**
+ * \brief A function that signs a hash or short message with a private key in
+ * a secure element
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] key_slot Key slot of an asymmetric key pair
+ * \param[in] alg A signature algorithm that is compatible
+ * with the type of `key`
+ * \param[in] p_hash The hash to sign
+ * \param[in] hash_length Size of the `p_hash` buffer in bytes
+ * \param[out] p_signature Buffer where the signature is to be written
+ * \param[in] signature_size Size of the `p_signature` buffer in bytes
+ * \param[out] p_signature_length On success, the number of bytes
+ * that make up the returned signature value
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_asymmetric_sign_t)(psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t alg,
+ const uint8_t *p_hash,
+ size_t hash_length,
+ uint8_t *p_signature,
+ size_t signature_size,
+ size_t *p_signature_length);
+
+/**
+ * \brief A function that verifies the signature a hash or short message using
+ * an asymmetric public key in a secure element
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] key_slot Key slot of a public key or an asymmetric key
+ * pair
+ * \param[in] alg A signature algorithm that is compatible with
+ * the type of `key`
+ * \param[in] p_hash The hash whose signature is to be verified
+ * \param[in] hash_length Size of the `p_hash` buffer in bytes
+ * \param[in] p_signature Buffer containing the signature to verify
+ * \param[in] signature_length Size of the `p_signature` buffer in bytes
+ *
+ * \retval #PSA_SUCCESS
+ * The signature is valid.
+ */
+typedef psa_status_t (*psa_drv_se_asymmetric_verify_t)(psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t alg,
+ const uint8_t *p_hash,
+ size_t hash_length,
+ const uint8_t *p_signature,
+ size_t signature_length);
+
+/**
+ * \brief A function that encrypts a short message with an asymmetric public
+ * key in a secure element
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] key_slot Key slot of a public key or an asymmetric key
+ * pair
+ * \param[in] alg An asymmetric encryption algorithm that is
+ * compatible with the type of `key`
+ * \param[in] p_input The message to encrypt
+ * \param[in] input_length Size of the `p_input` buffer in bytes
+ * \param[in] p_salt A salt or label, if supported by the
+ * encryption algorithm
+ * If the algorithm does not support a
+ * salt, pass `NULL`.
+ * If the algorithm supports an optional
+ * salt and you do not want to pass a salt,
+ * pass `NULL`.
+ * For #PSA_ALG_RSA_PKCS1V15_CRYPT, no salt is
+ * supported.
+ * \param[in] salt_length Size of the `p_salt` buffer in bytes
+ * If `p_salt` is `NULL`, pass 0.
+ * \param[out] p_output Buffer where the encrypted message is to
+ * be written
+ * \param[in] output_size Size of the `p_output` buffer in bytes
+ * \param[out] p_output_length On success, the number of bytes that make up
+ * the returned output
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_asymmetric_encrypt_t)(psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t alg,
+ const uint8_t *p_input,
+ size_t input_length,
+ const uint8_t *p_salt,
+ size_t salt_length,
+ uint8_t *p_output,
+ size_t output_size,
+ size_t *p_output_length);
+
+/**
+ * \brief A function that decrypts a short message with an asymmetric private
+ * key in a secure element.
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] key_slot Key slot of an asymmetric key pair
+ * \param[in] alg An asymmetric encryption algorithm that is
+ * compatible with the type of `key`
+ * \param[in] p_input The message to decrypt
+ * \param[in] input_length Size of the `p_input` buffer in bytes
+ * \param[in] p_salt A salt or label, if supported by the
+ * encryption algorithm
+ * If the algorithm does not support a
+ * salt, pass `NULL`.
+ * If the algorithm supports an optional
+ * salt and you do not want to pass a salt,
+ * pass `NULL`.
+ * For #PSA_ALG_RSA_PKCS1V15_CRYPT, no salt is
+ * supported.
+ * \param[in] salt_length Size of the `p_salt` buffer in bytes
+ * If `p_salt` is `NULL`, pass 0.
