11ca1b917SEric Biggers /* SPDX-License-Identifier: GPL-2.0 */ 21ca1b917SEric Biggers /* 31ca1b917SEric Biggers * Common values and helper functions for the ChaCha and XChaCha stream ciphers. 41ca1b917SEric Biggers * 51ca1b917SEric Biggers * XChaCha extends ChaCha's nonce to 192 bits, while provably retaining ChaCha's 61ca1b917SEric Biggers * security. Here they share the same key size, tfm context, and setkey 71ca1b917SEric Biggers * function; only their IV size and encrypt/decrypt function differ. 8aa762409SEric Biggers * 9aa762409SEric Biggers * The ChaCha paper specifies 20, 12, and 8-round variants. In general, it is 10aa762409SEric Biggers * recommended to use the 20-round variant ChaCha20. However, the other 11aa762409SEric Biggers * variants can be needed in some performance-sensitive scenarios. The generic 12aa762409SEric Biggers * ChaCha code currently allows only the 20 and 12-round variants. 131ca1b917SEric Biggers */ 141ca1b917SEric Biggers 151ca1b917SEric Biggers #ifndef _CRYPTO_CHACHA_H 161ca1b917SEric Biggers #define _CRYPTO_CHACHA_H 171ca1b917SEric Biggers 18*5fb8ef25SArd Biesheuvel #include <asm/unaligned.h> 191ca1b917SEric Biggers #include <linux/types.h> 201ca1b917SEric Biggers 211ca1b917SEric Biggers /* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */ 221ca1b917SEric Biggers #define CHACHA_IV_SIZE 16 231ca1b917SEric Biggers 241ca1b917SEric Biggers #define CHACHA_KEY_SIZE 32 251ca1b917SEric Biggers #define CHACHA_BLOCK_SIZE 64 261ca1b917SEric Biggers #define CHACHAPOLY_IV_SIZE 12 271ca1b917SEric Biggers 281ca1b917SEric Biggers /* 192-bit nonce, then 64-bit stream position */ 291ca1b917SEric Biggers #define XCHACHA_IV_SIZE 32 301ca1b917SEric Biggers 31*5fb8ef25SArd Biesheuvel void chacha_block_generic(u32 *state, u8 *stream, int nrounds); 321ca1b917SEric Biggers static inline void chacha20_block(u32 *state, u8 *stream) 331ca1b917SEric Biggers { 34*5fb8ef25SArd Biesheuvel chacha_block_generic(state, stream, 20); 351ca1b917SEric Biggers } 361ca1b917SEric Biggers 37*5fb8ef25SArd Biesheuvel void hchacha_block_arch(const u32 *state, u32 *out, int nrounds); 38*5fb8ef25SArd Biesheuvel void hchacha_block_generic(const u32 *state, u32 *out, int nrounds); 391ca1b917SEric Biggers 40*5fb8ef25SArd Biesheuvel static inline void hchacha_block(const u32 *state, u32 *out, int nrounds) 41*5fb8ef25SArd Biesheuvel { 42*5fb8ef25SArd Biesheuvel if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 43*5fb8ef25SArd Biesheuvel hchacha_block_arch(state, out, nrounds); 44*5fb8ef25SArd Biesheuvel else 45*5fb8ef25SArd Biesheuvel hchacha_block_generic(state, out, nrounds); 46*5fb8ef25SArd Biesheuvel } 471ca1b917SEric Biggers 48*5fb8ef25SArd Biesheuvel void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv); 49*5fb8ef25SArd Biesheuvel static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv) 50*5fb8ef25SArd Biesheuvel { 51*5fb8ef25SArd Biesheuvel state[0] = 0x61707865; /* "expa" */ 52*5fb8ef25SArd Biesheuvel state[1] = 0x3320646e; /* "nd 3" */ 53*5fb8ef25SArd Biesheuvel state[2] = 0x79622d32; /* "2-by" */ 54*5fb8ef25SArd Biesheuvel state[3] = 0x6b206574; /* "te k" */ 55*5fb8ef25SArd Biesheuvel state[4] = key[0]; 56*5fb8ef25SArd Biesheuvel state[5] = key[1]; 57*5fb8ef25SArd Biesheuvel state[6] = key[2]; 58*5fb8ef25SArd Biesheuvel state[7] = key[3]; 59*5fb8ef25SArd Biesheuvel state[8] = key[4]; 60*5fb8ef25SArd Biesheuvel state[9] = key[5]; 61*5fb8ef25SArd Biesheuvel state[10] = key[6]; 62*5fb8ef25SArd Biesheuvel state[11] = key[7]; 63*5fb8ef25SArd Biesheuvel state[12] = get_unaligned_le32(iv + 0); 64*5fb8ef25SArd Biesheuvel state[13] = get_unaligned_le32(iv + 4); 65*5fb8ef25SArd Biesheuvel state[14] = get_unaligned_le32(iv + 8); 66*5fb8ef25SArd Biesheuvel state[15] = get_unaligned_le32(iv + 12); 67*5fb8ef25SArd Biesheuvel } 68*5fb8ef25SArd Biesheuvel 69*5fb8ef25SArd Biesheuvel static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv) 70*5fb8ef25SArd Biesheuvel { 71*5fb8ef25SArd Biesheuvel if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 72*5fb8ef25SArd Biesheuvel chacha_init_arch(state, key, iv); 73*5fb8ef25SArd Biesheuvel else 74*5fb8ef25SArd Biesheuvel chacha_init_generic(state, key, iv); 75*5fb8ef25SArd Biesheuvel } 76*5fb8ef25SArd Biesheuvel 77*5fb8ef25SArd Biesheuvel void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, 78*5fb8ef25SArd Biesheuvel unsigned int bytes, int nrounds); 79*5fb8ef25SArd Biesheuvel void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src, 80*5fb8ef25SArd Biesheuvel unsigned int bytes, int nrounds); 81*5fb8ef25SArd Biesheuvel 82*5fb8ef25SArd Biesheuvel static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src, 83*5fb8ef25SArd Biesheuvel unsigned int bytes, int nrounds) 84*5fb8ef25SArd Biesheuvel { 85*5fb8ef25SArd Biesheuvel if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 86*5fb8ef25SArd Biesheuvel chacha_crypt_arch(state, dst, src, bytes, nrounds); 87*5fb8ef25SArd Biesheuvel else 88*5fb8ef25SArd Biesheuvel chacha_crypt_generic(state, dst, src, bytes, nrounds); 89*5fb8ef25SArd Biesheuvel } 90*5fb8ef25SArd Biesheuvel 91*5fb8ef25SArd Biesheuvel static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src, 92*5fb8ef25SArd Biesheuvel unsigned int bytes) 93*5fb8ef25SArd Biesheuvel { 94*5fb8ef25SArd Biesheuvel chacha_crypt(state, dst, src, bytes, 20); 95*5fb8ef25SArd Biesheuvel } 961ca1b917SEric Biggers 971ca1b917SEric Biggers #endif /* _CRYPTO_CHACHA_H */ 98