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Diffstat (limited to 'include/mbedtls/chachapoly.h')
| -rw-r--r-- | include/mbedtls/chachapoly.h | 342 |
1 files changed, 342 insertions, 0 deletions
diff --git a/include/mbedtls/chachapoly.h b/include/mbedtls/chachapoly.h new file mode 100644 index 0000000..3dc21e3 --- /dev/null +++ b/include/mbedtls/chachapoly.h @@ -0,0 +1,342 @@ +/** + * \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 The Mbed TLS Contributors + * SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later + */ + +#ifndef MBEDTLS_CHACHAPOLY_H +#define MBEDTLS_CHACHAPOLY_H +#include "mbedtls/private_access.h" + +#include "mbedtls/build_info.h" + +/* for shared error codes */ +#include "mbedtls/poly1305.h" + +/** The requested operation is not permitted in the current state. */ +#define MBEDTLS_ERR_CHACHAPOLY_BAD_STATE -0x0054 +/** Authenticated decryption failed: data was not authentic. */ +#define MBEDTLS_ERR_CHACHAPOLY_AUTH_FAILED -0x0056 + +#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 "mbedtls/chacha20.h" + +typedef struct mbedtls_chachapoly_context { + mbedtls_chacha20_context MBEDTLS_PRIVATE(chacha20_ctx); /**< The ChaCha20 context. */ + mbedtls_poly1305_context MBEDTLS_PRIVATE(poly1305_ctx); /**< The Poly1305 context. */ + uint64_t MBEDTLS_PRIVATE(aad_len); /**< The length (bytes) of the Additional Authenticated Data. */ + uint64_t MBEDTLS_PRIVATE(ciphertext_len); /**< The length (bytes) of the ciphertext. */ + int MBEDTLS_PRIVATE(state); /**< The current state of the context. */ + mbedtls_chachapoly_mode_t MBEDTLS_PRIVATE(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 readable 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 */ |