[331] | 1 | /*
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| 2 | * Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
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| 3 | *
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| 4 | * Licensed under the OpenSSL license (the "License"). You may not use
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| 5 | * this file except in compliance with the License. You can obtain a copy
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| 6 | * in the file LICENSE in the source distribution or at
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| 7 | * https://www.openssl.org/source/license.html
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| 8 | */
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| 9 |
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| 10 | #ifndef HEADER_CHACHA_H
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| 11 | #define HEADER_CHACHA_H
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| 12 |
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| 13 | #include <stddef.h>
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| 14 |
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| 15 | #ifdef __cplusplus
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| 16 | extern "C" {
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| 17 | #endif
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| 18 |
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| 19 | /*
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| 20 | * ChaCha20_ctr32 encrypts |len| bytes from |inp| with the given key and
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| 21 | * nonce and writes the result to |out|, which may be equal to |inp|.
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| 22 | * The |key| is not 32 bytes of verbatim key material though, but the
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| 23 | * said material collected into 8 32-bit elements array in host byte
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| 24 | * order. Same approach applies to nonce: the |counter| argument is
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| 25 | * pointer to concatenated nonce and counter values collected into 4
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| 26 | * 32-bit elements. This, passing crypto material collected into 32-bit
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| 27 | * elements as opposite to passing verbatim byte vectors, is chosen for
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| 28 | * efficiency in multi-call scenarios.
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| 29 | */
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| 30 | void ChaCha20_ctr32(unsigned char *out, const unsigned char *inp,
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| 31 | size_t len, const unsigned int key[8],
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| 32 | const unsigned int counter[4]);
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| 33 | /*
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| 34 | * You can notice that there is no key setup procedure. Because it's
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| 35 | * as trivial as collecting bytes into 32-bit elements, it's reckoned
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| 36 | * that below macro is sufficient.
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| 37 | */
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| 38 | #define CHACHA_U8TOU32(p) ( \
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| 39 | ((unsigned int)(p)[0]) | ((unsigned int)(p)[1]<<8) | \
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| 40 | ((unsigned int)(p)[2]<<16) | ((unsigned int)(p)[3]<<24) )
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| 41 |
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| 42 | #define CHACHA_KEY_SIZE 32
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| 43 | #define CHACHA_CTR_SIZE 16
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| 44 | #define CHACHA_BLK_SIZE 64
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| 45 |
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| 46 | #ifdef __cplusplus
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| 47 | }
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| 48 | #endif
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| 49 | #endif
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