NetBSD/bin/ed/cbc.c

437 lines
11 KiB
C

/* cbc.c: This file contains the encryption routines for the ed line editor */
/*-
* Copyright (c) 1991 The Regents of the University of California.
* All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Matt Bishop of Dartmouth College.
*
* The United States Government has rights in this work pursuant
* to contract no. NAG 2-680 between the National Aeronautics and
* Space Administration and Dartmouth College.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#ifndef lint
/*static char sccsid[] = "from: @(#)cbc.c 5.5 (Berkeley) 6/27/91";*/
static char rcsid[] = "$Id: cbc.c,v 1.5 1993/08/01 18:59:49 mycroft Exp $";
#endif /* not lint */
/* Author: Matt Bishop
* Department of Mathematics and Computer Science
* Dartmouth College
* Hanover, NH 03755
* Email: Matt.Bishop@dartmouth.edu
* ...!decvax!dartvax!Matt.Bishop
*
* See Technical Report PCS-TR91-158, Department of Mathematics and Computer
* Science, Dartmouth College, for a detailed description of the implemen-
* tation and differences between it and Sun's. The DES is described in
* FIPS PUB 46, and the modes in FIPS PUB 81 (see either the manual page
* or the technical report for a complete reference).
*/
#include <errno.h>
#include <pwd.h>
#include <unistd.h>
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include "ed.h"
/*
* Define a divisor for rand() that yields a uniform distribution in the
* range 0-255.
*/
#define RAND_DIV (((unsigned) RAND_MAX + 1) >> 8)
/*
* BSD and System V systems offer special library calls that do
* block moves and fills, so if possible we take advantage of them
*/
#define MEMCPY(dest,src,len) memcpy((dest),(src),(len))
#define MEMZERO(dest,len) memset((dest), 0, (len))
/* Hide the calls to the primitive encryption routines. */
#define DES_KEY(buf) \
if (des_setkey(buf)) \
err("des_setkey");
#define DES_XFORM(buf) \
if (des_cipher(buf, buf, 0L, (inverse ? -1 : 1))) \
err("des_cipher");
/*
* read/write - no error checking
*/
#define READ(buf, n, fp) fread(buf, sizeof(char), n, fp)
#define WRITE(buf, n, fp) fwrite(buf, sizeof(char), n, fp)
/*
* some things to make references easier
*/
typedef char Desbuf[8];
#define CHAR(x,i) (x[i])
#define UCHAR(x,i) (x[i])
#define BUFFER(x) (x)
#define UBUFFER(x) (x)
/*
* global variables and related macros
*/
enum { /* encrypt, decrypt, authenticate */
MODE_ENCRYPT, MODE_DECRYPT, MODE_AUTHENTICATE
} mode = MODE_ENCRYPT;
Desbuf ivec; /* initialization vector */
Desbuf pvec; /* padding vector */
char bits[] = { /* used to extract bits from a char */
'\200', '\100', '\040', '\020', '\010', '\004', '\002', '\001'
};
int pflag; /* 1 to preserve parity bits */
char des_buf[8]; /* shared buffer for desgetc/desputc */
int des_ct = 0; /* count for desgetc/desputc */
int des_n = 0; /* index for desputc/desgetc */
/* desinit: initialize DES */
void
desinit()
{
#ifdef DES
int i;
des_ct = des_n = 0;
/* initialize the initialization vctor */
MEMZERO(ivec, 8);
/* intialize the padding vector */
srand((unsigned) time((time_t *) 0));
for (i = 0; i < 8; i++)
CHAR(pvec, i) = (char) (rand()/RAND_DIV);
#endif
}
/* desgetc: return next char in an encrypted file */
desgetc(fp)
FILE *fp;
{
#ifdef DES
if (des_n >= des_ct) {
des_n = 0;
des_ct = cbcdec(des_buf, fp);
}
return (des_ct > 0) ? des_buf[des_n++] : EOF;
#endif
}
/* desputc: write a char to an encrypted file; return char written */
desputc(c, fp)
int c;
FILE *fp;
{
#ifdef DES
if (des_n == sizeof des_buf) {
des_ct = cbcenc(des_buf, des_n, fp);
des_n = 0;
}
