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Diffstat (limited to 'include/mbedtls/chacha20.h')
| -rw-r--r-- | include/mbedtls/chacha20.h | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/include/mbedtls/chacha20.h b/include/mbedtls/chacha20.h new file mode 100644 index 0000000..680fe36 --- /dev/null +++ b/include/mbedtls/chacha20.h @@ -0,0 +1,202 @@ +/** + * \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 <damaki.gh@gmail.com> + */ + +/* + * Copyright The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ + +#ifndef MBEDTLS_CHACHA20_H +#define MBEDTLS_CHACHA20_H +#include "mbedtls/private_access.h" + +#include "mbedtls/build_info.h" + +#include <stdint.h> +#include <stddef.h> + +/** Invalid input parameter(s). */ +#define MBEDTLS_ERR_CHACHA20_BAD_INPUT_DATA -0x0051 + +#ifdef __cplusplus +extern "C" { +#endif + +#if !defined(MBEDTLS_CHACHA20_ALT) + +typedef struct mbedtls_chacha20_context { + uint32_t MBEDTLS_PRIVATE(state)[16]; /*! The state (before round operations). */ + uint8_t MBEDTLS_PRIVATE(keystream8)[64]; /*! Leftover keystream bytes. */ + size_t MBEDTLS_PRIVATE(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. + * This must not be \c NULL. + */ +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. This may be \c NULL, + * in which case this function is a no-op. If it is not + * \c NULL, it must point to an initialized context. + * + */ +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. + * It must be initialized. + * \param key The encryption/decryption key. This must be \c 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. + * It must be initialized and bound to a key. + * \param nonce The nonce. This must be \c 12 Bytes in size. + * \param counter The initial counter value. This is usually \c 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. + * It must be initialized and bound to a key and nonce. + * \param size The length of the input data in Bytes. + * \param input The buffer holding the input data. + * This pointer can be \c NULL if `size == 0`. + * \param output The buffer holding the output data. + * This must be able to hold \p size Bytes. + * This pointer can be \c NULL if `size == 0`. + * + * \return \c 0 on success. + * \return A negative error code on failure. + */ +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. + * This must be \c 32 Bytes in length. + * \param nonce The nonce. This must be \c 12 Bytes in size. + * \param counter The initial counter value. This is usually \c 0. + * \param size The length of the input data in Bytes. + * \param input The buffer holding the input data. + * This pointer can be \c NULL if `size == 0`. + * \param output The buffer holding the output data. + * This must be able to hold \p size Bytes. + * This pointer can be \c NULL if `size == 0`. + * + * \return \c 0 on success. + * \return A negative error code on failure. + */ +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 */ |