/* 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 <linux/unaligned.h>#include <linux/string.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_KEY_WORDS	8#define CHACHA_STATE_WORDS	16#define HCHACHA_OUT_WORDS	8 /* 192-bit nonce, then 64-bit stream position */#define XCHACHA_IV_SIZE		32 struct chacha_state {	u32 x[CHACHA_STATE_WORDS];}; void chacha_block_generic(struct chacha_state *state,			  u8 out[at_least CHACHA_BLOCK_SIZE], int nrounds);static inline void chacha20_block(struct chacha_state *state,				  u8 out[at_least CHACHA_BLOCK_SIZE]){	chacha_block_generic(state, out, 20);} void hchacha_block_generic(const struct chacha_state *state,			   u32 out[at_least HCHACHA_OUT_WORDS], int nrounds); void hchacha_block(const struct chacha_state *state,		   u32 out[at_least HCHACHA_OUT_WORDS], int 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(struct chacha_state *state){	state->x[0]  = CHACHA_CONSTANT_EXPA;	state->x[1]  = CHACHA_CONSTANT_ND_3;	state->x[2]  = CHACHA_CONSTANT_2_BY;	state->x[3]  = CHACHA_CONSTANT_TE_K;} static inline void chacha_init(struct chacha_state *state,			       const u32 key[at_least CHACHA_KEY_WORDS],			       const u8 iv[at_least CHACHA_IV_SIZE]){	chacha_init_consts(state);	state->x[4]  = key[0];	state->x[5]  = key[1];	state->x[6]  = key[2];	state->x[7]  = key[3];	state->x[8]  = key[4];	state->x[9]  = key[5];	state->x[10] = key[6];	state->x[11] = key[7];	state->x[12] = get_unaligned_le32(iv +  0);	state->x[13] = get_unaligned_le32(iv +  4);	state->x[14] = get_unaligned_le32(iv +  8);	state->x[15] = get_unaligned_le32(iv + 12);} void chacha_crypt(struct chacha_state *state, u8 *dst, const u8 *src,		  unsigned int bytes, int nrounds); static inline void chacha20_crypt(struct chacha_state *state,				  u8 *dst, const u8 *src, unsigned int bytes){	chacha_crypt(state, dst, src, bytes, 20);} static inline void chacha_zeroize_state(struct chacha_state *state){	memzero_explicit(state, sizeof(*state));} #endif /* _CRYPTO_CHACHA_H */