+ * \param[out] p_output Buffer where the decrypted message is to
+ * be written
+ * \param[in] output_size Size of the `p_output` buffer in bytes
+ * \param[out] p_output_length On success, the number of bytes
+ * that make up the returned output
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_asymmetric_decrypt_t)(psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t alg,
+ const uint8_t *p_input,
+ size_t input_length,
+ const uint8_t *p_salt,
+ size_t salt_length,
+ uint8_t *p_output,
+ size_t output_size,
+ size_t *p_output_length);
+
+/**
+ * \brief A struct containing all of the function pointers needed to implement
+ * asymmetric cryptographic operations using secure elements.
+ *
+ * PSA Crypto API implementations should populate instances of the table as
+ * appropriate upon startup or at build time.
+ *
+ * If one of the functions is not implemented, it should be set to NULL.
+ */
+typedef struct {
+ /** Function that performs an asymmetric sign operation */
+ psa_drv_se_asymmetric_sign_t p_sign;
+ /** Function that performs an asymmetric verify operation */
+ psa_drv_se_asymmetric_verify_t p_verify;
+ /** Function that performs an asymmetric encrypt operation */
+ psa_drv_se_asymmetric_encrypt_t p_encrypt;
+ /** Function that performs an asymmetric decrypt operation */
+ psa_drv_se_asymmetric_decrypt_t p_decrypt;
+} psa_drv_se_asymmetric_t;
+
+/**@}*/
+
+/** \defgroup se_aead Secure Element Authenticated Encryption with Additional Data
+ * Authenticated Encryption with Additional Data (AEAD) operations with secure
+ * elements must be done in one function call. While this creates a burden for
+ * implementers as there must be sufficient space in memory for the entire
+ * message, it prevents decrypted data from being made available before the
+ * authentication operation is complete and the data is known to be authentic.
+ */
+/**@{*/
+
+/** \brief A function that performs a secure element authenticated encryption
+ * operation
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] key_slot Slot containing the key to use.
+ * \param[in] algorithm The AEAD algorithm to compute
+ * (\c PSA_ALG_XXX value such that
+ * #PSA_ALG_IS_AEAD(`alg`) is true)
+ * \param[in] p_nonce Nonce or IV to use
+ * \param[in] nonce_length Size of the `p_nonce` buffer in bytes
+ * \param[in] p_additional_data Additional data that will be
+ * authenticated but not encrypted
+ * \param[in] additional_data_length Size of `p_additional_data` in bytes
+ * \param[in] p_plaintext Data that will be authenticated and
+ * encrypted
+ * \param[in] plaintext_length Size of `p_plaintext` in bytes
+ * \param[out] p_ciphertext Output buffer for the authenticated and
+ * encrypted data. The additional data is
+ * not part of this output. For algorithms
+ * where the encrypted data and the
+ * authentication tag are defined as
+ * separate outputs, the authentication
+ * tag is appended to the encrypted data.
+ * \param[in] ciphertext_size Size of the `p_ciphertext` buffer in
+ * bytes
+ * \param[out] p_ciphertext_length On success, the size of the output in
+ * the `p_ciphertext` buffer
+ *
+ * \retval #PSA_SUCCESS
+ * Success.
+ */
+typedef psa_status_t (*psa_drv_se_aead_encrypt_t)(psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t algorithm,
+ const uint8_t *p_nonce,
+ size_t nonce_length,
+ const uint8_t *p_additional_data,
+ size_t additional_data_length,
+ const uint8_t *p_plaintext,
+ size_t plaintext_length,
+ uint8_t *p_ciphertext,
+ size_t ciphertext_size,
+ size_t *p_ciphertext_length);
+
+/** A function that peforms a secure element authenticated decryption operation
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] key_slot Slot containing the key to use
+ * \param[in] algorithm The AEAD algorithm to compute
+ * (\c PSA_ALG_XXX value such that
+ * #PSA_ALG_IS_AEAD(`alg`) is true)
+ * \param[in] p_nonce Nonce or IV to use
+ * \param[in] nonce_length Size of the `p_nonce` buffer in bytes
+ * \param[in] p_additional_data Additional data that has been
+ * authenticated but not encrypted
+ * \param[in] additional_data_length Size of `p_additional_data` in bytes
+ * \param[in] p_ciphertext Data that has been authenticated and
+ * encrypted.
+ * For algorithms where the encrypted data
+ * and the authentication tag are defined
+ * as separate inputs, the buffer must
+ * contain the encrypted data followed by
+ * the authentication tag.
