crypto/include/internal/chacha.h

   1 /* ====================================================================
   2  * Copyright (c) 2014 The OpenSSL Project.  All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or without
   5  * modification, are permitted provided that the following conditions
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   9  *    notice, this list of conditions and the following disclaimer.
  10  *
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in
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  15  *
  16  * 3. All advertising materials mentioning features or use of this
  17  *    software must display the following acknowledgment:
  18  *    "This product includes software developed by the OpenSSL Project
  19  *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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  21  * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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  31  *    acknowledgment:
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  50
  51 #ifndef HEADER_CHACHA_H
  52 #define HEADER_CHACHA_H
  53
  54 #include <stddef.h>
  55
  56 #ifdef __cplusplus
  57 extern "C" {
  58 #endif
  59
  60 # ifdef OPENSSL_NO_CHACHA
  61 #  error CHACHA is disabled.
  62 # endif
  63
  64 /*
  65  * ChaCha20_ctr32 encrypts |len| bytes from |inp| with the given key and
  66  * nonce and writes the result to |out|, which may be equal to |inp|.
  67  * The |key| is not 32 bytes of verbatim key material though, but the
  68  * said material collected into 8 32-bit elements array in host byte
  69  * order. Same approach applies to nonce: the |counter| argument is
  70  * pointer to concatenated nonce and counter values collected into 4
  71  * 32-bit elements. This, passing crypto material collected into 32-bit
  72  * elements as opposite to passing verbatim byte vectors, is chosen for
  73  * efficiency in multi-call scenarios.
  74  */
  75 void ChaCha20_ctr32(unsigned char *out, const unsigned char *inp,
  76                     size_t len, const unsigned int key[8],
  77                     const unsigned int counter[4]);
  78 /*
  79  * You can notice that there is no key setup procedure. Because it's
  80  * as trivial as collecting bytes into 32-bit elements, it's reckoned
  81  * that below macro is sufficient.
  82  */
  83 #define CHACHA_U8TOU32(p)  ( \
  84                 ((unsigned int)(p)[0])     | ((unsigned int)(p)[1]<<8) | \
  85                 ((unsigned int)(p)[2]<<16) | ((unsigned int)(p)[3]<<24)  )
  86
  87 #define CHACHA_KEY_SIZE         32
  88 #define CHACHA_CTR_SIZE         16
  89 #define CHACHA_BLK_SIZE         64
  90
  91 #ifdef __cplusplus
  92 }
  93 #endif
  94 #endif