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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's6 * security. Here they share the same key size, tfm context, and setkey7 * 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 is10 * recommended to use the 20-round variant ChaCha20. However, the other11 * variants can be needed in some performance-sensitive scenarios. The generic12 * ChaCha code currently allows only the 20 and 12-round variants.13 */14 15#ifndef _CRYPTO_CHACHA_H16#define _CRYPTO_CHACHA_H17 18#include <linux/unaligned.h>19#include <linux/types.h>20 21/* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */22#define CHACHA_IV_SIZE 1623 24#define CHACHA_KEY_SIZE 3225#define CHACHA_BLOCK_SIZE 6426#define CHACHAPOLY_IV_SIZE 1227 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 3232 33void chacha_block_generic(u32 *state, u8 *stream, int nrounds);34static inline void chacha20_block(u32 *state, u8 *stream)35{36 chacha_block_generic(state, stream, 20);37}38 39void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);40void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);41 42static 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 else47 hchacha_block_generic(state, out, nrounds);48}49 50enum chacha_constants { /* expand 32-byte k */51 CHACHA_CONSTANT_EXPA = 0x61707865U,52 CHACHA_CONSTANT_ND_3 = 0x3320646eU,53 CHACHA_CONSTANT_2_BY = 0x79622d32U,54 CHACHA_CONSTANT_TE_K = 0x6b206574U55};56 57static inline void chacha_init_consts(u32 *state)58{59 state[0] = CHACHA_CONSTANT_EXPA;60 state[1] = CHACHA_CONSTANT_ND_3;61 state[2] = CHACHA_CONSTANT_2_BY;62 state[3] = CHACHA_CONSTANT_TE_K;63}64 65void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);66static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)67{68 chacha_init_consts(state);69 state[4] = key[0];70 state[5] = key[1];71 state[6] = key[2];72 state[7] = key[3];73 state[8] = key[4];74 state[9] = key[5];75 state[10] = key[6];76 state[11] = key[7];77 state[12] = get_unaligned_le32(iv + 0);78 state[13] = get_unaligned_le32(iv + 4);79 state[14] = get_unaligned_le32(iv + 8);80 state[15] = get_unaligned_le32(iv + 12);81}82 83static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)84{85 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))86 chacha_init_arch(state, key, iv);87 else88 chacha_init_generic(state, key, iv);89}90 91void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,92 unsigned int bytes, int nrounds);93void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,94 unsigned int bytes, int nrounds);95 96static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,97 unsigned int bytes, int nrounds)98{99 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))100 chacha_crypt_arch(state, dst, src, bytes, nrounds);101 else102 chacha_crypt_generic(state, dst, src, bytes, nrounds);103}104 105static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,106 unsigned int bytes)107{108 chacha_crypt(state, dst, src, bytes, 20);109}110 111#endif /* _CRYPTO_CHACHA_H */112