+ * \param[in] ciphertext_length Size of `p_ciphertext` in bytes
+ * \param[out] p_plaintext Output buffer for the decrypted data
+ * \param[in] plaintext_size Size of the `p_plaintext` buffer in
+ * bytes
+ * \param[out] p_plaintext_length On success, the size of the output in
+ * the `p_plaintext` buffer
+ *
+ * \retval #PSA_SUCCESS
+ * Success.
+ */
+typedef psa_status_t (*psa_drv_se_aead_decrypt_t)(psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ psa_algorithm_t algorithm,
+ const uint8_t *p_nonce,
+ size_t nonce_length,
+ const uint8_t *p_additional_data,
+ size_t additional_data_length,
+ const uint8_t *p_ciphertext,
+ size_t ciphertext_length,
+ uint8_t *p_plaintext,
+ size_t plaintext_size,
+ size_t *p_plaintext_length);
+
+/**
+ * \brief A struct containing all of the function pointers needed to implement
+ * secure element Authenticated Encryption with Additional Data operations
+ *
+ * PSA Crypto API implementations should populate instances of the table as
+ * appropriate upon startup.
+ *
+ * If one of the functions is not implemented, it should be set to NULL.
+ */
+typedef struct {
+ /** Function that performs the AEAD encrypt operation */
+ psa_drv_se_aead_encrypt_t p_encrypt;
+ /** Function that performs the AEAD decrypt operation */
+ psa_drv_se_aead_decrypt_t p_decrypt;
+} psa_drv_se_aead_t;
+/**@}*/
+
+/** \defgroup se_key_management Secure Element Key Management
+ * Currently, key management is limited to importing keys in the clear,
+ * destroying keys, and exporting keys in the clear.
+ * Whether a key may be exported is determined by the key policies in place
+ * on the key slot.
+ */
+/**@{*/
+
+/** An enumeration indicating how a key is created.
+ */
+typedef enum
+{
+ PSA_KEY_CREATION_IMPORT, /**< During psa_import_key() */
+ PSA_KEY_CREATION_GENERATE, /**< During psa_generate_key() */
+ PSA_KEY_CREATION_DERIVE, /**< During psa_key_derivation_output_key() */
+ PSA_KEY_CREATION_COPY, /**< During psa_copy_key() */
+
+#ifndef __DOXYGEN_ONLY__
+ /** A key is being registered with mbedtls_psa_register_se_key().
+ *
+ * The core only passes this value to
+ * psa_drv_se_key_management_t::p_validate_slot_number, not to
+ * psa_drv_se_key_management_t::p_allocate. The call to
+ * `p_validate_slot_number` is not followed by any other call to the
+ * driver: the key is considered successfully registered if the call to
+ * `p_validate_slot_number` succeeds, or if `p_validate_slot_number` is
+ * null.
+ *
+ * With this creation method, the driver must return #PSA_SUCCESS if
+ * the given attributes are compatible with the existing key in the slot,
+ * and #PSA_ERROR_DOES_NOT_EXIST if the driver can determine that there
+ * is no key with the specified slot number.
+ *
+ * This is an Mbed Crypto extension.
+ */
+ PSA_KEY_CREATION_REGISTER,
+#endif
+} psa_key_creation_method_t;
+
+/** \brief A function that allocates a slot for a key.
+ *
+ * To create a key in a specific slot in a secure element, the core
+ * first calls this function to determine a valid slot number,
+ * then calls a function to create the key material in that slot.
+ * In nominal conditions (that is, if no error occurs),
+ * the effect of a call to a key creation function in the PSA Cryptography
+ * API with a lifetime that places the key in a secure element is the
+ * following:
+ * -# The core calls psa_drv_se_key_management_t::p_allocate
+ * (or in some implementations
+ * psa_drv_se_key_management_t::p_validate_slot_number). The driver
+ * selects (or validates) a suitable slot number given the key attributes
+ * and the state of the secure element.
+ * -# The core calls a key creation function in the driver.
+ *
+ * The key creation functions in the PSA Cryptography API are:
+ * - psa_import_key(), which causes
+ * a call to `p_allocate` with \p method = #PSA_KEY_CREATION_IMPORT
+ * then a call to psa_drv_se_key_management_t::p_import.
+ * - psa_generate_key(), which causes
+ * a call to `p_allocate` with \p method = #PSA_KEY_CREATION_GENERATE
+ * then a call to psa_drv_se_key_management_t::p_import.
