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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 <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#ifdef CONFIG_X86_64
29#define CHACHA_STATE_WORDS ((CHACHA_BLOCK_SIZE + 12) / sizeof(u32))
30#else
31#define CHACHA_STATE_WORDS (CHACHA_BLOCK_SIZE / sizeof(u32))
32#endif
33
34/* 192-bit nonce, then 64-bit stream position */
35#define XCHACHA_IV_SIZE 32
36
37void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
38static inline void chacha20_block(u32 *state, u8 *stream)
39{
40 chacha_block_generic(state, stream, 20);
41}
42
43void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
44void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
45
46static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
47{
48 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
49 hchacha_block_arch(state, out, nrounds);
50 else
51 hchacha_block_generic(state, out, nrounds);
52}
53
54void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
55static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
56{
57 state[0] = 0x61707865; /* "expa" */
58 state[1] = 0x3320646e; /* "nd 3" */
59 state[2] = 0x79622d32; /* "2-by" */
60 state[3] = 0x6b206574; /* "te k" */
61 state[4] = key[0];
62 state[5] = key[1];
63 state[6] = key[2];
64 state[7] = key[3];
65 state[8] = key[4];
66 state[9] = key[5];
67 state[10] = key[6];
68 state[11] = key[7];
69 state[12] = get_unaligned_le32(iv + 0);
70 state[13] = get_unaligned_le32(iv + 4);
71 state[14] = get_unaligned_le32(iv + 8);
72 state[15] = get_unaligned_le32(iv + 12);
73}
74
75static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
76{
77 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
78 chacha_init_arch(state, key, iv);
79 else
80 chacha_init_generic(state, key, iv);
81}
82
83void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
84 unsigned int bytes, int nrounds);
85void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
86 unsigned int bytes, int nrounds);
87
88static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
89 unsigned int bytes, int nrounds)
90{
91 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
92 chacha_crypt_arch(state, dst, src, bytes, nrounds);
93 else
94 chacha_crypt_generic(state, dst, src, bytes, nrounds);
95}
96
97static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,
98 unsigned int bytes)
99{
100 chacha_crypt(state, dst, src, bytes, 20);
101}
102
103#endif /* _CRYPTO_CHACHA_H */