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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: rc4.c,v 1.4 2000/06/17 11:55:22 mdw Exp $ |
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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 $ |
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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 | * |
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37 | * Revision 1.3 1999/12/13 15:34:01 mdw |
38 | * Add support for seeding from a generic pseudorandom source. |
39 | * |
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40 | * Revision 1.2 1999/12/10 23:27:35 mdw |
41 | * Generic cipher and RNG interfaces. |
42 | * |
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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> |
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51 | #include <stdarg.h> |
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52 | #include <stdio.h> |
53 | |
54 | #include <mLib/bits.h> |
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55 | #include <mLib/sub.h> |
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56 | |
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57 | #include "arena.h" |
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58 | #include "gcipher.h" |
59 | #include "grand.h" |
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60 | #include "paranoia.h" |
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61 | #include "rc4.h" |
62 | |
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63 | /*----- Global variables --------------------------------------------------*/ |
64 | |
65 | const octet rc4_keysz[] = { KSZ_RANGE, RC4_KEYSZ, 1, 255, 1 }; |
66 | |
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67 | /*----- Main code ---------------------------------------------------------*/ |
68 | |
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69 | /* --- @rc4_addkey@ --- * |
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70 | * |
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71 | * Arguments: @rc4_ctx *ctx@ = pointer to context to key |
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72 | * @const void *k@ = pointer to key data to use |
73 | * @size_t sz@ = size of the key data |
74 | * |
75 | * Returns: --- |
76 | * |
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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. |
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80 | */ |
81 | |
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82 | void rc4_addkey(rc4_ctx *ctx, const void *k, size_t sz) |
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83 | { |
84 | unsigned i, j; |
85 | const octet *p = k, *q = p + sz; |
86 | |
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87 | KSZ_ASSERT(rc4, sz); |
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88 | |
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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; |
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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); |
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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 | |
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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 | { |
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164 | gctx *g = S_CREATE(gctx); |
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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; |
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179 | BURN(*g); |
180 | S_DESTROY(g); |
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181 | } |
182 | |
183 | static const gcipher_ops gops = { |
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184 | &rc4, |
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185 | gencrypt, gencrypt, gdestroy, 0, 0 |
186 | }; |
187 | |
188 | const gccipher rc4 = { |
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189 | "rc4", rc4_keysz, 0, |
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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; |
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203 | BURN(*g); |
204 | S_DESTROY(g); |
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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: |
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222 | case GRAND_SEEDRAND: |
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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)); |
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232 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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233 | break; |
234 | case GRAND_SEEDUINT32: |
235 | STORE32(buf, va_arg(ap, uint32)); |
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236 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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237 | break; |
238 | case GRAND_SEEDBLOCK: { |
239 | const void *p = va_arg(ap, const void *); |
240 | size_t sz = va_arg(ap, size_t); |
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241 | rc4_addkey(&g->rc4, p, sz); |
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242 | } break; |
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243 | case GRAND_SEEDRAND: { |
244 | grand *rr = va_arg(ap, grand *); |
245 | octet buf[16]; |
246 | rr->ops->fill(rr, buf, sizeof(buf)); |
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247 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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248 | } break; |
249 | default: |
250 | GRAND_BADOP; |
251 | break; |
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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", |
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285 | GRAND_CRYPTO, 0, |
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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 | { |
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303 | grctx *g = S_CREATE(grctx); |
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304 | g->r.ops = &grops; |
305 | rc4_init(&g->rc4, k, sz); |
306 | return (&g->r); |
307 | } |
308 | |
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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 -------------------------------------------------*/ |