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_DESCRIPTION("ChaCha stream cipher (RFC7539)");
36 MODULE_LICENSE("GPL");
37
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