[398] | 1 | /**
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| 2 | * \file chachapoly.h
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| 3 | *
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| 4 | * \brief This file contains the AEAD-ChaCha20-Poly1305 definitions and
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| 5 | * functions.
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| 6 | *
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| 7 | * ChaCha20-Poly1305 is an algorithm for Authenticated Encryption
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| 8 | * with Associated Data (AEAD) that can be used to encrypt and
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| 9 | * authenticate data. It is based on ChaCha20 and Poly1305 by Daniel
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| 10 | * Bernstein and was standardized 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_CHACHAPOLY_H
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| 34 | #define MBEDTLS_CHACHAPOLY_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 | /* for shared error codes */
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| 43 | #include "poly1305.h"
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| 44 |
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| 45 | #define MBEDTLS_ERR_CHACHAPOLY_BAD_STATE -0x0054 /**< The requested operation is not permitted in the current state. */
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| 46 | #define MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED -0x0056 /**< Authenticated decryption failed: data was not authentic. */
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| 47 |
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| 48 | #ifdef __cplusplus
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| 49 | extern "C" {
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| 50 | #endif
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| 51 |
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| 52 | typedef enum
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| 53 | {
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| 54 | MBEDTLS_CHACHAPOLY_ENCRYPT, /**< The mode value for performing encryption. */
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| 55 | MBEDTLS_CHACHAPOLY_DECRYPT /**< The mode value for performing decryption. */
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| 56 | }
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| 57 | mbedtls_chachapoly_mode_t;
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| 58 |
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| 59 | #if !defined(MBEDTLS_CHACHAPOLY_ALT)
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| 60 |
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| 61 | #include "chacha20.h"
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| 62 |
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| 63 | typedef struct mbedtls_chachapoly_context
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| 64 | {
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| 65 | mbedtls_chacha20_context chacha20_ctx; /**< The ChaCha20 context. */
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| 66 | mbedtls_poly1305_context poly1305_ctx; /**< The Poly1305 context. */
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| 67 | uint64_t aad_len; /**< The length (bytes) of the Additional Authenticated Data. */
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| 68 | uint64_t ciphertext_len; /**< The length (bytes) of the ciphertext. */
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| 69 | int state; /**< The current state of the context. */
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| 70 | mbedtls_chachapoly_mode_t mode; /**< Cipher mode (encrypt or decrypt). */
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| 71 | }
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| 72 | mbedtls_chachapoly_context;
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| 73 |
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| 74 | #else /* !MBEDTLS_CHACHAPOLY_ALT */
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| 75 | #include "chachapoly_alt.h"
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| 76 | #endif /* !MBEDTLS_CHACHAPOLY_ALT */
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| 77 |
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| 78 | /**
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| 79 | * \brief This function initializes the specified ChaCha20-Poly1305 context.
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| 80 | *
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| 81 | * It must be the first API called before using
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| 82 | * the context. It must be followed by a call to
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| 83 | * \c mbedtls_chachapoly_setkey() before any operation can be
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| 84 | * done, and to \c mbedtls_chachapoly_free() once all
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| 85 | * operations with that context have been finished.
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| 86 | *
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| 87 | * In order to encrypt or decrypt full messages at once, for
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| 88 | * each message you should make a single call to
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| 89 | * \c mbedtls_chachapoly_crypt_and_tag() or
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| 90 | * \c mbedtls_chachapoly_auth_decrypt().
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| 91 | *
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| 92 | * In order to encrypt messages piecewise, for each
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| 93 | * message you should make a call to
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| 94 | * \c mbedtls_chachapoly_starts(), then 0 or more calls to
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| 95 | * \c mbedtls_chachapoly_update_aad(), then 0 or more calls to
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| 96 | * \c mbedtls_chachapoly_update(), then one call to
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| 97 | * \c mbedtls_chachapoly_finish().
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| 98 | *
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| 99 | * \warning Decryption with the piecewise API is discouraged! Always
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| 100 | * use \c mbedtls_chachapoly_auth_decrypt() when possible!
