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change DSA default back to 1024, as it's defined for 1024 bits only
and this causes interop problems with other clients.  moreover,
in order to improve the security of DSA you need to change more
components of DSA key generation (e.g. the internal SHA1 hash);
ok deraadt

/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1994 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * Identity and host key generation and maintenance.
 *
 * As far as I am concerned, the code I have written for this software
 * can be used freely for any purpose.  Any derived versions of this
 * software must be clearly marked as such, and if the derived work is
 * incompatible with the protocol description in the RFC file, it must be
 * called by a name other than "ssh" or "Secure Shell".
 */

#include "includes.h"
RCSID("$OpenBSD: ssh-keygen.c,v 1.130 2005/10/07 11:13:57 markus Exp $");

#include <openssl/evp.h>
#include <openssl/pem.h>

#include "xmalloc.h"
#include "key.h"
#include "rsa.h"
#include "authfile.h"
#include "uuencode.h"
#include "buffer.h"
#include "bufaux.h"
#include "pathnames.h"
#include "log.h"
#include "misc.h"
#include "match.h"
#include "hostfile.h"

#ifdef SMARTCARD
#include "scard.h"
#endif
#include "dns.h"

/* Number of bits in the RSA/DSA key.  This value can be set on the command line. */
#define DEFAULT_BITS		2048
#define DEFAULT_BITS_DSA	1024
u_int32_t bits = 0;

/*
 * Flag indicating that we just want to change the passphrase.  This can be
 * set on the command line.
 */
int change_passphrase = 0;

/*
 * Flag indicating that we just want to change the comment.  This can be set
 * on the command line.
 */
int change_comment = 0;

int quiet = 0;

/* Flag indicating that we want to hash a known_hosts file */
int hash_hosts = 0;
/* Flag indicating that we want lookup a host in known_hosts file */
int find_host = 0;
/* Flag indicating that we want to delete a host from a known_hosts file */
int delete_host = 0;

/* Flag indicating that we just want to see the key fingerprint */
int print_fingerprint = 0;
int print_bubblebabble = 0;

/* The identity file name, given on the command line or entered by the user. */
char identity_file[1024];
int have_identity = 0;

/* This is set to the passphrase if given on the command line. */
char *identity_passphrase = NULL;

/* This is set to the new passphrase if given on the command line. */
char *identity_new_passphrase = NULL;

/* This is set to the new comment if given on the command line. */
char *identity_comment = NULL;

/* Dump public key file in format used by real and the original SSH 2 */
int convert_to_ssh2 = 0;
int convert_from_ssh2 = 0;
int print_public = 0;
int print_generic = 0;

char *key_type_name = NULL;

/* argv0 */
extern char *__progname;

char hostname[MAXHOSTNAMELEN];

/* moduli.c */
int gen_candidates(FILE *, u_int32_t, u_int32_t, BIGNUM *);
int prime_test(FILE *, FILE *, u_int32_t, u_int32_t);

static void
ask_filename(struct passwd *pw, const char *prompt)
{
	char buf[1024];
	char *name = NULL;

	if (key_type_name == NULL)
		name = _PATH_SSH_CLIENT_ID_RSA;
	else
		switch (key_type_from_name(key_type_name)) {
		case KEY_RSA1:
			name = _PATH_SSH_CLIENT_IDENTITY;
			break;
		case KEY_DSA:
			name = _PATH_SSH_CLIENT_ID_DSA;
			break;
		case KEY_RSA:
			name = _PATH_SSH_CLIENT_ID_RSA;
			break;
		default:
			fprintf(stderr, "bad key type");
			exit(1);
			break;
		}

	snprintf(identity_file, sizeof(identity_file), "%s/%s", pw->pw_dir, name);
	fprintf(stderr, "%s (%s): ", prompt, identity_file);
	if (fgets(buf, sizeof(buf), stdin) == NULL)
		exit(1);
	if (strchr(buf, '\n'))
		*strchr(buf, '\n') = 0;
	if (strcmp(buf, "") != 0)
		strlcpy(identity_file, buf, sizeof(identity_file));
	have_identity = 1;
}

static Key *
load_identity(char *filename)
{
	char *pass;
	Key *prv;

	prv = key_load_private(filename, "", NULL);
	if (prv == NULL) {
		if (identity_passphrase)
			pass = xstrdup(identity_passphrase);
		else
			pass = read_passphrase("Enter passphrase: ",
			    RP_ALLOW_STDIN);
		prv = key_load_private(filename, pass, NULL);
		memset(pass, 0, strlen(pass));
		xfree(pass);
	}
	return prv;
}

#define SSH_COM_PUBLIC_BEGIN		"---- BEGIN SSH2 PUBLIC KEY ----"
#define SSH_COM_PUBLIC_END		"---- END SSH2 PUBLIC KEY ----"
#define SSH_COM_PRIVATE_BEGIN		"---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----"
#define	SSH_COM_PRIVATE_KEY_MAGIC	0x3f6ff9eb

static void
do_convert_to_ssh2(struct passwd *pw)
{
	Key *k;
	u_int len;
	u_char *blob;
	struct stat st;

