3 * $Id: rc4.c,v 1.6 2004/04/08 01:36:15 mdw Exp $
5 * The alleged RC4 stream cipher
7 * (c) 1999 Straylight/Edgeware
10 /*----- Licensing notice --------------------------------------------------*
12 * This file is part of Catacomb.
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.
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.
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,
30 /*----- Header files ------------------------------------------------------*/
36 #include <mLib/bits.h>
45 /*----- Global variables --------------------------------------------------*/
47 const octet rc4_keysz
[] = { KSZ_RANGE
, RC4_KEYSZ
, 1, 255, 1 };
49 /*----- Main code ---------------------------------------------------------*/
51 /* --- @rc4_addkey@ --- *
53 * Arguments: @rc4_ctx *ctx@ = pointer to context to key
54 * @const void *k@ = pointer to key data to use
55 * @size_t sz@ = size of the key data
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.
64 void rc4_addkey(rc4_ctx
*ctx
, const void *k
, size_t sz
)
67 const octet
*p
= k
, *q
= p
+ sz
;
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
];
83 /* --- @rc4_init@ --- *
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
91 * Use: Initializes an RC4 context ready for use.
94 void rc4_init(rc4_ctx
*ctx
, const void *k
, size_t sz
)
98 for (i
= 0; i
< 256; i
++)
101 rc4_addkey(ctx
, k
, sz
);
104 /* --- @rc4_encrypt@ --- *
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
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.
121 void rc4_encrypt(rc4_ctx
*ctx
, const void *src
, void *dest
, size_t sz
)
123 const octet
*s
= src
;
127 RC4_OPEN(ctx
, while (sz
) { unsigned x
; RC4_BYTE(x
); sz
--; });
129 RC4_OPEN(ctx
, while (sz
) { RC4_BYTE(*d
++); sz
--; });
132 while (sz
) { unsigned x
; RC4_BYTE(x
); *d
++ = *s
++ ^ x
; sz
--; });
135 /*----- Generic cipher interface ------------------------------------------*/
137 typedef struct gctx
{
142 static const gcipher_ops gops
;
144 static gcipher
*ginit(const void *k
, size_t sz
)
146 gctx
*g
= S_CREATE(gctx
);
148 rc4_init(&g
->rc4
, k
, sz
);
152 static void gencrypt(gcipher
*c
, const void *s
, void *t
, size_t sz
)
155 rc4_encrypt(&g
->rc4
, s
, t
, sz
);
158 static void gdestroy(gcipher
*c
)
165 static const gcipher_ops gops
= {
167 gencrypt
, gencrypt
, gdestroy
, 0, 0
170 const gccipher rc4
= {
175 /*----- Generic random number generator interface -------------------------*/
177 typedef struct grctx
{
182 static void grdestroy(grand
*r
)
184 grctx
*g
= (grctx
*)r
;
189 static int grmisc(grand
*r
, unsigned op
, ...)
191 grctx
*g
= (grctx
*)r
;
200 switch (va_arg(ap
, unsigned)) {
203 case GRAND_SEEDUINT32
:
204 case GRAND_SEEDBLOCK
:
214 i
= va_arg(ap
, unsigned);
216 rc4_addkey(&g
->rc4
, buf
, sizeof(buf
));
218 case GRAND_SEEDUINT32
:
219 i
= va_arg(ap
, uint32
);
221 rc4_addkey(&g
->rc4
, buf
, sizeof(buf
));
223 case GRAND_SEEDBLOCK
: {
224 const void *p
= va_arg(ap
, const void *);
225 size_t sz
= va_arg(ap
, size_t);
226 rc4_addkey(&g
->rc4
, p
, sz
);
228 case GRAND_SEEDRAND
: {
229 grand
*rr
= va_arg(ap
, grand
*);
231 rr
->ops
->fill(rr
, buf
, sizeof(buf
));
232 rc4_addkey(&g
->rc4
, buf
, sizeof(buf
));
243 static octet
grbyte(grand
*r
)
245 grctx
*g
= (grctx
*)r
;
247 RC4_OPEN(&g
->rc4
, RC4_BYTE(o
););
251 static uint32
grword(grand
*r
)
253 grctx
*g
= (grctx
*)r
;
257 for (i
= 0; i
< sizeof(b
); i
++)
262 static void grfill(grand
*r
, void *p
, size_t sz
)
264 grctx
*g
= (grctx
*)r
;
265 rc4_encrypt(&g
->rc4
, 0, p
, sz
);
268 static const grand_ops grops
= {
272 grword
, grbyte
, grword
, grand_range
, grfill
275 /* --- @rc4_rand@ --- *
277 * Arguments: @const void *k@ = pointer to key material
278 * @size_t sz@ = size of key material
280 * Returns: Pointer to generic random number generator interface.
282 * Use: Creates a random number interface wrapper around an
283 * OFB-mode block cipher.
286 grand
*rc4_rand(const void *k
, size_t sz
)
288 grctx
*g
= S_CREATE(grctx
);
290 rc4_init(&g
->rc4
, k
, sz
);
294 /*----- Test rig ----------------------------------------------------------*/
301 #include <mLib/quis.h>
302 #include <mLib/testrig.h>
304 static int v_encrypt(dstr
*v
)
310 rc4_init(&ctx
, v
[0].buf
, v
[0].len
);
311 dstr_ensure(&d
, v
[1].len
);
313 rc4_encrypt(&ctx
, v
[1].buf
, d
.buf
, d
.len
);
315 if (memcmp(v
[2].buf
, d
.buf
, d
.len
) != 0) {
317 printf("\nfail encryption:"
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
);
329 static int v_generate(dstr
*v
)
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
);
339 rc4_encrypt(&ctx
, 0, d
.buf
, d
.len
);
341 if (memcmp(v
[2].buf
, d
.buf
, d
.len
) != 0) {
343 printf("\nfail generation:"
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
);
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 } },
361 int main(int argc
, char *argv
[])
363 test_run(argc
, argv
, defs
, SRCDIR
"/tests/rc4");
369 /*----- That's all, folks -------------------------------------------------*/