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| 101 | *
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| 102 | * If however this is not possible because the data is too
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| 103 | * large to fit in memory, you need to:
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| 104 | *
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| 105 | * - call \c mbedtls_chachapoly_starts() and (if needed)
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| 106 | * \c mbedtls_chachapoly_update_aad() as above,
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| 107 | * - call \c mbedtls_chachapoly_update() multiple times and
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| 108 | * ensure its output (the plaintext) is NOT used in any other
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| 109 | * way than placing it in temporary storage at this point,
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| 110 | * - call \c mbedtls_chachapoly_finish() to compute the
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| 111 | * authentication tag and compared it in constant time to the
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| 112 | * tag received with the ciphertext.
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| 113 | *
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| 114 | * If the tags are not equal, you must immediately discard
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| 115 | * all previous outputs of \c mbedtls_chachapoly_update(),
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| 116 | * otherwise you can now safely use the plaintext.
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| 117 | *
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| 118 | * \param ctx The ChachaPoly context to initialize. Must not be \c NULL.
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| 119 | */
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| 120 | void mbedtls_chachapoly_init( mbedtls_chachapoly_context *ctx );
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| 121 |
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| 122 | /**
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| 123 | * \brief This function releases and clears the specified
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| 124 | * ChaCha20-Poly1305 context.
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| 125 | *
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| 126 | * \param ctx The ChachaPoly context to clear. This may be \c NULL, in which
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| 127 | * case this function is a no-op.
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| 128 | */
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| 129 | void mbedtls_chachapoly_free( mbedtls_chachapoly_context *ctx );
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| 130 |
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| 131 | /**
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| 132 | * \brief This function sets the ChaCha20-Poly1305
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| 133 | * symmetric encryption key.
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| 134 | *
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| 135 | * \param ctx The ChaCha20-Poly1305 context to which the key should be
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| 136 | * bound. This must be initialized.
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| 137 | * \param key The \c 256 Bit (\c 32 Bytes) key.
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| 138 | *
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| 139 | * \return \c 0 on success.
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| 140 | * \return A negative error code on failure.
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| 141 | */
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| 142 | int mbedtls_chachapoly_setkey( mbedtls_chachapoly_context *ctx,
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| 143 | const unsigned char key[32] );
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| 144 |
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| 145 | /**
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| 146 | * \brief This function starts a ChaCha20-Poly1305 encryption or
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| 147 | * decryption operation.
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| 148 | *
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| 149 | * \warning You must never use the same nonce twice with the same key.
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| 150 | * This would void any confidentiality and authenticity
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| 151 | * guarantees for the messages encrypted with the same nonce
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| 152 | * and key.
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| 153 | *
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| 154 | * \note If the context is being used for AAD only (no data to
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| 155 | * encrypt or decrypt) then \p mode can be set to any value.
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| 156 | *
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| 157 | * \warning Decryption with the piecewise API is discouraged, see the
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| 158 | * warning on \c mbedtls_chachapoly_init().
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| 159 | *
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| 160 | * \param ctx The ChaCha20-Poly1305 context. This must be initialized
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| 161 | * and bound to a key.
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| 162 | * \param nonce The nonce/IV to use for the message.
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| 163 | * This must be a redable buffer of length \c 12 Bytes.
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| 164 | * \param mode The operation to perform: #MBEDTLS_CHACHAPOLY_ENCRYPT or
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| 165 | * #MBEDTLS_CHACHAPOLY_DECRYPT (discouraged, see warning).
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| 166 | *
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| 167 | * \return \c 0 on success.
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| 168 | * \return A negative error code on failure.
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| 169 | */
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| 170 | int mbedtls_chachapoly_starts( mbedtls_chachapoly_context *ctx,
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| 171 | const unsigned char nonce[12],
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| 172 | mbedtls_chachapoly_mode_t mode );
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| 173 |
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| 174 | /**
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| 175 | * \brief This function feeds additional data to be authenticated
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| 176 | * into an ongoing ChaCha20-Poly1305 operation.
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| 177 | *
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| 178 | * The Additional Authenticated Data (AAD), also called
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| 179 | * Associated Data (AD) is only authenticated but not
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| 180 | * encrypted nor included in the encrypted output. It is
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| 181 | * usually transmitted separately from the ciphertext or
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| 182 | * computed locally by each party.
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| 183 | *
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| 184 | * \note This function is called before data is encrypted/decrypted.
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| 185 | * I.e. call this function to process the AAD before calling
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| 186 | * \c mbedtls_chachapoly_update().
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| 187 | *
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| 188 | * You may call this function multiple times to process
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| 189 | * an arbitrary amount of AAD. It is permitted to call
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| 190 | * this function 0 times, if no AAD is used.