	if (!have_identity)
		ask_filename(pw, "Enter file in which the key is");
	if (stat(identity_file, &st) < 0) {
		perror(identity_file);
		exit(1);
	}
	if ((k = key_load_public(identity_file, NULL)) == NULL) {
		if ((k = load_identity(identity_file)) == NULL) {
			fprintf(stderr, "load failed\n");
			exit(1);
		}
	}
	if (k->type == KEY_RSA1) {
		fprintf(stderr, "version 1 keys are not supported\n");
		exit(1);
	}
	if (key_to_blob(k, &blob, &len) <= 0) {
		fprintf(stderr, "key_to_blob failed\n");
		exit(1);
	}
	fprintf(stdout, "%s\n", SSH_COM_PUBLIC_BEGIN);
	fprintf(stdout,
	    "Comment: \"%u-bit %s, converted from OpenSSH by %s@%s\"\n",
	    key_size(k), key_type(k),
	    pw->pw_name, hostname);
	dump_base64(stdout, blob, len);
	fprintf(stdout, "%s\n", SSH_COM_PUBLIC_END);
	key_free(k);
	xfree(blob);
	exit(0);
}

static void
buffer_get_bignum_bits(Buffer *b, BIGNUM *value)
{
	u_int bignum_bits = buffer_get_int(b);
	u_int bytes = (bignum_bits + 7) / 8;

	if (buffer_len(b) < bytes)
		fatal("buffer_get_bignum_bits: input buffer too small: "
		    "need %d have %d", bytes, buffer_len(b));
	BN_bin2bn(buffer_ptr(b), bytes, value);
	buffer_consume(b, bytes);
}

static Key *
do_convert_private_ssh2_from_blob(u_char *blob, u_int blen)
{
	Buffer b;
	Key *key = NULL;
	char *type, *cipher;
	u_char *sig, data[] = "abcde12345";
	int magic, rlen, ktype, i1, i2, i3, i4;
	u_int slen;
	u_long e;

	buffer_init(&b);
	buffer_append(&b, blob, blen);

	magic  = buffer_get_int(&b);
	if (magic != SSH_COM_PRIVATE_KEY_MAGIC) {
		error("bad magic 0x%x != 0x%x", magic, SSH_COM_PRIVATE_KEY_MAGIC);
		buffer_free(&b);
		return NULL;
	}
	i1 = buffer_get_int(&b);
	type   = buffer_get_string(&b, NULL);
	cipher = buffer_get_string(&b, NULL);
	i2 = buffer_get_int(&b);
	i3 = buffer_get_int(&b);
	i4 = buffer_get_int(&b);
	debug("ignore (%d %d %d %d)", i1,i2,i3,i4);
	if (strcmp(cipher, "none") != 0) {
		error("unsupported cipher %s", cipher);
		xfree(cipher);
		buffer_free(&b);
		xfree(type);
		return NULL;
	}
	xfree(cipher);

	if (strstr(type, "dsa")) {
		ktype = KEY_DSA;
	} else if (strstr(type, "rsa")) {
		ktype = KEY_RSA;
	} else {
		buffer_free(&b);
		xfree(type);
		return NULL;
	}
	key = key_new_private(ktype);
	xfree(type);

	switch (key->type) {
	case KEY_DSA:
		buffer_get_bignum_bits(&b, key->dsa->p);
		buffer_get_bignum_bits(&b, key->dsa->g);
		buffer_get_bignum_bits(&b, key->dsa->q);
		buffer_get_bignum_bits(&b, key->dsa->pub_key);
		buffer_get_bignum_bits(&b, key->dsa->priv_key);
		break;
	case KEY_RSA:
		e  = buffer_get_char(&b);
		debug("e %lx", e);
		if (e < 30) {
			e <<= 8;
			e += buffer_get_char(&b);
			debug("e %lx", e);
			e <<= 8;
			e += buffer_get_char(&b);
			debug("e %lx", e);
		}
		if (!BN_set_word(key->rsa->e, e)) {
			buffer_free(&b);
			key_free(key);
			return NULL;
		}
		buffer_get_bignum_bits(&b, key->rsa->d);
		buffer_get_bignum_bits(&b, key->rsa->n);
		buffer_get_bignum_bits(&b, key->rsa->iqmp);
		buffer_get_bignum_bits(&b, key->rsa->q);
		buffer_get_bignum_bits(&b, key->rsa->p);
		rsa_generate_additional_parameters(key->rsa);
		break;
	}
	rlen = buffer_len(&b);
	if (rlen != 0)
		error("do_convert_private_ssh2_from_blob: "
		    "remaining bytes in key blob %d", rlen);
	buffer_free(&b);

	/* try the key */
	key_sign(key, &sig, &slen, data, sizeof(data));
	key_verify(key, sig, slen, data, sizeof(data));
	xfree(sig);
	return key;
}

static void
do_convert_from_ssh2(struct passwd *pw)
{
	Key *k;
	int blen;
	u_int len;
	char line[1024], *p;
	u_char blob[8096];
	char encoded[8096];
	struct stat st;
	int escaped = 0, private = 0, ok;
	FILE *fp;

