/*	$NetBSD: ntp_genkeys.c,v 1.1.1.1 2000/04/22 14:54:31 simonb Exp $	*/

/*
 * Program to generate MD5 and RSA keys for NTP clients and servers
 */
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <sys/time.h>
#include "ntpd.h"
#include "ntp_stdlib.h"
#include "ntp_string.h"
#include "ntp_crypto.h"

/*
 * Cryptodefines
 */
#define MAXKEYLEN	1024	/* maximum encoded key length */
#define MODULUSLEN	512	/* length of RSA modulus */
#define PRIMELEN	512	/* length of D_H prime, generator */
#define GENLEN		256	/* length of D-H key and subprime */

/*
 * This program generates four files: ntp.keys containing the DES/MD5
 * private keys, ntpkey containing the RSA private key, ntpkey_host
 * containing the RSA public key, where host is the DNS name of the
 * generating machine, and ntpkey_dh containing the parameters for the
 * Diffie-Hellman key-agreement algorithm. The files contain
 * cryptographic values generated by the algorithms of the rsaref20
 * package and are in printable ASCII format. Since the algorythms are
 * seeded by the system clock, each run of this program will produce a
 * different outcome. There are no options or frills of any sort,
 * although a number of options would seem to be appropriate. Waving
 * this program in the breeze will no doubt bring a cast of thousands to
 * wiggle the options this way and that for various useful purposes.
 *
 * The ntp.keys file contains 16 MD5 keys. Each key consists of 16
 * characters randomized over the ASCII 95-character printing subset.
 * The file is read by the daemon at the location specified by the keys
 * configuration file command and made visible only to root. An
 * additional key consisting of a easily remembered password should be
 * added by hand for use with the ntpdc program. The file must be
 * distributed by secure means to other servers and clients sharing the
 * same security compartment.
 *
 * The key identifiers for MD5 and DES keys must be less than 65536,
 * although this program uses only the identifiers from 1 to 16. The key
 * identifier for each association is specified as the key argument in
 * the server or peer configuration file command.
 *
 * The ntpkey file contains the RSA private key. It is read by the
 * daemon at the location specified by the private argument of the
 * crypto configuration file command and made visible only to root. This
 * file is useful only to the machine that generated it and never shared
 * with any other daemon or application program.
 *
 * The ntpkey_host file contains the RSA public key, where host is the
 * DNS name of the host that generated it. The file is read by the
 * daemon at the location specified by the public argument to the server
 * or peer configuration file command. This file can be widely
 * distributed and stored without using secure means, since the data are
 * public values.
 *
 * The ntp_dh file contains two Diffie-Hellman parameters, the prime
 * modulus and the generator. The file is read by the daemon at the
 * location specified by the dhparams argument of the crypto
 * configuration file command. This file can be widely distributed and
 * stored without using secure means, since the data are public values.
 *
 * The file formats all begin with two lines, the first containing the
 * generating system DNS name and the second the datestamp. Lines
 * beginning with # are considered comments and ignored by the daemon.
 * In the ntp.keys file, the next 16 lines contain the MD5 keys in
 * order. In the ntpkey and ntpkey_host files, the next line contains
 * the modulus length in bits followed by the key as a PEM encoded
 * string. In the ntpkey_dh file, the next line contains the prime
 * length in bytes followed by the prime as a PEM encoded string, and
 * the next and final line contains the generator length in bytes
 * followed by the generator as a PEM encoded string.
 *
 * Note: See the file ./source/rsaref.h in the rsaref20 package for
 * explanation of return values, if necessary. 
 */
int
main(
	int argc,
	char *argv[]
	)
{
	R_RSA_PRIVATE_KEY rsaref_private; /* RSA private key */
	R_RSA_PUBLIC_KEY rsaref_public;	/* RSA public key */
	R_RSA_PROTO_KEY protokey;	/* RSA prototype key */
	R_DH_PARAMS dh_params;		/* Diffie-Hellman parameters */
	R_RANDOM_STRUCT randomstr;	/* random structure */
	u_char encoded_key[MAXKEYLEN];	/* encoded PEM string buffer */
	u_int modulus;			/* modulus length */
	struct timeval tv;		/* initialization vector */
	u_char hostname[256];		/* DNS host name */
	u_char filename[256];		/* public key file name */
	u_char md5key[17];		/* generated MD5 key */ 
	FILE *str;			/* file handle */
	int rval;			/* return value */
	u_int temp, len;
	int i, j;