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| 191 | *
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| 192 | * This function cannot be called any more if data has
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| 193 | * been processed by \c mbedtls_chachapoly_update(),
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| 194 | * or if the context has been finished.
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| 195 | *
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| 196 | * \warning Decryption with the piecewise API is discouraged, see the
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| 197 | * warning on \c mbedtls_chachapoly_init().
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| 198 | *
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| 199 | * \param ctx The ChaCha20-Poly1305 context. This must be initialized
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| 200 | * and bound to a key.
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| 201 | * \param aad_len The length in Bytes of the AAD. The length has no
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| 202 | * restrictions.
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| 203 | * \param aad Buffer containing the AAD.
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| 204 | * This pointer can be \c NULL if `aad_len == 0`.
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| 205 | *
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| 206 | * \return \c 0 on success.
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| 207 | * \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
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| 208 | * if \p ctx or \p aad are NULL.
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| 209 | * \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
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| 210 | * if the operations has not been started or has been
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| 211 | * finished, or if the AAD has been finished.
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| 212 | */
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| 213 | int mbedtls_chachapoly_update_aad( mbedtls_chachapoly_context *ctx,
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| 214 | const unsigned char *aad,
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| 215 | size_t aad_len );
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| 216 |
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| 217 | /**
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| 218 | * \brief Thus function feeds data to be encrypted or decrypted
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| 219 | * into an on-going ChaCha20-Poly1305
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| 220 | * operation.
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| 221 | *
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| 222 | * The direction (encryption or decryption) depends on the
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| 223 | * mode that was given when calling
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| 224 | * \c mbedtls_chachapoly_starts().
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| 225 | *
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| 226 | * You may call this function multiple times to process
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| 227 | * an arbitrary amount of data. It is permitted to call
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| 228 | * this function 0 times, if no data is to be encrypted
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| 229 | * or decrypted.
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| 230 | *
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| 231 | * \warning Decryption with the piecewise API is discouraged, see the
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| 232 | * warning on \c mbedtls_chachapoly_init().
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| 233 | *
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| 234 | * \param ctx The ChaCha20-Poly1305 context to use. This must be initialized.
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| 235 | * \param len The length (in bytes) of the data to encrypt or decrypt.
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| 236 | * \param input The buffer containing the data to encrypt or decrypt.
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| 237 | * This pointer can be \c NULL if `len == 0`.
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| 238 | * \param output The buffer to where the encrypted or decrypted data is
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| 239 | * written. This must be able to hold \p len bytes.
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| 240 | * This pointer can be \c NULL if `len == 0`.
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| 241 | *
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| 242 | * \return \c 0 on success.
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| 243 | * \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
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| 244 | * if the operation has not been started or has been
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| 245 | * finished.
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| 246 | * \return Another negative error code on other kinds of failure.
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| 247 | */
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| 248 | int mbedtls_chachapoly_update( mbedtls_chachapoly_context *ctx,
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| 249 | size_t len,
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| 250 | const unsigned char *input,
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| 251 | unsigned char *output );
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| 252 |
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| 253 | /**
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| 254 | * \brief This function finished the ChaCha20-Poly1305 operation and
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| 255 | * generates the MAC (authentication tag).
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| 256 | *
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| 257 | * \param ctx The ChaCha20-Poly1305 context to use. This must be initialized.
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| 258 | * \param mac The buffer to where the 128-bit (16 bytes) MAC is written.
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| 259 | *
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| 260 | * \warning Decryption with the piecewise API is discouraged, see the
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| 261 | * warning on \c mbedtls_chachapoly_init().
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| 262 | *
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| 263 | * \return \c 0 on success.
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| 264 | * \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
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| 265 | * if the operation has not been started or has been
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| 266 | * finished.
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| 267 | * \return Another negative error code on other kinds of failure.
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| 268 | */
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| 269 | int mbedtls_chachapoly_finish( mbedtls_chachapoly_context *ctx,
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| 270 | unsigned char mac[16] );
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| 271 |
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| 272 | /**
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| 273 | * \brief This function performs a complete ChaCha20-Poly1305
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| 274 | * authenticated encryption with the previously-set key.
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| 275 | *
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| 276 | * \note Before using this function, you must set the key with
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| 277 | * \c mbedtls_chachapoly_setkey().
