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, const struct chacha_ctx *ctx, const 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 */