423 lines
11 KiB
C
423 lines
11 KiB
C
/* cbc.c: This file contains the encryption routines for the ed line editor */
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/*-
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* Copyright (c) 1993 The Regents of the University of California.
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* All rights reserved.
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*
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* Copyright (c) 1993 Andrew Moore, Talke Studio.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* from: @(#)bdes.c 5.5 (Berkeley) 6/27/91
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* $Id$
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*/
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#ifndef lint
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static char *rcsid = "@(#)cbc.c,v 1.2 1994/02/01 00:34:36 alm Exp";
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#endif /* not lint */
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#include <sys/types.h>
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#include <ctype.h>
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#include <errno.h>
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#include <pwd.h>
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#include "ed.h"
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/*
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* Define a divisor for rand() that yields a uniform distribution in the
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* range 0-255.
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*/
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#define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8)
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/*
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* BSD and System V systems offer special library calls that do
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* block move_liness and fills, so if possible we take advantage of them
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*/
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#define MEMCPY(dest,src,len) memcpy((dest),(src),(len))
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#define MEMZERO(dest,len) memset((dest), 0, (len))
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/* Hide the calls to the primitive encryption routines. */
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#define DES_KEY(buf) \
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if (des_setkey(buf)) \
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des_error("des_setkey");
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#define DES_XFORM(buf) \
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if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \
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des_error("des_cipher");
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/*
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* read/write - no error checking
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*/
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#define READ(buf, n, fp) fread(buf, sizeof(char), n, fp)
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#define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp)
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/*
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* some things to make references easier
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*/
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typedef char Desbuf[8];
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#define CHAR(x,i) (x[i])
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#define UCHAR(x,i) (x[i])
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#define BUFFER(x) (x)
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#define UBUFFER(x) (x)
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/*
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* global variables and related macros
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*/
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enum { /* encrypt, decrypt, authenticate */
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MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE
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} mode = MODE_ENCRYPT;
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Desbuf ivec; /* initialization vector */
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Desbuf pvec; /* padding vector */
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char bits[] = { /* used to extract bits from a char */
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'\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
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};
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int pflag; /* 1 to preserve parity bits */
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unsigned char des_buf[8]; /* shared buffer for get_des_char/put_des_char */
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int des_ct = 0; /* count for get_des_char/put_des_char */
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int des_n = 0; /* index for put_des_char/get_des_char */
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/* init_des_cipher: initialize DES */
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void
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init_des_cipher()
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{
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#ifdef DES
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int i;
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des_ct = des_n = 0;
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/* initialize the initialization vctor */
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MEMZERO(ivec, 8);
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/* intialize the padding vector */
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srand((unsigned) time((time_t *) 0));
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for (i = 0; i < 8; i++)
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CHAR(pvec, i) = (char) (rand()/RAND_DIV);
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#endif
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}
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/* get_des_char: return next char in an encrypted file */
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int
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get_des_char(fp)
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FILE *fp;
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{
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#ifdef DES
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if (des_n >= des_ct) {
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des_n = 0;
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des_ct = cbc_decode(des_buf, fp);
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}
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return (des_ct > 0) ? des_buf[des_n++] : EOF;
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#endif
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}
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/* put_des_char: write a char to an encrypted file; return char written */
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int
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put_des_char(c, fp)
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int c;
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FILE *fp;
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{
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#ifdef DES
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if (des_n == sizeof des_buf) {
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des_ct = cbc_encode(des_buf, des_n, fp);
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des_n = 0;
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}
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return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF;
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#endif
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}
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/* flush_des_file: flush an encrypted file's output; return status */
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int
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flush_des_file(fp)
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FILE *fp;
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{
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#ifdef DES
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if (des_n == sizeof des_buf) {
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des_ct = cbc_encode(des_buf, des_n, fp);
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des_n = 0;
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}
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return (des_ct >= 0 && cbc_encode(des_buf, des_n, fp) >= 0) ? 0 : EOF;
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#endif
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}
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#ifdef DES
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/*
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* get keyword from tty or stdin
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*/
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int
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get_keyword()
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{
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register char *p; /* used to obtain the key */
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Desbuf msgbuf; /* I/O buffer */
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/*
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* get the key
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*/
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if (*(p = getpass("Enter key: "))) {
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/*
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* copy it, nul-padded, into the key area
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*/
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expand_des_key(BUFFER(msgbuf), p);
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MEMZERO(p, _PASSWORD_LEN);
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set_des_key(msgbuf);
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MEMZERO(msgbuf, sizeof msgbuf);
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return 1;
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}
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return 0;
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}
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/*
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* print a warning message and, possibly, terminate
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*/
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void
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des_error(s)
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char *s; /* the message */
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{
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(void)sprintf(errmsg, "%s", s ? s : strerror(errno));
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}
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/*
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* map a hex character to an integer
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*/
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int
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hex_to_binary(c, radix)
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int c; /* char to be converted */
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int radix; /* base (2 to 16) */
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{
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switch(c) {
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case '0': return(0x0);
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case '1': return(0x1);
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case '2': return(radix > 2 ? 0x2 : -1);
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case '3': return(radix > 3 ? 0x3 : -1);
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case '4': return(radix > 4 ? 0x4 : -1);
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case '5': return(radix > 5 ? 0x5 : -1);
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case '6': return(radix > 6 ? 0x6 : -1);
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case '7': return(radix > 7 ? 0x7 : -1);
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case '8': return(radix > 8 ? 0x8 : -1);
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case '9': return(radix > 9 ? 0x9 : -1);
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case 'A': case 'a': return(radix > 10 ? 0xa : -1);
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case 'B': case 'b': return(radix > 11 ? 0xb : -1);
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case 'C': case 'c': return(radix > 12 ? 0xc : -1);
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case 'D': case 'd': return(radix > 13 ? 0xd : -1);
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case 'E': case 'e': return(radix > 14 ? 0xe : -1);
