cbc.c
1 /* cbc.c: This file contains the encryption routines for the ed line editor */
2 /*-
3 * Copyright (c) 1993 The Regents of the University of California.
4 * All rights reserved.
5 *
6 * Copyright (c) 1993 Andrew Moore, Talke Studio.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 4. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <sys/cdefs.h>
35 __FBSDID("$FreeBSD: src/bin/ed/cbc.c,v 1.20 2004/04/06 20:06:47 markm Exp $");
36
37 #include <sys/types.h>
38 #include <errno.h>
39 #include <pwd.h>
40 #ifdef DES
41 #include <time.h>
42 #include <openssl/des.h>
43 #define ED_DES_INCLUDES
44 #endif
45
46 #include "ed.h"
47
48
49 /*
50 * BSD and System V systems offer special library calls that do
51 * block move_liness and fills, so if possible we take advantage of them
52 */
53 #define MEMCPY(dest,src,len) memcpy((dest),(src),(len))
54 #define MEMZERO(dest,len) memset((dest), 0, (len))
55
56 /* Hide the calls to the primitive encryption routines. */
57 #define DES_XFORM(buf) \
58 DES_ecb_encrypt(buf, buf, &schedule, \
59 inverse ? DES_DECRYPT : DES_ENCRYPT);
60
61 /*
62 * read/write - no error checking
63 */
64 #define READ(buf, n, fp) fread(buf, sizeof(char), n, fp)
65 #define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp)
66
67 /*
68 * global variables and related macros
69 */
70
71 enum { /* encrypt, decrypt, authenticate */
72 MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE
73 } mode = MODE_ENCRYPT;
74
75 #ifdef DES
76 DES_cblock ivec; /* initialization vector */
77 DES_cblock pvec; /* padding vector */
78 #endif
79
80 char bits[] = { /* used to extract bits from a char */
81 '\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
82 };
83
84 int pflag; /* 1 to preserve parity bits */
85
86 #ifdef DES
87 DES_key_schedule schedule; /* expanded DES key */
88 #endif
89
90 unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */
91 int des_ct = 0; /* count for get_des_char/put_des_char */
92 int des_n = 0; /* index for put_des_char/get_des_char */
93
94 /* init_des_cipher: initialize DES */
95 void
96 init_des_cipher(void)
97 {
98 #ifdef DES
99 int i;
100
101 des_ct = des_n = 0;
102
103 /* initialize the initialization vector */
104 MEMZERO(ivec, 8);
105
106 /* initialize the padding vector */
107 for (i = 0; i < 8; i++)
108 pvec[i] = (char) (arc4random() % 256);
109 #endif
110 }
111
112
113 /* get_des_char: return next char in an encrypted file */
114 int
115 get_des_char(FILE *fp)
116 {
117 #ifdef DES
118 if (des_n >= des_ct) {
119 des_n = 0;
120 des_ct = cbc_decode(des_buf, fp);
121 }
122 return (des_ct > 0) ? des_buf[des_n++] : EOF;
123 #else
124 return (getc(fp));
125 #endif
126 }
127
128
129 /* put_des_char: write a char to an encrypted file; return char written */
130 int
131 put_des_char(int c, FILE *fp)
132 {
133 #ifdef DES
134 if (des_n == sizeof des_buf) {
135 des_ct = cbc_encode(des_buf, des_n, fp);
136 des_n = 0;
137 }
138 return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF;
139 #else
140 return (fputc(c, fp));
141 #endif
142 }
143
144
145 /* flush_des_file: flush an encrypted file's output; return status */
146 int
147 flush_des_file(FILE *fp)
148 {
149 #ifdef DES
150 if (des_n == sizeof des_buf) {
151 des_ct = cbc_encode(des_buf, des_n, fp);
152 des_n = 0;
153 }
154 return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF;
155 #else
156 return (fflush(fp));
157 #endif
158 }
159
160 #ifdef DES
161 /*
162 * get keyword from tty or stdin
163 */
164 int
165 get_keyword(void)
166 {
167 char *p; /* used to obtain the key */
