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/* SPDX-License-Identifier: GPL-2.0 OR MIT */
/*
* Copyright (C) 2015-2019 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#ifndef CURVE25519_H
#define CURVE25519_H
#include <crypto/algapi.h> // For crypto_memneq.
#include <linux/types.h>
#include <linux/random.h>
enum curve25519_lengths {
CURVE25519_KEY_SIZE = 32
};
extern const u8 curve25519_null_point[];
extern const u8 curve25519_base_point[];
void curve25519_generic(u8 out[CURVE25519_KEY_SIZE],
const u8 scalar[CURVE25519_KEY_SIZE],
const u8 point[CURVE25519_KEY_SIZE]);
void curve25519_arch(u8 out[CURVE25519_KEY_SIZE],
const u8 scalar[CURVE25519_KEY_SIZE],
const u8 point[CURVE25519_KEY_SIZE]);
void curve25519_base_arch(u8 pub[CURVE25519_KEY_SIZE],
const u8 secret[CURVE25519_KEY_SIZE]);
bool curve25519_selftest(void);
static inline
bool __must_check curve25519(u8 mypublic[CURVE25519_KEY_SIZE],
const u8 secret[CURVE25519_KEY_SIZE],
const u8 basepoint[CURVE25519_KEY_SIZE])
{
if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519))
curve25519_arch(mypublic, secret, basepoint);
else
curve25519_generic(mypublic, secret, basepoint);
return crypto_memneq(mypublic, curve25519_null_point,
CURVE25519_KEY_SIZE);
}
static inline bool
__must_check curve25519_generate_public(u8 pub[CURVE25519_KEY_SIZE],
const u8 secret[CURVE25519_KEY_SIZE])
{
if (unlikely(!crypto_memneq(secret, curve25519_null_point,
CURVE25519_KEY_SIZE)))
return false;
if (IS_ENABLED(CONFIG_CRYPTO_ARCH_HAVE_LIB_CURVE25519))
curve25519_base_arch(pub, secret);
else
curve25519_generic(pub, secret, curve25519_base_point);
return crypto_memneq(pub, curve25519_null_point, CURVE25519_KEY_SIZE);
}
static inline void curve25519_clamp_secret(u8 secret[CURVE25519_KEY_SIZE])
{
secret[0] &= 248;
secret[31] = (secret[31] & 127) | 64;
}
static inline void curve25519_generate_secret(u8 secret[CURVE25519_KEY_SIZE])
{
get_random_bytes_wait(secret, CURVE25519_KEY_SIZE);
curve25519_clamp_secret(secret);
}
#endif /* CURVE25519_H */
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