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Diffstat (limited to 'include/crypto/chacha.h')
| -rw-r--r-- | include/crypto/chacha.h | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/include/crypto/chacha.h b/include/crypto/chacha.h new file mode 100644 index 000000000..b3ea73b81 --- /dev/null +++ b/include/crypto/chacha.h @@ -0,0 +1,111 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Common values and helper functions for the ChaCha and XChaCha stream ciphers. + * + * XChaCha extends ChaCha's nonce to 192 bits, while provably retaining ChaCha's + * security. Here they share the same key size, tfm context, and setkey + * function; only their IV size and encrypt/decrypt function differ. + * + * The ChaCha paper specifies 20, 12, and 8-round variants. In general, it is + * recommended to use the 20-round variant ChaCha20. However, the other + * variants can be needed in some performance-sensitive scenarios. The generic + * ChaCha code currently allows only the 20 and 12-round variants. + */ + +#ifndef _CRYPTO_CHACHA_H +#define _CRYPTO_CHACHA_H + +#include <asm/unaligned.h> +#include <linux/types.h> + +/* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */ +#define CHACHA_IV_SIZE 16 + +#define CHACHA_KEY_SIZE 32 +#define CHACHA_BLOCK_SIZE 64 +#define CHACHAPOLY_IV_SIZE 12 + +#define CHACHA_STATE_WORDS (CHACHA_BLOCK_SIZE / sizeof(u32)) + +/* 192-bit nonce, then 64-bit stream position */ +#define XCHACHA_IV_SIZE 32 + +void chacha_block_generic(u32 *state, u8 *stream, int nrounds); +static inline void chacha20_block(u32 *state, u8 *stream) +{ + chacha_block_generic(state, stream, 20); +} + +void hchacha_block_arch(const u32 *state, u32 *out, int nrounds); +void hchacha_block_generic(const u32 *state, u32 *out, int nrounds); + +static inline void hchacha_block(const u32 *state, u32 *out, int nrounds) +{ + if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) + hchacha_block_arch(state, out, nrounds); + else + hchacha_block_generic(state, out, nrounds); +} + +enum chacha_constants { /* expand 32-byte k */ + CHACHA_CONSTANT_EXPA = 0x61707865U, + CHACHA_CONSTANT_ND_3 = 0x3320646eU, + CHACHA_CONSTANT_2_BY = 0x79622d32U, + CHACHA_CONSTANT_TE_K = 0x6b206574U +}; + +static inline void chacha_init_consts(u32 *state) +{ + state[0] = CHACHA_CONSTANT_EXPA; + state[1] = CHACHA_CONSTANT_ND_3; + state[2] = CHACHA_CONSTANT_2_BY; + state[3] = CHACHA_CONSTANT_TE_K; +} + +void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv); +static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv) +{ + chacha_init_consts(state); + state[4] = key[0]; + state[5] = key[1]; + state[6] = key[2]; + state[7] = key[3]; + state[8] = key[4]; + state[9] = key[5]; + state[10] = key[6]; + state[11] = key[7]; + state[12] = get_unaligned_le32(iv + 0); + state[13] = get_unaligned_le32(iv + 4); + state[14] = get_unaligned_le32(iv + 8); + state[15] = get_unaligned_le32(iv + 12); +} + +static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv) +{ + if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) + chacha_init_arch(state, key, iv); + else + chacha_init_generic(state, key, iv); +} + +void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, + unsigned int bytes, int nrounds); +void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src, + unsigned int bytes, int nrounds); + +static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src, + unsigned int bytes, int nrounds) +{ + if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) + chacha_crypt_arch(state, dst, src, bytes, nrounds); + else + chacha_crypt_generic(state, dst, src, bytes, nrounds); +} + +static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src, + unsigned int bytes) +{ + chacha_crypt(state, dst, src, bytes, 20); +} + +#endif /* _CRYPTO_CHACHA_H */ |