| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: rc2.c,v 1.2 2001/04/29 17:39:52 mdw Exp $ |
| 4 | * |
| 5 | * The RC2 block cipher |
| 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: rc2.c,v $ |
| 33 | * Revision 1.2 2001/04/29 17:39:52 mdw |
| 34 | * Moved big horrible table to a separate header. |
| 35 | * |
| 36 | * Revision 1.1 2000/06/17 11:54:34 mdw |
| 37 | * New cipher. |
| 38 | * |
| 39 | */ |
| 40 | |
| 41 | /*----- Header files ------------------------------------------------------*/ |
| 42 | |
| 43 | #include <assert.h> |
| 44 | #include <stdio.h> |
| 45 | |
| 46 | #include <mLib/bits.h> |
| 47 | |
| 48 | #include "blkc.h" |
| 49 | #include "gcipher.h" |
| 50 | #include "paranoia.h" |
| 51 | #include "rc2.h" |
| 52 | #include "rc2-tab.h" |
| 53 | |
| 54 | /*----- Global variables --------------------------------------------------*/ |
| 55 | |
| 56 | const octet rc2_keysz[] = { KSZ_RANGE, RC2_KEYSZ, 1, 128, 1 }; |
| 57 | |
| 58 | /*----- Important tables --------------------------------------------------*/ |
| 59 | |
| 60 | static const octet pi[256] = RC2_PI; |
| 61 | |
| 62 | /*----- Main code ---------------------------------------------------------*/ |
| 63 | |
| 64 | /* --- @rc2_braindamage@ --- * |
| 65 | * |
| 66 | * Arguments: @rc2_ctx *k@ = pointer to context to initialize |
| 67 | * @const void *buf@ = pointer to key material |
| 68 | * @size_t sz@ = size of key material in bytes |
| 69 | * @unsigned eb@ = desired effective key size, in bits |
| 70 | * |
| 71 | * Returns: --- |
| 72 | * |
| 73 | * Use: Initializes an RC2 expanded key, and braindamages it to the |
| 74 | * requested effective key size. This is here for compatibility |
| 75 | * reasons. You should be using @rc2_init@ in normal code, |
| 76 | * which doesn't actually apply braindamage. |
| 77 | */ |
| 78 | |
| 79 | void rc2_braindamage(rc2_ctx *k, const void *buf, size_t sz, unsigned eb) |
| 80 | { |
| 81 | unsigned t8; |
| 82 | uint16 tm; |
| 83 | unsigned i; |
| 84 | uint16 *kk; |
| 85 | octet l[128]; |
| 86 | |
| 87 | KSZ_ASSERT(rc2, sz); |
| 88 | |
| 89 | /* --- Compute the braindamage parameters --- */ |
| 90 | |
| 91 | t8 = (eb + 7) / 8; |
| 92 | tm = 0xff & ((1 << (8 + eb - 8 * t8)) - 1); |
| 93 | |
| 94 | /* --- Copy and expand the initial key --- */ |
| 95 | |
| 96 | if (sz > sizeof(l)) |
| 97 | sz = sizeof(l); |
| 98 | memcpy(l, buf, sz); |
| 99 | |
| 100 | for (i = sz; i < sizeof(l); i++) |
| 101 | l[i] = pi[U8(l[i - 1] + l[i - sz])]; |
| 102 | |
| 103 | /* --- Braindamage the key --- */ |
| 104 | |
| 105 | i = sizeof(l) - t8; |
| 106 | l[i] = pi[l[i] & tm]; |
| 107 | while (i) { |
| 108 | i--; |
| 109 | l[i] = pi[U8(l[i + 1] ^ l[i + t8])]; |
| 110 | } |
| 111 | |
| 112 | /* --- Write it to the key block --- */ |
| 113 | |
| 114 | kk = k->k; |
| 115 | for (i = 0; i < sizeof(l); i += 2) |
| 116 | *kk++ = LOAD16_L(l + i); |
| 117 | BURN(l); |
| 118 | } |
| 119 | |
| 120 | /* --- @rc2_init@ --- * |
| 121 | * |
| 122 | * Arguments: @rc2_ctx *k@ = pointer to context to initialize |
| 123 | * @const void *buf@ = pointer to key material |
| 124 | * @size_t sz@ = size of key material in bytes |
| 125 | * |
| 126 | * Returns: --- |
| 127 | * |
| 128 | * Use: Initializes an RC2 expanded key. The effective key size is |
| 129 | * set to be equal to the real key size, in bits. |
| 130 | */ |
| 131 | |
| 132 | void rc2_init(rc2_ctx *k, const void *buf, size_t sz) |
| 133 | { |
| 134 | rc2_braindamage(k, buf, sz, sz * 8); |
| 135 | } |
| 136 | |
| 137 | /*----- Encryption and decryption -----------------------------------------*/ |
| 138 | |
| 139 | #define MIX(a, b, c, d, r, kk) do { \ |
| 140 | a += *kk++ + (d & c) + (~d & b); \ |
| 141 | a = ROL16(a, r); \ |
| 142 | } while (0) |
| 143 | |
| 144 | #define MASH(a, d, k) do { \ |
| 145 | a += k[d & 63]; \ |
| 146 | } while (0) |
| 147 | |
| 148 | #define UNMIX(a, b, c, d, r, kk) do { \ |
| 149 | a = ROR16(a, r); \ |
