| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: rc5.c,v 1.1 1999/09/03 08:41:12 mdw Exp $ |
| 4 | * |
| 5 | * The RC5-32/12 block cipher |
| 6 | * |
| 7 | * (c) 1999 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: rc5.c,v $ |
| 33 | * Revision 1.1 1999/09/03 08:41:12 mdw |
| 34 | * Initial import. |
| 35 | * |
| 36 | */ |
| 37 | |
| 38 | /*----- Header files ------------------------------------------------------*/ |
| 39 | |
| 40 | #include <assert.h> |
| 41 | #include <stdlib.h> |
| 42 | #include <string.h> |
| 43 | |
| 44 | #include <mLib/alloc.h> |
| 45 | #include <mLib/bits.h> |
| 46 | |
| 47 | #include "blkc.h" |
| 48 | #include "rc5.h" |
| 49 | |
| 50 | /*----- Internal magical constants ----------------------------------------*/ |
| 51 | |
| 52 | #define RC5_ROUNDS 12 |
| 53 | |
| 54 | #define T ((RC5_ROUNDS + 1) * 2) |
| 55 | #define P 0xb7e15163 |
| 56 | #define Q 0x9e3779b9 |
| 57 | |
| 58 | /*----- Main code ---------------------------------------------------------*/ |
| 59 | |
| 60 | /* --- @rc5_init@ --- * |
| 61 | * |
| 62 | * Arguments: @rc5_ctx *k@ = pointer to a key block |
| 63 | * @const void *sbuf@ = pointer to key material |
| 64 | * @size_t sz@ = size of the key material |
| 65 | * |
| 66 | * Returns: --- |
| 67 | * |
| 68 | * Use: Initializes an RC5 key block. |
| 69 | */ |
| 70 | |
| 71 | void rc5_init(rc5_ctx *k, const void *sbuf, size_t sz) |
| 72 | { |
| 73 | uint32 *l; |
| 74 | size_t w; |
| 75 | |
| 76 | /* --- Set up the @L@ table --- * |
| 77 | * |
| 78 | * This is slightly unfortunately defined. |
| 79 | */ |
| 80 | |
| 81 | assert(((void)"RC5 does not support zero-length keys", sz != 0)); |
| 82 | |
| 83 | { |
| 84 | int i; |
| 85 | const octet *p = sbuf; |
| 86 | |
| 87 | /* --- Create the buffer --- */ |
| 88 | |
| 89 | w = (sz + 3) / 4; |
| 90 | l = xmalloc(w * sizeof(uint32)); |
| 91 | |
| 92 | /* --- Extract the key material --- */ |
| 93 | |
| 94 | for (i = 0; sz > 3; i++) { |
| 95 | l[i] = LOAD32_L(p); |
| 96 | p += 4; |
| 97 | sz -= 4; |
| 98 | } |
| 99 | |
| 100 | /* --- Fix up the tail end --- */ |
| 101 | |
| 102 | if (sz) { |
| 103 | uint32 x = U8(*p++); |
| 104 | if (sz > 1) x |= (U8(*p++) << 8); |
| 105 | if (sz > 2) x |= (U8(*p++) << 16); |
| 106 | l[i] = x; |
| 107 | } |
| 108 | } |
| 109 | |
| 110 | /* --- Initialize the @S@ table --- */ |
| 111 | |
| 112 | { |
| 113 | int i; |
| 114 | |
| 115 | k->s[0] = P; |
| 116 | for (i = 1; i < T; i++) |
| 117 | k->s[i] = k->s[i - 1] + Q; |
| 118 | } |
| 119 | |
| 120 | /* --- Mix in the key --- */ |
| 121 | |
| 122 | { |
| 123 | int m = 3 * (w > T ? w : T); |
| 124 | int i, j, c; |
| 125 | uint32 a, b; |
| 126 | |
| 127 | for (c = i = j = a = b = 0; c < m; c++) { |
| 128 | uint32 x; |
| 129 | |
| 130 | x = k->s[i] + a + b; |
| 131 | k->s[i] = a = ROL32(x, 3); |
| 132 | i++; if (i >= T) i = 0; |
| 133 | |
| 134 | x = l[j] + a + b; |
