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/*
* Copyright 2015-2021 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the Apache License 2.0 (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#ifndef OSSL_CRYPTO_CHACHA_H
#define OSSL_CRYPTO_CHACHA_H
# pragma once
#include <stddef.h>
/*
* ChaCha20_ctr32 encrypts |len| bytes from |inp| with the given key and
* nonce and writes the result to |out|, which may be equal to |inp|.
* The |key| is not 32 bytes of verbatim key material though, but the
* said material collected into 8 32-bit elements array in host byte
* order. Same approach applies to nonce: the |counter| argument is
* pointer to concatenated nonce and counter values collected into 4
* 32-bit elements. This, passing crypto material collected into 32-bit
* elements as opposite to passing verbatim byte vectors, is chosen for
* efficiency in multi-call scenarios.
*/
void ChaCha20_ctr32(unsigned char *out, const unsigned char *inp,
size_t len, const unsigned int key[8],
const unsigned int counter[4]);
/*
* You can notice that there is no key setup procedure. Because it's
* as trivial as collecting bytes into 32-bit elements, it's reckoned
* that below macro is sufficient.
*/
#define CHACHA_U8TOU32(p) ( \
((unsigned int)(p)[0]) | ((unsigned int)(p)[1]<<8) | \
((unsigned int)(p)[2]<<16) | ((unsigned int)(p)[3]<<24) )
#define CHACHA_KEY_SIZE 32
#define CHACHA_CTR_SIZE 16
#define CHACHA_BLK_SIZE 64
#endif
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