[398] | 1 | /**
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| 2 | * \file chacha20.h
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| 3 | *
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| 4 | * \brief This file contains ChaCha20 definitions and functions.
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| 5 | *
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| 6 | * ChaCha20 is a stream cipher that can encrypt and decrypt
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| 7 | * information. ChaCha was created by Daniel Bernstein as a variant of
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| 8 | * its Salsa cipher https://cr.yp.to/chacha/chacha-20080128.pdf
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| 9 | * ChaCha20 is the variant with 20 rounds, that was also standardized
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| 10 | * in RFC 7539.
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| 11 | *
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| 12 | * \author Daniel King <damaki.gh@gmail.com>
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| 13 | */
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| 14 |
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| 15 | /* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved.
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| 16 | * SPDX-License-Identifier: Apache-2.0
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| 17 | *
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| 18 | * Licensed under the Apache License, Version 2.0 (the "License"); you may
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| 19 | * not use this file except in compliance with the License.
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| 20 | * You may obtain a copy of the License at
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| 21 | *
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| 22 | * http://www.apache.org/licenses/LICENSE-2.0
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| 23 | *
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| 24 | * Unless required by applicable law or agreed to in writing, software
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| 25 | * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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| 26 | * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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| 27 | * See the License for the specific language governing permissions and
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| 28 | * limitations under the License.
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| 29 | *
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| 30 | * This file is part of Mbed TLS (https://tls.mbed.org)
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| 31 | */
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| 32 |
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| 33 | #ifndef MBEDTLS_CHACHA20_H
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| 34 | #define MBEDTLS_CHACHA20_H
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| 35 |
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| 36 | #if !defined(MBEDTLS_CONFIG_FILE)
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| 37 | #include "config.h"
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| 38 | #else
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| 39 | #include MBEDTLS_CONFIG_FILE
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| 40 | #endif
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| 41 |
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| 42 | #include <stdint.h>
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| 43 | #include <stddef.h>
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| 44 |
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| 45 | #define MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA -0x0051 /**< Invalid input parameter(s). */
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| 46 |
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| 47 | /* MBEDTLS_ERR_CHACHA20_FEATURE_UNAVAILABLE is deprecated and should not be
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| 48 | * used. */
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| 49 | #define MBEDTLS_ERR_CHACHA20_FEATURE_UNAVAILABLE -0x0053 /**< Feature not available. For example, s part of the API is not implemented. */
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| 50 |
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| 51 | /* MBEDTLS_ERR_CHACHA20_HW_ACCEL_FAILED is deprecated and should not be used.
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| 52 | */
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| 53 | #define MBEDTLS_ERR_CHACHA20_HW_ACCEL_FAILED -0x0055 /**< Chacha20 hardware accelerator failed. */
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| 54 |
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| 55 | #ifdef __cplusplus
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| 56 | extern "C" {
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| 57 | #endif
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| 58 |
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| 59 | #if !defined(MBEDTLS_CHACHA20_ALT)
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| 60 |
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| 61 | typedef struct mbedtls_chacha20_context
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| 62 | {
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| 63 | uint32_t state[16]; /*! The state (before round operations). */
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| 64 | uint8_t keystream8[64]; /*! Leftover keystream bytes. */
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| 65 | size_t keystream_bytes_used; /*! Number of keystream bytes already used. */
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| 66 | }
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| 67 | mbedtls_chacha20_context;
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| 68 |
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| 69 | #else /* MBEDTLS_CHACHA20_ALT */
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| 70 | #include "chacha20_alt.h"
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| 71 | #endif /* MBEDTLS_CHACHA20_ALT */
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| 72 |
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| 73 | /**
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| 74 | * \brief This function initializes the specified ChaCha20 context.
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| 75 | *
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| 76 | * It must be the first API called before using
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| 77 | * the context.
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| 78 | *
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| 79 | * It is usually followed by calls to
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| 80 | * \c mbedtls_chacha20_setkey() and
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| 81 | * \c mbedtls_chacha20_starts(), then one or more calls to
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| 82 | * to \c mbedtls_chacha20_update(), and finally to
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| 83 | * \c mbedtls_chacha20_free().
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| 84 | *
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| 85 | * \param ctx The ChaCha20 context to initialize.
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| 86 | * This must not be \c NULL.
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| 87 | */
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| 88 | void mbedtls_chacha20_init( mbedtls_chacha20_context *ctx );
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| 89 |
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| 90 | /**
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| 91 | * \brief This function releases and clears the specified
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| 92 | * ChaCha20 context.
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| 93 | *
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| 94 | * \param ctx The ChaCha20 context to clear. This may be \c NULL,
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| 95 | * in which case this function is a no-op. If it is not
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| 96 | * \c NULL, it must point to an initialized context.
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| 97 | *
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| 98 | */
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| 99 | void mbedtls_chacha20_free( mbedtls_chacha20_context *ctx );
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| 100 |
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| 101 | /**
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| 102 | * \brief This function sets the encryption/decryption key.
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| 103 | *
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| 104 | * \note After using this function, you must also call
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| 105 | * \c mbedtls_chacha20_starts() to set a nonce before you
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| 106 | * start encrypting/decrypting data with
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| 107 | * \c mbedtls_chacha_update().
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| 108 | *
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| 109 | * \param ctx The ChaCha20 context to which the key should be bound.
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| 110 | * It must be initialized.
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| 111 | * \param key The encryption/decryption key. This must be \c 32 Bytes
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| 112 | * in length.
