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 185fb8ef25SArd 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 2884e03fa3SArd Biesheuvel #define CHACHA_STATE_WORDS (CHACHA_BLOCK_SIZE / sizeof(u32)) 2984e03fa3SArd Biesheuvel 301ca1b917SEric Biggers /* 192-bit nonce, then 64-bit stream position */ 311ca1b917SEric Biggers #define XCHACHA_IV_SIZE 32 321ca1b917SEric Biggers 335fb8ef25SArd Biesheuvel void chacha_block_generic(u32 *state, u8 *stream, int nrounds); 341ca1b917SEric Biggers static inline void chacha20_block(u32 *state, u8 *stream) 351ca1b917SEric Biggers { 365fb8ef25SArd Biesheuvel chacha_block_generic(state, stream, 20); 371ca1b917SEric Biggers } 381ca1b917SEric Biggers 395fb8ef25SArd Biesheuvel void hchacha_block_arch(const u32 *state, u32 *out, int nrounds); 405fb8ef25SArd Biesheuvel void hchacha_block_generic(const u32 *state, u32 *out, int nrounds); 411ca1b917SEric Biggers 425fb8ef25SArd Biesheuvel static inline void hchacha_block(const u32 *state, u32 *out, int nrounds) 435fb8ef25SArd Biesheuvel { 445fb8ef25SArd Biesheuvel if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 455fb8ef25SArd Biesheuvel hchacha_block_arch(state, out, nrounds); 465fb8ef25SArd Biesheuvel else 475fb8ef25SArd Biesheuvel hchacha_block_generic(state, out, nrounds); 485fb8ef25SArd Biesheuvel } 491ca1b917SEric Biggers 50*a181e0fdSEric Biggers static inline void chacha_init_consts(u32 *state) 515fb8ef25SArd Biesheuvel { 525fb8ef25SArd Biesheuvel state[0] = 0x61707865; /* "expa" */ 535fb8ef25SArd Biesheuvel state[1] = 0x3320646e; /* "nd 3" */ 545fb8ef25SArd Biesheuvel state[2] = 0x79622d32; /* "2-by" */ 555fb8ef25SArd Biesheuvel state[3] = 0x6b206574; /* "te k" */ 56*a181e0fdSEric Biggers } 57*a181e0fdSEric Biggers 58*a181e0fdSEric Biggers void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv); 59*a181e0fdSEric Biggers static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv) 60*a181e0fdSEric Biggers { 61*a181e0fdSEric Biggers chacha_init_consts(state); 625fb8ef25SArd Biesheuvel state[4] = key[0]; 635fb8ef25SArd Biesheuvel state[5] = key[1]; 645fb8ef25SArd Biesheuvel state[6] = key[2]; 655fb8ef25SArd Biesheuvel state[7] = key[3]; 665fb8ef25SArd Biesheuvel state[8] = key[4]; 675fb8ef25SArd Biesheuvel state[9] = key[5]; 685fb8ef25SArd Biesheuvel state[10] = key[6]; 695fb8ef25SArd Biesheuvel state[11] = key[7]; 705fb8ef25SArd Biesheuvel state[12] = get_unaligned_le32(iv + 0); 715fb8ef25SArd Biesheuvel state[13] = get_unaligned_le32(iv + 4); 725fb8ef25SArd Biesheuvel state[14] = get_unaligned_le32(iv + 8); 735fb8ef25SArd Biesheuvel state[15] = get_unaligned_le32(iv + 12); 745fb8ef25SArd Biesheuvel } 755fb8ef25SArd Biesheuvel 765fb8ef25SArd Biesheuvel static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv) 775fb8ef25SArd Biesheuvel { 785fb8ef25SArd Biesheuvel if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 795fb8ef25SArd Biesheuvel chacha_init_arch(state, key, iv); 805fb8ef25SArd Biesheuvel else 815fb8ef25SArd Biesheuvel chacha_init_generic(state, key, iv); 825fb8ef25SArd Biesheuvel } 835fb8ef25SArd Biesheuvel 845fb8ef25SArd Biesheuvel void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, 855fb8ef25SArd Biesheuvel unsigned int bytes, int nrounds); 865fb8ef25SArd Biesheuvel void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src, 875fb8ef25SArd Biesheuvel unsigned int bytes, int nrounds); 885fb8ef25SArd Biesheuvel 895fb8ef25SArd Biesheuvel static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src, 905fb8ef25SArd Biesheuvel unsigned int bytes, int nrounds) 915fb8ef25SArd Biesheuvel { 925fb8ef25SArd Biesheuvel if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 935fb8ef25SArd Biesheuvel chacha_crypt_arch(state, dst, src, bytes, nrounds); 945fb8ef25SArd Biesheuvel else 955fb8ef25SArd Biesheuvel chacha_crypt_generic(state, dst, src, bytes, nrounds); 965fb8ef25SArd Biesheuvel } 975fb8ef25SArd Biesheuvel 985fb8ef25SArd Biesheuvel static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src, 995fb8ef25SArd Biesheuvel unsigned int bytes) 1005fb8ef25SArd Biesheuvel { 1015fb8ef25SArd Biesheuvel chacha_crypt(state, dst, src, bytes, 20); 1025fb8ef25SArd Biesheuvel } 1031ca1b917SEric Biggers 1041ca1b917SEric Biggers #endif /* _CRYPTO_CHACHA_H */ 105