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/* SPDX-License-Identifier: GPL-2.0-or-later
* Copyright Red Hat
* Author: Stefano Brivio <sbrivio@redhat.com>
* Author: David Gibson <david@gibson.dropbear.id.au>
*
* This is an implementation of the SipHash-2-4-64 functions needed for TCP
* initial sequence numbers and socket lookup table hash for IPv4 and IPv6, see:
*
* Aumasson, J.P. and Bernstein, D.J., 2012, December. SipHash: a fast
* short-input PRF. In International Conference on Cryptology in India
* (pp. 489-508). Springer, Berlin, Heidelberg.
*
* http://cr.yp.to/siphash/siphash-20120918.pdf
*
* This includes code from the reference SipHash implementation at
* https://github.com/veorq/SipHash/ originally licensed as follows:
*
* --
* SipHash reference C implementation
*
* Copyright (c) 2012-2021 Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
* Copyright (c) 2012-2014 Daniel J. Bernstein <djb@cr.yp.to>
*
* To the extent possible under law, the author(s) have dedicated all copyright
* and related and neighboring rights to this software to the public domain
* worldwide. This software is distributed without any warranty.
*
* You should have received a copy of the CC0 Public Domain Dedication along
* with this software. If not, see
* <http://creativecommons.org/publicdomain/zero/1.0/>.
* --
*
* and from the Linux kernel implementation (lib/siphash.c), originally licensed
* as follows:
*
* --
* Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*
* This file is provided under a dual BSD/GPLv2 license.
* --
*
*/
#ifndef SIPHASH_H
#define SIPHASH_H
/**
* struct siphash_state - Internal state of siphash calculation
*/
struct siphash_state {
uint64_t v[4];
};
#define SIPHASH_INIT(k) { { \
0x736f6d6570736575ULL ^ (k)[0], \
0x646f72616e646f6dULL ^ (k)[1], \
0x6c7967656e657261ULL ^ (k)[0], \
0x7465646279746573ULL ^ (k)[1] \
} }
/**
* sipround() - Perform rounds of SipHash scrambling
* @v: siphash state (4 x 64-bit integers)
* @n: Number of rounds to apply
*/
static inline void sipround(struct siphash_state *state, int n)
{
int i;
#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
for (i = 0; i < n; i++) {
state->v[0] += state->v[1];
state->v[1] = ROTL(state->v[1], 13) ^ state->v[0];
state->v[0] = ROTL(state->v[0], 32);
state->v[2] += state->v[3];
state->v[3] = ROTL(state->v[3], 16) ^ state->v[2];
state->v[0] += state->v[3];
state->v[3] = ROTL(state->v[3], 21) ^ state->v[0];
state->v[2] += state->v[1];
state->v[1] = ROTL(state->v[1], 17) ^ state->v[2];
state->v[2] = ROTL(state->v[2], 32);
}
#undef ROTL
}
/**
* siphash_feed() - Fold 64-bits of data into the hash state
* @v: siphash state (4 x 64-bit integers)
* @in: New value to fold into hash
*/
static inline void siphash_feed(struct siphash_state *state, uint64_t in)
{
state->v[3] ^= in;
sipround(state, 2);
state->v[0] ^= in;
}
/**
* siphash_final - Finalize SipHash calculations
* @v: siphash state (4 x 64-bit integers)
* @len: Total length of input data
* @tail: Final data for the hash (<= 7 bytes)
*/
static inline uint64_t siphash_final(struct siphash_state *state,
size_t len, uint64_t tail)
{
uint64_t b = (uint64_t)(len) << 56 | tail;
siphash_feed(state, b);
state->v[2] ^= 0xff;
sipround(state, 4);
return state->v[0] ^ state->v[1] ^ state->v[2] ^ state->v[3];
}
#endif /* SIPHASH_H */
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