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- /**
- * \file chachapoly.h
- *
- * \brief This file contains the AEAD-ChaCha20-Poly1305 definitions and
- * functions.
- *
- * ChaCha20-Poly1305 is an algorithm for Authenticated Encryption
- * with Associated Data (AEAD) that can be used to encrypt and
- * authenticate data. It is based on ChaCha20 and Poly1305 by Daniel
- * Bernstein and was standardized in RFC 7539.
- *
- * \author Daniel King <damaki.gh@gmail.com>
- */
- /* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved.
- * SPDX-License-Identifier: Apache-2.0
- *
- * Licensed under the Apache License, Version 2.0 (the "License"); you may
- * not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
- * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- *
- * This file is part of Mbed TLS (https://tls.mbed.org)
- */
- #ifndef MBEDTLS_CHACHAPOLY_H
- #define MBEDTLS_CHACHAPOLY_H
- #if !defined(MBEDTLS_CONFIG_FILE)
- #include "config.h"
- #else
- #include MBEDTLS_CONFIG_FILE
- #endif
- /* for shared error codes */
- #include "poly1305.h"
- #define MBEDTLS_ERR_CHACHAPOLY_BAD_STATE -0x0054 /**< The requested operation is not permitted in the current state. */
- #define MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED -0x0056 /**< Authenticated decryption failed: data was not authentic. */
- #ifdef __cplusplus
- extern "C" {
- #endif
- typedef enum
- {
- MBEDTLS_CHACHAPOLY_ENCRYPT, /**< The mode value for performing encryption. */
- MBEDTLS_CHACHAPOLY_DECRYPT /**< The mode value for performing decryption. */
- }
- mbedtls_chachapoly_mode_t;
- #if !defined(MBEDTLS_CHACHAPOLY_ALT)
- #include "chacha20.h"
- typedef struct mbedtls_chachapoly_context
- {
- mbedtls_chacha20_context chacha20_ctx; /**< The ChaCha20 context. */
- mbedtls_poly1305_context poly1305_ctx; /**< The Poly1305 context. */
- uint64_t aad_len; /**< The length (bytes) of the Additional Authenticated Data. */
- uint64_t ciphertext_len; /**< The length (bytes) of the ciphertext. */
- int state; /**< The current state of the context. */
- mbedtls_chachapoly_mode_t mode; /**< Cipher mode (encrypt or decrypt). */
- }
- mbedtls_chachapoly_context;
- #else /* !MBEDTLS_CHACHAPOLY_ALT */
- #include "chachapoly_alt.h"
- #endif /* !MBEDTLS_CHACHAPOLY_ALT */
- /**
- * \brief This function initializes the specified ChaCha20-Poly1305 context.
- *
- * It must be the first API called before using
- * the context. It must be followed by a call to
- * \c mbedtls_chachapoly_setkey() before any operation can be
- * done, and to \c mbedtls_chachapoly_free() once all
- * operations with that context have been finished.
- *
- * In order to encrypt or decrypt full messages at once, for
- * each message you should make a single call to
- * \c mbedtls_chachapoly_crypt_and_tag() or
- * \c mbedtls_chachapoly_auth_decrypt().
- *
- * In order to encrypt messages piecewise, for each
- * message you should make a call to
- * \c mbedtls_chachapoly_starts(), then 0 or more calls to
- * \c mbedtls_chachapoly_update_aad(), then 0 or more calls to
- * \c mbedtls_chachapoly_update(), then one call to
- * \c mbedtls_chachapoly_finish().
- *
- * \warning Decryption with the piecewise API is discouraged! Always
- * use \c mbedtls_chachapoly_auth_decrypt() when possible!
- *
- * If however this is not possible because the data is too
- * large to fit in memory, you need to:
- *
- * - call \c mbedtls_chachapoly_starts() and (if needed)
- * \c mbedtls_chachapoly_update_aad() as above,
- * - call \c mbedtls_chachapoly_update() multiple times and
- * ensure its output (the plaintext) is NOT used in any other
- * way than placing it in temporary storage at this point,
- * - call \c mbedtls_chachapoly_finish() to compute the
- * authentication tag and compared it in constant time to the
- * tag received with the ciphertext.
- *
- * If the tags are not equal, you must immediately discard
- * all previous outputs of \c mbedtls_chachapoly_update(),
- * otherwise you can now safely use the plaintext.
- *
- * \param ctx The ChachaPoly context to initialize. Must not be \c NULL.
- */
- void mbedtls_chachapoly_init( mbedtls_chachapoly_context *ctx );
- /**
- * \brief This function releases and clears the specified
- * ChaCha20-Poly1305 context.
