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
15void 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}
33EXPORT_SYMBOL(chacha_crypt_generic);
34
35MODULE_LICENSE("GPL");
36