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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: rc4.c,v 1.6 2004/04/08 01:36:15 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 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <assert.h> |
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33 | #include <stdarg.h> |
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34 | #include <stdio.h> |
35 | |
36 | #include <mLib/bits.h> |
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37 | #include <mLib/sub.h> |
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38 | |
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39 | #include "arena.h" |
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40 | #include "gcipher.h" |
41 | #include "grand.h" |
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42 | #include "paranoia.h" |
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43 | #include "rc4.h" |
44 | |
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45 | /*----- Global variables --------------------------------------------------*/ |
46 | |
47 | const octet rc4_keysz[] = { KSZ_RANGE, RC4_KEYSZ, 1, 255, 1 }; |
48 | |
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49 | /*----- Main code ---------------------------------------------------------*/ |
50 | |
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51 | /* --- @rc4_addkey@ --- * |
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52 | * |
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53 | * Arguments: @rc4_ctx *ctx@ = pointer to context to key |
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54 | * @const void *k@ = pointer to key data to use |
55 | * @size_t sz@ = size of the key data |
56 | * |
57 | * Returns: --- |
58 | * |
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59 | * Use: Mixes key data with an RC4 context. The RC4 context is not |
60 | * reset before mixing. This may be used to mix new key |
61 | * material with an existing RC4 context. |
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62 | */ |
63 | |
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64 | void rc4_addkey(rc4_ctx *ctx, const void *k, size_t sz) |
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65 | { |
66 | unsigned i, j; |
67 | const octet *p = k, *q = p + sz; |
68 | |
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69 | KSZ_ASSERT(rc4, sz); |
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70 | |
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71 | for (i = j = 0; i < 256; i++) { |
72 | unsigned si = ctx->s[i]; |
73 | j = (j + si + *p++) & 0xff; |
74 | ctx->s[i] = ctx->s[j]; |
75 | ctx->s[j] = si; |
76 | if (p == q) |
77 | p = k; |
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78 | } |
79 | |
80 | ctx->i = ctx->j = 0; |
81 | } |
82 | |
83 | /* --- @rc4_init@ --- * |
84 | * |
85 | * Arguments: @rc4_ctx *ctx@ = pointer to context to initialize |
86 | * @const void *k@ = pointer to key data to use |
87 | * @size_t sz@ = size of the key data |
88 | * |
89 | * Returns: --- |
90 | * |
91 | * Use: Initializes an RC4 context ready for use. |
92 | */ |
93 | |
94 | void rc4_init(rc4_ctx *ctx, const void *k, size_t sz) |
95 | { |
96 | unsigned i; |
97 | |
98 | for (i = 0; i < 256; i++) |
99 | ctx->s[i] = i; |
100 | ctx->f = 0; |
101 | rc4_addkey(ctx, k, sz); |
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102 | } |
103 | |
104 | /* --- @rc4_encrypt@ --- * |
105 | * |
106 | * Arguments: @rc4_ctx *ctx@ = pointer to context to use |
107 | * @const void *src@ = pointer to the source block |
108 | * @void *dest@ = pointer to the destination block |
109 | * @size_t sz@ = size of the block |
110 | * |
111 | * Returns: --- |
112 | * |
113 | * Use: Encrypts or decrypts a block of data. The destination may |
114 | * be null to just grind the generator around for a while. It's |
115 | * recommended that you say `@rc4_encrypt(&ctx, 0, 0, 1024)@' |
116 | * after initializing a new context, to prevent keystream |
117 | * guessing attacks. The source may be null to just extract a |
118 | * big lump of data from the generator. |
119 | */ |
120 | |
