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1 | /* -*-c-*- |
2 | * |
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3 | * The alleged RC4 stream cipher |
4 | * |
5 | * (c) 1999 Straylight/Edgeware |
6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
10 | * This file is part of Catacomb. |
11 | * |
12 | * Catacomb is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the |
15 | * License, or (at your option) any later version. |
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16 | * |
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17 | * Catacomb is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU Library General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with Catacomb; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
25 | * MA 02111-1307, USA. |
26 | */ |
27 | |
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28 | /*----- Header files ------------------------------------------------------*/ |
29 | |
30 | #include <assert.h> |
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31 | #include <stdarg.h> |
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32 | #include <stdio.h> |
33 | |
34 | #include <mLib/bits.h> |
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35 | #include <mLib/sub.h> |
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36 | |
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37 | #include "arena.h" |
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38 | #include "gcipher.h" |
39 | #include "grand.h" |
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40 | #include "paranoia.h" |
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41 | #include "rc4.h" |
42 | |
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43 | /*----- Global variables --------------------------------------------------*/ |
44 | |
45 | const octet rc4_keysz[] = { KSZ_RANGE, RC4_KEYSZ, 1, 255, 1 }; |
46 | |
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47 | /*----- Main code ---------------------------------------------------------*/ |
48 | |
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49 | /* --- @rc4_addkey@ --- * |
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50 | * |
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51 | * Arguments: @rc4_ctx *ctx@ = pointer to context to key |
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52 | * @const void *k@ = pointer to key data to use |
53 | * @size_t sz@ = size of the key data |
54 | * |
55 | * Returns: --- |
56 | * |
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57 | * Use: Mixes key data with an RC4 context. The RC4 context is not |
58 | * reset before mixing. This may be used to mix new key |
59 | * material with an existing RC4 context. |
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60 | */ |
61 | |
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62 | void rc4_addkey(rc4_ctx *ctx, const void *k, size_t sz) |
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63 | { |
64 | unsigned i, j; |
65 | const octet *p = k, *q = p + sz; |
66 | |
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67 | KSZ_ASSERT(rc4, sz); |
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68 | |
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69 | for (i = j = 0; i < 256; i++) { |
70 | unsigned si = ctx->s[i]; |
71 | j = (j + si + *p++) & 0xff; |
72 | ctx->s[i] = ctx->s[j]; |
73 | ctx->s[j] = si; |
74 | if (p == q) |
75 | p = k; |
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76 | } |
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77 | |
78 | ctx->i = ctx->j = 0; |
79 | } |
80 | |
81 | /* --- @rc4_init@ --- * |
82 | * |
83 | * Arguments: @rc4_ctx *ctx@ = pointer to context to initialize |
84 | * @const void *k@ = pointer to key data to use |
85 | * @size_t sz@ = size of the key data |
86 | * |
87 | * Returns: --- |
88 | * |
89 | * Use: Initializes an RC4 context ready for use. |
90 | */ |
91 | |
92 | void rc4_init(rc4_ctx *ctx, const void *k, size_t sz) |
93 | { |
94 | unsigned i; |
95 | |
96 | for (i = 0; i < 256; i++) |
97 | ctx->s[i] = i; |
98 | ctx->f = 0; |
99 | rc4_addkey(ctx, k, sz); |
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100 | } |
101 | |
102 | /* --- @rc4_encrypt@ --- * |
103 | * |
104 | * Arguments: @rc4_ctx *ctx@ = pointer to context to use |
105 | * @const void *src@ = pointer to the source block |
106 | * @void *dest@ = pointer to the destination block |
107 | * @size_t sz@ = size of the block |
108 | * |
109 | * Returns: --- |
110 | * |
