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
71enum { 					/* encrypt, decrypt, authenticate */
72	MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE
73} mode = MODE_ENCRYPT;
74
75#ifdef DES
76DES_cblock ivec;			/* initialization vector */
77DES_cblock pvec;			/* padding vector */
78#endif
79
80char bits[] = {				/* used to extract bits from a char */
81	'\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
82};
83
84int pflag;				/* 1 to preserve parity bits */
85
86#ifdef DES
87DES_key_schedule schedule;		/* expanded DES key */
88#endif
89
90unsigned char des_buf[8];	/* shared buffer for get_des_char/put_des_char */
91int des_ct = 0;			/* count for get_des_char/put_des_char */
92int des_n = 0;			/* index for put_des_char/get_des_char */
93
94/* init_des_cipher: initialize DES */
95void
96init_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 */
114int
115get_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 */
130int
131put_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 */
146int
147flush_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 */
164int
165get_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 */
191void
192des_error(const char *s)
193{
194	errmsg = s ? s : strerror(errno);
195}
196
197/*
198 * map a hex character to an integer
199 */
200int
201hex_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 */
232void
233expand_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 */
298void
299set_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 */
328int
329cbc_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 */
366int
367cbc_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 */
403