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1/*
2 * Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
7dcb2186 3 *
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4 * Licensed under the OpenSSL license (the "License"). You may not use
5 * this file except in compliance with the License. You can obtain a copy
6 * in the file LICENSE in the source distribution or at
7 * https://www.openssl.org/source/license.html
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8 */
9
10#ifndef HEADER_CHACHA_H
11#define HEADER_CHACHA_H
12
13#include <stddef.h>
14
15#ifdef __cplusplus
16extern "C" {
17#endif
18
19/*
20 * ChaCha20_ctr32 encrypts |len| bytes from |inp| with the given key and
21 * nonce and writes the result to |out|, which may be equal to |inp|.
22 * The |key| is not 32 bytes of verbatim key material though, but the
23 * said material collected into 8 32-bit elements array in host byte
24 * order. Same approach applies to nonce: the |counter| argument is
25 * pointer to concatenated nonce and counter values collected into 4
26 * 32-bit elements. This, passing crypto material collected into 32-bit
27 * elements as opposite to passing verbatim byte vectors, is chosen for
28 * efficiency in multi-call scenarios.
29 */
30void ChaCha20_ctr32(unsigned char *out, const unsigned char *inp,
31 size_t len, const unsigned int key[8],
32 const unsigned int counter[4]);
33/*
34 * You can notice that there is no key setup procedure. Because it's
35 * as trivial as collecting bytes into 32-bit elements, it's reckoned
36 * that below macro is sufficient.
37 */
38#define CHACHA_U8TOU32(p) ( \
39 ((unsigned int)(p)[0]) | ((unsigned int)(p)[1]<<8) | \
40 ((unsigned int)(p)[2]<<16) | ((unsigned int)(p)[3]<<24) )
41
42#define CHACHA_KEY_SIZE 32
43#define CHACHA_CTR_SIZE 16
44#define CHACHA_BLK_SIZE 64
45
46#ifdef __cplusplus
47}
48#endif
49#endif