lib/crypto/libchacha.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * The ChaCha stream cipher (RFC7539)
   4  *
   5  * Copyright (C) 2015 Martin Willi
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/export.h>
  10 #include <linux/module.h>
  11
  12 #include <crypto/algapi.h> // for crypto_xor_cpy
  13 #include <crypto/chacha.h>
  14
  15 void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
  16                           unsigned int bytes, int nrounds)
  17 {
  18         /* aligned to potentially speed up crypto_xor() */
  19         u8 stream[CHACHA_BLOCK_SIZE] __aligned(sizeof(long));
  20
  21         while (bytes >= CHACHA_BLOCK_SIZE) {
  22                 chacha_block_generic(state, stream, nrounds);
  23                 crypto_xor_cpy(dst, src, stream, CHACHA_BLOCK_SIZE);
  24                 bytes -= CHACHA_BLOCK_SIZE;
  25                 dst += CHACHA_BLOCK_SIZE;
  26                 src += CHACHA_BLOCK_SIZE;
  27         }
  28         if (bytes) {
  29                 chacha_block_generic(state, stream, nrounds);
  30                 crypto_xor_cpy(dst, src, stream, bytes);
  31         }
  32 }
  33 EXPORT_SYMBOL(chacha_crypt_generic);
  34
  35 MODULE_LICENSE("GPL");