return (des_ct >= 0) ? (des_buf[des_n++] = c) : EOF;
#endif
}
/* desflush: flush an encrypted file's output; return status */
desflush(fp)
FILE *fp;
{
#ifdef DES
if (des_n == sizeof des_buf) {
des_ct = cbcenc(des_buf, des_n, fp);
des_n = 0;
}
return (des_ct >= 0 && cbcenc(des_buf, des_n, fp) >= 0) ? 0 : EOF;
#endif
}
#ifdef DES
/*
* get keyword from tty or stdin
*/
getkey()
{
register char *p; /* used to obtain the key */
Desbuf msgbuf; /* I/O buffer */
/*
* get the key
*/
if (*(p = getpass("Enter key: "))) {
/*
* copy it, nul-padded, into the key area
*/
cvtkey(BUFFER(msgbuf), p);
MEMZERO(p, _PASSWORD_LEN);
makekey(msgbuf);
MEMZERO(msgbuf, sizeof msgbuf);
return 1;
}
return 0;
}
extern char errmsg[];
/*
* print a warning message and, possibly, terminate
*/
void
err(s)
char *s; /* the message */
{
(void)sprintf(errmsg, "%s", s ? s : strerror(errno));
}
/*
* map a hex character to an integer
*/
tobinhex(c, radix)
int c; /* char to be converted */
int radix; /* base (2 to 16) */
{
switch(c) {
case '0': return(0x0);
case '1': return(0x1);
case '2': return(radix > 2 ? 0x2 : -1);
case '3': return(radix > 3 ? 0x3 : -1);
case '4': return(radix > 4 ? 0x4 : -1);
case '5': return(radix > 5 ? 0x5 : -1);
case '6': return(radix > 6 ? 0x6 : -1);
case '7': return(radix > 7 ? 0x7 : -1);
case '8': return(radix > 8 ? 0x8 : -1);
case '9': return(radix > 9 ? 0x9 : -1);
case 'A': case 'a': return(radix > 10 ? 0xa : -1);
case 'B': case 'b': return(radix > 11 ? 0xb : -1);
case 'C': case 'c': return(radix > 12 ? 0xc : -1);
case 'D': case 'd': return(radix > 13 ? 0xd : -1);
case 'E': case 'e': return(radix > 14 ? 0xe : -1);
case 'F': case 'f': return(radix > 15 ? 0xf : -1);
}
/*
* invalid character
*/
return(-1);
}
/*
* convert the key to a bit pattern
*/
void
cvtkey(obuf, ibuf)
char *obuf; /* bit pattern */
char *ibuf; /* the key itself */
{
register int i, j; /* counter in a for loop */
int nbuf[64]; /* used for hex/key translation */
/*
* leading '0x' or '0X' == hex key
*/
if (ibuf[0] == '0' && (ibuf[1] == 'x' || ibuf[1] == 'X')) {
ibuf = &ibuf[2];
/*
* now translate it, bombing on any illegal hex digit
*/
for (i = 0; ibuf[i] && i < 16; i++)
if ((nbuf[i] = tobinhex((int) ibuf[i], 16)) == -1)
err("bad hex digit in key");
while (i < 16)
nbuf[i++] = 0;
for (i = 0; i < 8; i++)
obuf[i] =
((nbuf[2*i]&0xf)<<4) | (nbuf[2*i+1]&0xf);
/* preserve parity bits */
pflag = 1;
return;
}
/*
* leading '0b' or '0B' == binary key
*/
if (ibuf[0] == '0' && (ibuf[1] == 'b' || ibuf[1] == 'B')) {
ibuf = &ibuf[2];
/*
* now translate it, bombing on any illegal binary digit
*/
for (i = 0; ibuf[i] && i < 16; i++)
if ((nbuf[i] = tobinhex((int) ibuf[i], 2)) == -1)
err("bad binary digit in key");
while (i < 64)
nbuf[i++] = 0;
for (i = 0; i < 8; i++)
for (j = 0; j < 8; j++)
obuf[i] = (obuf[i]<<1)|nbuf[8*i+j];
/* preserve parity bits */
pflag = 1;
return;
}
/*
* no special leader -- ASCII
*/
(void)strncpy(obuf, ibuf, 8);
}
/*****************
* DES FUNCTIONS *
*****************/
/*
* This sets the DES key and (if you're using the deszip version)
* the direction of the transformation. This uses the Sun
* to map the 64-bit key onto the 56 bits that the key schedule
* generation routines use: the old way, which just uses the user-
* supplied 64 bits as is, and the new way, which resets the parity
* bit to be the same as the low-order bit in each character. The
* new way generates a greater variety of key schedules, since many
* systems set the parity (high) bit of each character to 0, and the
* DES ignores the low order bit of each character.
