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 <asm/unaligned.h>
19#include <linux/types.h>
20
21/* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
22#define CHACHA_IV_SIZE		16
23
24#define CHACHA_KEY_SIZE		32
25#define CHACHA_BLOCK_SIZE	64
26#define CHACHAPOLY_IV_SIZE	12
27
28#define CHACHA_STATE_WORDS	(CHACHA_BLOCK_SIZE / sizeof(u32))
29
30/* 192-bit nonce, then 64-bit stream position */
31#define XCHACHA_IV_SIZE		32
32
33void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
34static inline void chacha20_block(u32 *state, u8 *stream)
35{
36	chacha_block_generic(state, stream, 20);
37}
38
39void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
40void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
41
42static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
43{
44	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
45		hchacha_block_arch(state, out, nrounds);
46	else
47		hchacha_block_generic(state, out, nrounds);
48}
49
50void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
51static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
52{
53	state[0]  = 0x61707865; /* "expa" */
54	state[1]  = 0x3320646e; /* "nd 3" */
55	state[2]  = 0x79622d32; /* "2-by" */
56	state[3]  = 0x6b206574; /* "te k" */
57	state[4]  = key[0];
58	state[5]  = key[1];
59	state[6]  = key[2];
60	state[7]  = key[3];
61	state[8]  = key[4];
62	state[9]  = key[5];
63	state[10] = key[6];
64	state[11] = key[7];
65	state[12] = get_unaligned_le32(iv +  0);
66	state[13] = get_unaligned_le32(iv +  4);
67	state[14] = get_unaligned_le32(iv +  8);
68	state[15] = get_unaligned_le32(iv + 12);
69}
70
71static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
72{
73	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
74		chacha_init_arch(state, key, iv);
75	else
76		chacha_init_generic(state, key, iv);
77}
78
79void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
80		       unsigned int bytes, int nrounds);
81void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
82			  unsigned int bytes, int nrounds);
83
84static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
85				unsigned int bytes, int nrounds)
86{
87	if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
88		chacha_crypt_arch(state, dst, src, bytes, nrounds);
89	else
90		chacha_crypt_generic(state, dst, src, bytes, nrounds);
91}
92
93static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,
94				  unsigned int bytes)
95{
96	chacha_crypt(state, dst, src, bytes, 20);
97}
98
99#endif /* _CRYPTO_CHACHA_H */