/* 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 <asm/unaligned.h>
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#include <linux/types.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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#define CHACHA_STATE_WORDS (CHACHA_BLOCK_SIZE / sizeof(u32))
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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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void chacha_block_generic(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_generic(state, stream, 20);
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}
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void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
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void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
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static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
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{
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if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
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hchacha_block_arch(state, out, nrounds);
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else
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hchacha_block_generic(state, out, nrounds);
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}
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enum chacha_constants { /* expand 32-byte k */
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CHACHA_CONSTANT_EXPA = 0x61707865U,
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CHACHA_CONSTANT_ND_3 = 0x3320646eU,
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CHACHA_CONSTANT_2_BY = 0x79622d32U,
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CHACHA_CONSTANT_TE_K = 0x6b206574U
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};
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static inline void chacha_init_consts(u32 *state)
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{
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state[0] = CHACHA_CONSTANT_EXPA;
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state[1] = CHACHA_CONSTANT_ND_3;
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state[2] = CHACHA_CONSTANT_2_BY;
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state[3] = CHACHA_CONSTANT_TE_K;
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}
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void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
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static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
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{
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chacha_init_consts(state);
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state[4] = key[0];
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state[5] = key[1];
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state[6] = key[2];
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state[7] = key[3];
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state[8] = key[4];
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state[9] = key[5];
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state[10] = key[6];
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state[11] = key[7];
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state[12] = get_unaligned_le32(iv + 0);
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state[13] = get_unaligned_le32(iv + 4);
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state[14] = get_unaligned_le32(iv + 8);
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state[15] = get_unaligned_le32(iv + 12);
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}
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static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
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{
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if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
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chacha_init_arch(state, key, iv);
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else
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chacha_init_generic(state, key, iv);
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}
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void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds);
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void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds);
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static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes, int nrounds)
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{
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if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
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chacha_crypt_arch(state, dst, src, bytes, nrounds);
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else
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chacha_crypt_generic(state, dst, src, bytes, nrounds);
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}
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static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,
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unsigned int bytes)
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{
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chacha_crypt(state, dst, src, bytes, 20);
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}
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#endif /* _CRYPTO_CHACHA_H */
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