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 #ifdef CONFIG_X86_64 29 #define CHACHA_STATE_WORDS ((CHACHA_BLOCK_SIZE + 12) / sizeof(u32)) 30 #else 31 #define CHACHA_STATE_WORDS (CHACHA_BLOCK_SIZE / sizeof(u32)) 32 #endif 33 34 /* 192-bit nonce, then 64-bit stream position */ 35 #define XCHACHA_IV_SIZE 32 36 37 void chacha_block_generic(u32 *state, u8 *stream, int nrounds); 38 static inline void chacha20_block(u32 *state, u8 *stream) 39 { 40 chacha_block_generic(state, stream, 20); 41 } 42 43 void hchacha_block_arch(const u32 *state, u32 *out, int nrounds); 44 void hchacha_block_generic(const u32 *state, u32 *out, int nrounds); 45 46 static inline void hchacha_block(const u32 *state, u32 *out, int nrounds) 47 { 48 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 49 hchacha_block_arch(state, out, nrounds); 50 else 51 hchacha_block_generic(state, out, nrounds); 52 } 53 54 void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv); 55 static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv) 56 { 57 state[0] = 0x61707865; /* "expa" */ 58 state[1] = 0x3320646e; /* "nd 3" */ 59 state[2] = 0x79622d32; /* "2-by" */ 60 state[3] = 0x6b206574; /* "te k" */ 61 state[4] = key[0]; 62 state[5] = key[1]; 63 state[6] = key[2]; 64 state[7] = key[3]; 65 state[8] = key[4]; 66 state[9] = key[5]; 67 state[10] = key[6]; 68 state[11] = key[7]; 69 state[12] = get_unaligned_le32(iv + 0); 70 state[13] = get_unaligned_le32(iv + 4); 71 state[14] = get_unaligned_le32(iv + 8); 72 state[15] = get_unaligned_le32(iv + 12); 73 } 74 75 static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv) 76 { 77 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 78 chacha_init_arch(state, key, iv); 79 else 80 chacha_init_generic(state, key, iv); 81 } 82 83 void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src, 84 unsigned int bytes, int nrounds); 85 void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src, 86 unsigned int bytes, int nrounds); 87 88 static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src, 89 unsigned int bytes, int nrounds) 90 { 91 if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA)) 92 chacha_crypt_arch(state, dst, src, bytes, nrounds); 93 else 94 chacha_crypt_generic(state, dst, src, bytes, nrounds); 95 } 96 97 static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src, 98 unsigned int bytes) 99 { 100 chacha_crypt(state, dst, src, bytes, 20); 101 } 102 103 #endif /* _CRYPTO_CHACHA_H */ 104