xref: /openbmc/linux/fs/reiserfs/hashes.c (revision ae213c44)
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 #include <linux/kernel.h>
16 #include "reiserfs.h"
17 #include <asm/types.h>
18 
19 #define DELTA 0x9E3779B9
20 #define FULLROUNDS 10		/* 32 is overkill, 16 is strong crypto */
21 #define PARTROUNDS 6		/* 6 gets complete mixing */
22 
23 /* a, b, c, d - data; h0, h1 - accumulated hash */
24 #define TEACORE(rounds)							\
25 	do {								\
26 		u32 sum = 0;						\
27 		int n = rounds;						\
28 		u32 b0, b1;						\
29 									\
30 		b0 = h0;						\
31 		b1 = h1;						\
32 									\
33 		do							\
34 		{							\
35 			sum += DELTA;					\
36 			b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);	\
37 			b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);	\
38 		} while(--n);						\
39 									\
40 		h0 += b0;						\
41 		h1 += b1;						\
42 	} while(0)
43 
44 u32 keyed_hash(const signed char *msg, int len)
45 {
46 	u32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3 };
47 
48 	u32 h0 = k[0], h1 = k[1];
49 	u32 a, b, c, d;
50 	u32 pad;
51 	int i;
52 
53 	/*      assert(len >= 0 && len < 256); */
54 
55 	pad = (u32) len | ((u32) len << 8);
56 	pad |= pad << 16;
57 
58 	while (len >= 16) {
59 		a = (u32) msg[0] |
60 		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
61 		b = (u32) msg[4] |
62 		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
63 		c = (u32) msg[8] |
64 		    (u32) msg[9] << 8 |
65 		    (u32) msg[10] << 16 | (u32) msg[11] << 24;
66 		d = (u32) msg[12] |
67 		    (u32) msg[13] << 8 |
68 		    (u32) msg[14] << 16 | (u32) msg[15] << 24;
69 
70 		TEACORE(PARTROUNDS);
71 
72 		len -= 16;
73 		msg += 16;
74 	}
75 
76 	if (len >= 12) {
77 		a = (u32) msg[0] |
78 		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
79 		b = (u32) msg[4] |
80 		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
81 		c = (u32) msg[8] |
82 		    (u32) msg[9] << 8 |
83 		    (u32) msg[10] << 16 | (u32) msg[11] << 24;
84 
85 		d = pad;
86 		for (i = 12; i < len; i++) {
87 			d <<= 8;
88 			d |= msg[i];
89 		}
90 	} else if (len >= 8) {
91 		a = (u32) msg[0] |
92 		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
93 		b = (u32) msg[4] |
94 		    (u32) msg[5] << 8 | (u32) msg[6] << 16 | (u32) msg[7] << 24;
95 
96 		c = d = pad;
97 		for (i = 8; i < len; i++) {
98 			c <<= 8;
99 			c |= msg[i];
100 		}
101 	} else if (len >= 4) {
102 		a = (u32) msg[0] |
103 		    (u32) msg[1] << 8 | (u32) msg[2] << 16 | (u32) msg[3] << 24;
104 
105 		b = c = d = pad;
106 		for (i = 4; i < len; i++) {
107 			b <<= 8;
108 			b |= msg[i];
109 		}
110 	} else {
111 		a = b = c = d = pad;
112 		for (i = 0; i < len; i++) {
113 			a <<= 8;
114 			a |= msg[i];
115 		}
116 	}
117 
118 	TEACORE(FULLROUNDS);
119 
120 /*	return 0;*/
121 	return h0 ^ h1;
122 }
123 
124 /*
125  * What follows in this file is copyright 2000 by Hans Reiser, and the
126  * licensing of what follows is governed by reiserfs/README
127  */
128 u32 yura_hash(const signed char *msg, int len)
129 {
130 	int j, pow;
131 	u32 a, c;
132 	int i;
133 
134 	for (pow = 1, i = 1; i < len; i++)
135 		pow = pow * 10;
136 
137 	if (len == 1)
138 		a = msg[0] - 48;
139 	else
140 		a = (msg[0] - 48) * pow;
141 
142 	for (i = 1; i < len; i++) {
143 		c = msg[i] - 48;
144 		for (pow = 1, j = i; j < len - 1; j++)
145 			pow = pow * 10;
146 		a = a + c * pow;
147 	}
148 
149 	for (; i < 40; i++) {
150 		c = '0' - 48;
151 		for (pow = 1, j = i; j < len - 1; j++)
152 			pow = pow * 10;
153 		a = a + c * pow;
154 	}
155 
156 	for (; i < 256; i++) {
157 		c = i;
158 		for (pow = 1, j = i; j < len - 1; j++)
159 			pow = pow * 10;
160 		a = a + c * pow;
161 	}
162 
163 	a = a << 7;
164 	return a;
165 }
166 
167 u32 r5_hash(const signed char *msg, int len)
168 {
169 	u32 a = 0;
170 	while (*msg) {
171 		a += *msg << 4;
172 		a += *msg >> 4;
173 		a *= 11;
174 		msg++;
175 	}
176 	return a;
177 }
178