+ * - psa_key_derivation_output_key(), which causes
+ * a call to `p_allocate` with \p method = #PSA_KEY_CREATION_DERIVE
+ * then a call to psa_drv_se_key_derivation_t::p_derive.
+ * - psa_copy_key(), which causes
+ * a call to `p_allocate` with \p method = #PSA_KEY_CREATION_COPY
+ * then a call to psa_drv_se_key_management_t::p_export.
+ *
+ * In case of errors, other behaviors are possible.
+ * - If the PSA Cryptography subsystem dies after the first step,
+ * for example because the device has lost power abruptly,
+ * the second step may never happen, or may happen after a reset
+ * and re-initialization. Alternatively, after a reset and
+ * re-initialization, the core may call
+ * psa_drv_se_key_management_t::p_destroy on the slot number that
+ * was allocated (or validated) instead of calling a key creation function.
+ * - If an error occurs, the core may call
+ * psa_drv_se_key_management_t::p_destroy on the slot number that
+ * was allocated (or validated) instead of calling a key creation function.
+ *
+ * Errors and system resets also have an impact on the driver's persistent
+ * data. If a reset happens before the overall key creation process is
+ * completed (before or after the second step above), it is unspecified
+ * whether the persistent data after the reset is identical to what it
+ * was before or after the call to `p_allocate` (or `p_validate_slot_number`).
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in,out] persistent_data A pointer to the persistent data
+ * that allows writing.
+ * \param[in] attributes Attributes of the key.
+ * \param method The way in which the key is being created.
+ * \param[out] key_slot Slot where the key will be stored.
+ * This must be a valid slot for a key of the
+ * chosen type. It must be unoccupied.
+ *
+ * \retval #PSA_SUCCESS
+ * Success.
+ * The core will record \c *key_slot as the key slot where the key
+ * is stored and will update the persistent data in storage.
+ * \retval #PSA_ERROR_NOT_SUPPORTED
+ * \retval #PSA_ERROR_INSUFFICIENT_STORAGE
+ */
+typedef psa_status_t (*psa_drv_se_allocate_key_t)(
+ psa_drv_se_context_t *drv_context,
+ void *persistent_data,
+ const psa_key_attributes_t *attributes,
+ psa_key_creation_method_t method,
+ psa_key_slot_number_t *key_slot);
+
+/** \brief A function that determines whether a slot number is valid
+ * for a key.
+ *
+ * To create a key in a specific slot in a secure element, the core
+ * first calls this function to validate the choice of slot number,
+ * then calls a function to create the key material in that slot.
+ * See the documentation of #psa_drv_se_allocate_key_t for more details.
+ *
+ * As of the PSA Cryptography API specification version 1.0, there is no way
+ * for applications to trigger a call to this function. However some
+ * implementations offer the capability to create or declare a key in
+ * a specific slot via implementation-specific means, generally for the
+ * sake of initial device provisioning or onboarding. Such a mechanism may
+ * be added to a future version of the PSA Cryptography API specification.
+ *
+ * This function may update the driver's persistent data through
+ * \p persistent_data. The core will save the updated persistent data at the
+ * end of the key creation process. See the description of
+ * ::psa_drv_se_allocate_key_t for more information.
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in,out] persistent_data A pointer to the persistent data
+ * that allows writing.
+ * \param[in] attributes Attributes of the key.
+ * \param method The way in which the key is being created.
+ * \param[in] key_slot Slot where the key is to be stored.
+ *
+ * \retval #PSA_SUCCESS
+ * The given slot number is valid for a key with the given
+ * attributes.
+ * \retval #PSA_ERROR_INVALID_ARGUMENT
+ * The given slot number is not valid for a key with the
+ * given attributes. This includes the case where the slot
+ * number is not valid at all.
+ * \retval #PSA_ERROR_ALREADY_EXISTS
+ * There is already a key with the specified slot number.
+ * Drivers may choose to return this error from the key
+ * creation function instead.
+ */
+typedef psa_status_t (*psa_drv_se_validate_slot_number_t)(
+ psa_drv_se_context_t *drv_context,
+ void *persistent_data,
+ const psa_key_attributes_t *attributes,
+ psa_key_creation_method_t method,
+ psa_key_slot_number_t key_slot);
+
+/** \brief A function that imports a key into a secure element in binary format
+ *
+ * This function can support any output from psa_export_key(). Refer to the
+ * documentation of psa_export_key() for the format for each key type.