	/*
	 * Generate the file "ntp.keys" containing 16 random MD5 keys in
	 * the format expected at daemon run time.
	 */
	gethostname(&hostname, sizeof hostname);
	printf("Generating MD5 keys...\n");
	str = fopen("ntp.keys", "w");
	if (str == NULL) {
		perror("MD5/DES key file");
		return (-1);
	}
	gettimeofday(&tv, 0);
	srandom((u_int)tv.tv_sec);
	fprintf(str, "# MD5/DES key file generated by %s\n# %s",
	    hostname, ctime(&tv.tv_sec));
	for (i = 1; i <= 16; i++) {
		for (j = 0; j < 16; j++) {
			while (1) {
				temp = random() & 0xff;
				if (temp > 0x20 && temp < 0x7f)
					break;
			}
			md5key[j] = (u_char)temp;
		}
		md5key[16] = 0;
		fprintf(str, "%2d M %16s	# MD5 key\n", i,
		    md5key);
	}
	fclose(str);

	/*
	 * Roll a RSA public/private key pair.
	 */
	printf("Generating RSA public/private key pair %d bits...\n",
	    MODULUSLEN);
	protokey.bits = MODULUSLEN;
	protokey.useFermat4 = 1;
	R_RandomInit(&randomstr);
	R_GetRandomBytesNeeded(&len, &randomstr);
	for (i = 0; i < len; i++) {
		temp = random();
		R_RandomUpdate(&randomstr, (u_char *)&temp, 1);
	}
	rval = R_GeneratePEMKeys(&rsaref_public, &rsaref_private,
	    &protokey, &randomstr);
	if (rval) {
		printf("R_GeneratePEMKeys error %x\n", rval);
		return (-1);
	}

	/*
	 * Generate the file "ntpkey" containing the RSA private key in
	 * printable ASCII format.
	 */
	str = fopen("ntpkey", "w");
	if (str == NULL) { 
		perror("RSA private key file");
		return (-1);
	}
	len = sizeof(rsaref_private) - sizeof(rsaref_private.bits);
	modulus = (u_int32)rsaref_private.bits;
	fprintf(str, "# RSA private key file generated by %s\n# %s",
	    hostname, ctime(&tv.tv_sec));
	R_EncodePEMBlock(encoded_key, &temp,
	    (u_char *)&rsaref_private.modulus, len);
	encoded_key[temp] = '\0';
	fprintf(str, "%d %s\n", modulus, encoded_key);
	fclose(str);

	/*
	 * Generate the file "ntpkey_host" containing the RSA public key
	 * in printable ASCII format.
	 */
	snprintf(filename, sizeof filename, "ntpkey_%s", hostname); 
	str = fopen(filename, "w");
	if (str == NULL) { 
		perror("RSA public key file");
		return (-1);
	}
	len = sizeof(rsaref_public) - sizeof(rsaref_public.bits);
	modulus = (u_int32)rsaref_public.bits;
	fprintf(str, "# RSA public key file generated by %s\n# %s",
	    hostname, ctime(&tv.tv_sec));
	R_EncodePEMBlock(encoded_key, &temp,
	    (u_char *)&rsaref_public.modulus, len);
	encoded_key[temp] = '\0';
	fprintf(str, "%d %s\n", modulus, encoded_key);
	fclose(str);

	/*
	 * Roll the prime and generator for the Diffie-Hellman key
	 * agreement algorithm.
	 */
	printf("Generating Diffie-Hellman parameters %d bits...\n",
	    PRIMELEN);
	str = fopen("ntpkey_dh", "w");
	if (str == NULL) { 
		perror("Diffie-Hellman parameters file");
		return (-1);
	}
	R_RandomInit(&randomstr);
	R_GetRandomBytesNeeded(&len, &randomstr);
	for (i = 0; i < len; i++) {
		temp = random();
		R_RandomUpdate(&randomstr, (u_char *)&temp, 1);
	}

	/*
	 * Generate the file "ntpkey_dh" containing the Diffie-Hellman
	 * prime and generator in printable ASCII format.
	 */
	len = DH_PRIME_LEN(PRIMELEN);
	dh_params.prime = (u_char *)malloc(len);
	dh_params.generator = (u_char *)malloc(len);
	rval = R_GenerateDHParams(&dh_params, PRIMELEN, GENLEN,
	    &randomstr);
	if (rval) {
		printf("R_GenerateDHParams error %x\n", rval);
		return (-1);
	}
	fprintf(str,
	    "# Diffie-Hellman parameter file generated by %s\n# %s",
	    hostname, ctime(&tv.tv_sec));
	R_EncodePEMBlock(encoded_key, &temp,
	    (u_char *)dh_params.prime, dh_params.primeLen);
	encoded_key[temp] = '\0';
	fprintf(str, "%d %s\n", dh_params.primeLen, encoded_key);
	R_EncodePEMBlock(encoded_key, &temp,
	    (u_char *)dh_params.generator, dh_params.generatorLen);
	encoded_key[temp] = '\0';
	fprintf(str, "%d %s\n", dh_params.generatorLen, encoded_key);
	fclose(str);

	return (0);
}