| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: rc4.c,v 1.4 2000/06/17 11:55:22 mdw Exp $ |
| 4 | * |
| 5 | * The alleged RC4 stream 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: rc4.c,v $ |
| 33 | * Revision 1.4 2000/06/17 11:55:22 mdw |
| 34 | * New key size interface. Allow key material to be combined with an |
| 35 | * existing initialized context. Use secure arena for memory allocation. |
| 36 | * |
| 37 | * Revision 1.3 1999/12/13 15:34:01 mdw |
| 38 | * Add support for seeding from a generic pseudorandom source. |
| 39 | * |
| 40 | * Revision 1.2 1999/12/10 23:27:35 mdw |
| 41 | * Generic cipher and RNG interfaces. |
| 42 | * |
| 43 | * Revision 1.1 1999/09/03 08:41:12 mdw |
| 44 | * Initial import. |
| 45 | * |
| 46 | */ |
| 47 | |
| 48 | /*----- Header files ------------------------------------------------------*/ |
| 49 | |
| 50 | #include <assert.h> |
| 51 | #include <stdarg.h> |
| 52 | #include <stdio.h> |
| 53 | |
| 54 | #include <mLib/bits.h> |
| 55 | #include <mLib/sub.h> |
| 56 | |
| 57 | #include "arena.h" |
| 58 | #include "gcipher.h" |
| 59 | #include "grand.h" |
| 60 | #include "paranoia.h" |
| 61 | #include "rc4.h" |
| 62 | |
| 63 | /*----- Global variables --------------------------------------------------*/ |
| 64 | |
| 65 | const octet rc4_keysz[] = { KSZ_RANGE, RC4_KEYSZ, 1, 255, 1 }; |
| 66 | |
| 67 | /*----- Main code ---------------------------------------------------------*/ |
| 68 | |
| 69 | /* --- @rc4_addkey@ --- * |
| 70 | * |
| 71 | * Arguments: @rc4_ctx *ctx@ = pointer to context to key |
| 72 | * @const void *k@ = pointer to key data to use |
| 73 | * @size_t sz@ = size of the key data |
| 74 | * |
| 75 | * Returns: --- |
| 76 | * |
| 77 | * Use: Mixes key data with an RC4 context. The RC4 context is not |
| 78 | * reset before mixing. This may be used to mix new key |
| 79 | * material with an existing RC4 context. |
| 80 | */ |
| 81 | |
| 82 | void rc4_addkey(rc4_ctx *ctx, const void *k, size_t sz) |
| 83 | { |
| 84 | unsigned i, j; |
| 85 | const octet *p = k, *q = p + sz; |
| 86 | |
| 87 | KSZ_ASSERT(rc4, sz); |
| 88 | |
| 89 | for (i = j = 0; i < 256; i++) { |
| 90 | unsigned si = ctx->s[i]; |
| 91 | j = (j + si + *p++) & 0xff; |
| 92 | ctx->s[i] = ctx->s[j]; |
| 93 | ctx->s[j] = si; |
| 94 | if (p == q) |
| 95 | p = k; |
| 96 | } |
| 97 | |
| 98 | ctx->i = ctx->j = 0; |
| 99 | } |
| 100 | |
| 101 | /* --- @rc4_init@ --- * |
| 102 | * |
| 103 | * Arguments: @rc4_ctx *ctx@ = pointer to context to initialize |
| 104 | * @const void *k@ = pointer to key data to use |
| 105 | * @size_t sz@ = size of the key data |
| 106 | * |
| 107 | * Returns: --- |
| 108 | * |
| 109 | * Use: Initializes an RC4 context ready for use. |
| 110 | */ |
| 111 | |
| 112 | void rc4_init(rc4_ctx *ctx, const void *k, size_t sz) |
| 113 | { |
| 114 | unsigned i; |
| 115 | |
| 116 | for (i = 0; i < 256; i++) |
| 117 | ctx->s[i] = i; |
| 118 | ctx->f = 0; |
| 119 | rc4_addkey(ctx, k, sz); |
| 120 | } |
| 121 | |
| 122 | /* --- @rc4_encrypt@ --- * |
| 123 | * |
| 124 | * Arguments: @rc4_ctx *ctx@ = pointer to context to use |
| 125 | * @const void *src@ = pointer to the source block |
| 126 | * @void *dest@ = pointer to the destination block |
| 127 | * @size_t sz@ = size of the block |
| 128 | * |
| 129 | * Returns: --- |
| 130 | * |
| 131 | * Use: Encrypts or decrypts a block of data. The destination may |
| 132 | * be null to just grind the generator around for a while. It's |
| 133 | * recommended that you say `@rc4_encrypt(&ctx, 0, 0, 1024)@' |
| 134 | * after initializing a new context, to prevent keystream |