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| 113 | *
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| 114 | * \return \c 0 on success.
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| 115 | * \return #MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA if ctx or key is NULL.
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| 116 | */
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| 117 | int mbedtls_chacha20_setkey( mbedtls_chacha20_context *ctx,
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| 118 | const unsigned char key[32] );
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| 119 |
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| 120 | /**
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| 121 | * \brief This function sets the nonce and initial counter value.
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| 122 | *
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| 123 | * \note A ChaCha20 context can be re-used with the same key by
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| 124 | * calling this function to change the nonce.
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| 125 | *
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| 126 | * \warning You must never use the same nonce twice with the same key.
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| 127 | * This would void any confidentiality guarantees for the
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| 128 | * messages encrypted with the same nonce and key.
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| 129 | *
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| 130 | * \param ctx The ChaCha20 context to which the nonce should be bound.
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| 131 | * It must be initialized and bound to a key.
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| 132 | * \param nonce The nonce. This must be \c 12 Bytes in size.
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| 133 | * \param counter The initial counter value. This is usually \c 0.
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| 134 | *
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| 135 | * \return \c 0 on success.
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| 136 | * \return #MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA if ctx or nonce is
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| 137 | * NULL.
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| 138 | */
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| 139 | int mbedtls_chacha20_starts( mbedtls_chacha20_context* ctx,
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| 140 | const unsigned char nonce[12],
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| 141 | uint32_t counter );
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| 142 |
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| 143 | /**
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| 144 | * \brief This function encrypts or decrypts data.
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| 145 | *
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| 146 | * Since ChaCha20 is a stream cipher, the same operation is
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| 147 | * used for encrypting and decrypting data.
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| 148 | *
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| 149 | * \note The \p input and \p output pointers must either be equal or
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| 150 | * point to non-overlapping buffers.
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| 151 | *
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| 152 | * \note \c mbedtls_chacha20_setkey() and
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| 153 | * \c mbedtls_chacha20_starts() must be called at least once
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| 154 | * to setup the context before this function can be called.
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| 155 | *
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| 156 | * \note This function can be called multiple times in a row in
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| 157 | * order to encrypt of decrypt data piecewise with the same
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| 158 | * key and nonce.
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| 159 | *
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| 160 | * \param ctx The ChaCha20 context to use for encryption or decryption.
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| 161 | * It must be initialized and bound to a key and nonce.
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| 162 | * \param size The length of the input data in Bytes.
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| 163 | * \param input The buffer holding the input data.
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| 164 | * This pointer can be \c NULL if `size == 0`.
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| 165 | * \param output The buffer holding the output data.
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| 166 | * This must be able to hold \p size Bytes.
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| 167 | * This pointer can be \c NULL if `size == 0`.
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| 168 | *
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| 169 | * \return \c 0 on success.
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| 170 | * \return A negative error code on failure.
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| 171 | */
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| 172 | int mbedtls_chacha20_update( mbedtls_chacha20_context *ctx,
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| 173 | size_t size,
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| 174 | const unsigned char *input,
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| 175 | unsigned char *output );
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| 176 |
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| 177 | /**
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| 178 | * \brief This function encrypts or decrypts data with ChaCha20 and
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| 179 | * the given key and nonce.
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| 180 | *
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| 181 | * Since ChaCha20 is a stream cipher, the same operation is
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| 182 | * used for encrypting and decrypting data.
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| 183 | *
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| 184 | * \warning You must never use the same (key, nonce) pair more than
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| 185 | * once. This would void any confidentiality guarantees for
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| 186 | * the messages encrypted with the same nonce and key.
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| 187 | *
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| 188 | * \note The \p input and \p output pointers must either be equal or
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| 189 | * point to non-overlapping buffers.
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| 190 | *
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| 191 | * \param key The encryption/decryption key.
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| 192 | * This must be \c 32 Bytes in length.
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| 193 | * \param nonce The nonce. This must be \c 12 Bytes in size.
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| 194 | * \param counter The initial counter value. This is usually \c 0.
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| 195 | * \param size The length of the input data in Bytes.
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| 196 | * \param input The buffer holding the input data.
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| 197 | * This pointer can be \c NULL if `size == 0`.
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| 198 | * \param output The buffer holding the output data.
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| 199 | * This must be able to hold \p size Bytes.
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| 200 | * This pointer can be \c NULL if `size == 0`.
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| 201 | *
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| 202 | * \return \c 0 on success.
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| 203 | * \return A negative error code on failure.
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| 204 | */
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| 205 | int mbedtls_chacha20_crypt( const unsigned char key[32],
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| 206 | const unsigned char nonce[12],
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| 207 | uint32_t counter,
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| 208 | size_t size,
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| 209 | const unsigned char* input,
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| 210 | unsigned char* output );
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| 211 |
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| 212 | #if defined(MBEDTLS_SELF_TEST)
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| 213 | /**
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| 214 | * \brief The ChaCha20 checkup routine.
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| 215 | *
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| 216 | * \return \c 0 on success.
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| 217 | * \return \c 1 on failure.
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| 218 | */
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| 219 | int mbedtls_chacha20_self_test( int verbose );
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| 220 | #endif /* MBEDTLS_SELF_TEST */
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| 221 |
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| 222 | #ifdef __cplusplus
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| 223 | }
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| 224 | #endif
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| 225 |
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| 226 | #endif /* MBEDTLS_CHACHA20_H */
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