	if (!have_identity)
		ask_filename(pw, "Enter file in which the key is");
	if (stat(identity_file, &st) < 0) {
		perror(identity_file);
		exit(1);
	}
	fp = fopen(identity_file, "r");
	if (fp == NULL) {
		perror(identity_file);
		exit(1);
	}
	encoded[0] = '\0';
	while (fgets(line, sizeof(line), fp)) {
		if (!(p = strchr(line, '\n'))) {
			fprintf(stderr, "input line too long.\n");
			exit(1);
		}
		if (p > line && p[-1] == '\\')
			escaped++;
		if (strncmp(line, "----", 4) == 0 ||
		    strstr(line, ": ") != NULL) {
			if (strstr(line, SSH_COM_PRIVATE_BEGIN) != NULL)
				private = 1;
			if (strstr(line, " END ") != NULL) {
				break;
			}
			/* fprintf(stderr, "ignore: %s", line); */
			continue;
		}
		if (escaped) {
			escaped--;
			/* fprintf(stderr, "escaped: %s", line); */
			continue;
		}
		*p = '\0';
		strlcat(encoded, line, sizeof(encoded));
	}
	len = strlen(encoded);
	if (((len % 4) == 3) &&
	    (encoded[len-1] == '=') &&
	    (encoded[len-2] == '=') &&
	    (encoded[len-3] == '='))
		encoded[len-3] = '\0';
	blen = uudecode(encoded, blob, sizeof(blob));
	if (blen < 0) {
		fprintf(stderr, "uudecode failed.\n");
		exit(1);
	}
	k = private ?
	    do_convert_private_ssh2_from_blob(blob, blen) :
	    key_from_blob(blob, blen);
	if (k == NULL) {
		fprintf(stderr, "decode blob failed.\n");
		exit(1);
	}
	ok = private ?
	    (k->type == KEY_DSA ?
		 PEM_write_DSAPrivateKey(stdout, k->dsa, NULL, NULL, 0, NULL, NULL) :
		 PEM_write_RSAPrivateKey(stdout, k->rsa, NULL, NULL, 0, NULL, NULL)) :
	    key_write(k, stdout);
	if (!ok) {
		fprintf(stderr, "key write failed");
		exit(1);
	}
	key_free(k);
	if (!private)
		fprintf(stdout, "\n");
	fclose(fp);
	exit(0);
}

static void
do_print_public(struct passwd *pw)
{
	Key *prv;
	struct stat st;

	if (!have_identity)
		ask_filename(pw, "Enter file in which the key is");
	if (stat(identity_file, &st) < 0) {
		perror(identity_file);
		exit(1);
	}
	prv = load_identity(identity_file);
	if (prv == NULL) {
		fprintf(stderr, "load failed\n");
		exit(1);
	}
	if (!key_write(prv, stdout))
		fprintf(stderr, "key_write failed");
	key_free(prv);
	fprintf(stdout, "\n");
	exit(0);
}

#ifdef SMARTCARD
static void
do_upload(struct passwd *pw, const char *sc_reader_id)
{
	Key *prv = NULL;
	struct stat st;
	int ret;

	if (!have_identity)
		ask_filename(pw, "Enter file in which the key is");
	if (stat(identity_file, &st) < 0) {
		perror(identity_file);
		exit(1);
	}
	prv = load_identity(identity_file);
	if (prv == NULL) {
		error("load failed");
		exit(1);
	}
	ret = sc_put_key(prv, sc_reader_id);
	key_free(prv);
	if (ret < 0)
		exit(1);
	logit("loading key done");
	exit(0);
}

static void
do_download(struct passwd *pw, const char *sc_reader_id)
{
	Key **keys = NULL;
	int i;

	keys = sc_get_keys(sc_reader_id, NULL);
	if (keys == NULL)
		fatal("cannot read public key from smartcard");
	for (i = 0; keys[i]; i++) {
		key_write(keys[i], stdout);
		key_free(keys[i]);
		fprintf(stdout, "\n");
	}
	xfree(keys);
	exit(0);
}
#endif /* SMARTCARD */

static void
do_fingerprint(struct passwd *pw)
{
	FILE *f;
	Key *public;
	char *comment = NULL, *cp, *ep, line[16*1024], *fp;
	int i, skip = 0, num = 1, invalid = 1;
	enum fp_rep rep;
	enum fp_type fptype;
	struct stat st;

	fptype = print_bubblebabble ? SSH_FP_SHA1 : SSH_FP_MD5;
	rep =    print_bubblebabble ? SSH_FP_BUBBLEBABBLE : SSH_FP_HEX;

	if (!have_identity)
		ask_filename(pw, "Enter file in which the key is");
	if (stat(identity_file, &st) < 0) {
		perror(identity_file);
		exit(1);
	}
	public = key_load_public(identity_file, &comment);
	if (public != NULL) {
		fp = key_fingerprint(public, fptype, rep);
		printf("%u %s %s\n", key_size(public), fp, comment);
		key_free(public);
		xfree(comment);
		xfree(fp);
		exit(0);
	}
	if (comment)
		xfree(comment);

	f = fopen(identity_file, "r");
	if (f != NULL) {
		while (fgets(line, sizeof(line), f)) {
			i = strlen(line) - 1;
			if (line[i] != '\n') {
				error("line %d too long: %.40s...", num, line);
				skip = 1;
				continue;
			}
			num++;
			if (skip) {
				skip = 0;
				continue;
			}
			line[i] = '\0';

