1/*	$OpenBSD: siphash.c,v 1.5 2018/01/05 19:05:09 mikeb Exp $ */
2
3/*-
4 * Copyright (c) 2013 Andre Oppermann <andre@FreeBSD.org>
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 3. The name of the author may not be used to endorse or promote
16 *    products derived from this software without specific prior written
17 *    permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32/*
33 * SipHash is a family of PRFs SipHash-c-d where the integer parameters c and d
34 * are the number of compression rounds and the number of finalization rounds.
35 * A compression round is identical to a finalization round and this round
36 * function is called SipRound.  Given a 128-bit key k and a (possibly empty)
37 * byte string m, SipHash-c-d returns a 64-bit value SipHash-c-d(k; m).
38 *
39 * Implemented from the paper "SipHash: a fast short-input PRF", 2012.09.18,
40 * by Jean-Philippe Aumasson and Daniel J. Bernstein,
41 * Permanent Document ID b9a943a805fbfc6fde808af9fc0ecdfa
42 * https://131002.net/siphash/siphash.pdf
43 * https://131002.net/siphash/
44 */
45
46#include <sys/param.h>
47#include <sys/systm.h>
48
49#include <crypto/siphash.h>
50
51static void	SipHash_CRounds(SIPHASH_CTX *, int);
52static void	SipHash_Rounds(SIPHASH_CTX *, int);
53
54void
55SipHash_Init(SIPHASH_CTX *ctx, const SIPHASH_KEY *key)
56{
57	uint64_t k0, k1;
58
59	k0 = lemtoh64(&key->k0);
60	k1 = lemtoh64(&key->k1);
61
62	ctx->v[0] = 0x736f6d6570736575ULL ^ k0;
63	ctx->v[1] = 0x646f72616e646f6dULL ^ k1;
64	ctx->v[2] = 0x6c7967656e657261ULL ^ k0;
65	ctx->v[3] = 0x7465646279746573ULL ^ k1;
66
67	memset(ctx->buf, 0, sizeof(ctx->buf));
68	ctx->bytes = 0;
69}
70
71void
72SipHash_Update(SIPHASH_CTX *ctx, int rc, int rf, const void *src, size_t len)
73{
74	const uint8_t *ptr = src;
75	size_t left, used;
76
77	if (len == 0)
78		return;
79
80	used = ctx->bytes % sizeof(ctx->buf);
81	ctx->bytes += len;
82
83	if (used > 0) {
84		left = sizeof(ctx->buf) - used;
85
86		if (len >= left) {
87			memcpy(&ctx->buf[used], ptr, left);
88			SipHash_CRounds(ctx, rc);
89			len -= left;
90			ptr += left;
91		} else {
92			memcpy(&ctx->buf[used], ptr, len);
93			return;
94		}
95	}
96
97	while (len >= sizeof(ctx->buf)) {
98		memcpy(ctx->buf, ptr, sizeof(ctx->buf));
99		SipHash_CRounds(ctx, rc);
100		len -= sizeof(ctx->buf);
101		ptr += sizeof(ctx->buf);
102	}
103
104	if (len > 0)
105		memcpy(ctx->buf, ptr, len);
106}
107
108void
109SipHash_Final(void *dst, SIPHASH_CTX *ctx, int rc, int rf)
110{
111	uint64_t r;
112
113	htolem64(&r, SipHash_End(ctx, rc, rf));
114	memcpy(dst, &r, sizeof r);
115}
116
117uint64_t
118SipHash_End(SIPHASH_CTX *ctx, int rc, int rf)
119{
120	uint64_t r;
121	size_t left, used;
122
123	used = ctx->bytes % sizeof(ctx->buf);
124	left = sizeof(ctx->buf) - used;
125	memset(&ctx->buf[used], 0, left - 1);
126	ctx->buf[7] = ctx->bytes;
127
128	SipHash_CRounds(ctx, rc);
129	ctx->v[2] ^= 0xff;
130	SipHash_Rounds(ctx, rf);
131
132	r = (ctx->v[0] ^ ctx->v[1]) ^ (ctx->v[2] ^ ctx->v[3]);
133	explicit_bzero(ctx, sizeof(*ctx));
134	return (r);
135}
136
137uint64_t
138SipHash(const SIPHASH_KEY *key, int rc, int rf, const void *src, size_t len)
139{
140	SIPHASH_CTX ctx;
141
142	SipHash_Init(&ctx, key);
143	SipHash_Update(&ctx, rc, rf, src, len);
144	return (SipHash_End(&ctx, rc, rf));
145}
146
147#define SIP_ROTL(x, b) ((x) << (b)) | ( (x) >> (64 - (b)))
148
149static void
150SipHash_Rounds(SIPHASH_CTX *ctx, int rounds)
151{
152	while (rounds--) {
153		ctx->v[0] += ctx->v[1];
154		ctx->v[2] += ctx->v[3];
155		ctx->v[1] = SIP_ROTL(ctx->v[1], 13);
156		ctx->v[3] = SIP_ROTL(ctx->v[3], 16);
157
158		ctx->v[1] ^= ctx->v[0];
159		ctx->v[3] ^= ctx->v[2];
160		ctx->v[0] = SIP_ROTL(ctx->v[0], 32);
161
162		ctx->v[2] += ctx->v[1];
163		ctx->v[0] += ctx->v[3];
164		ctx->v[1] = SIP_ROTL(ctx->v[1], 17);
165		ctx->v[3] = SIP_ROTL(ctx->v[3], 21);
166
167		ctx->v[1] ^= ctx->v[2];
168		ctx->v[3] ^= ctx->v[0];
169		ctx->v[2] = SIP_ROTL(ctx->v[2], 32);
170	}
171}
172
173static void
174SipHash_CRounds(SIPHASH_CTX *ctx, int rounds)
175{
176	uint64_t m = lemtoh64((uint64_t *)ctx->buf);
177
178	ctx->v[3] ^= m;
179	SipHash_Rounds(ctx, rounds);
180	ctx->v[0] ^= m;
181}
182