356 lines
16 KiB
C
356 lines
16 KiB
C
/**
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* \file chachapoly.h
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*
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* \brief This file contains the AEAD-ChaCha20-Poly1305 definitions and
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* functions.
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*
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* ChaCha20-Poly1305 is an algorithm for Authenticated Encryption
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* with Associated Data (AEAD) that can be used to encrypt and
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* authenticate data. It is based on ChaCha20 and Poly1305 by Daniel
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* Bernstein and was standardized in RFC 7539.
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*
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* \author Daniel King <damaki.gh@gmail.com>
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*/
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/* Copyright (C) 2006-2018, Arm Limited (or its affiliates), 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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* This file is part of Mbed TLS (https://tls.mbed.org)
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*/
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#ifndef MBEDTLS_CHACHAPOLY_H
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#define MBEDTLS_CHACHAPOLY_H
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#if !defined(MBEDTLS_CONFIG_FILE)
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#include "config.h"
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#else
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#include MBEDTLS_CONFIG_FILE
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#endif
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/* for shared error codes */
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#include "poly1305.h"
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#define MBEDTLS_ERR_CHACHAPOLY_BAD_STATE -0x0054 /**< The requested operation is not permitted in the current state. */
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#define MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED -0x0056 /**< Authenticated decryption failed: data was not authentic. */
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#ifdef __cplusplus
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extern "C" {
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#endif
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typedef enum
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{
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MBEDTLS_CHACHAPOLY_ENCRYPT, /**< The mode value for performing encryption. */
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MBEDTLS_CHACHAPOLY_DECRYPT /**< The mode value for performing decryption. */
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}
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mbedtls_chachapoly_mode_t;
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#if !defined(MBEDTLS_CHACHAPOLY_ALT)
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#include "chacha20.h"
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typedef struct mbedtls_chachapoly_context
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{
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mbedtls_chacha20_context chacha20_ctx; /**< The ChaCha20 context. */
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mbedtls_poly1305_context poly1305_ctx; /**< The Poly1305 context. */
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uint64_t aad_len; /**< The length (bytes) of the Additional Authenticated Data. */
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uint64_t ciphertext_len; /**< The length (bytes) of the ciphertext. */
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int state; /**< The current state of the context. */
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mbedtls_chachapoly_mode_t mode; /**< Cipher mode (encrypt or decrypt). */
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}
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mbedtls_chachapoly_context;
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#else /* !MBEDTLS_CHACHAPOLY_ALT */
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#include "chachapoly_alt.h"
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#endif /* !MBEDTLS_CHACHAPOLY_ALT */
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/**
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* \brief This function initializes the specified ChaCha20-Poly1305 context.
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*
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* It must be the first API called before using
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* the context. It must be followed by a call to
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* \c mbedtls_chachapoly_setkey() before any operation can be
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* done, and to \c mbedtls_chachapoly_free() once all
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* operations with that context have been finished.
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*
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* In order to encrypt or decrypt full messages at once, for
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* each message you should make a single call to
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* \c mbedtls_chachapoly_crypt_and_tag() or
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* \c mbedtls_chachapoly_auth_decrypt().
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*
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* In order to encrypt messages piecewise, for each
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* message you should make a call to
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* \c mbedtls_chachapoly_starts(), then 0 or more calls to
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* \c mbedtls_chachapoly_update_aad(), then 0 or more calls to
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* \c mbedtls_chachapoly_update(), then one call to
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* \c mbedtls_chachapoly_finish().
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*
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* \warning Decryption with the piecewise API is discouraged! Always
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* use \c mbedtls_chachapoly_auth_decrypt() when possible!
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*
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* If however this is not possible because the data is too
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* large to fit in memory, you need to:
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*
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* - call \c mbedtls_chachapoly_starts() and (if needed)
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* \c mbedtls_chachapoly_update_aad() as above,
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* - call \c mbedtls_chachapoly_update() multiple times and
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* ensure its output (the plaintext) is NOT used in any other
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* way than placing it in temporary storage at this point,
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* - call \c mbedtls_chachapoly_finish() to compute the
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* authentication tag and compared it in constant time to the
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* tag received with the ciphertext.
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*
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* If the tags are not equal, you must immediately discard
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* all previous outputs of \c mbedtls_chachapoly_update(),
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* otherwise you can now safely use the plaintext.