| 150 | a -= *--kk + (d & c) + (~d & b); \ |
| 151 | } while (0) |
| 152 | |
| 153 | #define UNMASH(a, d, k) do { \ |
| 154 | a -= k[d & 63]; \ |
| 155 | } while (0) |
| 156 | |
| 157 | /* --- @rc2_eblk@, @rc2_dblk@ --- * |
| 158 | * |
| 159 | * Arguments: @const rc2_ctx *k@ = pointer to RC2 context |
| 160 | * @const uint32 s[2]@ = pointer to source block |
| 161 | * @const uint32 d[2]@ = pointer to destination block |
| 162 | * |
| 163 | * Returns: --- |
| 164 | * |
| 165 | * Use: Low-level block encryption and decryption. |
| 166 | */ |
| 167 | |
| 168 | void rc2_eblk(const rc2_ctx *k, const uint32 *s, uint32 *dst) |
| 169 | { |
| 170 | uint16 a = U16(s[0] >> 0), b = U16(s[0] >> 16); |
| 171 | uint16 c = U16(s[1] >> 0), d = U16(s[1] >> 16); |
| 172 | const uint16 *kk = k->k; |
| 173 | |
| 174 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 175 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 176 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 177 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 178 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 179 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 180 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 181 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 182 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 183 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 184 | MASH(a, d, k->k); MASH(b, a, k->k); |
| 185 | MASH(c, b, k->k); MASH(d, c, k->k); |
| 186 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 187 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 188 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 189 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 190 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 191 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 192 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 193 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 194 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 195 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 196 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 197 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 198 | MASH(a, d, k->k); MASH(b, a, k->k); |
| 199 | MASH(c, b, k->k); MASH(d, c, k->k); |
| 200 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 201 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 202 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 203 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 204 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 205 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 206 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 207 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 208 | MIX(a, b, c, d, 1, kk); MIX(b, c, d, a, 2, kk); |
| 209 | MIX(c, d, a, b, 3, kk); MIX(d, a, b, c, 5, kk); |
| 210 | |
| 211 | dst[0] = a | (b << 16); dst[1] = c | (d << 16); |
| 212 | } |
| 213 | |
| 214 | void rc2_dblk(const rc2_ctx *k, const uint32 *s, uint32 *dst) |
| 215 | { |
| 216 | uint16 a = U16(s[0] >> 0), b = U16(s[0] >> 16); |
| 217 | uint16 c = U16(s[1] >> 0), d = U16(s[1] >> 16); |
| 218 | const uint16 *kk = k->k + 64; |
| 219 | |
| 220 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 221 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 222 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 223 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 224 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 225 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 226 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 227 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 228 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 229 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 230 | UNMASH(d, c, k->k); UNMASH(c, b, k->k); |
| 231 | UNMASH(b, a, k->k); UNMASH(a, d, k->k); |