| 135 | * guessing attacks. The source may be null to just extract a |
| 136 | * big lump of data from the generator. |
| 137 | */ |
| 138 | |
| 139 | void rc4_encrypt(rc4_ctx *ctx, const void *src, void *dest, size_t sz) |
| 140 | { |
| 141 | const octet *s = src; |
| 142 | octet *d = dest; |
| 143 | |
| 144 | if (!d) |
| 145 | RC4_OPEN(ctx, while (sz) { unsigned x; RC4_BYTE(x); sz--; }); |
| 146 | else if (!s) |
| 147 | RC4_OPEN(ctx, while (sz) { RC4_BYTE(*d++); sz--; }); |
| 148 | else |
| 149 | RC4_OPEN(ctx, |
| 150 | while (sz) { unsigned x; RC4_BYTE(x); *d++ = *s++ ^ x; sz--; }); |
| 151 | } |
| 152 | |
| 153 | /*----- Generic cipher interface ------------------------------------------*/ |
| 154 | |
| 155 | typedef struct gctx { |
| 156 | gcipher c; |
| 157 | rc4_ctx rc4; |
| 158 | } gctx; |
| 159 | |
| 160 | static const gcipher_ops gops; |
| 161 | |
| 162 | static gcipher *ginit(const void *k, size_t sz) |
| 163 | { |
| 164 | gctx *g = S_CREATE(gctx); |
| 165 | g->c.ops = &gops; |
| 166 | rc4_init(&g->rc4, k, sz); |
| 167 | return (&g->c); |
| 168 | } |
| 169 | |
| 170 | static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) |
| 171 | { |
| 172 | gctx *g = (gctx *)c; |
| 173 | rc4_encrypt(&g->rc4, s, t, sz); |
| 174 | } |
| 175 | |
| 176 | static void gdestroy(gcipher *c) |
| 177 | { |
| 178 | gctx *g = (gctx *)c; |
| 179 | BURN(*g); |
| 180 | S_DESTROY(g); |
| 181 | } |
| 182 | |
| 183 | static const gcipher_ops gops = { |
| 184 | &rc4, |
| 185 | gencrypt, gencrypt, gdestroy, 0, 0 |
| 186 | }; |
| 187 | |
| 188 | const gccipher rc4 = { |
| 189 | "rc4", rc4_keysz, 0, |
| 190 | ginit |
| 191 | }; |
| 192 | |
| 193 | /*----- Generic random number generator interface -------------------------*/ |
| 194 | |
| 195 | typedef struct grctx { |
| 196 | grand r; |
| 197 | rc4_ctx rc4; |
| 198 | } grctx; |
| 199 | |
| 200 | static void grdestroy(grand *r) |
| 201 | { |
| 202 | grctx *g = (grctx *)r; |
| 203 | BURN(*g); |
| 204 | S_DESTROY(g); |
| 205 | } |
| 206 | |
| 207 | static int grmisc(grand *r, unsigned op, ...) |
| 208 | { |
| 209 | grctx *g = (grctx *)r; |
| 210 | va_list ap; |
| 211 | int rc = 0; |
| 212 | octet buf[4]; |
| 213 | va_start(ap, op); |
| 214 | |
| 215 | switch (op) { |
| 216 | case GRAND_CHECK: |
| 217 | switch (va_arg(ap, unsigned)) { |
| 218 | case GRAND_CHECK: |
| 219 | case GRAND_SEEDINT: |
| 220 | case GRAND_SEEDUINT32: |
| 221 | case GRAND_SEEDBLOCK: |
| 222 | case GRAND_SEEDRAND: |
| 223 | rc = 1; |
| 224 | break; |
| 225 | default: |
| 226 | rc = 0; |
| 227 | break; |
| 228 | } |
| 229 | break; |
| 230 | case GRAND_SEEDINT: |
| 231 | STORE32(buf, va_arg(ap, unsigned)); |
| 232 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
| 233 | break; |
| 234 | case GRAND_SEEDUINT32: |
| 235 | STORE32(buf, va_arg(ap, uint32)); |
| 236 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
| 237 | break; |
| 238 | case GRAND_SEEDBLOCK: { |
| 239 | const void *p = va_arg(ap, const void *); |
| 240 | size_t sz = va_arg(ap, size_t); |
| 241 | rc4_addkey(&g->rc4, p, sz); |
| 242 | } break; |
| 243 | case GRAND_SEEDRAND: { |
| 244 | grand *rr = va_arg(ap, grand *); |
| 245 | octet buf[16]; |
| 246 | rr->ops->fill(rr, buf, sizeof(buf)); |
| 247 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
| 248 | } break; |
| 249 | default: |
| 250 | GRAND_BADOP; |
| 251 | break; |
| 252 | } |
| 253 | |
| 254 | va_end(ap); |
| 255 | return (rc); |
| 256 | } |
| 257 | |
| 258 | static octet grbyte(grand *r) |
| 259 | { |
| 260 | grctx *g = (grctx *)r; |
| 261 | octet o; |
| 262 | RC4_OPEN(&g->rc4, RC4_BYTE(o);); |
| 263 | return (o); |
| 264 | } |
| 265 | |
