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