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's 6 * security. Here they share the same key size, tfm context, and setkey 7 * 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 is 10 * recommended to use the 20-round variant ChaCha20. However, the other 11 * variants can be needed in some performance-sensitive scenarios. The generic 12 * ChaCha code currently allows only the 20 and 12-round variants. 13 */ 14 15 #ifndef _CRYPTO_CHACHA_H 16 #define _CRYPTO_CHACHA_H 17 18 #include <asm/unaligned.h> 19 #include <linux/types.h> 20 21 /* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */ 22 #define CHACHA_IV_SIZE 16 23 24 #define CHACHA_KEY_SIZE 32 25 #define CHACHA_BLOCK_SIZE 64 26 #define CHACHAPOLY_IV_SIZE 12 27 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 32 32 33 void chacha_block_generic(u32 *state, u8 *stream, int nrounds); 34 static inline void chacha20_block(u32 *state, u8 *stream) 35 { 36 chacha_block_generic(state, stream, 20); 37 } 38 39 void hchacha_block_arch(const u32 *state, u32 *out, int nrounds); 40 void hchacha_block_generic(const u32 *state, u32 *out, int nrounds); 41 42 static 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 else 47 hchacha_block_generic(state, out, nrounds); 48 } 49 50 enum 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 = 0x6b206574U 55 }; 56 57 static 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 65 void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv); 66 static 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 83 static 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 else 88 chacha_init_generic(state, key, iv); 89 } 90 91 void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, 92 unsigned int bytes, int nrounds); 93 void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src, 94 unsigned int bytes, int nrounds); 95 96 static 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 else 102 chacha_crypt_generic(state, dst, src, bytes, nrounds); 103 } 104 105 static 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