			/* Skip leading whitespace, empty and comment lines. */
			for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
				;
			if (!*cp || *cp == '\n' || *cp == '#')
				continue ;
			i = strtol(cp, &ep, 10);
			if (i == 0 || ep == NULL || (*ep != ' ' && *ep != '\t')) {
				int quoted = 0;
				comment = cp;
				for (; *cp && (quoted || (*cp != ' ' &&
				    *cp != '\t')); cp++) {
					if (*cp == '\\' && cp[1] == '"')
						cp++;	/* Skip both */
					else if (*cp == '"')
						quoted = !quoted;
				}
				if (!*cp)
					continue;
				*cp++ = '\0';
			}
			ep = cp;
			public = key_new(KEY_RSA1);
			if (key_read(public, &cp) != 1) {
				cp = ep;
				key_free(public);
				public = key_new(KEY_UNSPEC);
				if (key_read(public, &cp) != 1) {
					key_free(public);
					continue;
				}
			}
			comment = *cp ? cp : comment;
			fp = key_fingerprint(public, fptype, rep);
			printf("%u %s %s\n", key_size(public), fp,
			    comment ? comment : "no comment");
			xfree(fp);
			key_free(public);
			invalid = 0;
		}
		fclose(f);
	}
	if (invalid) {
		printf("%s is not a public key file.\n", identity_file);
		exit(1);
	}
	exit(0);
}

static void
print_host(FILE *f, char *name, Key *public, int hash)
{
	if (hash && (name = host_hash(name, NULL, 0)) == NULL)
		fatal("hash_host failed");
	fprintf(f, "%s ", name);
	if (!key_write(public, f))
		fatal("key_write failed");
	fprintf(f, "\n");
}

static void
do_known_hosts(struct passwd *pw, const char *name)
{
	FILE *in, *out = stdout;
	Key *public;
	char *cp, *cp2, *kp, *kp2;
	char line[16*1024], tmp[MAXPATHLEN], old[MAXPATHLEN];
	int c, i, skip = 0, inplace = 0, num = 0, invalid = 0, has_unhashed = 0;

	if (!have_identity) {
		cp = tilde_expand_filename(_PATH_SSH_USER_HOSTFILE, pw->pw_uid);
		if (strlcpy(identity_file, cp, sizeof(identity_file)) >=
		    sizeof(identity_file))
			fatal("Specified known hosts path too long");
		xfree(cp);
		have_identity = 1;
	}
	if ((in = fopen(identity_file, "r")) == NULL)
		fatal("fopen: %s", strerror(errno));

	/*
	 * Find hosts goes to stdout, hash and deletions happen in-place
	 * A corner case is ssh-keygen -HF foo, which should go to stdout
	 */
	if (!find_host && (hash_hosts || delete_host)) {
		if (strlcpy(tmp, identity_file, sizeof(tmp)) >= sizeof(tmp) ||
		    strlcat(tmp, ".XXXXXXXXXX", sizeof(tmp)) >= sizeof(tmp) ||
		    strlcpy(old, identity_file, sizeof(old)) >= sizeof(old) ||
		    strlcat(old, ".old", sizeof(old)) >= sizeof(old))
			fatal("known_hosts path too long");
		umask(077);
		if ((c = mkstemp(tmp)) == -1)
			fatal("mkstemp: %s", strerror(errno));
		if ((out = fdopen(c, "w")) == NULL) {
			c = errno;
			unlink(tmp);
			fatal("fdopen: %s", strerror(c));
		}
		inplace = 1;
	}

	while (fgets(line, sizeof(line), in)) {
		num++;
		i = strlen(line) - 1;
		if (line[i] != '\n') {
			error("line %d too long: %.40s...", num, line);
			skip = 1;
			invalid = 1;
			continue;
		}
		if (skip) {
			skip = 0;
			continue;
		}
		line[i] = '\0';

		/* Skip leading whitespace, empty and comment lines. */
		for (cp = line; *cp == ' ' || *cp == '\t'; cp++)
			;
		if (!*cp || *cp == '\n' || *cp == '#') {
			if (inplace)
				fprintf(out, "%s\n", cp);
			continue;
		}
		/* Find the end of the host name portion. */
		for (kp = cp; *kp && *kp != ' ' && *kp != '\t'; kp++)
			;
		if (*kp == '\0' || *(kp + 1) == '\0') {
			error("line %d missing key: %.40s...",
			    num, line);
			invalid = 1;
			continue;
		}
		*kp++ = '\0';
		kp2 = kp;

		public = key_new(KEY_RSA1);
		if (key_read(public, &kp) != 1) {
			kp = kp2;
			key_free(public);
			public = key_new(KEY_UNSPEC);
			if (key_read(public, &kp) != 1) {
				error("line %d invalid key: %.40s...",
				    num, line);
				key_free(public);
				invalid = 1;
				continue;
			}
		}

		if (*cp == HASH_DELIM) {
			if (find_host || delete_host) {
				cp2 = host_hash(name, cp, strlen(cp));
				if (cp2 == NULL) {
					error("line %d: invalid hashed "
					    "name: %.64s...", num, line);
					invalid = 1;
					continue;
				}
				c = (strcmp(cp2, cp) == 0);
				if (find_host && c) {
					printf("# Host %s found: "
					    "line %d type %s\n", name,
					    num, key_type(public));
					print_host(out, cp, public, 0);
				}
				if (delete_host && !c)
					print_host(out, cp, public, 0);
			} else if (hash_hosts)
				print_host(out, cp, public, 0);
		} else {
			if (find_host || delete_host) {
				c = (match_hostname(name, cp,
				    strlen(cp)) == 1);
				if (find_host && c) {
					printf("# Host %s found: "
					    "line %d type %s\n", name,
					    num, key_type(public));
					print_host(out, cp, public, hash_hosts);
				}
				if (delete_host && !c)
					print_host(out, cp, public, 0);
			} else if (hash_hosts) {
				for (cp2 = strsep(&cp, ",");
				    cp2 != NULL && *cp2 != '\0';
				    cp2 = strsep(&cp, ",")) {
					if (strcspn(cp2, "*?!") != strlen(cp2))
						fprintf(stderr, "Warning: "
						    "ignoring host name with "
						    "metacharacters: %.64s\n",
						    cp2);
					else
						print_host(out, cp2, public, 1);
				}
				has_unhashed = 1;
			}
		}
		key_free(public);
	}
	fclose(in);

	if (invalid) {
		fprintf(stderr, "%s is not a valid known_host file.\n",
		    identity_file);
		if (inplace) {
			fprintf(stderr, "Not replacing existing known_hosts "
			    "file because of errors\n");
			fclose(out);
			unlink(tmp);
		}
		exit(1);
	}

	if (inplace) {
		fclose(out);