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*
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* \param ctx The ChachaPoly context to initialize.
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*/
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void mbedtls_chachapoly_init( mbedtls_chachapoly_context *ctx );
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/**
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* \brief This function releases and clears the specified ChaCha20-Poly1305 context.
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*
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* \param ctx The ChachaPoly context to clear.
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*/
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void mbedtls_chachapoly_free( mbedtls_chachapoly_context *ctx );
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/**
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* \brief This function sets the ChaCha20-Poly1305 symmetric encryption key.
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*
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* \param ctx The ChaCha20-Poly1305 context to which the key should be
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* bound.
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* \param key The 256-bit (32 bytes) key.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
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* if \p ctx or \p key are NULL.
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*/
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int mbedtls_chachapoly_setkey( mbedtls_chachapoly_context *ctx,
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const unsigned char key[32] );
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/**
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* \brief This function starts a ChaCha20-Poly1305 encryption or
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* decryption operation.
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*
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* \warning You must never use the same nonce twice with the same key.
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* This would void any confidentiality and authenticity
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* guarantees for the messages encrypted with the same nonce
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* and key.
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*
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* \note If the context is being used for AAD only (no data to
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* encrypt or decrypt) then \p mode can be set to any value.
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*
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* \warning Decryption with the piecewise API is discouraged, see the
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* warning on \c mbedtls_chachapoly_init().
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*
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* \param ctx The ChaCha20-Poly1305 context.
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* \param nonce The nonce/IV to use for the message. Must be 12 bytes.
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* \param mode The operation to perform: #MBEDTLS_CHACHAPOLY_ENCRYPT or
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* #MBEDTLS_CHACHAPOLY_DECRYPT (discouraged, see warning).
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
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* if \p ctx or \p mac are NULL.
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*/
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int mbedtls_chachapoly_starts( mbedtls_chachapoly_context *ctx,
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const unsigned char nonce[12],
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mbedtls_chachapoly_mode_t mode );
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/**
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* \brief This function feeds additional data to be authenticated
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* into an ongoing ChaCha20-Poly1305 operation.
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*
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* The Additional Authenticated Data (AAD), also called
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* Associated Data (AD) is only authenticated but not
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* encrypted nor included in the encrypted output. It is
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* usually transmitted separately from the ciphertext or
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* computed locally by each party.
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*
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* \note This function is called before data is encrypted/decrypted.
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* I.e. call this function to process the AAD before calling
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* \c mbedtls_chachapoly_update().
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*
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* You may call this function multiple times to process
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* an arbitrary amount of AAD. It is permitted to call
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* this function 0 times, if no AAD is used.
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*
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* This function cannot be called any more if data has
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* been processed by \c mbedtls_chachapoly_update(),
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* or if the context has been finished.
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*
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* \warning Decryption with the piecewise API is discouraged, see the
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* warning on \c mbedtls_chachapoly_init().
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*
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* \param ctx The ChaCha20-Poly1305 context to use.
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* \param aad_len The length (in bytes) of the AAD. The length has no
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* restrictions.
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* \param aad Buffer containing the AAD.
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* This pointer can be NULL if aad_len == 0.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
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* if \p ctx or \p aad are NULL.
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* \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
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* if the operations has not been started or has been
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* finished, or if the AAD has been finished.
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*/
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int mbedtls_chachapoly_update_aad( mbedtls_chachapoly_context *ctx,
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const unsigned char *aad,
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size_t aad_len );
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/**
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* \brief Thus function feeds data to be encrypted or decrypted
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* into an on-going ChaCha20-Poly1305
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* operation.
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*
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* The direction (encryption or decryption) depends on the
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* mode that was given when calling
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* \c mbedtls_chachapoly_starts().
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*
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* You may call this function multiple times to process
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* an arbitrary amount of data. It is permitted to call
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* this function 0 times, if no data is to be encrypted
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* or decrypted.
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*
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* \warning Decryption with the piecewise API is discouraged, see the
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* warning on \c mbedtls_chachapoly_init().
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*
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* \param ctx The ChaCha20-Poly1305 context to use.
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* \param len The length (in bytes) of the data to encrypt or decrypt.
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* \param input The buffer containing the data to encrypt or decrypt.
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* This pointer can be NULL if len == 0.
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* \param output The buffer to where the encrypted or decrypted data is written.