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case 'F': case 'f': return(radix > 15 ? 0xf : -1);
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}
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/*
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* invalid character
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*/
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return(-1);
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}
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/*
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* convert the key to a bit pattern
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*/
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void
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expand_des_key(obuf, ibuf)
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char *obuf; /* bit pattern */
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char *ibuf; /* the key itself */
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{
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register int i, j; /* counter in a for loop */
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int nbuf[64]; /* used for hex/key translation */
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/*
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* leading '0x' or '0X' == hex key
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*/
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if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) {
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ibuf = &ibuf[2];
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/*
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* now translate it, bombing on any illegal hex digit
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*/
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for (i = 0; ibuf[i] && i < 16; i++)
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if ((nbuf[i] = hex_to_binary((int) ibuf[i], 16)) == -1)
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des_error("bad hex digit in key");
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while (i < 16)
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nbuf[i++] = 0;
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for (i = 0; i < 8; i++)
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obuf[i] =
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((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf);
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/* preserve parity bits */
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pflag = 1;
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return;
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}
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/*
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* leading '0b' or '0B' == binary key
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*/
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if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) {
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ibuf = &ibuf[2];
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/*
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* now translate it, bombing on any illegal binary digit
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*/
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for (i = 0; ibuf[i] && i < 16; i++)
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if ((nbuf[i] = hex_to_binary((int) ibuf[i], 2)) == -1)
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des_error("bad binary digit in key");
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while (i < 64)
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nbuf[i++] = 0;
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for (i = 0; i < 8; i++)
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for (j = 0; j < 8; j++)
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obuf[i] = (obuf[i]<<1)|nbuf[8*i+j];
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/* preserve parity bits */
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pflag = 1;
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return;
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}
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/*
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* no special leader -- ASCII
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*/
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(void)strncpy(obuf, ibuf, 8);
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}
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/*****************
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* DES FUNCTIONS *
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*****************/
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/*
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* This sets the DES key and (if you're using the deszip version)
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* the direction of the transformation. This uses the Sun
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* to map the 64-bit key onto the 56 bits that the key schedule
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* generation routines use: the old way, which just uses the user-
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* supplied 64 bits as is, and the new way, which resets the parity
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* bit to be the same as the low-order bit in each character. The
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* new way generates a greater variety of key schedules, since many
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* systems set the parity (high) bit of each character to 0, and the
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* DES ignores the low order bit of each character.
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*/
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void
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set_des_key(buf)
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Desbuf buf; /* key block */
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{
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register int i, j; /* counter in a for loop */
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register int par; /* parity counter */
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/*
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* if the parity is not preserved, flip it
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*/
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if (!pflag) {
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for (i = 0; i < 8; i++) {
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par = 0;
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for (j = 1; j < 8; j++)
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if ((bits[j]&UCHAR(buf, i)) != 0)
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par++;
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if ((par&01) == 01)
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UCHAR(buf, i) = UCHAR(buf, i)&0177;
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else
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UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200;
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}
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}
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DES_KEY(UBUFFER(buf));
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}
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/*
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* This encrypts using the Cipher Block Chaining mode of DES
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*/
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int
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cbc_encode(msgbuf, n, fp)
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char *msgbuf;
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int n;
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FILE *fp;
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{
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int inverse = 0; /* 0 to encrypt, 1 to decrypt */
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/*
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* do the transformation
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*/
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if (n == 8) {
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for (n = 0; n < 8; n++)
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CHAR(msgbuf, n) ^= CHAR(ivec, n);
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DES_XFORM(UBUFFER(msgbuf));
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MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8);
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return WRITE(BUFFER(msgbuf), 8, fp);
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}
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/*
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* at EOF or last block -- in either case, the last byte contains
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* the character representation of the number of bytes in it
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*/
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/*
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MEMZERO(msgbuf + n, 8 - n);
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*/
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/*
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* Pad the last block randomly
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*/
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(void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n);
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CHAR(msgbuf, 7) = n;
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for (n = 0; n < 8; n++)
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CHAR(msgbuf, n) ^= CHAR(ivec, n);
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DES_XFORM(UBUFFER(msgbuf));
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return WRITE(BUFFER(msgbuf), 8, fp);
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}
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/*
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* This decrypts using the Cipher Block Chaining mode of DES
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*/
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int
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cbc_decode(msgbuf, fp)
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char *msgbuf; /* I/O buffer */
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FILE *fp; /* input file descriptor */
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{
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Desbuf ibuf; /* temp buffer for initialization vector */
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register int n; /* number of bytes actually read */
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register int c; /* used to test for EOF */
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int inverse = 1; /* 0 to encrypt, 1 to decrypt */
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if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) {
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/*
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* do the transformation
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*/
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MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8);
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DES_XFORM(UBUFFER(msgbuf));
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for (c = 0; c < 8; c++)
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UCHAR(msgbuf, c) ^= UCHAR(ivec, c);
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MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8);
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/*
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* if the last one, handle it specially
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*/
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if ((c = fgetc(fp)) == EOF) {
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n = CHAR(msgbuf, 7);
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if (n < 0 || n > 7) {
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des_error("decryption failed (block corrupted)");
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return EOF;
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}
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} else
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(void)ungetc(c, fp);
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return n;
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}
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if (n > 0)
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des_error("decryption failed (incomplete block)");
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else if (n < 0)
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des_error("cannot read file");
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return EOF;
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}
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#endif /* DES */
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