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chacha.h 1.9 KB

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  1. /*
  2. * Copyright 2015-2021 The OpenSSL Project Authors. All Rights Reserved.
  3. *
  4. * Licensed under the Apache License 2.0 (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
  8. */
  9. #ifndef OSSL_CRYPTO_CHACHA_H
  10. #define OSSL_CRYPTO_CHACHA_H
  11. # pragma once
  12. #include <stddef.h>
  13. /*
  14. * ChaCha20_ctr32 encrypts |len| bytes from |inp| with the given key and
  15. * nonce and writes the result to |out|, which may be equal to |inp|.
  16. * The |key| is not 32 bytes of verbatim key material though, but the
  17. * said material collected into 8 32-bit elements array in host byte
  18. * order. Same approach applies to nonce: the |counter| argument is
  19. * pointer to concatenated nonce and counter values collected into 4
  20. * 32-bit elements. This, passing crypto material collected into 32-bit
  21. * elements as opposite to passing verbatim byte vectors, is chosen for
  22. * efficiency in multi-call scenarios.
  23. */
  24. void ChaCha20_ctr32(unsigned char *out, const unsigned char *inp,
  25. size_t len, const unsigned int key[8],
  26. const unsigned int counter[4]);
  27. #ifdef INCLUDE_C_CHACHA20
  28. /* The fallback implementation for `ChaCha20_ctr32`. */
  29. void ChaCha20_ctr32_c(unsigned char *out, const unsigned char *inp, size_t len,
  30. const unsigned int key[8], const unsigned int counter[4]);
  31. #endif
  32. /*
  33. * You can notice that there is no key setup procedure. Because it's
  34. * as trivial as collecting bytes into 32-bit elements, it's reckoned
  35. * that below macro is sufficient.
  36. */
  37. #define CHACHA_U8TOU32(p) ( \
  38. ((unsigned int)(p)[0]) | ((unsigned int)(p)[1]<<8) | \
  39. ((unsigned int)(p)[2]<<16) | ((unsigned int)(p)[3]<<24) )
  40. #define CHACHA_KEY_SIZE 32
  41. #define CHACHA_CTR_SIZE 16
  42. #define CHACHA_BLK_SIZE 64
  43. #endif