		/* Backup existing file */
		if (unlink(old) == -1 && errno != ENOENT)
			fatal("unlink %.100s: %s", old, strerror(errno));
		if (link(identity_file, old) == -1)
			fatal("link %.100s to %.100s: %s", identity_file, old,
			    strerror(errno));
		/* Move new one into place */
		if (rename(tmp, identity_file) == -1) {
			error("rename\"%s\" to \"%s\": %s", tmp, identity_file,
			    strerror(errno));
			unlink(tmp);
			unlink(old);
			exit(1);
		}

		fprintf(stderr, "%s updated.\n", identity_file);
		fprintf(stderr, "Original contents retained as %s\n", old);
		if (has_unhashed) {
			fprintf(stderr, "WARNING: %s contains unhashed "
			    "entries\n", old);
			fprintf(stderr, "Delete this file to ensure privacy "
			    "of hostnames\n");
		}
	}

	exit(0);
}

/*
 * Perform changing a passphrase.  The argument is the passwd structure
 * for the current user.
 */
static void
do_change_passphrase(struct passwd *pw)
{
	char *comment;
	char *old_passphrase, *passphrase1, *passphrase2;
	struct stat st;
	Key *private;

	if (!have_identity)
		ask_filename(pw, "Enter file in which the key is");
	if (stat(identity_file, &st) < 0) {
		perror(identity_file);
		exit(1);
	}
	/* Try to load the file with empty passphrase. */
	private = key_load_private(identity_file, "", &comment);
	if (private == NULL) {
		if (identity_passphrase)
			old_passphrase = xstrdup(identity_passphrase);
		else
			old_passphrase =
			    read_passphrase("Enter old passphrase: ",
			    RP_ALLOW_STDIN);
		private = key_load_private(identity_file, old_passphrase,
		    &comment);
		memset(old_passphrase, 0, strlen(old_passphrase));
		xfree(old_passphrase);
		if (private == NULL) {
			printf("Bad passphrase.\n");
			exit(1);
		}
	}
	printf("Key has comment '%s'\n", comment);

	/* Ask the new passphrase (twice). */
	if (identity_new_passphrase) {
		passphrase1 = xstrdup(identity_new_passphrase);
		passphrase2 = NULL;
	} else {
		passphrase1 =
			read_passphrase("Enter new passphrase (empty for no "
			    "passphrase): ", RP_ALLOW_STDIN);
		passphrase2 = read_passphrase("Enter same passphrase again: ",
		    RP_ALLOW_STDIN);

		/* Verify that they are the same. */
		if (strcmp(passphrase1, passphrase2) != 0) {
			memset(passphrase1, 0, strlen(passphrase1));
			memset(passphrase2, 0, strlen(passphrase2));
			xfree(passphrase1);
			xfree(passphrase2);
			printf("Pass phrases do not match.  Try again.\n");
			exit(1);
		}
		/* Destroy the other copy. */
		memset(passphrase2, 0, strlen(passphrase2));
		xfree(passphrase2);
	}

	/* Save the file using the new passphrase. */
	if (!key_save_private(private, identity_file, passphrase1, comment)) {
		printf("Saving the key failed: %s.\n", identity_file);
		memset(passphrase1, 0, strlen(passphrase1));
		xfree(passphrase1);
		key_free(private);
		xfree(comment);
		exit(1);
	}
	/* Destroy the passphrase and the copy of the key in memory. */
	memset(passphrase1, 0, strlen(passphrase1));
	xfree(passphrase1);
	key_free(private);		 /* Destroys contents */
	xfree(comment);

	printf("Your identification has been saved with the new passphrase.\n");
	exit(0);
}

/*
 * Print the SSHFP RR.
 */
static void
do_print_resource_record(struct passwd *pw, char *hname)
{
	Key *public;
	char *comment = NULL;
	struct stat st;

	if (!have_identity)
		ask_filename(pw, "Enter file in which the key is");
	if (stat(identity_file, &st) < 0) {
		perror(identity_file);
		exit(1);
	}
	public = key_load_public(identity_file, &comment);
	if (public != NULL) {
		export_dns_rr(hname, public, stdout, print_generic);
		key_free(public);
		xfree(comment);
		exit(0);
	}
	if (comment)
		xfree(comment);

	printf("failed to read v2 public key from %s.\n", identity_file);
	exit(1);
}

/*
 * Change the comment of a private key file.
 */
static void
do_change_comment(struct passwd *pw)
{
	char new_comment[1024], *comment, *passphrase;
	Key *private;
	Key *public;
	struct stat st;
	FILE *f;
	int fd;