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param key_slot Slot where the key will be stored.
+ * This must be a valid slot for a key of the
+ * chosen type. It must be unoccupied.
+ * \param[in] attributes The key attributes, including the lifetime,
+ * the key type and the usage policy.
+ * Drivers should not access the key size stored
+ * in the attributes: it may not match the
+ * data passed in \p data.
+ * Drivers can call psa_get_key_lifetime(),
+ * psa_get_key_type(),
+ * psa_get_key_usage_flags() and
+ * psa_get_key_algorithm() to access this
+ * information.
+ * \param[in] data Buffer containing the key data.
+ * \param[in] data_length Size of the \p data buffer in bytes.
+ * \param[out] bits On success, the key size in bits. The driver
+ * must determine this value after parsing the
+ * key according to the key type.
+ * This value is not used if the function fails.
+ *
+ * \retval #PSA_SUCCESS
+ * Success.
+ */
+typedef psa_status_t (*psa_drv_se_import_key_t)(
+ psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ const psa_key_attributes_t *attributes,
+ const uint8_t *data,
+ size_t data_length,
+ size_t *bits);
+
+/**
+ * \brief A function that destroys a secure element key and restore the slot to
+ * its default state
+ *
+ * This function destroys the content of the key from a secure element.
+ * Implementations shall make a best effort to ensure that any previous content
+ * of the slot is unrecoverable.
+ *
+ * This function returns the specified slot to its default state.
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in,out] persistent_data A pointer to the persistent data
+ * that allows writing.
+ * \param key_slot The key slot to erase.
+ *
+ * \retval #PSA_SUCCESS
+ * The slot's content, if any, has been erased.
+ */
+typedef psa_status_t (*psa_drv_se_destroy_key_t)(
+ psa_drv_se_context_t *drv_context,
+ void *persistent_data,
+ psa_key_slot_number_t key_slot);
+
+/**
+ * \brief A function that exports a secure element key in binary format
+ *
+ * The output of this function can be passed to psa_import_key() to
+ * create an equivalent object.
+ *
+ * If a key is created with `psa_import_key()` and then exported with
+ * this function, it is not guaranteed that the resulting data is
+ * identical: the implementation may choose a different representation
+ * of the same key if the format permits it.
+ *
+ * This function should generate output in the same format that
+ * `psa_export_key()` does. Refer to the
+ * documentation of `psa_export_key()` for the format for each key type.
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in] key Slot whose content is to be exported. This must
+ * be an occupied key slot.
+ * \param[out] p_data Buffer where the key data is to be written.
+ * \param[in] data_size Size of the `p_data` buffer in bytes.
+ * \param[out] p_data_length On success, the number of bytes
+ * that make up the key data.
+ *
+ * \retval #PSA_SUCCESS
+ * \retval #PSA_ERROR_DOES_NOT_EXIST
+ * \retval #PSA_ERROR_NOT_PERMITTED
+ * \retval #PSA_ERROR_NOT_SUPPORTED
+ * \retval #PSA_ERROR_COMMUNICATION_FAILURE
+ * \retval #PSA_ERROR_HARDWARE_FAILURE
+ * \retval #PSA_ERROR_CORRUPTION_DETECTED
+ */
+typedef psa_status_t (*psa_drv_se_export_key_t)(psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key,
+ uint8_t *p_data,
+ size_t data_size,
+ size_t *p_data_length);
+
+/**
+ * \brief A function that generates a symmetric or asymmetric key on a secure
+ * element
+ *
+ * If the key type \c type recorded in \p attributes
+ * is asymmetric (#PSA_KEY_TYPE_IS_ASYMMETRIC(\c type) = 1),
+ * the driver may export the public key at the time of generation,
+ * in the format documented for psa_export_public_key() by writing it
+ * to the \p pubkey buffer.
+ * This is optional, intended for secure elements that output the
+ * public key at generation time and that cannot export the public key
+ * later. Drivers that do not need this feature should leave
+ * \p *pubkey_length set to 0 and should
+ * implement the psa_drv_key_management_t::p_export_public function.
+ * Some implementations do not support this feature, in which case
+ * \p pubkey is \c NULL and \p pubkey_size is 0.
