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50 lines
1.7 KiB
C
50 lines
1.7 KiB
C
/*
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* Copyright 2015-2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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#ifndef HEADER_CHACHA_H
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#define HEADER_CHACHA_H
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#include <stddef.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* ChaCha20_ctr32 encrypts |len| bytes from |inp| with the given key and
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* nonce and writes the result to |out|, which may be equal to |inp|.
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* The |key| is not 32 bytes of verbatim key material though, but the
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* said material collected into 8 32-bit elements array in host byte
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* order. Same approach applies to nonce: the |counter| argument is
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* pointer to concatenated nonce and counter values collected into 4
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* 32-bit elements. This, passing crypto material collected into 32-bit
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* elements as opposite to passing verbatim byte vectors, is chosen for
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* efficiency in multi-call scenarios.
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*/
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void ChaCha20_ctr32(unsigned char *out, const unsigned char *inp,
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size_t len, const unsigned int key[8],
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const unsigned int counter[4]);
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/*
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* You can notice that there is no key setup procedure. Because it's
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* as trivial as collecting bytes into 32-bit elements, it's reckoned
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* that below macro is sufficient.
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*/
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#define CHACHA_U8TOU32(p) ( \
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((unsigned int)(p)[0]) | ((unsigned int)(p)[1]<<8) | \
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((unsigned int)(p)[2]<<16) | ((unsigned int)(p)[3]<<24) )
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#define CHACHA_KEY_SIZE 32
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#define CHACHA_CTR_SIZE 16
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#define CHACHA_BLK_SIZE 64
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#ifdef __cplusplus
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}
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#endif
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#endif
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