	if (!have_identity)
		ask_filename(pw, "Enter file in which the key is");
	if (stat(identity_file, &st) < 0) {
		perror(identity_file);
		exit(1);
	}
	private = key_load_private(identity_file, "", &comment);
	if (private == NULL) {
		if (identity_passphrase)
			passphrase = xstrdup(identity_passphrase);
		else if (identity_new_passphrase)
			passphrase = xstrdup(identity_new_passphrase);
		else
			passphrase = read_passphrase("Enter passphrase: ",
			    RP_ALLOW_STDIN);
		/* Try to load using the passphrase. */
		private = key_load_private(identity_file, passphrase, &comment);
		if (private == NULL) {
			memset(passphrase, 0, strlen(passphrase));
			xfree(passphrase);
			printf("Bad passphrase.\n");
			exit(1);
		}
	} else {
		passphrase = xstrdup("");
	}
	if (private->type != KEY_RSA1) {
		fprintf(stderr, "Comments are only supported for RSA1 keys.\n");
		key_free(private);
		exit(1);
	}
	printf("Key now has comment '%s'\n", comment);

	if (identity_comment) {
		strlcpy(new_comment, identity_comment, sizeof(new_comment));
	} else {
		printf("Enter new comment: ");
		fflush(stdout);
		if (!fgets(new_comment, sizeof(new_comment), stdin)) {
			memset(passphrase, 0, strlen(passphrase));
			key_free(private);
			exit(1);
		}
		if (strchr(new_comment, '\n'))
			*strchr(new_comment, '\n') = 0;
	}

	/* Save the file using the new passphrase. */
	if (!key_save_private(private, identity_file, passphrase, new_comment)) {
		printf("Saving the key failed: %s.\n", identity_file);
		memset(passphrase, 0, strlen(passphrase));
		xfree(passphrase);
		key_free(private);
		xfree(comment);
		exit(1);
	}
	memset(passphrase, 0, strlen(passphrase));
	xfree(passphrase);
	public = key_from_private(private);
	key_free(private);

	strlcat(identity_file, ".pub", sizeof(identity_file));
	fd = open(identity_file, O_WRONLY | O_CREAT | O_TRUNC, 0644);
	if (fd == -1) {
		printf("Could not save your public key in %s\n", identity_file);
		exit(1);
	}
	f = fdopen(fd, "w");
	if (f == NULL) {
		printf("fdopen %s failed", identity_file);
		exit(1);
	}
	if (!key_write(public, f))
		fprintf(stderr, "write key failed");
	key_free(public);
	fprintf(f, " %s\n", new_comment);
	fclose(f);

	xfree(comment);

	printf("The comment in your key file has been changed.\n");
	exit(0);
}

static void
usage(void)
{
	fprintf(stderr, "Usage: %s [options]\n", __progname);
	fprintf(stderr, "Options:\n");
	fprintf(stderr, "  -a trials   Number of trials for screening DH-GEX moduli.\n");
	fprintf(stderr, "  -B          Show bubblebabble digest of key file.\n");
	fprintf(stderr, "  -b bits     Number of bits in the key to create.\n");
	fprintf(stderr, "  -C comment  Provide new comment.\n");
	fprintf(stderr, "  -c          Change comment in private and public key files.\n");
#ifdef SMARTCARD
	fprintf(stderr, "  -D reader   Download public key from smartcard.\n");
#endif /* SMARTCARD */
	fprintf(stderr, "  -e          Convert OpenSSH to IETF SECSH key file.\n");
	fprintf(stderr, "  -F hostname Find hostname in known hosts file.\n");
	fprintf(stderr, "  -f filename Filename of the key file.\n");
	fprintf(stderr, "  -G file     Generate candidates for DH-GEX moduli.\n");
	fprintf(stderr, "  -g          Use generic DNS resource record format.\n");
	fprintf(stderr, "  -H          Hash names in known_hosts file.\n");
	fprintf(stderr, "  -i          Convert IETF SECSH to OpenSSH key file.\n");
	fprintf(stderr, "  -l          Show fingerprint of key file.\n");
	fprintf(stderr, "  -M memory   Amount of memory (MB) to use for generating DH-GEX moduli.\n");
	fprintf(stderr, "  -N phrase   Provide new passphrase.\n");
	fprintf(stderr, "  -P phrase   Provide old passphrase.\n");
	fprintf(stderr, "  -p          Change passphrase of private key file.\n");
	fprintf(stderr, "  -q          Quiet.\n");
	fprintf(stderr, "  -R hostname Remove host from known_hosts file.\n");
	fprintf(stderr, "  -r hostname Print DNS resource record.\n");
	fprintf(stderr, "  -S start    Start point (hex) for generating DH-GEX moduli.\n");
	fprintf(stderr, "  -T file     Screen candidates for DH-GEX moduli.\n");
	fprintf(stderr, "  -t type     Specify type of key to create.\n");
#ifdef SMARTCARD
	fprintf(stderr, "  -U reader   Upload private key to smartcard.\n");
#endif /* SMARTCARD */
	fprintf(stderr, "  -v          Verbose.\n");
	fprintf(stderr, "  -W gen      Generator to use for generating DH-GEX moduli.\n");
	fprintf(stderr, "  -y          Read private key file and print public key.\n");

	exit(1);
}

/*
 * Main program for key management.
 */
int
main(int ac, char **av)
{
	char dotsshdir[MAXPATHLEN], comment[1024], *passphrase1, *passphrase2;
	char out_file[MAXPATHLEN], *reader_id = NULL;
	char *rr_hostname = NULL;
	Key *private, *public;
	struct passwd *pw;
	struct stat st;
	int opt, type, fd, download = 0;
	u_int32_t memory = 0, generator_wanted = 0, trials = 100;
	int do_gen_candidates = 0, do_screen_candidates = 0;
	int log_level = SYSLOG_LEVEL_INFO;
	BIGNUM *start = NULL;
	FILE *f;
	const char *errstr;

	extern int optind;
	extern char *optarg;

