/** * \file chacha20.h * * \brief This file contains ChaCha20 definitions and functions. * * ChaCha20 is a stream cipher that can encrypt and decrypt * information. ChaCha was created by Daniel Bernstein as a variant of * its Salsa cipher https://cr.yp.to/chacha/chacha-20080128.pdf * ChaCha20 is the variant with 20 rounds, that was also standardized * in RFC 7539. * * \author Daniel King */ /* Copyright (C) 2006-2018, Arm Limited (or its affiliates), All Rights Reserved. * SPDX-License-Identifier: GPL-2.0 * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. * * This file is part of Mbed TLS (https://tls.mbed.org) */ #ifndef MBEDTLS_CHACHA20_H #define MBEDTLS_CHACHA20_H #if !defined(MBEDTLS_CONFIG_FILE) #include "config.h" #else #include MBEDTLS_CONFIG_FILE #endif #include #include #define MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA -0x0051 /**< Invalid input parameter(s). */ #define MBEDTLS_ERR_CHACHA20_FEATURE_UNAVAILABLE -0x0053 /**< Feature not available. For example, s part of the API is not implemented. */ #define MBEDTLS_ERR_CHACHA20_HW_ACCEL_FAILED -0x0055 /**< Chacha20 hardware accelerator failed. */ #ifdef __cplusplus extern "C" { #endif #if !defined(MBEDTLS_CHACHA20_ALT) typedef struct { uint32_t state[16]; /*! The state (before round operations). */ uint8_t keystream8[64]; /*! Leftover keystream bytes. */ size_t keystream_bytes_used; /*! Number of keystream bytes already used. */ } mbedtls_chacha20_context; #else /* MBEDTLS_CHACHA20_ALT */ #include "chacha20_alt.h" #endif /* MBEDTLS_CHACHA20_ALT */ /** * \brief This function initializes the specified ChaCha20 context. * * It must be the first API called before using * the context. * * It is usually followed by calls to * \c mbedtls_chacha20_setkey() and * \c mbedtls_chacha20_starts(), then one or more calls to * to \c mbedtls_chacha20_update(), and finally to * \c mbedtls_chacha20_free(). * * \param ctx The ChaCha20 context to initialize. */ void mbedtls_chacha20_init( mbedtls_chacha20_context *ctx ); /** * \brief This function releases and clears the specified ChaCha20 context. * * \param ctx The ChaCha20 context to clear. */ void mbedtls_chacha20_free( mbedtls_chacha20_context *ctx ); /** * \brief This function sets the encryption/decryption key. * * \note After using this function, you must also call * \c mbedtls_chacha20_starts() to set a nonce before you * start encrypting/decrypting data with * \c mbedtls_chacha_update(). * * \param ctx The ChaCha20 context to which the key should be bound. * \param key The encryption/decryption key. Must be 32 bytes in length. * * \return \c 0 on success. * \return #MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA if ctx or key is NULL. */ int mbedtls_chacha20_setkey( mbedtls_chacha20_context *ctx, const unsigned char key[32] ); /** * \brief This function sets the nonce and initial counter value. * * \note A ChaCha20 context can be re-used with the same key by * calling this function to change the nonce. * * \warning You must never use the same nonce twice with the same key. * This would void any confidentiality guarantees for the * messages encrypted with the same nonce and key. * * \param ctx The ChaCha20 context to which the nonce should be bound. * \param nonce The nonce. Must be 12 bytes in size. * \param counter The initial counter value. This is usually 0. * * \return \c 0 on success. * \return #MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA if ctx or nonce is * NULL. */ int mbedtls_chacha20_starts( mbedtls_chacha20_context* ctx, const unsigned char nonce[12], uint32_t counter ); /** * \brief This function encrypts or decrypts data. * * Since ChaCha20 is a stream cipher, the same operation is * used for encrypting and decrypting data. * * \note The \p input and \p output pointers must either be equal or * point to non-overlapping buffers. * * \note \c mbedtls_chacha20_setkey() and * \c mbedtls_chacha20_starts() must be called at least once * to setup the context before this function can be called. * * \note This function can be called multiple times in a row in * order to encrypt of decrypt data piecewise with the same * key and nonce. * * \param ctx The ChaCha20 context to use for encryption or decryption. * \param size The length of the input data in bytes. * \param input The buffer holding the input data. * This pointer can be NULL if size == 0. * \param output The buffer holding the output data. * Must be able to hold \p size bytes. * This pointer can be NULL if size == 0. * * \return \c 0 on success. * \return #MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA if the ctx, input, or * output pointers are NULL. */ int mbedtls_chacha20_update( mbedtls_chacha20_context *ctx, size_t size, const unsigned char *input, unsigned char *output ); /** * \brief This function encrypts or decrypts data with ChaCha20 and * the given key and nonce. * * Since ChaCha20 is a stream cipher, the same operation is * used for encrypting and decrypting data. * * \warning You must never use the same (key, nonce) pair more than * once. This would void any confidentiality guarantees for * the messages encrypted with the same nonce and key. * * \note The \p input and \p output pointers must either be equal or * point to non-overlapping buffers. * * \param key The encryption/decryption key. Must be 32 bytes in length. * \param nonce The nonce. Must be 12 bytes in size. * \param counter The initial counter value. This is usually 0. * \param size The length of the input data in bytes. * \param input The buffer holding the input data. * This pointer can be NULL if size == 0. * \param output The buffer holding the output data. * Must be able to hold \p size bytes. * This pointer can be NULL if size == 0. * * \return \c 0 on success. * \return #MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA if key, nonce, input, * or output is NULL. */ int mbedtls_chacha20_crypt( const unsigned char key[32], const unsigned char nonce[12], uint32_t counter, size_t size, const unsigned char* input, unsigned char* output ); #if defined(MBEDTLS_SELF_TEST) /** * \brief The ChaCha20 checkup routine. * * \return \c 0 on success. * \return \c 1 on failure. */ int mbedtls_chacha20_self_test( int verbose ); #endif /* MBEDTLS_SELF_TEST */ #ifdef __cplusplus } #endif #endif /* MBEDTLS_CHACHA20_H */