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| 278 | *
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| 279 | * \warning You must never use the same nonce twice with the same key.
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| 280 | * This would void any confidentiality and authenticity
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| 281 | * guarantees for the messages encrypted with the same nonce
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| 282 | * and key.
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| 283 | *
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| 284 | * \param ctx The ChaCha20-Poly1305 context to use (holds the key).
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| 285 | * This must be initialized.
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| 286 | * \param length The length (in bytes) of the data to encrypt or decrypt.
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| 287 | * \param nonce The 96-bit (12 bytes) nonce/IV to use.
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| 288 | * \param aad The buffer containing the additional authenticated
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| 289 | * data (AAD). This pointer can be \c NULL if `aad_len == 0`.
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| 290 | * \param aad_len The length (in bytes) of the AAD data to process.
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| 291 | * \param input The buffer containing the data to encrypt or decrypt.
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| 292 | * This pointer can be \c NULL if `ilen == 0`.
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| 293 | * \param output The buffer to where the encrypted or decrypted data
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| 294 | * is written. This pointer can be \c NULL if `ilen == 0`.
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| 295 | * \param tag The buffer to where the computed 128-bit (16 bytes) MAC
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| 296 | * is written. This must not be \c NULL.
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| 297 | *
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| 298 | * \return \c 0 on success.
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| 299 | * \return A negative error code on failure.
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| 300 | */
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| 301 | int mbedtls_chachapoly_encrypt_and_tag( mbedtls_chachapoly_context *ctx,
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| 302 | size_t length,
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| 303 | const unsigned char nonce[12],
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| 304 | const unsigned char *aad,
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| 305 | size_t aad_len,
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| 306 | const unsigned char *input,
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| 307 | unsigned char *output,
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| 308 | unsigned char tag[16] );
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| 309 |
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| 310 | /**
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| 311 | * \brief This function performs a complete ChaCha20-Poly1305
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| 312 | * authenticated decryption with the previously-set key.
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| 313 | *
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| 314 | * \note Before using this function, you must set the key with
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| 315 | * \c mbedtls_chachapoly_setkey().
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| 316 | *
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| 317 | * \param ctx The ChaCha20-Poly1305 context to use (holds the key).
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| 318 | * \param length The length (in Bytes) of the data to decrypt.
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| 319 | * \param nonce The \c 96 Bit (\c 12 bytes) nonce/IV to use.
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| 320 | * \param aad The buffer containing the additional authenticated data (AAD).
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| 321 | * This pointer can be \c NULL if `aad_len == 0`.
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| 322 | * \param aad_len The length (in bytes) of the AAD data to process.
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| 323 | * \param tag The buffer holding the authentication tag.
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| 324 | * This must be a readable buffer of length \c 16 Bytes.
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| 325 | * \param input The buffer containing the data to decrypt.
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| 326 | * This pointer can be \c NULL if `ilen == 0`.
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| 327 | * \param output The buffer to where the decrypted data is written.
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| 328 | * This pointer can be \c NULL if `ilen == 0`.
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| 329 | *
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| 330 | * \return \c 0 on success.
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| 331 | * \return #MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED
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| 332 | * if the data was not authentic.
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| 333 | * \return Another negative error code on other kinds of failure.
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| 334 | */
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| 335 | int mbedtls_chachapoly_auth_decrypt( mbedtls_chachapoly_context *ctx,
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| 336 | size_t length,
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| 337 | const unsigned char nonce[12],
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| 338 | const unsigned char *aad,
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| 339 | size_t aad_len,
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| 340 | const unsigned char tag[16],
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| 341 | const unsigned char *input,
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| 342 | unsigned char *output );
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| 343 |
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| 344 | #if defined(MBEDTLS_SELF_TEST)
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| 345 | /**
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| 346 | * \brief The ChaCha20-Poly1305 checkup routine.
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| 347 | *
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| 348 | * \return \c 0 on success.
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| 349 | * \return \c 1 on failure.
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| 350 | */
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| 351 | int mbedtls_chachapoly_self_test( int verbose );
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| 352 | #endif /* MBEDTLS_SELF_TEST */
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| 353 |
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| 354 | #ifdef __cplusplus
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| 355 | }
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| 356 | #endif
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| 357 |
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| 358 | #endif /* MBEDTLS_CHACHAPOLY_H */
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