- *
- * \param ctx The ChachaPoly context to clear. This may be \c NULL, in which
- * case this function is a no-op.
- */
- void mbedtls_chachapoly_free( mbedtls_chachapoly_context *ctx );
- /**
- * \brief This function sets the ChaCha20-Poly1305
- * symmetric encryption key.
- *
- * \param ctx The ChaCha20-Poly1305 context to which the key should be
- * bound. This must be initialized.
- * \param key The \c 256 Bit (\c 32 Bytes) key.
- *
- * \return \c 0 on success.
- * \return A negative error code on failure.
- */
- int mbedtls_chachapoly_setkey( mbedtls_chachapoly_context *ctx,
- const unsigned char key[32] );
- /**
- * \brief This function starts a ChaCha20-Poly1305 encryption or
- * decryption operation.
- *
- * \warning You must never use the same nonce twice with the same key.
- * This would void any confidentiality and authenticity
- * guarantees for the messages encrypted with the same nonce
- * and key.
- *
- * \note If the context is being used for AAD only (no data to
- * encrypt or decrypt) then \p mode can be set to any value.
- *
- * \warning Decryption with the piecewise API is discouraged, see the
- * warning on \c mbedtls_chachapoly_init().
- *
- * \param ctx The ChaCha20-Poly1305 context. This must be initialized
- * and bound to a key.
- * \param nonce The nonce/IV to use for the message.
- * This must be a redable buffer of length \c 12 Bytes.
- * \param mode The operation to perform: #MBEDTLS_CHACHAPOLY_ENCRYPT or
- * #MBEDTLS_CHACHAPOLY_DECRYPT (discouraged, see warning).
- *
- * \return \c 0 on success.
- * \return A negative error code on failure.
- */
- int mbedtls_chachapoly_starts( mbedtls_chachapoly_context *ctx,
- const unsigned char nonce[12],
- mbedtls_chachapoly_mode_t mode );
- /**
- * \brief This function feeds additional data to be authenticated
- * into an ongoing ChaCha20-Poly1305 operation.
- *
- * The Additional Authenticated Data (AAD), also called
- * Associated Data (AD) is only authenticated but not
- * encrypted nor included in the encrypted output. It is
- * usually transmitted separately from the ciphertext or
- * computed locally by each party.
- *
- * \note This function is called before data is encrypted/decrypted.
- * I.e. call this function to process the AAD before calling
- * \c mbedtls_chachapoly_update().
- *
- * You may call this function multiple times to process
- * an arbitrary amount of AAD. It is permitted to call
- * this function 0 times, if no AAD is used.
- *
- * This function cannot be called any more if data has
- * been processed by \c mbedtls_chachapoly_update(),
- * or if the context has been finished.
- *
- * \warning Decryption with the piecewise API is discouraged, see the
- * warning on \c mbedtls_chachapoly_init().
- *
- * \param ctx The ChaCha20-Poly1305 context. This must be initialized
- * and bound to a key.
- * \param aad_len The length in Bytes of the AAD. The length has no
- * restrictions.
- * \param aad Buffer containing the AAD.
- * This pointer can be \c NULL if `aad_len == 0`.
- *
- * \return \c 0 on success.
- * \return #MBEDTLS_ERR_POLY1305_BAD_INPUT_DATA
- * if \p ctx or \p aad are NULL.
- * \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
- * if the operations has not been started or has been
- * finished, or if the AAD has been finished.
- */
- int mbedtls_chachapoly_update_aad( mbedtls_chachapoly_context *ctx,
- const unsigned char *aad,
- size_t aad_len );
- /**
- * \brief Thus function feeds data to be encrypted or decrypted
- * into an on-going ChaCha20-Poly1305
- * operation.
- *
- * The direction (encryption or decryption) depends on the
- * mode that was given when calling
- * \c mbedtls_chachapoly_starts().
- *
- * You may call this function multiple times to process
- * an arbitrary amount of data. It is permitted to call
- * this function 0 times, if no data is to be encrypted
- * or decrypted.
- *
- * \warning Decryption with the piecewise API is discouraged, see the
- * warning on \c mbedtls_chachapoly_init().
- *
- * \param ctx The ChaCha20-Poly1305 context to use. This must be initialized.
- * \param len The length (in bytes) of the data to encrypt or decrypt.
- * \param input The buffer containing the data to encrypt or decrypt.
- * This pointer can be \c NULL if `len == 0`.
- * \param output The buffer to where the encrypted or decrypted data is
- * written. This must be able to hold \p len bytes.
- * This pointer can be \c NULL if `len == 0`.
