6c1035f5 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: gfshare-mktab.c,v 1.1 2000/06/17 10:56:30 mdw Exp $ |
4 | * |
5 | * Generate tables for %$\gf(2^8)$% multiplication |
6 | * |
7 | * (c) 2000 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: gfshare-mktab.c,v $ |
33 | * Revision 1.1 2000/06/17 10:56:30 mdw |
34 | * Fast but nonstandard secret sharing system. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <stdio.h> |
41 | #include <stdlib.h> |
42 | |
43 | #include <mLib/bits.h> |
44 | |
45 | /*----- Magic numbers -----------------------------------------------------*/ |
46 | |
47 | #define MOD 0x11d |
48 | |
49 | /*----- Main code ---------------------------------------------------------*/ |
50 | |
51 | int main(int argc, char *argv[]) |
52 | { |
53 | octet log[256], alog[256]; |
54 | unsigned x; |
55 | unsigned i; |
56 | |
57 | x = 1; |
58 | for (i = 0; i < 255; i++) { |
59 | alog[i] = x; |
60 | log[x] = i; |
61 | x <<= 1; |
62 | if (x & 0x100) |
63 | x ^= MOD; |
64 | } |
65 | log[0] = 0; |
66 | alog[255] = 1; |
67 | |
68 | fputs("\ |
69 | /* -*-c-*-\n\ |
70 | *\n\ |
71 | * Log tables for secret sharing in %$\\gf(2^8)$% [generated]\n\ |
72 | */\n\ |
73 | \n\ |
74 | #ifndef GFSHARE_TAB_H\n\ |
75 | #define GFSHARE_TAB_H\n\ |
76 | \n\ |
77 | #define GFSHARE_LOG { \\\n\ |
78 | ", stdout); |
79 | |
80 | for (i = 0; i < 256; i++) { |
81 | printf("0x%02x", log[i]); |
82 | if (i == 255) |
83 | puts(" \\\n}\n"); |
84 | else if (i % 8 == 7) |
85 | fputs(", \\\n ", stdout); |
86 | else |
87 | fputs(", ", stdout); |
88 | } |
89 | |
90 | fputs("\ |
91 | #define GFSHARE_EXP { \\\n\ |
92 | ", stdout); |
93 | |
94 | for (i = 0; i < 510; i++) { |
95 | printf("0x%02x", alog[i % 255]); |
96 | if (i == 509) |
97 | puts(" \\\n}\n"); |
98 | else if (i % 8 == 7) |
99 | fputs(", \\\n ", stdout); |
100 | else |
101 | fputs(", ", stdout); |
102 | } |
103 | |
104 | /* --- Done --- */ |
105 | |
106 | fputs("#endif\n", stdout); |
107 | |
108 | if (fclose(stdout)) { |
109 | fprintf(stderr, "error writing data\n"); |
110 | exit(EXIT_FAILURE); |
111 | } |
112 | |
113 | return (0); |
114 | } |
115 | |
116 | /*----- That's all, folks -------------------------------------------------*/ |