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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * Common values and helper functions for the ChaCha and XChaCha stream ciphers.
4 *
5 * XChaCha extends ChaCha's nonce to 192 bits, while provably retaining ChaCha's
6 * security. Here they share the same key size, tfm context, and setkey
7 * function; only their IV size and encrypt/decrypt function differ.
8 *
9 * The ChaCha paper specifies 20, 12, and 8-round variants. In general, it is
10 * recommended to use the 20-round variant ChaCha20. However, the other
11 * variants can be needed in some performance-sensitive scenarios. The generic
12 * ChaCha code currently allows only the 20 and 12-round variants.
13 */
14
15#ifndef _CRYPTO_CHACHA_H
16#define _CRYPTO_CHACHA_H
17
18#include <crypto/skcipher.h>
19#include <linux/types.h>
20#include <linux/crypto.h>
21
22/* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
23#define CHACHA_IV_SIZE 16
24
25#define CHACHA_KEY_SIZE 32
26#define CHACHA_BLOCK_SIZE 64
27#define CHACHAPOLY_IV_SIZE 12
28
29/* 192-bit nonce, then 64-bit stream position */
30#define XCHACHA_IV_SIZE 32
31
32struct chacha_ctx {
33 u32 key[8];
34 int nrounds;
35};
36
37void chacha_block(u32 *state, u8 *stream, int nrounds);
38static inline void chacha20_block(u32 *state, u8 *stream)
39{
40 chacha_block(state, stream, 20);
41}
42void hchacha_block(const u32 *in, u32 *out, int nrounds);
43
44void crypto_chacha_init(u32 *state, struct chacha_ctx *ctx, u8 *iv);
45
46int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key,
47 unsigned int keysize);
48int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key,
49 unsigned int keysize);
50
51int crypto_chacha_crypt(struct skcipher_request *req);
52int crypto_xchacha_crypt(struct skcipher_request *req);
53
54#endif /* _CRYPTO_CHACHA_H */