/*  * This file is part of the UCB release of Plan 9. It is subject to the license * terms in the LICENSE file found in the top-level directory of this * distribution and at http://akaros.cs.berkeley.edu/files/Plan9License. No * part of the UCB release of Plan 9, including this file, may be copied, * modified, propagated, or distributed except according to the terms contained * in the LICENSE file. */ #include <u.h>#include <libc.h>#include <bio.h>#include "authcmdlib.h" /* * compute the key verification checksum */voidchecksum(char key[], char csum[]) {	uchar buf[8]; 	memset(buf, 0, 8);	encrypt(key, buf, 8);	sprint(csum, "C %.2ux%.2ux%.2ux%.2ux", buf[0], buf[1], buf[2], buf[3]);} /* * compute the proper response.  We encrypt the ascii of * challenge number, with trailing binary zero fill. * This process was derived empirically. * this was copied from inet's guard. */char *netresp(char *key, long chal, char *answer){	uchar buf[8]; 	memset(buf, 0, 8);	snprint((char *)buf, sizeof buf, "%lud", chal);	if(encrypt(key, buf, 8) < 0)		error("can't encrypt response");	chal = (buf[0]<<24)+(buf[1]<<16)+(buf[2]<<8)+buf[3];	sprint(answer, "%.8lux", chal); 	return answer;} char *netdecimal(char *answer){	int i; 	for(i = 0; answer[i]; i++)		switch(answer[i]){		case 'a': case 'b': case 'c':			answer[i] = '2';			break;		case 'd': case 'e': case 'f':			answer[i] = '3';			break;		}	return answer;} intnetcheck(void *key, long chal, char *response){	char answer[32], *p;	int i; 	if(smartcheck(key, chal, response))		return 1; 	if(p = strchr(response, '\n'))		*p = '\0';	netresp(key, chal, answer); 	/*	 * check for hex response -- securenet mode 1 or 5	 */	for(i = 0; response[i]; i++)		if(response[i] >= 'A' && response[i] <= 'Z')			response[i] -= 'A' - 'a';	if(strcmp(answer, response) == 0)		return 1; 	/*	 * check for decimal response -- securenet mode 0 or 4	 */	return strcmp(netdecimal(answer), response) == 0;} intsmartcheck(void *key, long chal, char *response){	uchar buf[2*8];	int i, c, cslo, cshi; 	snprint((char*)buf, sizeof buf, "%lud        ", chal);	cslo = 0x52;	cshi = cslo;	for(i = 0; i < 8; i++){		c = buf[i];		if(c >= '0' && c <= '9')			c -= '0';		cslo += c;		if(cslo > 0xff)			cslo -= 0xff;		cshi += cslo;		if(cshi > 0xff)			cshi -= 0xff;		buf[i] = c | (cshi & 0xf0);	} 	encrypt(key, buf, 8);	for(i = 0; i < 8; i++)		if(response[i] != buf[i] % 10 + '0')			return 0;	return 1;}