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param key_slot Slot where the key will be stored.
+ * This must be a valid slot for a key of the
+ * chosen type. It must be unoccupied.
+ * \param[in] attributes The key attributes, including the lifetime,
+ * the key type and size, and the usage policy.
+ * Drivers can call psa_get_key_lifetime(),
+ * psa_get_key_type(), psa_get_key_bits(),
+ * psa_get_key_usage_flags() and
+ * psa_get_key_algorithm() to access this
+ * information.
+ * \param[out] pubkey A buffer where the driver can write the
+ * public key, when generating an asymmetric
+ * key pair.
+ * This is \c NULL when generating a symmetric
+ * key or if the core does not support
+ * exporting the public key at generation time.
+ * \param pubkey_size The size of the `pubkey` buffer in bytes.
+ * This is 0 when generating a symmetric
+ * key or if the core does not support
+ * exporting the public key at generation time.
+ * \param[out] pubkey_length On entry, this is always 0.
+ * On success, the number of bytes written to
+ * \p pubkey. If this is 0 or unchanged on return,
+ * the core will not read the \p pubkey buffer,
+ * and will instead call the driver's
+ * psa_drv_key_management_t::p_export_public
+ * function to export the public key when needed.
+ */
+typedef psa_status_t (*psa_drv_se_generate_key_t)(
+ psa_drv_se_context_t *drv_context,
+ psa_key_slot_number_t key_slot,
+ const psa_key_attributes_t *attributes,
+ uint8_t *pubkey, size_t pubkey_size, size_t *pubkey_length);
+
+/**
+ * \brief A struct containing all of the function pointers needed to for secure
+ * element key management
+ *
+ * PSA Crypto API implementations should populate instances of the table as
+ * appropriate upon startup or at build time.
+ *
+ * If one of the functions is not implemented, it should be set to NULL.
+ */
+typedef struct {
+ /** Function that allocates a slot for a key. */
+ psa_drv_se_allocate_key_t p_allocate;
+ /** Function that checks the validity of a slot for a key. */
+ psa_drv_se_validate_slot_number_t p_validate_slot_number;
+ /** Function that performs a key import operation */
+ psa_drv_se_import_key_t p_import;
+ /** Function that performs a generation */
+ psa_drv_se_generate_key_t p_generate;
+ /** Function that performs a key destroy operation */
+ psa_drv_se_destroy_key_t p_destroy;
+ /** Function that performs a key export operation */
+ psa_drv_se_export_key_t p_export;
+ /** Function that performs a public key export operation */
+ psa_drv_se_export_key_t p_export_public;
+} psa_drv_se_key_management_t;
+
+/**@}*/
+
+/** \defgroup driver_derivation Secure Element Key Derivation and Agreement
+ * Key derivation is the process of generating new key material using an
+ * existing key and additional parameters, iterating through a basic
+ * cryptographic function, such as a hash.
+ * Key agreement is a part of cryptographic protocols that allows two parties
+ * to agree on the same key value, but starting from different original key
+ * material.
+ * The flows are similar, and the PSA Crypto Driver Model uses the same functions
+ * for both of the flows.
+ *
+ * There are two different final functions for the flows,
+ * `psa_drv_se_key_derivation_derive` and `psa_drv_se_key_derivation_export`.
+ * `psa_drv_se_key_derivation_derive` is used when the key material should be
+ * placed in a slot on the hardware and not exposed to the caller.
+ * `psa_drv_se_key_derivation_export` is used when the key material should be
+ * returned to the PSA Cryptographic API implementation.
+ *
+ * Different key derivation algorithms require a different number of inputs.