168 DES_cblock msgbuf; /* I/O buffer */
169
170 /*
171 * get the key
172 */
173 if (*(p = getpass("Enter key: "))) {
174
175 /*
176 * copy it, nul-padded, into the key area
177 */
178 expand_des_key(msgbuf, p);
179 MEMZERO(p, _PASSWORD_LEN);
180 set_des_key(&msgbuf);
181 MEMZERO(msgbuf, sizeof msgbuf);
182 return 1;
183 }
184 return 0;
185 }
186
187
188 /*
189 * print a warning message and, possibly, terminate
190 */
191 void
192 des_error(const char *s)
193 {
194 errmsg = s ? s : strerror(errno);
195 }
196
197 /*
198 * map a hex character to an integer
199 */
200 int
201 hex_to_binary(int c, int radix)
202 {
203 switch(c) {
204 case '0': return(0x0);
205 case '1': return(0x1);
206 case '2': return(radix > 2 ? 0x2 : -1);
207 case '3': return(radix > 3 ? 0x3 : -1);
208 case '4': return(radix > 4 ? 0x4 : -1);
209 case '5': return(radix > 5 ? 0x5 : -1);
210 case '6': return(radix > 6 ? 0x6 : -1);
211 case '7': return(radix > 7 ? 0x7 : -1);
212 case '8': return(radix > 8 ? 0x8 : -1);
213 case '9': return(radix > 9 ? 0x9 : -1);
214 case 'A': case 'a': return(radix > 10 ? 0xa : -1);
215 case 'B': case 'b': return(radix > 11 ? 0xb : -1);
216 case 'C': case 'c': return(radix > 12 ? 0xc : -1);
217 case 'D': case 'd': return(radix > 13 ? 0xd : -1);
218 case 'E': case 'e': return(radix > 14 ? 0xe : -1);
219 case 'F': case 'f': return(radix > 15 ? 0xf : -1);
220 }
221 /*
222 * invalid character
223 */
224 return(-1);
225 }
226
227 /*
228 * convert the key to a bit pattern
229 * obuf bit pattern
230 * kbuf the key itself
231 */
232 void
233 expand_des_key(char *obuf, char *kbuf)
234 {
235 int i, j; /* counter in a for loop */
236 int nbuf[64]; /* used for hex/key translation */
237
238 /*
239 * leading '0x' or '0X' == hex key
240 */
241 if (kbuf[0] == '0' && (kbuf[1] == 'x' || kbuf[1] == 'X')) {
242 kbuf = &kbuf[2];
243 /*
244 * now translate it, bombing on any illegal hex digit
245 */
246 for (i = 0; kbuf[i] && i < 16; i++)
247 if ((nbuf[i] = hex_to_binary((int) kbuf[i], 16)) == -1)
248 des_error("bad hex digit in key");
249 while (i < 16)
250 nbuf[i++] = 0;
251 for (i = 0; i < 8; i++)
252 obuf[i] =
253 ((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf);
254 /* preserve parity bits */
255 pflag = 1;
256 return;
257 }
258 /*
259 * leading '0b' or '0B' == binary key
260 */
261 if (kbuf[0] == '0' && (kbuf[1] == 'b' || kbuf[1] == 'B')) {
262 kbuf = &kbuf[2];
263 /*
264 * now translate it, bombing on any illegal binary digit
265 */
266 for (i = 0; kbuf[i] && i < 16; i++)
267 if ((nbuf[i] = hex_to_binary((int) kbuf[i], 2)) == -1)
268 des_error("bad binary digit in key");
269 while (i < 64)
270 nbuf[i++] = 0;
271 for (i = 0; i < 8; i++)
272 for (j = 0; j < 8; j++)
273 obuf[i] = (obuf[i]<<1)|nbuf[8*i+j];
274 /* preserve parity bits */
275 pflag = 1;
276 return;
277 }
278 /*
279 * no special leader -- ASCII
280 */
281 (void)strncpy(obuf, kbuf, 8);
282 }
283
284 /*****************
285 * DES FUNCTIONS *
286 *****************/
287 /*
288 * This sets the DES key and (if you're using the deszip version)
289 * the direction of the transformation. This uses the Sun
290 * to map the 64-bit key onto the 56 bits that the key schedule
291 * generation routines use: the old way, which just uses the user-
292 * supplied 64 bits as is, and the new way, which resets the parity
293 * bit to be the same as the low-order bit in each character. The
294 * new way generates a greater variety of key schedules, since many
295 * systems set the parity (high) bit of each character to 0, and the
296 * DES ignores the low order bit of each character.
