freebsd-dev/usr.sbin/xntpd/authstuff/keyparity.c
1995-05-30 03:57:47 +00:00

280 lines
5.2 KiB
C

/*
* keyparity - add parity bits to key and/or change an ascii key to binary
*/
#include <stdio.h>
#include <sys/types.h>
#include <ctype.h>
#include "ntp_string.h"
#include "ntp_stdlib.h"
#define STREQ(a, b) (*(a) == *(b) && strcmp((a), (b)) == 0)
/*
* Types of ascii representations for keys. "Standard" means a 64 bit
* hex number in NBS format, i.e. with the low order bit of each byte
* a parity bit. "NTP" means a 64 bit key in NTP format, with the
* high order bit of each byte a parity bit. "Ascii" means a 1-to-8
* character string whose ascii representation is used as the key.
*/
#define KEY_TYPE_STD 1
#define KEY_TYPE_NTP 2
#define KEY_TYPE_ASCII 3
#define STD_PARITY_BITS 0x01010101
char *progname;
int debug;
int ntpflag = 0;
int stdflag = 0;
int asciiflag = 0;
int ntpoutflag = 0;
int gotoopt = 0;
static int parity P((u_long *));
static int decodekey P((int, char *, u_long *));
static void output P((u_long *, int));
/*
* main - parse arguments and handle options
*/
void
main(argc, argv)
int argc;
char *argv[];
{
int c;
int errflg = 0;
int keytype;
u_long key[2];
extern int ntp_optind;
extern char *ntp_optarg;
progname = argv[0];
while ((c = ntp_getopt(argc, argv, "adno:s")) != EOF)
switch (c) {
case 'a':
asciiflag = 1;
break;
case 'd':
++debug;
break;
case 'n':
ntpflag = 1;
break;
case 's':
stdflag = 1;
break;
case 'o':
if (*ntp_optarg == 'n') {
ntpoutflag = 1;
gotoopt = 1;
} else if (*ntp_optarg == 's') {
ntpoutflag = 0;
gotoopt = 1;
} else {
(void) fprintf(stderr,
"%s: output format must be `n' or `s'\n",
progname);
errflg++;
}
break;
default:
errflg++;
break;
}
if (errflg || ntp_optind == argc) {
(void) fprintf(stderr,
"usage: %s -n|-s [-a] [-o n|s] key [...]\n",
progname);
exit(2);
}
if (!ntpflag && !stdflag) {
(void) fprintf(stderr,
"%s: one of either the -n or -s flags must be specified\n",
progname);
exit(2);
}
if (ntpflag && stdflag) {
(void) fprintf(stderr,
"%s: only one of the -n and -s flags may be specified\n",
progname);
exit(2);
}
if (!gotoopt) {
if (ntpflag)
ntpoutflag = 1;
}
if (asciiflag)
keytype = KEY_TYPE_ASCII;
else if (ntpflag)
keytype = KEY_TYPE_NTP;
else
keytype = KEY_TYPE_STD;
for (; ntp_optind < argc; ntp_optind++) {
if (!decodekey(keytype, argv[ntp_optind], key)) {
(void) fprintf(stderr,
"%s: format of key %s invalid\n",
progname, argv[ntp_optind]);
exit(1);
}
(void) parity(key);
output(key, ntpoutflag);
}
exit(0);
}
/*
* parity - set parity on a key/check for odd parity
*/
static int
parity(key)
u_long *key;
{
u_long mask;
int parity_err;
int bitcount;
int half;
int byte;
int i;
/*
* Go through counting bits in each byte. Check to see if
* each parity bit was set correctly. If not, note the error
* and set it right.
*/
parity_err = 0;
for (half = 0; half < 2; half++) { /* two halves of key */
mask = 0x80000000;
for (byte = 0; byte < 4; byte++) { /* 4 bytes per half */
bitcount = 0;
for (i = 0; i < 7; i++) { /* 7 data bits / byte */
if (key[half] & mask)
bitcount++;
mask >>= 1;
}
/*
* If bitcount is even, parity must be set. If
* bitcount is odd, parity must be clear.
*/
if ((bitcount & 0x1) == 0) {
if (!(key[half] & mask)) {
parity_err++;
key[half] |= mask;
}
} else {
if (key[half] & mask) {
parity_err++;
key[half] &= ~mask;
}
}
mask >>= 1;
}
}
/*
* Return the result of the parity check.
*/
return (parity_err == 0);
}
static int
decodekey(keytype, str, key)
int keytype;
char *str;
u_long *key;
{
u_char keybytes[8];
char *cp;
char *xdigit;
int len;
int i;
static char *hex = "0123456789abcdef";
cp = str;
len = strlen(cp);
if (len == 0)
return 0;
switch(keytype) {
case KEY_TYPE_STD:
case KEY_TYPE_NTP:
if (len != 16) /* Lazy. Should define constant */
return 0;
/*
* Decode hex key.
*/
key[0] = 0;
key[1] = 0;
for (i = 0; i < 16; i++) {
if (!isascii(*cp))
return 0;
xdigit = strchr(hex, isupper(*cp) ? tolower(*cp) : *cp);
cp++;
if (xdigit == 0)
return 0;
key[i>>3] <<= 4;
key[i>>3] |= (u_long)(xdigit - hex) & 0xf;
}
/*
* If this is an NTP format key, put it into NBS format
*/
if (keytype == KEY_TYPE_NTP) {
for (i = 0; i < 2; i++)
key[i] = ((key[i] << 1) & ~STD_PARITY_BITS)
| ((key[i] >> 7) & STD_PARITY_BITS);
}
break;
case KEY_TYPE_ASCII:
/*
* Make up key from ascii representation
*/
memset(keybytes, 0, sizeof(keybytes));
for (i = 0; i < 8 && i < len; i++)
keybytes[i] = *cp++ << 1;
key[0] = keybytes[0] << 24 | keybytes[1] << 16
| keybytes[2] << 8 | keybytes[3];
key[1] = keybytes[4] << 24 | keybytes[5] << 16
| keybytes[6] << 8 | keybytes[7];
break;
default:
/* Oh, well */
return 0;
}
return 1;
}
/*
* output - print a hex key on the standard output
*/
static void
output(key, ntpformat)
u_long *key;
int ntpformat;
{
int i;
if (ntpformat) {
for (i = 0; i < 2; i++)
key[i] = ((key[i] & ~STD_PARITY_BITS) >> 1)
| ((key[i] & STD_PARITY_BITS) << 7);
}
(void) printf("%08x%08x\n", key[0], key[1]);
}