111 | * Use: Encrypts or decrypts a block of data. The destination may |
112 | * be null to just grind the generator around for a while. It's |
113 | * recommended that you say `@rc4_encrypt(&ctx, 0, 0, 1024)@' |
114 | * after initializing a new context, to prevent keystream |
115 | * guessing attacks. The source may be null to just extract a |
116 | * big lump of data from the generator. |
117 | */ |
118 | |
119 | void rc4_encrypt(rc4_ctx *ctx, const void *src, void *dest, size_t sz) |
120 | { |
121 | const octet *s = src; |
122 | octet *d = dest; |
123 | |
124 | if (!d) |
125 | RC4_OPEN(ctx, while (sz) { unsigned x; RC4_BYTE(x); sz--; }); |
126 | else if (!s) |
127 | RC4_OPEN(ctx, while (sz) { RC4_BYTE(*d++); sz--; }); |
128 | else |
129 | RC4_OPEN(ctx, |
130 | while (sz) { unsigned x; RC4_BYTE(x); *d++ = *s++ ^ x; sz--; }); |
131 | } |
132 | |
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133 | /*----- Generic cipher interface ------------------------------------------*/ |
134 | |
135 | typedef struct gctx { |
136 | gcipher c; |
137 | rc4_ctx rc4; |
138 | } gctx; |
139 | |
140 | static const gcipher_ops gops; |
141 | |
142 | static gcipher *ginit(const void *k, size_t sz) |
143 | { |
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144 | gctx *g = S_CREATE(gctx); |
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145 | g->c.ops = &gops; |
146 | rc4_init(&g->rc4, k, sz); |
147 | return (&g->c); |
148 | } |
149 | |
150 | static void gencrypt(gcipher *c, const void *s, void *t, size_t sz) |
151 | { |
152 | gctx *g = (gctx *)c; |
153 | rc4_encrypt(&g->rc4, s, t, sz); |
154 | } |
155 | |
156 | static void gdestroy(gcipher *c) |
157 | { |
158 | gctx *g = (gctx *)c; |
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159 | BURN(*g); |
160 | S_DESTROY(g); |
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161 | } |
162 | |
163 | static const gcipher_ops gops = { |
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164 | &rc4, |
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165 | gencrypt, gencrypt, gdestroy, 0, 0 |
166 | }; |
167 | |
168 | const gccipher rc4 = { |
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169 | "rc4", rc4_keysz, 0, |
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170 | ginit |
171 | }; |
172 | |
173 | /*----- Generic random number generator interface -------------------------*/ |
174 | |
175 | typedef struct grctx { |
176 | grand r; |
177 | rc4_ctx rc4; |
178 | } grctx; |
179 | |
180 | static void grdestroy(grand *r) |
181 | { |
182 | grctx *g = (grctx *)r; |
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183 | BURN(*g); |
184 | S_DESTROY(g); |
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185 | } |
186 | |
187 | static int grmisc(grand *r, unsigned op, ...) |
188 | { |
189 | grctx *g = (grctx *)r; |
190 | va_list ap; |
191 | int rc = 0; |
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192 | uint32 i; |
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193 | octet buf[4]; |
194 | va_start(ap, op); |
195 | |
196 | switch (op) { |
197 | case GRAND_CHECK: |
198 | switch (va_arg(ap, unsigned)) { |
199 | case GRAND_CHECK: |
200 | case GRAND_SEEDINT: |
201 | case GRAND_SEEDUINT32: |
202 | case GRAND_SEEDBLOCK: |
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203 | case GRAND_SEEDRAND: |
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204 | rc = 1; |
205 | break; |
206 | default: |
207 | rc = 0; |
208 | break; |
209 | } |
210 | break; |
211 | case GRAND_SEEDINT: |
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212 | i = va_arg(ap, unsigned); |
213 | STORE32(buf, i); |
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214 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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215 | break; |
216 | case GRAND_SEEDUINT32: |
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217 | i = va_arg(ap, uint32); |
218 | STORE32(buf, i); |
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219 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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220 | break; |
221 | case GRAND_SEEDBLOCK: { |
222 | const void *p = va_arg(ap, const void *); |
223 | size_t sz = va_arg(ap, size_t); |
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224 | rc4_addkey(&g->rc4, p, sz); |
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225 | } break; |
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226 | case GRAND_SEEDRAND: { |
227 | grand *rr = va_arg(ap, grand *); |
228 | octet buf[16]; |
