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109 lines
4.2 KiB
C
109 lines
4.2 KiB
C
/**
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* \file psa/crypto_entropy_driver.h
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* \brief PSA entropy source driver module
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*
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* This header declares types and function signatures for entropy sources.
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*
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* This file is part of the PSA Crypto Driver Model, containing functions for
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* driver developers to implement to enable hardware to be called in a
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* standardized way by a PSA Cryptographic API implementation. The functions
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* comprising the driver model, which driver authors implement, are not
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* intended to be called by application developers.
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*/
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/*
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* Copyright (C) 2018, ARM Limited, All Rights Reserved
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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_ENTROPY_DRIVER_H
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#define PSA_CRYPTO_ENTROPY_DRIVER_H
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#include "crypto_driver_common.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/** \defgroup driver_rng Entropy Generation
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*/
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/**@{*/
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/** \brief Initialize an entropy driver
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*
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*
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* \param[in,out] p_context A hardware-specific structure
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* containing any context information for
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* the implementation
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*
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* \retval PSA_SUCCESS
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*/
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typedef psa_status_t (*psa_drv_entropy_init_t)(void *p_context);
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/** \brief Get a specified number of bits from the entropy source
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*
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* It retrives `buffer_size` bytes of data from the entropy source. The entropy
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* source will always fill the provided buffer to its full size, however, most
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* entropy sources have biases, and the actual amount of entropy contained in
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* the buffer will be less than the number of bytes.
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* The driver will return the actual number of bytes of entropy placed in the
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* buffer in `p_received_entropy_bytes`.
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* A PSA Crypto API implementation will likely feed the output of this function
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* into a Digital Random Bit Generator (DRBG), and typically has a minimum
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* amount of entropy that it needs.
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* To accomplish this, the PSA Crypto implementation should be designed to call
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* this function multiple times until it has received the required amount of
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* entropy from the entropy source.
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*
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* \param[in,out] p_context A hardware-specific structure
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* containing any context information
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* for the implementation
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* \param[out] p_buffer A caller-allocated buffer for the
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* retrieved entropy to be placed in
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* \param[in] buffer_size The allocated size of `p_buffer`
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* \param[out] p_received_entropy_bits The amount of entropy (in bits)
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* actually provided in `p_buffer`
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*
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* \retval PSA_SUCCESS
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*/
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typedef psa_status_t (*psa_drv_entropy_get_bits_t)(void *p_context,
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uint8_t *p_buffer,
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uint32_t buffer_size,
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uint32_t *p_received_entropy_bits);
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/**
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* \brief A struct containing all of the function pointers needed to interface
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* to an entropy source
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*
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* PSA Crypto API implementations should populate instances of the table as
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* appropriate upon startup.
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*
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* If one of the functions is not implemented, it should be set to NULL.
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*/
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typedef struct {
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/** The driver-specific size of the entropy context */
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const size_t context_size;
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/** Function that performs initialization for the entropy source */
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psa_drv_entropy_init_t p_init;
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/** Function that performs the get_bits operation for the entropy source */
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psa_drv_entropy_get_bits_t p_get_bits;
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} psa_drv_entropy_t;
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/**@}*/
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#ifdef __cplusplus
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}
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#endif
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#endif /* PSA_CRYPTO_ENTROPY_DRIVER_H */
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