1/*
2   SipHash reference C implementation
3
4   Copyright (c) 2012-2016 Jean-Philippe Aumasson
5   <jeanphilippe.aumasson@gmail.com>
6   Copyright (c) 2012-2014 Daniel J. Bernstein <djb@cr.yp.to>
7
8   To the extent possible under law, the author(s) have dedicated all copyright
9   and related and neighboring rights to this software to the public domain
10   worldwide. This software is distributed without any warranty.
11
12   You should have received a copy of the CC0 Public Domain Dedication along
13   with
14   this software. If not, see
15   <http://creativecommons.org/publicdomain/zero/1.0/>.
16 */
17#include <assert.h>
18#include <stdint.h>
19#include <stdio.h>
20#include <string.h>
21
22/* default: SipHash-2-4 */
23#define cROUNDS 2
24#define dROUNDS 4
25
26#define ROTL(x, b) (uint64_t)(((x) << (b)) | ((x) >> (64 - (b))))
27
28#define U32TO8_LE(p, v)                                                        \
29    (p)[0] = (uint8_t)((v));                                                   \
30    (p)[1] = (uint8_t)((v) >> 8);                                              \
31    (p)[2] = (uint8_t)((v) >> 16);                                             \
32    (p)[3] = (uint8_t)((v) >> 24);
33
34#define U64TO8_LE(p, v)                                                        \
35    U32TO8_LE((p), (uint32_t)((v)));                                           \
36    U32TO8_LE((p) + 4, (uint32_t)((v) >> 32));
37
38#define U8TO64_LE(p)                                                           \
39    (((uint64_t)((p)[0])) | ((uint64_t)((p)[1]) << 8) |                        \
40     ((uint64_t)((p)[2]) << 16) | ((uint64_t)((p)[3]) << 24) |                 \
41     ((uint64_t)((p)[4]) << 32) | ((uint64_t)((p)[5]) << 40) |                 \
42     ((uint64_t)((p)[6]) << 48) | ((uint64_t)((p)[7]) << 56))
43
44#define SIPROUND                                                               \
45    do {                                                                       \
46        v0 += v1;                                                              \
47        v1 = ROTL(v1, 13);                                                     \
48        v1 ^= v0;                                                              \
49        v0 = ROTL(v0, 32);                                                     \
50        v2 += v3;                                                              \
51        v3 = ROTL(v3, 16);                                                     \
52        v3 ^= v2;                                                              \
53        v0 += v3;                                                              \
54        v3 = ROTL(v3, 21);                                                     \
55        v3 ^= v0;                                                              \
56        v2 += v1;                                                              \
57        v1 = ROTL(v1, 17);                                                     \
58        v1 ^= v2;                                                              \
59        v2 = ROTL(v2, 32);                                                     \
60    } while (0)
61
62#ifdef DEBUG
63#define TRACE                                                                  \
64    do {                                                                       \
65        printf("(%3d) v0 %08x %08x\n", (int)inlen, (uint32_t)(v0 >> 32),       \
66               (uint32_t)v0);                                                  \
67        printf("(%3d) v1 %08x %08x\n", (int)inlen, (uint32_t)(v1 >> 32),       \
68               (uint32_t)v1);                                                  \
69        printf("(%3d) v2 %08x %08x\n", (int)inlen, (uint32_t)(v2 >> 32),       \
70               (uint32_t)v2);                                                  \
71        printf("(%3d) v3 %08x %08x\n", (int)inlen, (uint32_t)(v3 >> 32),       \
72               (uint32_t)v3);                                                  \
73    } while (0)
74#else
75#define TRACE
76#endif
77
78int siphash(const uint8_t *in, const size_t inlen, const uint8_t *k,
79            uint8_t *out, const size_t outlen) {
80    uint64_t v0 = 0x736f6d6570736575ULL;
81    uint64_t v1 = 0x646f72616e646f6dULL;
82    uint64_t v2 = 0x6c7967656e657261ULL;
83    uint64_t v3 = 0x7465646279746573ULL;
84    uint64_t k0 = U8TO64_LE(k);
85    uint64_t k1 = U8TO64_LE(k + 8);
86    uint64_t m;
87    int i;
88    const uint8_t *end = in + inlen - (inlen % sizeof(uint64_t));
89    const int left = inlen & 7;
90    uint64_t b = ((uint64_t)inlen) << 56;
91    v3 ^= k1;
92    v2 ^= k0;
93    v1 ^= k1;
94    v0 ^= k0;
95
96    assert((outlen == 8) || (outlen == 16));
97    if (outlen == 16)
98        v1 ^= 0xee;
99
100    for (; in != end; in += 8) {
101        m = U8TO64_LE(in);
102        v3 ^= m;
103
104        TRACE;
105        for (i = 0; i < cROUNDS; ++i)
106            SIPROUND;
107
108        v0 ^= m;
109    }
110
111    switch (left) {
112    case 7:
113        b |= ((uint64_t)in[6]) << 48;
114	/* fallthrough */
115    case 6:
116        b |= ((uint64_t)in[5]) << 40;
117	/* fallthrough */
118    case 5:
119        b |= ((uint64_t)in[4]) << 32;
120	/* fallthrough */
121    case 4:
122        b |= ((uint64_t)in[3]) << 24;
123	/* fallthrough */
124    case 3:
125        b |= ((uint64_t)in[2]) << 16;
126	/* fallthrough */
127    case 2:
128        b |= ((uint64_t)in[1]) << 8;
129	/* fallthrough */
130    case 1:
131        b |= ((uint64_t)in[0]);
132        break;
133    case 0:
134        break;
135    }
136
137    v3 ^= b;
138
139    TRACE;
140    for (i = 0; i < cROUNDS; ++i)
141        SIPROUND;
142
143    v0 ^= b;
144
145    if (outlen == 16)
146        v2 ^= 0xee;
147    else
148        v2 ^= 0xff;
149
150    TRACE;
151    for (i = 0; i < dROUNDS; ++i)
152        SIPROUND;
153
154    b = v0 ^ v1 ^ v2 ^ v3;
155    U64TO8_LE(out, b);
156
157    if (outlen == 8)
158        return 0;
159
160    v1 ^= 0xdd;
161
162    TRACE;
163    for (i = 0; i < dROUNDS; ++i)
164        SIPROUND;
165
166    b = v0 ^ v1 ^ v2 ^ v3;
167    U64TO8_LE(out + 8, b);
168
169    return 0;
170}
171