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