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
33 void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
chacha20_block(u32 * state,u8 * stream)34 static inline void chacha20_block(u32 *state, u8 *stream)
35 {
36 chacha_block_generic(state, stream, 20);
37 }
38
39 void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
40 void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
41
hchacha_block(const u32 * state,u32 * out,int nrounds)42 static 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
50 void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
chacha_init_generic(u32 * state,const u32 * key,const u8 * iv)51 static 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
chacha_init(u32 * state,const u32 * key,const u8 * iv)71 static 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
79 void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
80 unsigned int bytes, int nrounds);
81 void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
82 unsigned int bytes, int nrounds);
83
chacha_crypt(u32 * state,u8 * dst,const u8 * src,unsigned int bytes,int nrounds)84 static 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
chacha20_crypt(u32 * state,u8 * dst,const u8 * src,unsigned int bytes)93 static 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 */
100
