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1 /* SPDX-License-Identifier: GPL-2.0 */
3 * Common values and helper functions for the ChaCha and XChaCha stream ciphers.
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.
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.
15 #ifndef _CRYPTO_CHACHA_H
16 #define _CRYPTO_CHACHA_H
18 #include <crypto/skcipher.h>
19 #include <linux/types.h>
20 #include <linux/crypto.h>
22 /* 32-bit stream position, then 96-bit nonce (RFC7539 convention) */
23 #define CHACHA_IV_SIZE 16
25 #define CHACHA_KEY_SIZE 32
26 #define CHACHA_BLOCK_SIZE 64
27 #define CHACHAPOLY_IV_SIZE 12
29 /* 192-bit nonce, then 64-bit stream position */
30 #define XCHACHA_IV_SIZE 32
37 void chacha_block(u32
*state
, u8
*stream
, int nrounds
);
38 static inline void chacha20_block(u32
*state
, u8
*stream
)
40 chacha_block(state
, stream
, 20);
42 void hchacha_block(const u32
*in
, u32
*out
, int nrounds
);
44 void crypto_chacha_init(u32
*state
, const struct chacha_ctx
*ctx
, const u8
*iv
);
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
);
51 int crypto_chacha_crypt(struct skcipher_request
*req
);
52 int crypto_xchacha_crypt(struct skcipher_request
*req
);
54 #endif /* _CRYPTO_CHACHA_H */