| /* SPDX-License-Identifier: GPL-2.0 */ |
| /* |
| * Common values and helper functions for the ChaCha and XChaCha stream ciphers. |
| * |
| * XChaCha extends ChaCha's nonce to 192 bits, while provably retaining ChaCha's |
| * security. Here they share the same key size, tfm context, and setkey |
| * function; only their IV size and encrypt/decrypt function differ. |
| * |
| * The ChaCha paper specifies 20, 12, and 8-round variants. In general, it is |
| * recommended to use the 20-round variant ChaCha20. However, the other |
| * variants can be needed in some performance-sensitive scenarios. The generic |
| * ChaCha code currently allows only the 20 and 12-round variants. |
| */ |
| |
| #ifndef _CRYPTO_CHACHA_H |
| #define _CRYPTO_CHACHA_H |
| |
| #include <crypto/skcipher.h> |
| #include <linux/types.h> |
| #include <linux/crypto.h> |
| |
| /* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */ |
| #define CHACHA_IV_SIZE 16 |
| |
| #define CHACHA_KEY_SIZE 32 |
| #define CHACHA_BLOCK_SIZE 64 |
| #define CHACHAPOLY_IV_SIZE 12 |
| |
| /* 192-bit nonce, then 64-bit stream position */ |
| #define XCHACHA_IV_SIZE 32 |
| |
| struct chacha_ctx { |
| u32 key[8]; |
| int nrounds; |
| }; |
| |
| void chacha_block(u32 *state, u8 *stream, int nrounds); |
| static inline void chacha20_block(u32 *state, u8 *stream) |
| { |
| chacha_block(state, stream, 20); |
| } |
| void hchacha_block(const u32 *in, u32 *out, int nrounds); |
| |
| void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv); |
| |
| int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key, |
| unsigned int keysize); |
| int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key, |
| unsigned int keysize); |
| |
| int crypto_chacha_crypt(struct skcipher_request *req); |
| int crypto_xchacha_crypt(struct skcipher_request *req); |
| |
| enum chacha_constants { /* expand 32-byte k */ |
| CHACHA_CONSTANT_EXPA = 0x61707865U, |
| CHACHA_CONSTANT_ND_3 = 0x3320646eU, |
| CHACHA_CONSTANT_2_BY = 0x79622d32U, |
| CHACHA_CONSTANT_TE_K = 0x6b206574U |
| }; |
| |
| static inline void chacha_init_consts(u32 *state) |
| { |
| state[0] = CHACHA_CONSTANT_EXPA; |
| state[1] = CHACHA_CONSTANT_ND_3; |
| state[2] = CHACHA_CONSTANT_2_BY; |
| state[3] = CHACHA_CONSTANT_TE_K; |
| } |
| |
| #endif /* _CRYPTO_CHACHA_H */ |