1
2 /*
3 * Keyed 32-bit hash function using TEA in a Davis-Meyer function
4 * H0 = Key
5 * Hi = E Mi(Hi-1) + Hi-1
6 *
7 * (see Applied Cryptography, 2nd edition, p448).
8 *
9 * Jeremy Fitzhardinge <jeremy@zip.com.au> 1998
10 *
11 * Jeremy has agreed to the contents of reiserfs/README. -Hans
12 * Yura's function is added (04/07/2000)
13 */
14
15 //
16 // keyed_hash
17 // yura_hash
18 // r5_hash
19 //
20
21 #include <linux/kernel.h>
22 #include "reiserfs.h"
23 #include <asm/types.h>
24
25 #define DELTA 0x9E3779B9
26 #define FULLROUNDS 10 /* 32 is overkill, 16 is strong crypto */
27 #define PARTROUNDS 6 /* 6 gets complete mixing */
28
29 /* a, b, c, d - data; h0, h1 - accumulated hash */
30 #define TEACORE(rounds) \
31 do { \
32 u32 sum = 0; \
33 int n = rounds; \
34 u32 b0, b1; \
35 \
36 b0 = h0; \
37 b1 = h1; \
38 \
39 do \
40 { \
41 sum += DELTA; \
42 b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b); \
43 b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d); \
44 } while(--n); \
45 \
46 h0 += b0; \
47 h1 += b1; \
48 } while(0)
49
keyed_hash(const signed char * msg,int len)50 u32 keyed_hash(const signed char *msg, int len)
51 {
52 u32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3 };
53
54 u32 h0 = k[0], h1 = k[1];
55 u32 a, b, c, d;
56 u32 pad;
57 int i;
58
59 // assert(len >= 0 && len < 256);
60
61 pad = (u32) len | ((u32) len << 8);
62 pad |= pad << 16;
63
64 while (len >= 16) {
65 a = (u32) msg[0] |
66 (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
67 b = (u32) msg[4] |
68 (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
69 c = (u32) msg[8] |
70 (u32) msg[9] << 8 |
71 (u32) msg[10] << 16 | (u32) msg[11] << 24;
72 d = (u32) msg[12] |
73 (u32) msg[13] << 8 |
74 (u32) msg[14] << 16 | (u32) msg[15] << 24;
75
76 TEACORE(PARTROUNDS);
77
78 len -= 16;
79 msg += 16;
80 }
81
82 if (len >= 12) {
83 a = (u32) msg[0] |
84 (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
85 b = (u32) msg[4] |
86 (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
87 c = (u32) msg[8] |
88 (u32) msg[9] << 8 |
89 (u32) msg[10] << 16 | (u32) msg[11] << 24;
90
91 d = pad;
92 for (i = 12; i < len; i++) {
93 d <<= 8;
94 d |= msg[i];
95 }
96 } else if (len >= 8) {
97 a = (u32) msg[0] |
98 (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
99 b = (u32) msg[4] |
100 (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
101
102 c = d = pad;
103 for (i = 8; i < len; i++) {
104 c <<= 8;
105 c |= msg[i];
106 }
107 } else if (len >= 4) {
108 a = (u32) msg[0] |
109 (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
110
111 b = c = d = pad;
112 for (i = 4; i < len; i++) {
113 b <<= 8;
114 b |= msg[i];
115 }
116 } else {
117 a = b = c = d = pad;
118 for (i = 0; i < len; i++) {
119 a <<= 8;
120 a |= msg[i];
121 }
122 }
123
124 TEACORE(FULLROUNDS);
125
126 /* return 0;*/
127 return h0 ^ h1;
128 }
129
130 /* What follows in this file is copyright 2000 by Hans Reiser, and the
131 * licensing of what follows is governed by reiserfs/README */
132
yura_hash(const signed char * msg,int len)133 u32 yura_hash(const signed char *msg, int len)
134 {
135 int j, pow;
136 u32 a, c;
137 int i;
138
139 for (pow = 1, i = 1; i < len; i++)
140 pow = pow * 10;
141
142 if (len == 1)
143 a = msg[0] - 48;
144 else
145 a = (msg[0] - 48) * pow;
146
147 for (i = 1; i < len; i++) {
148 c = msg[i] - 48;
149 for (pow = 1, j = i; j < len - 1; j++)
150 pow = pow * 10;
151 a = a + c * pow;
152 }
153
154 for (; i < 40; i++) {
155 c = '0' - 48;
156 for (pow = 1, j = i; j < len - 1; j++)
157 pow = pow * 10;
158 a = a + c * pow;
159 }
160
161 for (; i < 256; i++) {
162 c = i;
163 for (pow = 1, j = i; j < len - 1; j++)
164 pow = pow * 10;
165 a = a + c * pow;
166 }
167
168 a = a << 7;
169 return a;
170 }
171
r5_hash(const signed char * msg,int len)172 u32 r5_hash(const signed char *msg, int len)
173 {
174 u32 a = 0;
175 while (*msg) {
176 a += *msg << 4;
177 a += *msg >> 4;
178 a *= 11;
179 msg++;
180 }
181 return a;
182 }
183