- *
- * \return \c 0 on success.
- * \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
- * if the operation has not been started or has been
- * finished.
- * \return Another negative error code on other kinds of failure.
- */
- int mbedtls_chachapoly_update( mbedtls_chachapoly_context *ctx,
- size_t len,
- const unsigned char *input,
- unsigned char *output );
- /**
- * \brief This function finished the ChaCha20-Poly1305 operation and
- * generates the MAC (authentication tag).
- *
- * \param ctx The ChaCha20-Poly1305 context to use. This must be initialized.
- * \param mac The buffer to where the 128-bit (16 bytes) MAC is written.
- *
- * \warning Decryption with the piecewise API is discouraged, see the
- * warning on \c mbedtls_chachapoly_init().
- *
- * \return \c 0 on success.
- * \return #MBEDTLS_ERR_CHACHAPOLY_BAD_STATE
- * if the operation has not been started or has been
- * finished.
- * \return Another negative error code on other kinds of failure.
- */
- int mbedtls_chachapoly_finish( mbedtls_chachapoly_context *ctx,
- unsigned char mac[16] );
- /**
- * \brief This function performs a complete ChaCha20-Poly1305
- * authenticated encryption with the previously-set key.
- *
- * \note Before using this function, you must set the key with
- * \c mbedtls_chachapoly_setkey().
- *
- * \warning You must never use the same nonce twice with the same key.
- * This would void any confidentiality and authenticity
- * guarantees for the messages encrypted with the same nonce
- * and key.
- *
- * \param ctx The ChaCha20-Poly1305 context to use (holds the key).
- * This must be initialized.
- * \param length The length (in bytes) of the data to encrypt or decrypt.
- * \param nonce The 96-bit (12 bytes) nonce/IV to use.
- * \param aad The buffer containing the additional authenticated
- * data (AAD). This pointer can be \c NULL if `aad_len == 0`.
- * \param aad_len The length (in bytes) of the AAD data to process.
- * \param input The buffer containing the data to encrypt or decrypt.
- * This pointer can be \c NULL if `ilen == 0`.
- * \param output The buffer to where the encrypted or decrypted data
- * is written. This pointer can be \c NULL if `ilen == 0`.
- * \param tag The buffer to where the computed 128-bit (16 bytes) MAC
- * is written. This must not be \c NULL.
- *
- * \return \c 0 on success.
- * \return A negative error code on failure.
- */
- int mbedtls_chachapoly_encrypt_and_tag( mbedtls_chachapoly_context *ctx,
- size_t length,
- const unsigned char nonce[12],
- const unsigned char *aad,
- size_t aad_len,
- const unsigned char *input,
- unsigned char *output,
- unsigned char tag[16] );
- /**
- * \brief This function performs a complete ChaCha20-Poly1305
- * authenticated decryption with the previously-set key.
- *
- * \note Before using this function, you must set the key with
- * \c mbedtls_chachapoly_setkey().
- *
- * \param ctx The ChaCha20-Poly1305 context to use (holds the key).
- * \param length The length (in Bytes) of the data to decrypt.
- * \param nonce The \c 96 Bit (\c 12 bytes) nonce/IV to use.
- * \param aad The buffer containing the additional authenticated data (AAD).
- * This pointer can be \c NULL if `aad_len == 0`.
- * \param aad_len The length (in bytes) of the AAD data to process.
- * \param tag The buffer holding the authentication tag.
- * This must be a readable buffer of length \c 16 Bytes.
- * \param input The buffer containing the data to decrypt.
- * This pointer can be \c NULL if `ilen == 0`.
- * \param output The buffer to where the decrypted data is written.
- * This pointer can be \c NULL if `ilen == 0`.
- *
- * \return \c 0 on success.
- * \return #MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED
- * if the data was not authentic.
- * \return Another negative error code on other kinds of failure.
- */
- int mbedtls_chachapoly_auth_decrypt( mbedtls_chachapoly_context *ctx,
- size_t length,
- const unsigned char nonce[12],
- const unsigned char *aad,
- size_t aad_len,
- const unsigned char tag[16],
- const unsigned char *input,
- unsigned char *output );
- #if defined(MBEDTLS_SELF_TEST)
- /**
- * \brief The ChaCha20-Poly1305 checkup routine.
- *
- * \return \c 0 on success.
- * \return \c 1 on failure.
- */
- int mbedtls_chachapoly_self_test( int verbose );
- #endif /* MBEDTLS_SELF_TEST */
- #ifdef __cplusplus
- }
- #endif
- #endif /* MBEDTLS_CHACHAPOLY_H */
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