Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 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 <asm/types.h> |
| 23 | #include <asm/bug.h> |
| 24 | |
| 25 | |
| 26 | #define DELTA 0x9E3779B9 |
| 27 | #define FULLROUNDS 10 /* 32 is overkill, 16 is strong crypto */ |
| 28 | #define PARTROUNDS 6 /* 6 gets complete mixing */ |
| 29 | |
| 30 | /* a, b, c, d - data; h0, h1 - accumulated hash */ |
| 31 | #define TEACORE(rounds) \ |
| 32 | do { \ |
| 33 | u32 sum = 0; \ |
| 34 | int n = rounds; \ |
| 35 | u32 b0, b1; \ |
| 36 | \ |
| 37 | b0 = h0; \ |
| 38 | b1 = h1; \ |
| 39 | \ |
| 40 | do \ |
| 41 | { \ |
| 42 | sum += DELTA; \ |
| 43 | b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b); \ |
| 44 | b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d); \ |
| 45 | } while(--n); \ |
| 46 | \ |
| 47 | h0 += b0; \ |
| 48 | h1 += b1; \ |
| 49 | } while(0) |
| 50 | |
| 51 | |
| 52 | u32 keyed_hash(const signed char *msg, int len) |
| 53 | { |
| 54 | u32 k[] = { 0x9464a485, 0x542e1a94, 0x3e846bff, 0xb75bcfc3}; |
| 55 | |
| 56 | u32 h0 = k[0], h1 = k[1]; |
| 57 | u32 a, b, c, d; |
| 58 | u32 pad; |
| 59 | int i; |
| 60 | |
| 61 | // assert(len >= 0 && len < 256); |
| 62 | |
| 63 | pad = (u32)len | ((u32)len << 8); |
| 64 | pad |= pad << 16; |
| 65 | |
| 66 | while(len >= 16) |
| 67 | { |
| 68 | a = (u32)msg[ 0] | |
| 69 | (u32)msg[ 1] << 8 | |
| 70 | (u32)msg[ 2] << 16| |
| 71 | (u32)msg[ 3] << 24; |
| 72 | b = (u32)msg[ 4] | |
| 73 | (u32)msg[ 5] << 8 | |
| 74 | (u32)msg[ 6] << 16| |
| 75 | (u32)msg[ 7] << 24; |
| 76 | c = (u32)msg[ 8] | |
| 77 | (u32)msg[ 9] << 8 | |
| 78 | (u32)msg[10] << 16| |
| 79 | (u32)msg[11] << 24; |
| 80 | d = (u32)msg[12] | |
| 81 | (u32)msg[13] << 8 | |
| 82 | (u32)msg[14] << 16| |
| 83 | (u32)msg[15] << 24; |
| 84 | |
| 85 | TEACORE(PARTROUNDS); |
| 86 | |
| 87 | len -= 16; |
| 88 | msg += 16; |
| 89 | } |
| 90 | |
| 91 | if (len >= 12) |
| 92 | { |
| 93 | a = (u32)msg[ 0] | |
| 94 | (u32)msg[ 1] << 8 | |
| 95 | (u32)msg[ 2] << 16| |
| 96 | (u32)msg[ 3] << 24; |
| 97 | b = (u32)msg[ 4] | |
| 98 | (u32)msg[ 5] << 8 | |
| 99 | (u32)msg[ 6] << 16| |
| 100 | (u32)msg[ 7] << 24; |
| 101 | c = (u32)msg[ 8] | |
| 102 | (u32)msg[ 9] << 8 | |
| 103 | (u32)msg[10] << 16| |
| 104 | (u32)msg[11] << 24; |
| 105 | |
| 106 | d = pad; |
| 107 | for(i = 12; i < len; i++) |
| 108 | { |
| 109 | d <<= 8; |
| 110 | d |= msg[i]; |
| 111 | } |
| 112 | } |
| 113 | else if (len >= 8) |
| 114 | { |
| 115 | a = (u32)msg[ 0] | |
| 116 | (u32)msg[ 1] << 8 | |
| 117 | (u32)msg[ 2] << 16| |
| 118 | (u32)msg[ 3] << 24; |
| 119 | b = (u32)msg[ 4] | |
| 120 | (u32)msg[ 5] << 8 | |
| 121 | (u32)msg[ 6] << 16| |
| 122 | (u32)msg[ 7] << 24; |
| 123 | |
| 124 | c = d = pad; |
| 125 | for(i = 8; i < len; i++) |
| 126 | { |
| 127 | c <<= 8; |
| 128 | c |= msg[i]; |
| 129 | } |
| 130 | } |
| 131 | else if (len >= 4) |
| 132 | { |
| 133 | a = (u32)msg[ 0] | |
| 134 | (u32)msg[ 1] << 8 | |
| 135 | (u32)msg[ 2] << 16| |
| 136 | (u32)msg[ 3] << 24; |
| 137 | |
| 138 | b = c = d = pad; |
| 139 | for(i = 4; i < len; i++) |
| 140 | { |
| 141 | b <<= 8; |
| 142 | b |= msg[i]; |
| 143 | } |
| 144 | } |
| 145 | else |
| 146 | { |
| 147 | a = b = c = d = pad; |
| 148 | for(i = 0; i < len; i++) |
| 149 | { |
| 150 | a <<= 8; |
| 151 | a |= msg[i]; |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | TEACORE(FULLROUNDS); |
| 156 | |
| 157 | /* return 0;*/ |
| 158 | return h0^h1; |
| 159 | } |
| 160 | |
| 161 | /* What follows in this file is copyright 2000 by Hans Reiser, and the |
| 162 | * licensing of what follows is governed by reiserfs/README */ |
| 163 | |
| 164 | u32 yura_hash (const signed char *msg, int len) |
| 165 | { |
| 166 | int j, pow; |
| 167 | u32 a, c; |
| 168 | int i; |
| 169 | |
| 170 | for (pow=1,i=1; i < len; i++) pow = pow * 10; |
| 171 | |
| 172 | if (len == 1) |
| 173 | a = msg[0]-48; |
| 174 | else |
| 175 | a = (msg[0] - 48) * pow; |
| 176 | |
| 177 | for (i=1; i < len; i++) { |
| 178 | c = msg[i] - 48; |
| 179 | for (pow=1,j=i; j < len-1; j++) pow = pow * 10; |
| 180 | a = a + c * pow; |
| 181 | } |
| 182 | |
| 183 | for (; i < 40; i++) { |
| 184 | c = '0' - 48; |
| 185 | for (pow=1,j=i; j < len-1; j++) pow = pow * 10; |
| 186 | a = a + c * pow; |
| 187 | } |
| 188 | |
| 189 | for (; i < 256; i++) { |
| 190 | c = i; |
| 191 | for (pow=1,j=i; j < len-1; j++) pow = pow * 10; |
| 192 | a = a + c * pow; |
| 193 | } |
| 194 | |
| 195 | a = a << 7; |
| 196 | return a; |
| 197 | } |
| 198 | |
| 199 | u32 r5_hash (const signed char *msg, int len) |
| 200 | { |
| 201 | u32 a=0; |
| 202 | while(*msg) { |
| 203 | a += *msg << 4; |
| 204 | a += *msg >> 4; |
| 205 | a *= 11; |
| 206 | msg++; |
| 207 | } |
| 208 | return a; |
| 209 | } |