| 266 | static uint32 grword(grand *r) |
| 267 | { |
| 268 | grctx *g = (grctx *)r; |
| 269 | octet b[4]; |
| 270 | int i; |
| 271 | RC4_OPEN(&g->rc4, |
| 272 | for (i = 0; i < sizeof(b); i++) |
| 273 | RC4_BYTE(b[i]);); |
| 274 | return (LOAD32(b)); |
| 275 | } |
| 276 | |
| 277 | static void grfill(grand *r, void *p, size_t sz) |
| 278 | { |
| 279 | grctx *g = (grctx *)r; |
| 280 | rc4_encrypt(&g->rc4, 0, p, sz); |
| 281 | } |
| 282 | |
| 283 | static const grand_ops grops = { |
| 284 | "rc4", |
| 285 | GRAND_CRYPTO, 0, |
| 286 | grmisc, grdestroy, |
| 287 | grword, grbyte, grword, grand_range, grfill |
| 288 | }; |
| 289 | |
| 290 | /* --- @rc4_rand@ --- * |
| 291 | * |
| 292 | * Arguments: @const void *k@ = pointer to key material |
| 293 | * @size_t sz@ = size of key material |
| 294 | * |
| 295 | * Returns: Pointer to generic random number generator interface. |
| 296 | * |
| 297 | * Use: Creates a random number interface wrapper around an |
| 298 | * OFB-mode block cipher. |
| 299 | */ |
| 300 | |
| 301 | grand *rc4_rand(const void *k, size_t sz) |
| 302 | { |
| 303 | grctx *g = S_CREATE(grctx); |
| 304 | g->r.ops = &grops; |
| 305 | rc4_init(&g->rc4, k, sz); |
| 306 | return (&g->r); |
| 307 | } |
| 308 | |
| 309 | /*----- Test rig ----------------------------------------------------------*/ |
| 310 | |
| 311 | #ifdef TEST_RIG |
| 312 | |
| 313 | #include <stdio.h> |
| 314 | #include <string.h> |
| 315 | |
| 316 | #include <mLib/quis.h> |
| 317 | #include <mLib/testrig.h> |
| 318 | |
| 319 | static int v_encrypt(dstr *v) |
| 320 | { |
| 321 | rc4_ctx ctx; |
| 322 | dstr d = DSTR_INIT; |
| 323 | int ok = 1; |
| 324 | |
| 325 | rc4_init(&ctx, v[0].buf, v[0].len); |
| 326 | dstr_ensure(&d, v[1].len); |
| 327 | d.len = v[1].len; |
| 328 | rc4_encrypt(&ctx, v[1].buf, d.buf, d.len); |
| 329 | |
| 330 | if (memcmp(v[2].buf, d.buf, d.len) != 0) { |
| 331 | ok = 0; |
| 332 | printf("\nfail encryption:" |
| 333 | "\n\tkey = "); |
| 334 | type_hex.dump(&v[0], stdout); |
| 335 | printf("\n\tplaintext = "); type_hex.dump(&v[1], stdout); |
| 336 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
| 337 | printf("\n\tcalculated = "); type_hex.dump(&d, stdout); |
| 338 | putchar('\n'); |
| 339 | } |
| 340 | |
| 341 | return (ok); |
| 342 | } |
| 343 | |
| 344 | static int v_generate(dstr *v) |
| 345 | { |
| 346 | rc4_ctx ctx; |
| 347 | dstr d = DSTR_INIT; |
| 348 | int ok = 1; |
| 349 | |
| 350 | rc4_init(&ctx, v[0].buf, v[0].len); |
| 351 | rc4_encrypt(&ctx, 0, 0, *(int *)v[1].buf); |
| 352 | dstr_ensure(&d, v[2].len); |
| 353 | d.len = v[2].len; |
| 354 | rc4_encrypt(&ctx, 0, d.buf, d.len); |
| 355 | |
| 356 | if (memcmp(v[2].buf, d.buf, d.len) != 0) { |
| 357 | ok = 0; |
| 358 | printf("\nfail generation:" |
| 359 | "\n\tkey = "); |
| 360 | type_hex.dump(&v[0], stdout); |
| 361 | printf("\n\tskip len = %i", *(int *)v[1].buf); |
| 362 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
| 363 | printf("\n\tcalculated = "); type_hex.dump(&d, stdout); |
| 364 | putchar('\n'); |
| 365 | } |
| 366 | |
| 367 | return (ok); |
| 368 | } |
| 369 | |
| 370 | static test_chunk defs[] = { |
| 371 | { "rc4-encrypt", v_encrypt, { &type_hex, &type_hex, &type_hex, 0 } }, |
| 372 | { "rc4-generate", v_generate, { &type_hex, &type_int, &type_hex, 0 } }, |
| 373 | { 0, 0, { 0 } } |
| 374 | }; |
| 375 | |
| 376 | int main(int argc, char *argv[]) |
| 377 | { |
| 378 | test_run(argc, argv, defs, SRCDIR"/tests/rc4"); |
| 379 | return (0); |
| 380 | } |
| 381 | |
| 382 | #endif |
| 383 | |
| 384 | /*----- That's all, folks -------------------------------------------------*/ |