229 | rr->ops->fill(rr, buf, sizeof(buf)); |
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230 | rc4_addkey(&g->rc4, buf, sizeof(buf)); |
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231 | } break; |
232 | default: |
233 | GRAND_BADOP; |
234 | break; |
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235 | } |
236 | |
237 | va_end(ap); |
238 | return (rc); |
239 | } |
240 | |
241 | static octet grbyte(grand *r) |
242 | { |
243 | grctx *g = (grctx *)r; |
244 | octet o; |
245 | RC4_OPEN(&g->rc4, RC4_BYTE(o);); |
246 | return (o); |
247 | } |
248 | |
249 | static uint32 grword(grand *r) |
250 | { |
251 | grctx *g = (grctx *)r; |
252 | octet b[4]; |
253 | int i; |
254 | RC4_OPEN(&g->rc4, |
255 | for (i = 0; i < sizeof(b); i++) |
256 | RC4_BYTE(b[i]);); |
257 | return (LOAD32(b)); |
258 | } |
259 | |
260 | static void grfill(grand *r, void *p, size_t sz) |
261 | { |
262 | grctx *g = (grctx *)r; |
263 | rc4_encrypt(&g->rc4, 0, p, sz); |
264 | } |
265 | |
266 | static const grand_ops grops = { |
267 | "rc4", |
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268 | GRAND_CRYPTO, 0, |
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269 | grmisc, grdestroy, |
270 | grword, grbyte, grword, grand_range, grfill |
271 | }; |
272 | |
273 | /* --- @rc4_rand@ --- * |
274 | * |
275 | * Arguments: @const void *k@ = pointer to key material |
276 | * @size_t sz@ = size of key material |
277 | * |
278 | * Returns: Pointer to generic random number generator interface. |
279 | * |
280 | * Use: Creates a random number interface wrapper around an |
281 | * OFB-mode block cipher. |
282 | */ |
283 | |
284 | grand *rc4_rand(const void *k, size_t sz) |
285 | { |
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286 | grctx *g = S_CREATE(grctx); |
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287 | g->r.ops = &grops; |
288 | rc4_init(&g->rc4, k, sz); |
289 | return (&g->r); |
290 | } |
291 | |
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292 | /*----- Test rig ----------------------------------------------------------*/ |
293 | |
294 | #ifdef TEST_RIG |
295 | |
296 | #include <stdio.h> |
297 | #include <string.h> |
298 | |
299 | #include <mLib/quis.h> |
300 | #include <mLib/testrig.h> |
301 | |
302 | static int v_encrypt(dstr *v) |
303 | { |
304 | rc4_ctx ctx; |
305 | dstr d = DSTR_INIT; |
306 | int ok = 1; |
307 | |
308 | rc4_init(&ctx, v[0].buf, v[0].len); |
309 | dstr_ensure(&d, v[1].len); |
310 | d.len = v[1].len; |
311 | rc4_encrypt(&ctx, v[1].buf, d.buf, d.len); |
312 | |
313 | if (memcmp(v[2].buf, d.buf, d.len) != 0) { |
314 | ok = 0; |
315 | printf("\nfail encryption:" |
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316 | "\n\tkey = "); |
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317 | type_hex.dump(&v[0], stdout); |
318 | printf("\n\tplaintext = "); type_hex.dump(&v[1], stdout); |
319 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
320 | printf("\n\tcalculated = "); type_hex.dump(&d, stdout); |
321 | putchar('\n'); |
322 | } |
323 | |
324 | return (ok); |
325 | } |
326 | |
327 | static int v_generate(dstr *v) |
328 | { |
329 | rc4_ctx ctx; |
330 | dstr d = DSTR_INIT; |
331 | int ok = 1; |
332 | |
333 | rc4_init(&ctx, v[0].buf, v[0].len); |
334 | rc4_encrypt(&ctx, 0, 0, *(int *)v[1].buf); |
335 | dstr_ensure(&d, v[2].len); |
336 | d.len = v[2].len; |
337 | rc4_encrypt(&ctx, 0, d.buf, d.len); |
338 | |
339 | if (memcmp(v[2].buf, d.buf, d.len) != 0) { |
340 | ok = 0; |
341 | printf("\nfail generation:" |
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342 | "\n\tkey = "); |
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343 | type_hex.dump(&v[0], stdout); |
344 | printf("\n\tskip len = %i", *(int *)v[1].buf); |
345 | printf("\n\texpected = "); type_hex.dump(&v[2], stdout); |
346 | printf("\n\tcalculated = "); type_hex.dump(&d, stdout); |
347 | putchar('\n'); |
348 | } |
349 | |
350 | return (ok); |
351 | } |
352 | |
353 | static test_chunk defs[] = { |
354 | { "rc4-encrypt", v_encrypt, { &type_hex, &type_hex, &type_hex, 0 } }, |
355 | { "rc4-generate", v_generate, { &type_hex, &type_int, &type_hex, 0 } }, |
356 | { 0, 0, { 0 } } |
357 | }; |
358 | |
359 | int main(int argc, char *argv[]) |
360 | { |
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361 | test_run(argc, argv, defs, SRCDIR"/t/rc4"); |
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362 | return (0); |
363 | } |
364 | |
365 | #endif |
366 | |
367 | /*----- That's all, folks -------------------------------------------------*/ |