*/
void
makekey(buf)
Desbuf buf; /* key block */
{
register int i, j; /* counter in a for loop */
register int par; /* parity counter */
/*
* if the parity is not preserved, flip it
*/
if (!pflag) {
for (i = 0; i < 8; i++) {
par = 0;
for (j = 1; j < 8; j++)
if ((bits[j]&UCHAR(buf, i)) != 0)
par++;
if ((par&01) == 01)
UCHAR(buf, i) = UCHAR(buf, i)&0177;
else
UCHAR(buf, i) = (UCHAR(buf, i)&0177)|0200;
}
}
DES_KEY(UBUFFER(buf));
}
/*
* This encrypts using the Cipher Block Chaining mode of DES
*/
cbcenc(msgbuf, n, fp)
char *msgbuf;
int n;
FILE *fp;
{
int inverse = 0; /* 0 to encrypt, 1 to decrypt */
/*
* do the transformation
*/
if (n == 8) {
for (n = 0; n < 8; n++)
CHAR(msgbuf, n) ^= CHAR(ivec, n);
DES_XFORM(UBUFFER(msgbuf));
MEMCPY(BUFFER(ivec), BUFFER(msgbuf), 8);
return WRITE(BUFFER(msgbuf), 8, fp);
}
/*
* at EOF or last block -- in either case, the last byte contains
* the character representation of the number of bytes in it
*/
/*
MEMZERO(msgbuf + n, 8 - n);
*/
/*
* Pad the last block randomly
*/
(void)MEMCPY(BUFFER(msgbuf + n), BUFFER(pvec), 8 - n);
CHAR(msgbuf, 7) = n;
for (n = 0; n < 8; n++)
CHAR(msgbuf, n) ^= CHAR(ivec, n);
DES_XFORM(UBUFFER(msgbuf));
return WRITE(BUFFER(msgbuf), 8, fp);
}
/*
* This decrypts using the Cipher Block Chaining mode of DES
*/
cbcdec(msgbuf, fp)
char *msgbuf; /* I/O buffer */
FILE *fp; /* input file descriptor */
{
Desbuf ibuf; /* temp buffer for initialization vector */
register int n; /* number of bytes actually read */
register int c; /* used to test for EOF */
int inverse = 1; /* 0 to encrypt, 1 to decrypt */
if ((n = READ(BUFFER(msgbuf), 8, fp)) == 8) {
/*
* do the transformation
*/
MEMCPY(BUFFER(ibuf), BUFFER(msgbuf), 8);
DES_XFORM(UBUFFER(msgbuf));
for (c = 0; c < 8; c++)
UCHAR(msgbuf, c) ^= UCHAR(ivec, c);
MEMCPY(BUFFER(ivec), BUFFER(ibuf), 8);
/*
* if the last one, handle it specially
*/
if ((c = fgetc(fp)) == EOF) {
n = CHAR(msgbuf, 7);
if (n < 0 || n > 7) {
err("decryption failed (block corrupted)");
return EOF;
}
} else
(void)ungetc(c, fp);
return n;
}
if (n > 0)
err("decryption failed (incomplete block)");
else if (n < 0)
err("cannot read file");
return EOF;
}
#endif /* DES */