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* Must be able to hold \p len bytes.
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* This pointer can be NULL if len == 0.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
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* if \p ctx, \p input, or \p output are NULL.
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* \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
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* if the operation has not been started or has been
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* finished.
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*/
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int mbedtls_chachapoly_update( mbedtls_chachapoly_context *ctx,
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size_t len,
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const unsigned char *input,
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unsigned char *output );
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/**
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* \brief This function finished the ChaCha20-Poly1305 operation and
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* generates the MAC (authentication tag).
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*
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* \param ctx The ChaCha20-Poly1305 context to use.
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* \param mac The buffer to where the 128-bit (16 bytes) MAC is written.
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*
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* \warning Decryption with the piecewise API is discouraged, see the
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* warning on \c mbedtls_chachapoly_init().
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
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* if \p ctx or \p mac are NULL.
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* \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
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* if the operation has not been started or has been
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* finished.
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*/
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int mbedtls_chachapoly_finish( mbedtls_chachapoly_context *ctx,
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unsigned char mac[16] );
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/**
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* \brief This function performs a complete ChaCha20-Poly1305
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* authenticated encryption with the previously-set key.
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*
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* \note Before using this function, you must set the key with
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* \c mbedtls_chachapoly_setkey().
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*
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* \warning You must never use the same nonce twice with the same key.
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* This would void any confidentiality and authenticity
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* guarantees for the messages encrypted with the same nonce
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* and key.
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*
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* \param ctx The ChaCha20-Poly1305 context to use (holds the key).
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* \param length The length (in bytes) of the data to encrypt or decrypt.
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* \param nonce The 96-bit (12 bytes) nonce/IV to use.
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* \param aad The buffer containing the additional authenticated data (AAD).
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* This pointer can be NULL if aad_len == 0.
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* \param aad_len The length (in bytes) of the AAD data to process.
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* \param input The buffer containing the data to encrypt or decrypt.
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* This pointer can be NULL if ilen == 0.
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* \param output The buffer to where the encrypted or decrypted data is written.
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* This pointer can be NULL if ilen == 0.
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* \param tag The buffer to where the computed 128-bit (16 bytes) MAC is written.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
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* if one or more of the required parameters are NULL.
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*/
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int mbedtls_chachapoly_encrypt_and_tag( mbedtls_chachapoly_context *ctx,
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size_t length,
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const unsigned char nonce[12],
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const unsigned char *aad,
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size_t aad_len,
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const unsigned char *input,
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unsigned char *output,
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unsigned char tag[16] );
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/**
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* \brief This function performs a complete ChaCha20-Poly1305
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* authenticated decryption with the previously-set key.
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*
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* \note Before using this function, you must set the key with
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* \c mbedtls_chachapoly_setkey().
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*
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* \param ctx The ChaCha20-Poly1305 context to use (holds the key).
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* \param length The length (in bytes) of the data to decrypt.
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* \param nonce The 96-bit (12 bytes) nonce/IV to use.
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* \param aad The buffer containing the additional authenticated data (AAD).
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* This pointer can be NULL if aad_len == 0.
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* \param aad_len The length (in bytes) of the AAD data to process.
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* \param tag The buffer holding the authentication tag.
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* \param input The buffer containing the data to decrypt.
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* This pointer can be NULL if ilen == 0.
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* \param output The buffer to where the decrypted data is written.
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* This pointer can be NULL if ilen == 0.
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*
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* \return \c 0 on success.
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* \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
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* if one or more of the required parameters are NULL.
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* \return #MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED
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* if the data was not authentic.
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*/
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int mbedtls_chachapoly_auth_decrypt( mbedtls_chachapoly_context *ctx,
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size_t length,
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const unsigned char nonce[12],
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const unsigned char *aad,
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size_t aad_len,
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const unsigned char tag[16],
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const unsigned char *input,
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unsigned char *output );
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#if defined(MBEDTLS_SELF_TEST)
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/**
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* \brief The ChaCha20-Poly1305 checkup routine.
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*
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* \return \c 0 on success.
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* \return \c 1 on failure.
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*/
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int mbedtls_chachapoly_self_test( int verbose );
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#endif /* MBEDTLS_SELF_TEST */
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#ifdef __cplusplus
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}
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#endif
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#endif /* MBEDTLS_CHACHAPOLY_H */
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