297 */
298 void
299 set_des_key(DES_cblock *buf) /* key block */
300 {
301 int i, j; /* counter in a for loop */
302 int par; /* parity counter */
303
304 /*
305 * if the parity is not preserved, flip it
306 */
307 if (!pflag) {
308 for (i = 0; i < 8; i++) {
309 par = 0;
310 for (j = 1; j < 8; j++)
311 if ((bits[j] & (*buf)[i]) != 0)
312 par++;
313 if ((par & 0x01) == 0x01)
314 (*buf)[i] &= 0x7f;
315 else
316 (*buf)[i] = ((*buf)[i] & 0x7f) | 0x80;
317 }
318 }
319
320 DES_set_odd_parity(buf);
321 DES_set_key(buf, &schedule);
322 }
323
324
325 /*
326 * This encrypts using the Cipher Block Chaining mode of DES
327 */
328 int
329 cbc_encode(unsigned char *msgbuf, int n, FILE *fp)
330 {
331 int inverse = 0; /* 0 to encrypt, 1 to decrypt */
332
333 /*
334 * do the transformation
335 */
336 if (n == 8) {
337 for (n = 0; n < 8; n++)
338 msgbuf[n] ^= ivec[n];
339 DES_XFORM((DES_cblock *)msgbuf);
340 MEMCPY(ivec, msgbuf, 8);
341 return WRITE(msgbuf, 8, fp);
342 }
343 /*
344 * at EOF or last block -- in either case, the last byte contains
345 * the character representation of the number of bytes in it
346 */
347 /*
348 MEMZERO(msgbuf + n, 8 - n);
349 */
350 /*
351 * Pad the last block randomly
352 */
353 (void)MEMCPY(msgbuf + n, pvec, 8 - n);
354 msgbuf[7] = n;
355 for (n = 0; n < 8; n++)
356 msgbuf[n] ^= ivec[n];
357 DES_XFORM((DES_cblock *)msgbuf);
358 return WRITE(msgbuf, 8, fp);
359 }
360
361 /*
362 * This decrypts using the Cipher Block Chaining mode of DES
363 * msgbuf I/O buffer
364 * fp input file descriptor
365 */
366 int
367 cbc_decode(unsigned char *msgbuf, FILE *fp)
368 {
369 DES_cblock tbuf; /* temp buffer for initialization vector */
370 int n; /* number of bytes actually read */
371 int c; /* used to test for EOF */
372 int inverse = 1; /* 0 to encrypt, 1 to decrypt */
373
374 if ((n = READ(msgbuf, 8, fp)) == 8) {
375 /*
376 * do the transformation
377 */
378 MEMCPY(tbuf, msgbuf, 8);
379 DES_XFORM((DES_cblock *)msgbuf);
380 for (c = 0; c < 8; c++)
381 msgbuf[c] ^= ivec[c];
382 MEMCPY(ivec, tbuf, 8);
383 /*
384 * if the last one, handle it specially
385 */
386 if ((c = fgetc(fp)) == EOF) {
387 n = msgbuf[7];
388 if (n < 0 || n > 7) {
389 des_error("decryption failed (block corrupted)");
390 return EOF;
391 }
392 } else
393 (void)ungetc(c, fp);
394 return n;
395 }
396 if (n > 0)
397 des_error("decryption failed (incomplete block)");
398 else if (n < 0)
399 des_error("cannot read file");
400 return EOF;
401 }
402 #endif /* DES */
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