	/* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
	sanitise_stdfd();

	SSLeay_add_all_algorithms();
	log_init(av[0], SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_USER, 1);

	/* we need this for the home * directory.  */
	pw = getpwuid(getuid());
	if (!pw) {
		printf("You don't exist, go away!\n");
		exit(1);
	}
	if (gethostname(hostname, sizeof(hostname)) < 0) {
		perror("gethostname");
		exit(1);
	}

	while ((opt = getopt(ac, av,
	    "degiqpclBHvxXyF:b:f:t:U:D:P:N:C:r:g:R:T:G:M:S:a:W:")) != -1) {
		switch (opt) {
		case 'b':
			bits = strtonum(optarg, 512, 32768, &errstr);
			if (errstr)
				fatal("Bits has bad value %s (%s)",
					optarg, errstr);
			break;
		case 'F':
			find_host = 1;
			rr_hostname = optarg;
			break;
		case 'H':
			hash_hosts = 1;
			break;
		case 'R':
			delete_host = 1;
			rr_hostname = optarg;
			break;
		case 'l':
			print_fingerprint = 1;
			break;
		case 'B':
			print_bubblebabble = 1;
			break;
		case 'p':
			change_passphrase = 1;
			break;
		case 'c':
			change_comment = 1;
			break;
		case 'f':
			if (strlcpy(identity_file, optarg, sizeof(identity_file)) >=
			    sizeof(identity_file))
				fatal("Identity filename too long");
			have_identity = 1;
			break;
		case 'g':
			print_generic = 1;
			break;
		case 'P':
			identity_passphrase = optarg;
			break;
		case 'N':
			identity_new_passphrase = optarg;
			break;
		case 'C':
			identity_comment = optarg;
			break;
		case 'q':
			quiet = 1;
			break;
		case 'e':
		case 'x':
			/* export key */
			convert_to_ssh2 = 1;
			break;
		case 'i':
		case 'X':
			/* import key */
			convert_from_ssh2 = 1;
			break;
		case 'y':
			print_public = 1;
			break;
		case 'd':
			key_type_name = "dsa";
			break;
		case 't':
			key_type_name = optarg;
			break;
		case 'D':
			download = 1;
		case 'U':
			reader_id = optarg;
			break;
		case 'v':
			if (log_level == SYSLOG_LEVEL_INFO)
				log_level = SYSLOG_LEVEL_DEBUG1;
			else {
				if (log_level >= SYSLOG_LEVEL_DEBUG1 &&
				    log_level < SYSLOG_LEVEL_DEBUG3)
					log_level++;
			}
			break;
		case 'r':
			rr_hostname = optarg;
			break;
		case 'W':
			generator_wanted = strtonum(optarg, 1, UINT_MAX, &errstr);
			if (errstr)
				fatal("Desired generator has bad value: %s (%s)",
					optarg, errstr);
			break;
		case 'a':
			trials = strtonum(optarg, 1, UINT_MAX, &errstr);
			if (errstr)
				fatal("Invalid number of trials: %s (%s)",
					optarg, errstr);
			break;
		case 'M':
			memory = strtonum(optarg, 1, UINT_MAX, &errstr);
			if (errstr) {
				fatal("Memory limit is %s: %s", errstr, optarg);
			}
			break;
		case 'G':
			do_gen_candidates = 1;
			if (strlcpy(out_file, optarg, sizeof(out_file)) >=
			    sizeof(out_file))
				fatal("Output filename too long");
			break;
		case 'T':
			do_screen_candidates = 1;
			if (strlcpy(out_file, optarg, sizeof(out_file)) >=
			    sizeof(out_file))
				fatal("Output filename too long");
			break;
		case 'S':
			/* XXX - also compare length against bits */
			if (BN_hex2bn(&start, optarg) == 0)
				fatal("Invalid start point.");
			break;
		case '?':
		default:
			usage();
		}
	}

	/* reinit */
	log_init(av[0], log_level, SYSLOG_FACILITY_USER, 1);

	if (optind < ac) {
		printf("Too many arguments.\n");
		usage();
	}
	if (change_passphrase && change_comment) {
		printf("Can only have one of -p and -c.\n");
		usage();
	}
	if (delete_host || hash_hosts || find_host)
		do_known_hosts(pw, rr_hostname);
	if (print_fingerprint || print_bubblebabble)
		do_fingerprint(pw);
	if (change_passphrase)
		do_change_passphrase(pw);
	if (change_comment)
		do_change_comment(pw);
	if (convert_to_ssh2)
		do_convert_to_ssh2(pw);
	if (convert_from_ssh2)
		do_convert_from_ssh2(pw);
	if (print_public)
		do_print_public(pw);
	if (rr_hostname != NULL) {
		do_print_resource_record(pw, rr_hostname);
	}
	if (reader_id != NULL) {
#ifdef SMARTCARD
		if (download)
			do_download(pw, reader_id);
		else
			do_upload(pw, reader_id);
#else /* SMARTCARD */
		fatal("no support for smartcards.");
#endif /* SMARTCARD */
	}

	if (do_gen_candidates) {
		FILE *out = fopen(out_file, "w");

