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/* 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 <asm/unaligned.h>
#include <linux/types.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
#define CHACHA_STATE_WORDS (CHACHA_BLOCK_SIZE / sizeof(u32))
/* 192-bit nonce, then 64-bit stream position */
#define XCHACHA_IV_SIZE 32
void chacha_block_generic(u32 *state, u8 *stream, int nrounds);
static inline void chacha20_block(u32 *state, u8 *stream)
{
chacha_block_generic(state, stream, 20);
}
void hchacha_block_arch(const u32 *state, u32 *out, int nrounds);
void hchacha_block_generic(const u32 *state, u32 *out, int nrounds);
static inline void hchacha_block(const u32 *state, u32 *out, int nrounds)
{
if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
hchacha_block_arch(state, out, nrounds);
else
hchacha_block_generic(state, out, nrounds);
}
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;
}
void chacha_init_arch(u32 *state, const u32 *key, const u8 *iv);
static inline void chacha_init_generic(u32 *state, const u32 *key, const u8 *iv)
{
chacha_init_consts(state);
state[4] = key[0];
state[5] = key[1];
state[6] = key[2];
state[7] = key[3];
state[8] = key[4];
state[9] = key[5];
state[10] = key[6];
state[11] = key[7];
state[12] = get_unaligned_le32(iv + 0);
state[13] = get_unaligned_le32(iv + 4);
state[14] = get_unaligned_le32(iv + 8);
state[15] = get_unaligned_le32(iv + 12);
}
static inline void chacha_init(u32 *state, const u32 *key, const u8 *iv)
{
if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
chacha_init_arch(state, key, iv);
else
chacha_init_generic(state, key, iv);
}
void chacha_crypt_arch(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes, int nrounds);
void chacha_crypt_generic(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes, int nrounds);
static inline void chacha_crypt(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes, int nrounds)
{
if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CHACHA))
chacha_crypt_arch(state, dst, src, bytes, nrounds);
else
chacha_crypt_generic(state, dst, src, bytes, nrounds);
}
static inline void chacha20_crypt(u32 *state, u8 *dst, const u8 *src,
unsigned int bytes)
{
chacha_crypt(state, dst, src, bytes, 20);
}
#endif /* _CRYPTO_CHACHA_H */
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