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