+ * Instead of having an API that takes as input variable length arrays, which
+ * can be problemmatic to manage on embedded platforms, the inputs are passed
+ * to the driver via a function, `psa_drv_se_key_derivation_collateral`, that
+ * is called multiple times with different `collateral_id`s. Thus, for a key
+ * derivation algorithm that required 3 parameter inputs, the flow would look
+ * something like:
+ * ~~~~~~~~~~~~~{.c}
+ * psa_drv_se_key_derivation_setup(kdf_algorithm, source_key, dest_key_size_bytes);
+ * psa_drv_se_key_derivation_collateral(kdf_algorithm_collateral_id_0,
+ * p_collateral_0,
+ * collateral_0_size);
+ * psa_drv_se_key_derivation_collateral(kdf_algorithm_collateral_id_1,
+ * p_collateral_1,
+ * collateral_1_size);
+ * psa_drv_se_key_derivation_collateral(kdf_algorithm_collateral_id_2,
+ * p_collateral_2,
+ * collateral_2_size);
+ * psa_drv_se_key_derivation_derive();
+ * ~~~~~~~~~~~~~
+ *
+ * key agreement example:
+ * ~~~~~~~~~~~~~{.c}
+ * psa_drv_se_key_derivation_setup(alg, source_key. dest_key_size_bytes);
+ * psa_drv_se_key_derivation_collateral(DHE_PUBKEY, p_pubkey, pubkey_size);
+ * psa_drv_se_key_derivation_export(p_session_key,
+ * session_key_size,
+ * &session_key_length);
+ * ~~~~~~~~~~~~~
+ */
+/**@{*/
+
+/** \brief A function that Sets up a secure element key derivation operation by
+ * specifying the algorithm and the source key sot
+ *
+ * \param[in,out] drv_context The driver context structure.
+ * \param[in,out] op_context A hardware-specific structure containing any
+ * context information for the implementation
+ * \param[in] kdf_alg The algorithm to be used for the key derivation
+ * \param[in] source_key The key to be used as the source material for
+ * the key derivation
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_key_derivation_setup_t)(psa_drv_se_context_t *drv_context,
+ void *op_context,
+ psa_algorithm_t kdf_alg,
+ psa_key_slot_number_t source_key);
+
+/** \brief A function that provides collateral (parameters) needed for a secure
+ * element key derivation or key agreement operation
+ *
+ * Since many key derivation algorithms require multiple parameters, it is
+ * expected that this function may be called multiple times for the same
+ * operation, each with a different algorithm-specific `collateral_id`
+ *
+ * \param[in,out] op_context A hardware-specific structure containing any
+ * context information for the implementation
+ * \param[in] collateral_id An ID for the collateral being provided
+ * \param[in] p_collateral A buffer containing the collateral data
+ * \param[in] collateral_size The size in bytes of the collateral
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_key_derivation_collateral_t)(void *op_context,
+ uint32_t collateral_id,
+ const uint8_t *p_collateral,
+ size_t collateral_size);
+
+/** \brief A function that performs the final secure element key derivation
+ * step and place the generated key material in a slot
+ *
+ * \param[in,out] op_context A hardware-specific structure containing any
+ * context information for the implementation
+ * \param[in] dest_key The slot where the generated key material
+ * should be placed
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_key_derivation_derive_t)(void *op_context,
+ psa_key_slot_number_t dest_key);
+
+/** \brief A function that performs the final step of a secure element key
+ * agreement and place the generated key material in a buffer
+ *
+ * \param[out] p_output Buffer in which to place the generated key
+ * material
+ * \param[in] output_size The size in bytes of `p_output`
+ * \param[out] p_output_length Upon success, contains the number of bytes of
+ * key material placed in `p_output`
+ *
+ * \retval #PSA_SUCCESS
+ */
+typedef psa_status_t (*psa_drv_se_key_derivation_export_t)(void *op_context,
+ uint8_t *p_output,
+ size_t output_size,
+ size_t *p_output_length);
+
+/**
+ * \brief A struct containing all of the function pointers needed to for secure
+ * element key derivation and agreement
+ *
+ * PSA Crypto API implementations should populate instances of the table as
+ * appropriate upon startup.
+ *
+ * If one of the functions is not implemented, it should be set to NULL.
+ */
+typedef struct {
+ /** The driver-specific size of the key derivation context */
+ size_t context_size;
+ /** Function that performs a key derivation setup */
+ psa_drv_se_key_derivation_setup_t p_setup;
+ /** Function that sets key derivation collateral */
+ psa_drv_se_key_derivation_collateral_t p_collateral;
+ /** Function that performs a final key derivation step */
+ psa_drv_se_key_derivation_derive_t p_derive;
+ /** Function that perforsm a final key derivation or agreement and
+ * exports the key */
+ psa_drv_se_key_derivation_export_t p_export;
+} psa_drv_se_key_derivation_t;
+
+/**@}*/
+
+/** \defgroup se_registration Secure element driver registration
+ */
+/**@{*/
+
+/** A structure containing pointers to all the entry points of a
+ * secure element driver.