| 135 | l[j] = b = ROL32(x, a + b); |
| 136 | j++; if (j >= w) j = 0; |
| 137 | } |
| 138 | } |
| 139 | |
| 140 | free(l); |
| 141 | } |
| 142 | |
| 143 | /* --- @EROUND@, @DROUND@ --- */ |
| 144 | |
| 145 | #define EROUND(x, y, k) do { \ |
| 146 | uint32 _x; \ |
| 147 | _x = x ^ y; x = ROL32(_x, y) + k[0]; \ |
| 148 | _x = y ^ x; y = ROL32(_x, x) + k[1]; \ |
| 149 | k += 2; \ |
| 150 | } while (0) |
| 151 | |
| 152 | #define DROUND(x, y, k) do { \ |
| 153 | uint32 _x; \ |
| 154 | k -= 2; \ |
| 155 | _x = y - k[1]; y = ROR32(_x, x) ^ x; \ |
| 156 | _x = x - k[0]; x = ROR32(_x, y) ^ y; \ |
| 157 | } while (0) |
| 158 | |
| 159 | /* --- @EBLK@, @DBLK@ --- */ |
| 160 | |
| 161 | #define EBLK(a, b, c, d, k) do { \ |
| 162 | uint32 _l, _r; \ |
| 163 | const uint32 *_k = (k)->s; \ |
| 164 | \ |
| 165 | _l = (a) + _k[0]; \ |
| 166 | _r = (b) + _k[1]; \ |
| 167 | _k += 2; \ |
| 168 | \ |
| 169 | EROUND(_l, _r, _k); \ |
| 170 | EROUND(_l, _r, _k); \ |
| 171 | EROUND(_l, _r, _k); \ |
| 172 | EROUND(_l, _r, _k); \ |
| 173 | EROUND(_l, _r, _k); \ |
| 174 | EROUND(_l, _r, _k); \ |
| 175 | EROUND(_l, _r, _k); \ |
| 176 | EROUND(_l, _r, _k); \ |
| 177 | EROUND(_l, _r, _k); \ |
| 178 | EROUND(_l, _r, _k); \ |
| 179 | EROUND(_l, _r, _k); \ |
| 180 | EROUND(_l, _r, _k); \ |
| 181 | (c) = _l; \ |
| 182 | (d) = _r; \ |
| 183 | } while (0) |
| 184 | |
| 185 | #define DBLK(a, b, c, d, k) do { \ |
| 186 | uint32 _l, _r; \ |
| 187 | const uint32 *_k = (k)->s + T; \ |
| 188 | \ |
| 189 | _l = (a); \ |
| 190 | _r = (b); \ |
| 191 | \ |
| 192 | DROUND(_l, _r, _k); \ |
| 193 | DROUND(_l, _r, _k); \ |
| 194 | DROUND(_l, _r, _k); \ |
| 195 | DROUND(_l, _r, _k); \ |
| 196 | DROUND(_l, _r, _k); \ |
| 197 | DROUND(_l, _r, _k); \ |
| 198 | DROUND(_l, _r, _k); \ |
| 199 | DROUND(_l, _r, _k); \ |
| 200 | DROUND(_l, _r, _k); \ |
| 201 | DROUND(_l, _r, _k); \ |
| 202 | DROUND(_l, _r, _k); \ |
| 203 | DROUND(_l, _r, _k); \ |
| 204 | \ |
| 205 | _k -= 2; \ |
| 206 | (d) = _r - _k[1]; \ |
| 207 | (c) = _l - _k[0]; \ |
| 208 | } while (0) |
| 209 | |
| 210 | /* --- @rc5_eblk@, @rc5_dblk@ --- * |
| 211 | * |
| 212 | * Arguments: @const rc5_ctx *k@ = pointer to RC5 context block |
| 213 | * @const uint32 s[2]@ = pointer to source block |
| 214 | * @uint32 *d[2]@ = pointer to destination block |
| 215 | * |
| 216 | * Returns: --- |
| 217 | * |
| 218 | * Use: Low level block encryption and decryption. |
| 219 | */ |
| 220 | |
| 221 | void rc5_eblk(const rc5_ctx *k, const uint32 *s, uint32 *d) |
| 222 | { |
| 223 | EBLK(s[0], s[1], d[0], d[1], k); |
| 224 | } |
| 225 | |
| 226 | void rc5_dblk(const rc5_ctx *k, const uint32 *s, uint32 *d) |
| 227 | { |
| 228 | DBLK(s[0], s[1], d[0], d[1], k); |
| 229 | } |
| 230 | |
| 231 | /* --- Test rig --- */ |
| 232 | |
| 233 | BLKC_TEST(RC5, rc5) |
| 234 | |
| 235 | /*----- That's all, folks -------------------------------------------------*/ |