121 | void rc4_encrypt(rc4_ctx *ctx, const void *src, void *dest, size_t sz) |
122 | { |
123 | const octet *s = src; |
124 | octet *d = dest; |
125 | |
126 | if (!d) |
127 | RC4_OPEN(ctx, while (sz) { unsigned x; RC4_BYTE(x); sz--; }); |
128 | else if (!s) |
129 | RC4_OPEN(ctx, while (sz) { RC4_BYTE(*d++); sz--; }); |
130 | else |
131 | RC4_OPEN(ctx, |
132 | while (sz) { unsigned x; RC4_BYTE(x); *d++ = *s++ ^ x; sz--; }); |
133 | } |
134 | |
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135 | /*----- Generic cipher interface ------------------------------------------*/ |
136 | |
137 | typedef struct gctx { |
138 | gcipher c; |
139 | rc4_ctx rc4; |
140 | } gctx; |
141 | |
142 | static const gcipher_ops gops; |
143 | |
144 | static gcipher *ginit(const void *k, size_t sz) |
145 | { |
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146 | gctx *g = S_CREATE(gctx); |
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147 | g->c.ops = &gops; |
148 | rc4_init(&g->rc4, k, sz); |
149 | return (&g->c); |
150 | } |
151 | |
152 | static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) |
153 | { |
154 | gctx *g = (gctx *)c; |
155 | rc4_encrypt(&g->rc4, s, t, sz); |
156 | } |
157 | |
158 | static void gdestroy(gcipher *c) |
159 | { |
160 | gctx *g = (gctx *)c; |
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161 | BURN(*g); |
162 | S_DESTROY(g); |
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163 | } |
164 | |
165 | static const gcipher_ops gops = { |
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166 | &rc4, |
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167 | gencrypt, gencrypt, gdestroy, 0, 0 |
168 | }; |
169 | |
170 | const gccipher rc4 = { |
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171 | "rc4", rc4_keysz, 0, |
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172 | ginit |
173 | }; |
174 | |
175 | /*----- Generic random number generator interface -------------------------*/ |
176 | |
177 | typedef struct grctx { |
178 | grand r; |
179 | rc4_ctx rc4; |
180 | } grctx; |
181 | |
182 | static void grdestroy(grand *r) |
183 | { |
184 | grctx *g = (grctx *)r; |
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185 | BURN(*g); |
186 | S_DESTROY(g); |
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187 | } |
188 | |
189 | static int grmisc(grand *r, unsigned op, ...) |
190 | { |
191 | grctx *g = (grctx *)r; |
192 | va_list ap; |
193 | int rc = 0; |
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194 | uint32 i; |
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195 | octet buf[4]; |
196 | va_start(ap, op); |
197 | |
198 | switch (op) { |
199 | case GRAND_CHECK: |
200 | switch (va_arg(ap, unsigned)) { |
201 | case GRAND_CHECK: |
202 | case GRAND_SEEDINT: |
203 | case GRAND_SEEDUINT32: |
204 | case GRAND_SEEDBLOCK: |
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205 | case GRAND_SEEDRAND: |
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206 | rc = 1; |
207 | break; |
208 | default: |
209 | rc = 0; |
210 | break; |
211 | } |
212 | break; |
213 | case GRAND_SEEDINT: |
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214 | i = va_arg(ap, unsigned); |
215 | STORE32(buf, i); |
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216 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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217 | break; |
218 | case GRAND_SEEDUINT32: |
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219 | i = va_arg(ap, uint32); |
220 | STORE32(buf, i); |
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221 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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222 | break; |
223 | case GRAND_SEEDBLOCK: { |
224 | const void *p = va_arg(ap, const void *); |
225 | size_t sz = va_arg(ap, size_t); |
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226 | rc4_addkey(&g->rc4, p, sz); |
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227 | } break; |
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228 | case GRAND_SEEDRAND: { |
229 | grand *rr = va_arg(ap, grand *); |
230 | octet buf[16]; |
231 | rr->ops->fill(rr, buf, sizeof(buf)); |