+ *
+ * Future versions of this specification may add extra substructures at
+ * the end of this structure.
+ */
+typedef struct {
+ /** The version of the driver HAL that this driver implements.
+ * This is a protection against loading driver binaries built against
+ * a different version of this specification.
+ * Use #PSA_DRV_SE_HAL_VERSION.
+ */
+ uint32_t hal_version;
+
+ /** The size of the driver's persistent data in bytes.
+ *
+ * This can be 0 if the driver does not need persistent data.
+ *
+ * See the documentation of psa_drv_se_context_t::persistent_data
+ * for more information about why and how a driver can use
+ * persistent data.
+ */
+ size_t persistent_data_size;
+
+ /** The driver initialization function.
+ *
+ * This function is called once during the initialization of the
+ * PSA Cryptography subsystem, before any other function of the
+ * driver is called. If this function returns a failure status,
+ * the driver will be unusable, at least until the next system reset.
+ *
+ * If this field is \c NULL, it is equivalent to a function that does
+ * nothing and returns #PSA_SUCCESS.
+ */
+ psa_drv_se_init_t p_init;
+
+ const psa_drv_se_key_management_t *key_management;
+ const psa_drv_se_mac_t *mac;
+ const psa_drv_se_cipher_t *cipher;
+ const psa_drv_se_aead_t *aead;
+ const psa_drv_se_asymmetric_t *asymmetric;
+ const psa_drv_se_key_derivation_t *derivation;
+} psa_drv_se_t;
+
+/** The current version of the secure element driver HAL.
+ */
+/* 0.0.0 patchlevel 5 */
+#define PSA_DRV_SE_HAL_VERSION 0x00000005
+
+/** Register an external cryptoprocessor (secure element) driver.
+ *
+ * This function is only intended to be used by driver code, not by
+ * application code. In implementations with separation between the
+ * PSA cryptography module and applications, this function should
+ * only be available to callers that run in the same memory space as
+ * the cryptography module, and should not be exposed to applications
+ * running in a different memory space.
+ *
+ * This function may be called before psa_crypto_init(). It is
+ * implementation-defined whether this function may be called
+ * after psa_crypto_init().
+ *
+ * \note Implementations store metadata about keys including the lifetime
+ * value, which contains the driver's location indicator. Therefore,
+ * from one instantiation of the PSA Cryptography
+ * library to the next one, if there is a key in storage with a certain
+ * lifetime value, you must always register the same driver (or an
+ * updated version that communicates with the same secure element)
+ * with the same location value.
+ *
+ * \param location The location value through which this driver will
+ * be exposed to applications.
+ * This driver will be used for all keys such that
+ * `location == #PSA_KEY_LIFETIME_GET_LOCATION( lifetime )`.
+ * The value #PSA_KEY_LOCATION_LOCAL_STORAGE is reserved
+ * and may not be used for drivers. Implementations
+ * may reserve other values.
+ * \param[in] methods The method table of the driver. This structure must
+ * remain valid for as long as the cryptography
+ * module keeps running. It is typically a global
+ * constant.
+ *
+ * \return #PSA_SUCCESS
+ * The driver was successfully registered. Applications can now
+ * use \p location to access keys through the methods passed to
+ * this function.
+ * \return #PSA_ERROR_BAD_STATE
+ * This function was called after the initialization of the
+ * cryptography module, and this implementation does not support
+ * driver registration at this stage.
+ * \return #PSA_ERROR_ALREADY_EXISTS
+ * There is already a registered driver for this value of \p location.
+ * \return #PSA_ERROR_INVALID_ARGUMENT
+ * \p location is a reserved value.
+ * \return #PSA_ERROR_NOT_SUPPORTED
+ * `methods->hal_version` is not supported by this implementation.
+ * \return #PSA_ERROR_INSUFFICIENT_MEMORY
+ * \return #PSA_ERROR_NOT_PERMITTED
+ * \return #PSA_ERROR_STORAGE_FAILURE
+ * \return #PSA_ERROR_DATA_CORRUPT
+ */
+psa_status_t psa_register_se_driver(
+ psa_key_location_t location,
+ const psa_drv_se_t *methods);
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* PSA_CRYPTO_SE_DRIVER_H */