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
51 static void SipHash_CRounds(SIPHASH_CTX *, int);
52 static void SipHash_Rounds(SIPHASH_CTX *, int);
53
54 void
SipHash_Init(SIPHASH_CTX * ctx,const SIPHASH_KEY * key)55 SipHash_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
71 void
SipHash_Update(SIPHASH_CTX * ctx,int rc,int rf,const void * src,size_t len)72 SipHash_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
108 void
SipHash_Final(void * dst,SIPHASH_CTX * ctx,int rc,int rf)109 SipHash_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
117 uint64_t
SipHash_End(SIPHASH_CTX * ctx,int rc,int rf)118 SipHash_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
137 uint64_t
SipHash(const SIPHASH_KEY * key,int rc,int rf,const void * src,size_t len)138 SipHash(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
149 static void
SipHash_Rounds(SIPHASH_CTX * ctx,int rounds)150 SipHash_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
173 static void
SipHash_CRounds(SIPHASH_CTX * ctx,int rounds)174 SipHash_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