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-rw-r--r--src/postprocess/halfsiphash.c152
1 files changed, 152 insertions, 0 deletions
diff --git a/src/postprocess/halfsiphash.c b/src/postprocess/halfsiphash.c
new file mode 100644
index 0000000..d74d3be
--- /dev/null
+++ b/src/postprocess/halfsiphash.c
@@ -0,0 +1,152 @@
1
2/*
3 SipHash reference C implementation
4
5 Copyright (c) 2016 Jean-Philippe Aumasson <jeanphilippe.aumasson@gmail.com>
6
7 To the extent possible under law, the author(s) have dedicated all copyright
8 and related and neighboring rights to this software to the public domain
9 worldwide. This software is distributed without any warranty.
10
11 You should have received a copy of the CC0 Public Domain Dedication along
12 with
13 this software. If not, see
14 <http://creativecommons.org/publicdomain/zero/1.0/>.
15 */
16#include <assert.h>
17#include <stdint.h>
18#include <stdio.h>
19#include <string.h>
20
21/* default: SipHash-2-4 */
22#define cROUNDS 2
23#define dROUNDS 4
24
25#define ROTL(x, b) (uint32_t)(((x) << (b)) | ((x) >> (32 - (b))))
26
27#define U32TO8_LE(p, v) \
28 (p)[0] = (uint8_t)((v)); \
29 (p)[1] = (uint8_t)((v) >> 8); \
30 (p)[2] = (uint8_t)((v) >> 16); \
31 (p)[3] = (uint8_t)((v) >> 24);
32
33#define U32TO8_LE(p, v) \
34 (p)[0] = (uint8_t)((v)); \
35 (p)[1] = (uint8_t)((v) >> 8); \
36 (p)[2] = (uint8_t)((v) >> 16); \
37 (p)[3] = (uint8_t)((v) >> 24);
38
39#define U8TO32_LE(p) \
40 (((uint32_t)((p)[0])) | ((uint32_t)((p)[1]) << 8) | \
41 ((uint32_t)((p)[2]) << 16) | ((uint32_t)((p)[3]) << 24))
42
43#define SIPROUND \
44 do { \
45 v0 += v1; \
46 v1 = ROTL(v1, 5); \
47 v1 ^= v0; \
48 v0 = ROTL(v0, 16); \
49 v2 += v3; \
50 v3 = ROTL(v3, 8); \
51 v3 ^= v2; \
52 v0 += v3; \
53 v3 = ROTL(v3, 7); \
54 v3 ^= v0; \
55 v2 += v1; \
56 v1 = ROTL(v1, 13); \
57 v1 ^= v2; \
58 v2 = ROTL(v2, 16); \
59 } while (0)
60
61#ifdef DEBUG
62#define TRACE \
63 do { \
64 printf("(%3d) v0 %08x\n", (int)inlen, v0); \
65 printf("(%3d) v1 %08x\n", (int)inlen, v1); \
66 printf("(%3d) v2 %08x\n", (int)inlen, v2); \
67 printf("(%3d) v3 %08x\n", (int)inlen, v3); \
68 } while (0)
69#else
70#define TRACE
71#endif
72
73int halfsiphash(const uint8_t *in, const size_t inlen, const uint8_t *k,
74 uint8_t *out, const size_t outlen) {
75
76 assert((outlen == 4) || (outlen == 8));
77 uint32_t v0 = 0;
78 uint32_t v1 = 0;
79 uint32_t v2 = 0x6c796765;
80 uint32_t v3 = 0x74656462;
81 uint32_t k0 = U8TO32_LE(k);
82 uint32_t k1 = U8TO32_LE(k + 4);
83 uint32_t m;
84 int i;
85 const uint8_t *end = in + inlen - (inlen % sizeof(uint32_t));
86 const int left = inlen & 3;
87 uint32_t b = ((uint32_t)inlen) << 24;
88 v3 ^= k1;
89 v2 ^= k0;
90 v1 ^= k1;
91 v0 ^= k0;
92
93 if (outlen == 8)
94 v1 ^= 0xee;
95
96 for (; in != end; in += 4) {
97 m = U8TO32_LE(in);
98 v3 ^= m;
99
100 TRACE;
101 for (i = 0; i < cROUNDS; ++i)
102 SIPROUND;
103
104 v0 ^= m;
105 }
106
107 switch (left) {
108 case 3:
109 b |= ((uint32_t)in[2]) << 16;
110 case 2:
111 b |= ((uint32_t)in[1]) << 8;
112 case 1:
113 b |= ((uint32_t)in[0]);
114 break;
115 case 0:
116 break;
117 }
118
119 v3 ^= b;
120
121 TRACE;
122 for (i = 0; i < cROUNDS; ++i)
123 SIPROUND;
124
125 v0 ^= b;
126
127 if (outlen == 8)
128 v2 ^= 0xee;
129 else
130 v2 ^= 0xff;
131
132 TRACE;
133 for (i = 0; i < dROUNDS; ++i)
134 SIPROUND;
135
136 b = v1 ^ v3;
137 U32TO8_LE(out, b);
138
139 if (outlen == 4)
140 return 0;
141
142 v1 ^= 0xdd;
143
144 TRACE;
145 for (i = 0; i < dROUNDS; ++i)
146 SIPROUND;
147
148 b = v1 ^ v3;
149 U32TO8_LE(out + 4, b);
150
151 return 0;
152}