| 232 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 233 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 234 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 235 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 236 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 237 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 238 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 239 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 240 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 241 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 242 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 243 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 244 | UNMASH(d, c, k->k); UNMASH(c, b, k->k); |
| 245 | UNMASH(b, a, k->k); UNMASH(a, d, k->k); |
| 246 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 247 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 248 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 249 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 250 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 251 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 252 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 253 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 254 | UNMIX(d, a, b, c, 5, kk); UNMIX(c, d, a, b, 3, kk); |
| 255 | UNMIX(b, c, d, a, 2, kk); UNMIX(a, b, c, d, 1, kk); |
| 256 | |
| 257 | dst[0] = a | (b << 16); dst[1] = c | (d << 16); |
| 258 | } |
| 259 | |
| 260 | /*----- Custom test rig ---------------------------------------------------* |
| 261 | * |
| 262 | * I need to test the braindamage feature. |
| 263 | */ |
| 264 | |
| 265 | #ifdef TEST_RIG |
| 266 | |
| 267 | #include <mLib/quis.h> |
| 268 | #include <mLib/testrig.h> |
| 269 | |
| 270 | static int verify(dstr *v) |
| 271 | { |
| 272 | rc2_ctx k; |
| 273 | uint32 p[RC2_BLKSZ / 4]; |
| 274 | uint32 c[RC2_BLKSZ / 4]; |
| 275 | uint32 d[RC2_BLKSZ / 4]; |
| 276 | dstr b = DSTR_INIT; |
| 277 | unsigned bd = *(unsigned *)v[1].buf; |
| 278 | int ok = 1; |
| 279 | |
| 280 | /* --- Initialize the key buffer --- */ |
| 281 | |
| 282 | dstr_ensure(&b, RC2_BLKSZ); |
| 283 | b.len = RC2_BLKSZ; |
| 284 | rc2_braindamage(&k, v[0].buf, v[0].len, bd); |
| 285 | BLKC_LOAD(RC2, p, v[2].buf); |
| 286 | BLKC_LOAD(RC2, c, v[3].buf); |
| 287 | |
| 288 | /* --- Test encryption --- */ |
| 289 | |
| 290 | BLKC_MOVE(RC2, d, p); |
| 291 | rc2_eblk(&k, d, d); |
| 292 | BLKC_STORE(RC2, b.buf, d); |
| 293 | if (memcmp(b.buf, v[3].buf, RC2_BLKSZ)) { |
| 294 | ok = 0; |
| 295 | printf("\nfail encryption:" |
| 296 | "\n\tkey = "); |
| 297 | type_hex.dump(&v[0], stdout); |
| 298 | printf("\n\tbraindamage= %u", bd); |
| 299 | printf("\n\tplaintext = "); type_hex.dump(&v[2], stdout); |
| 300 | printf("\n\texpected = "); type_hex.dump(&v[3], stdout); |
| 301 | printf("\n\tcalculated = "); type_hex.dump(&b, stdout); |
| 302 | putchar('\n'); |
| 303 | } |
| 304 | |
| 305 | /* --- Test decryption --- */ |
| 306 | |
| 307 | BLKC_MOVE(RC2, d, c); |
| 308 | rc2_dblk(&k, d, d); |
| 309 | BLKC_STORE(RC2, b.buf, d); |
| 310 | if (memcmp(b.buf, v[2].buf, RC2_BLKSZ)) { |
| 311 | ok = 0; |
| 312 | printf("\nfail decryption:" |
| 313 | "\n\tkey = "); |
| 314 | type_hex.dump(&v[0], stdout); |
| 315 | printf("\n\tbraindamage= %u", bd); |
| 316 | printf("\n\tciphertext = "); type_hex.dump(&v[3], stdout); |
| 317 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
| 318 | printf("\n\tcalculated = "); type_hex.dump(&b, stdout); |
| 319 | putchar('\n'); |
| 320 | } |
| 321 | |
| 322 | /* --- Return --- */ |
| 323 | |
| 324 | return (ok); |
| 325 | } |
| 326 | |
| 327 | static test_chunk defs[] = { |
| 328 | { "rc2", verify, { &type_hex, &type_int, &type_hex, &type_hex, 0 } }, |
| 329 | { 0, 0, { 0 } } |
| 330 | }; |
| 331 | |
| 332 | int main(int argc, char *argv[]) |
| 333 | { |
| 334 | test_run(argc, argv, defs, SRCDIR"/tests/rc2"); |
| 335 | return (0); |
| 336 | } |
| 337 | |
| 338 | #endif |
| 339 | |
| 340 | /*----- That's all, folks -------------------------------------------------*/ |