1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Common values and helper functions for the ChaCha and XChaCha stream ciphers.
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.
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.
15 #ifndef _CRYPTO_CHACHA_H
16 #define _CRYPTO_CHACHA_H
18 #include <asm/unaligned.h>
19 #include <linux/types.h>
21 /* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
22 #define CHACHA_IV_SIZE 16
24 #define CHACHA_KEY_SIZE 32
25 #define CHACHA_BLOCK_SIZE 64
26 #define CHACHAPOLY_IV_SIZE 12
28 #define CHACHA_STATE_WORDS (CHACHA_BLOCK_SIZE / sizeof(u32))
30 /* 192-bit nonce, then 64-bit stream position */
31 #define XCHACHA_IV_SIZE 32
33 void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
34 static inline void chacha20_block(u32 *state, u8 *stream)
36 chacha_block_generic(state, stream, 20);
39 void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
40 void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
42 static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
44 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
45 hchacha_block_arch(state, out, nrounds);
47 hchacha_block_generic(state, out, nrounds);
50 void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
51 static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
53 state[0] = 0x61707865; /* "expa" */
54 state[1] = 0x3320646e; /* "nd 3" */
55 state[2] = 0x79622d32; /* "2-by" */
56 state[3] = 0x6b206574; /* "te k" */
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);
71 static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
73 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
74 chacha_init_arch(state, key, iv);
76 chacha_init_generic(state, key, iv);
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);
84 static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
85 unsigned int bytes, int nrounds)
87 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
88 chacha_crypt_arch(state, dst, src, bytes, nrounds);
90 chacha_crypt_generic(state, dst, src, bytes, nrounds);
93 static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,
96 chacha_crypt(state, dst, src, bytes, 20);
99 #endif /* _CRYPTO_CHACHA_H */