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 <crypto/skcipher.h> 19 #include <linux/types.h> 20 #include <linux/crypto.h> 21 22 /* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */ 23 #define CHACHA_IV_SIZE 16 24 25 #define CHACHA_KEY_SIZE 32 26 #define CHACHA_BLOCK_SIZE 64 27 #define CHACHAPOLY_IV_SIZE 12 28 29 /* 192-bit nonce, then 64-bit stream position */ 30 #define XCHACHA_IV_SIZE 32 31 32 struct chacha_ctx { 33 u32 key[8]; 34 int nrounds; 35 }; 36 37 void chacha_block(u32 *state, u8 *stream, int nrounds); 38 static inline void chacha20_block(u32 *state, u8 *stream) 39 { 40 chacha_block(state, stream, 20); 41 } 42 void hchacha_block(const u32 *in, u32 *out, int nrounds); 43 44 void crypto_chacha_init(u32 *state, const struct chacha_ctx *ctx, const u8 *iv); 45 46 int crypto_chacha20_setkey(struct crypto_skcipher *tfm, const u8 *key, 47 unsigned int keysize); 48 int crypto_chacha12_setkey(struct crypto_skcipher *tfm, const u8 *key, 49 unsigned int keysize); 50 51 int crypto_chacha_crypt(struct skcipher_request *req); 52 int crypto_xchacha_crypt(struct skcipher_request *req); 53 54 #endif /* _CRYPTO_CHACHA_H */ 55