1// SPDX-License-Identifier: BSD-3-Clause
2/* $OpenBSD: siphash.c,v 1.3 2015/02/20 11:51:03 tedu Exp $ */
3
4/*-
5 * Copyright (c) 2013 Andre Oppermann <andre@FreeBSD.org>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. The name of the author may not be used to endorse or promote
17 * products derived from this software without specific prior written
18 * permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33/*
34 * SipHash is a family of PRFs SipHash-c-d where the integer parameters c and d
35 * are the number of compression rounds and the number of finalization rounds.
36 * A compression round is identical to a finalization round and this round
37 * function is called SipRound. Given a 128-bit key k and a (possibly empty)
38 * byte string m, SipHash-c-d returns a 64-bit value SipHash-c-d(k; m).
39 *
40 * Implemented from the paper "SipHash: a fast short-input PRF", 2012.09.18,
41 * by Jean-Philippe Aumasson and Daniel J. Bernstein,
42 * Permanent Document ID b9a943a805fbfc6fde808af9fc0ecdfa
43 * https://131002.net/siphash/siphash.pdf
44 * https://131002.net/siphash/
45 */
46
47#include <asm/byteorder.h>
48#include <asm/unaligned.h>
49#include <linux/bitops.h>
50#include <linux/string.h>
51
52#include "siphash.h"
53
54static void SipHash_Rounds(SIPHASH_CTX *ctx, int rounds)
55{
56 while (rounds--) {
57 ctx->v[0] += ctx->v[1];
58 ctx->v[2] += ctx->v[3];
59 ctx->v[1] = rol64(word: ctx->v[1], shift: 13);
60 ctx->v[3] = rol64(word: ctx->v[3], shift: 16);
61
62 ctx->v[1] ^= ctx->v[0];
63 ctx->v[3] ^= ctx->v[2];
64 ctx->v[0] = rol64(word: ctx->v[0], shift: 32);
65
66 ctx->v[2] += ctx->v[1];
67 ctx->v[0] += ctx->v[3];
68 ctx->v[1] = rol64(word: ctx->v[1], shift: 17);
69 ctx->v[3] = rol64(word: ctx->v[3], shift: 21);
70
71 ctx->v[1] ^= ctx->v[2];
72 ctx->v[3] ^= ctx->v[0];
73 ctx->v[2] = rol64(word: ctx->v[2], shift: 32);
74 }
75}
76
77static void SipHash_CRounds(SIPHASH_CTX *ctx, const void *ptr, int rounds)
78{
79 u64 m = get_unaligned_le64(p: ptr);
80
81 ctx->v[3] ^= m;
82 SipHash_Rounds(ctx, rounds);
83 ctx->v[0] ^= m;
84}
85
86void SipHash_Init(SIPHASH_CTX *ctx, const SIPHASH_KEY *key)
87{
88 u64 k0, k1;
89
90 k0 = le64_to_cpu(key->k0);
91 k1 = le64_to_cpu(key->k1);
92
93 ctx->v[0] = 0x736f6d6570736575ULL ^ k0;
94 ctx->v[1] = 0x646f72616e646f6dULL ^ k1;
95 ctx->v[2] = 0x6c7967656e657261ULL ^ k0;
96 ctx->v[3] = 0x7465646279746573ULL ^ k1;
97
98 memset(ctx->buf, 0, sizeof(ctx->buf));
99 ctx->bytes = 0;
100}
101
102void SipHash_Update(SIPHASH_CTX *ctx, int rc, int rf,
103 const void *src, size_t len)
104{
105 const u8 *ptr = src;
106 size_t left, used;
107
108 if (len == 0)
109 return;
110
111 used = ctx->bytes % sizeof(ctx->buf);
112 ctx->bytes += len;
113
114 if (used > 0) {
115 left = sizeof(ctx->buf) - used;
116
117 if (len >= left) {
118 memcpy(&ctx->buf[used], ptr, left);
119 SipHash_CRounds(ctx, ptr: ctx->buf, rounds: rc);
120 len -= left;
121 ptr += left;
122 } else {
123 memcpy(&ctx->buf[used], ptr, len);
124 return;
125 }
126 }
127
128 while (len >= sizeof(ctx->buf)) {
129 SipHash_CRounds(ctx, ptr, rounds: rc);
130 len -= sizeof(ctx->buf);
131 ptr += sizeof(ctx->buf);
132 }
133
134 if (len > 0)
135 memcpy(&ctx->buf[used], ptr, len);
136}
137
138void SipHash_Final(void *dst, SIPHASH_CTX *ctx, int rc, int rf)
139{
140 u64 r;
141
142 r = SipHash_End(ctx, rc, rf);
143
144 *((__le64 *) dst) = cpu_to_le64(r);
145}
146
147u64 SipHash_End(SIPHASH_CTX *ctx, int rc, int rf)
148{
149 u64 r;
150 size_t left, used;
151
152 used = ctx->bytes % sizeof(ctx->buf);
153 left = sizeof(ctx->buf) - used;
154 memset(&ctx->buf[used], 0, left - 1);
155 ctx->buf[7] = ctx->bytes;
156
157 SipHash_CRounds(ctx, ptr: ctx->buf, rounds: rc);
158 ctx->v[2] ^= 0xff;
159 SipHash_Rounds(ctx, rounds: rf);
160
161 r = (ctx->v[0] ^ ctx->v[1]) ^ (ctx->v[2] ^ ctx->v[3]);
162 memset(ctx, 0, sizeof(*ctx));
163 return r;
164}
165
166u64 SipHash(const SIPHASH_KEY *key, int rc, int rf, const void *src, size_t len)
167{
168 SIPHASH_CTX ctx;
169
170 SipHash_Init(ctx: &ctx, key);
171 SipHash_Update(ctx: &ctx, rc, rf, src, len);
172 return SipHash_End(ctx: &ctx, rc, rf);
173}
174

source code of linux/fs/bcachefs/siphash.c