		if (out == NULL) {
			error("Couldn't open modulus candidate file \"%s\": %s",
			    out_file, strerror(errno));
			return (1);
		}
		if (bits == 0)
			bits = DEFAULT_BITS;
		if (gen_candidates(out, memory, bits, start) != 0)
			fatal("modulus candidate generation failed\n");

		return (0);
	}

	if (do_screen_candidates) {
		FILE *in;
		FILE *out = fopen(out_file, "w");

		if (have_identity && strcmp(identity_file, "-") != 0) {
			if ((in = fopen(identity_file, "r")) == NULL) {
				fatal("Couldn't open modulus candidate "
				    "file \"%s\": %s", identity_file,
				    strerror(errno));
			}
		} else
			in = stdin;

		if (out == NULL) {
			fatal("Couldn't open moduli file \"%s\": %s",
			    out_file, strerror(errno));
		}
		if (prime_test(in, out, trials, generator_wanted) != 0)
			fatal("modulus screening failed\n");
		return (0);
	}

	arc4random_stir();

	if (key_type_name == NULL) {
		printf("You must specify a key type (-t).\n");
		usage();
	}
	type = key_type_from_name(key_type_name);
	if (type == KEY_UNSPEC) {
		fprintf(stderr, "unknown key type %s\n", key_type_name);
		exit(1);
	}
	if (!quiet)
		printf("Generating public/private %s key pair.\n", key_type_name);
	if (bits == 0)
		bits = (type == KEY_DSA) ? DEFAULT_BITS_DSA : DEFAULT_BITS;
	private = key_generate(type, bits);
	if (private == NULL) {
		fprintf(stderr, "key_generate failed");
		exit(1);
	}
	public  = key_from_private(private);

	if (!have_identity)
		ask_filename(pw, "Enter file in which to save the key");

	/* Create ~/.ssh directory if it doesn\'t already exist. */
	snprintf(dotsshdir, sizeof dotsshdir, "%s/%s", pw->pw_dir, _PATH_SSH_USER_DIR);
	if (strstr(identity_file, dotsshdir) != NULL &&
	    stat(dotsshdir, &st) < 0) {
		if (mkdir(dotsshdir, 0700) < 0)
			error("Could not create directory '%s'.", dotsshdir);
		else if (!quiet)
			printf("Created directory '%s'.\n", dotsshdir);
	}
	/* If the file already exists, ask the user to confirm. */
	if (stat(identity_file, &st) >= 0) {
		char yesno[3];
		printf("%s already exists.\n", identity_file);
		printf("Overwrite (y/n)? ");
		fflush(stdout);
		if (fgets(yesno, sizeof(yesno), stdin) == NULL)
			exit(1);
		if (yesno[0] != 'y' && yesno[0] != 'Y')
			exit(1);
	}
	/* Ask for a passphrase (twice). */
	if (identity_passphrase)
		passphrase1 = xstrdup(identity_passphrase);
	else if (identity_new_passphrase)
		passphrase1 = xstrdup(identity_new_passphrase);
	else {
passphrase_again:
		passphrase1 =
			read_passphrase("Enter passphrase (empty for no "
			    "passphrase): ", RP_ALLOW_STDIN);
		passphrase2 = read_passphrase("Enter same passphrase again: ",
		    RP_ALLOW_STDIN);
		if (strcmp(passphrase1, passphrase2) != 0) {
			/*
			 * The passphrases do not match.  Clear them and
			 * retry.
			 */
			memset(passphrase1, 0, strlen(passphrase1));
			memset(passphrase2, 0, strlen(passphrase2));
			xfree(passphrase1);
			xfree(passphrase2);
			printf("Passphrases do not match.  Try again.\n");
			goto passphrase_again;
		}
		/* Clear the other copy of the passphrase. */
		memset(passphrase2, 0, strlen(passphrase2));
		xfree(passphrase2);
	}

	if (identity_comment) {
		strlcpy(comment, identity_comment, sizeof(comment));
	} else {
		/* Create default commend field for the passphrase. */
		snprintf(comment, sizeof comment, "%s@%s", pw->pw_name, hostname);
	}

	/* Save the key with the given passphrase and comment. */
	if (!key_save_private(private, identity_file, passphrase1, comment)) {
		printf("Saving the key failed: %s.\n", identity_file);
		memset(passphrase1, 0, strlen(passphrase1));
		xfree(passphrase1);
		exit(1);
	}
	/* Clear the passphrase. */
	memset(passphrase1, 0, strlen(passphrase1));
	xfree(passphrase1);

	/* Clear the private key and the random number generator. */
	key_free(private);
	arc4random_stir();

	if (!quiet)
		printf("Your identification has been saved in %s.\n", identity_file);

	strlcat(identity_file, ".pub", sizeof(identity_file));
	fd = open(identity_file, O_WRONLY | O_CREAT | O_TRUNC, 0644);
	if (fd == -1) {
		printf("Could not save your public key in %s\n", identity_file);
		exit(1);
	}
	f = fdopen(fd, "w");
	if (f == NULL) {
		printf("fdopen %s failed", identity_file);
		exit(1);
	}
	if (!key_write(public, f))
		fprintf(stderr, "write key failed");
	fprintf(f, " %s\n", comment);
	fclose(f);

	if (!quiet) {
		char *fp = key_fingerprint(public, SSH_FP_MD5, SSH_FP_HEX);
		printf("Your public key has been saved in %s.\n",
		    identity_file);
		printf("The key fingerprint is:\n");
		printf("%s %s\n", fp, comment);
		xfree(fp);
	}

	key_free(public);
	exit(0);
}