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/*
* cifra - embedded cryptography library
* Written in 2014 by Joseph Birr-Pixton <jpixton@gmail.com>
*
* To the extent possible under law, the author(s) have dedicated all
* copyright and related and neighboring rights to this software to the
* public domain worldwide. This software is distributed without any
* warranty.
*
* You should have received a copy of the CC0 Public Domain Dedication
* along with this software. If not, see
* <http://creativecommons.org/publicdomain/zero/1.0/>.
*/
#ifndef CHACHA20POLY1305_H
#define CHACHA20POLY1305_H
#include <stdint.h>
#include <stddef.h>
/**
* The ChaCha20-Poly1305 AEAD construction
* =======================================
* This is a composition of the ChaCha20 stream cipher and
* the Poly1305 polynomial MAC to form an AEAD.
* It's specified for use in TLS in the form of RFC7539.
*
* It uses a 256-bit key and a 96-bit nonce.
*
* This is a one-shot interface.
*/
/* .. c:function:: $DECL
* ChaCha20-Poly1305 authenticated encryption.
*
* :param key: key material.
* :param nonce: per-message nonce.
* :param header: header buffer.
* :param nheader: number of header bytes.
* :param plaintext: plaintext bytes to be encrypted.
* :param nbytes: number of plaintext/ciphertext bytes.
* :param ciphertext: ciphertext output buffer, nbytes in length.
* :param tag: authentication tag output buffer.
*/
void cf_chacha20poly1305_encrypt(const uint8_t key[32],
const uint8_t nonce[12],
const uint8_t *header, size_t nheader,
const uint8_t *plaintext, size_t nbytes,
uint8_t *ciphertext,
uint8_t tag[16]);
/* .. c:function:: $DECL
* ChaCha20-Poly1305 authenticated decryption.
*
* :return: 0 on success, non-zero on error. Plaintext is zeroed on error.
*
* :param key: key material.
* :param nonce: per-message nonce.
* :param header: header buffer.
* :param nheader: number of header bytes.
* :param ciphertext: ciphertext bytes to be decrypted.
* :param nbytes: number of plaintext/ciphertext bytes.
* :param plaintext: plaintext output buffer, nbytes in length.
* :param tag: authentication tag output buffer.
*/
int cf_chacha20poly1305_decrypt(const uint8_t key[32],
const uint8_t nonce[12],
const uint8_t *header, size_t nheader,
const uint8_t *ciphertext, size_t nbytes,
const uint8_t tag[16],
uint8_t *plaintext);
#endif
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