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232 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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233 | } break; |
234 | default: |
235 | GRAND_BADOP; |
236 | break; |
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237 | } |
238 | |
239 | va_end(ap); |
240 | return (rc); |
241 | } |
242 | |
243 | static octet grbyte(grand *r) |
244 | { |
245 | grctx *g = (grctx *)r; |
246 | octet o; |
247 | RC4_OPEN(&g->rc4, RC4_BYTE(o);); |
248 | return (o); |
249 | } |
250 | |
251 | static uint32 grword(grand *r) |
252 | { |
253 | grctx *g = (grctx *)r; |
254 | octet b[4]; |
255 | int i; |
256 | RC4_OPEN(&g->rc4, |
257 | for (i = 0; i < sizeof(b); i++) |
258 | RC4_BYTE(b[i]);); |
259 | return (LOAD32(b)); |
260 | } |
261 | |
262 | static void grfill(grand *r, void *p, size_t sz) |
263 | { |
264 | grctx *g = (grctx *)r; |
265 | rc4_encrypt(&g->rc4, 0, p, sz); |
266 | } |
267 | |
268 | static const grand_ops grops = { |
269 | "rc4", |
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270 | GRAND_CRYPTO, 0, |
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271 | grmisc, grdestroy, |
272 | grword, grbyte, grword, grand_range, grfill |
273 | }; |
274 | |
275 | /* --- @rc4_rand@ --- * |
276 | * |
277 | * Arguments: @const void *k@ = pointer to key material |
278 | * @size_t sz@ = size of key material |
279 | * |
280 | * Returns: Pointer to generic random number generator interface. |
281 | * |
282 | * Use: Creates a random number interface wrapper around an |
283 | * OFB-mode block cipher. |
284 | */ |
285 | |
286 | grand *rc4_rand(const void *k, size_t sz) |
287 | { |
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288 | grctx *g = S_CREATE(grctx); |
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289 | g->r.ops = &grops; |
290 | rc4_init(&g->rc4, k, sz); |
291 | return (&g->r); |
292 | } |
293 | |
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294 | /*----- Test rig ----------------------------------------------------------*/ |
295 | |
296 | #ifdef TEST_RIG |
297 | |
298 | #include <stdio.h> |
299 | #include <string.h> |
300 | |
301 | #include <mLib/quis.h> |
302 | #include <mLib/testrig.h> |
303 | |
304 | static int v_encrypt(dstr *v) |
305 | { |
306 | rc4_ctx ctx; |
307 | dstr d = DSTR_INIT; |
308 | int ok = 1; |
309 | |
310 | rc4_init(&ctx, v[0].buf, v[0].len); |
311 | dstr_ensure(&d, v[1].len); |
312 | d.len = v[1].len; |
313 | rc4_encrypt(&ctx, v[1].buf, d.buf, d.len); |
314 | |
315 | if (memcmp(v[2].buf, d.buf, d.len) != 0) { |
316 | ok = 0; |
317 | printf("\nfail encryption:" |
318 | "\n\tkey = "); |
319 | type_hex.dump(&v[0], stdout); |
320 | printf("\n\tplaintext = "); type_hex.dump(&v[1], stdout); |
321 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
322 | printf("\n\tcalculated = "); type_hex.dump(&d, stdout); |
323 | putchar('\n'); |
324 | } |
325 | |
326 | return (ok); |
327 | } |
328 | |
329 | static int v_generate(dstr *v) |
330 | { |
331 | rc4_ctx ctx; |
332 | dstr d = DSTR_INIT; |
333 | int ok = 1; |
334 | |
335 | rc4_init(&ctx, v[0].buf, v[0].len); |
336 | rc4_encrypt(&ctx, 0, 0, *(int *)v[1].buf); |
337 | dstr_ensure(&d, v[2].len); |
338 | d.len = v[2].len; |
339 | rc4_encrypt(&ctx, 0, d.buf, d.len); |
340 | |
341 | if (memcmp(v[2].buf, d.buf, d.len) != 0) { |
342 | ok = 0; |
343 | printf("\nfail generation:" |
344 | "\n\tkey = "); |
345 | type_hex.dump(&v[0], stdout); |
346 | printf("\n\tskip len = %i", *(int *)v[1].buf); |
347 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
348 | printf("\n\tcalculated = "); type_hex.dump(&d, stdout); |
349 | putchar('\n'); |
350 | } |
351 | |
352 | return (ok); |
353 | } |
354 | |
355 | static test_chunk defs[] = { |
356 | { "rc4-encrypt", v_encrypt, { &type_hex, &type_hex, &type_hex, 0 } }, |
357 | { "rc4-generate", v_generate, { &type_hex, &type_int, &type_hex, 0 } }, |
358 | { 0, 0, { 0 } } |
359 | }; |
360 | |
361 | int main(int argc, char *argv[]) |
362 | { |
363 | test_run(argc, argv, defs, SRCDIR"/tests/rc4"); |
364 | return (0); |
365 | } |
366 | |
367 | #endif |
368 | |
369 | /*----- That's all, folks -------------------------------------------------*/ |