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Implement Elliptic Curve Cryptography modes for key exchange (ECDH) and
host/user keys (ECDSA) as specified by RFC5656. ECDH and ECDSA offer
better performance than plain DH and DSA at the same equivalent symmetric
key length, as well as much shorter keys.

Only the mandatory sections of RFC5656 are implemented, specifically the
three REQUIRED curves nistp256, nistp384 and nistp521 and only ECDH and
ECDSA. Point compression (optional in RFC5656 is NOT implemented).

Certificate host and user keys using the new ECDSA key types are supported.

Note that this code has not been tested for interoperability and may be
subject to change.

feedback and ok markus@

/* $OpenBSD: authfile.c,v 1.83 2010/08/31 11:54:45 djm Exp $ */
/*
 * Author: Tatu Ylonen <ylo@cs.hut.fi>
 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
 *                    All rights reserved
 * This file contains functions for reading and writing identity files, and
 * for reading the passphrase from the user.
 *
 * 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".
 *
 *
 * Copyright (c) 2000 Markus Friedl.  All rights reserved.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */


#include <sys/types.h>
#include <sys/stat.h>
#include <sys/param.h>
#include <sys/uio.h>

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

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "xmalloc.h"
#include "cipher.h"
#include "buffer.h"
#include "key.h"
#include "ssh.h"
#include "log.h"
#include "authfile.h"
#include "rsa.h"
#include "misc.h"
#include "atomicio.h"

/* Version identification string for SSH v1 identity files. */
static const char authfile_id_string[] =
    "SSH PRIVATE KEY FILE FORMAT 1.1\n";

/*
 * Saves the authentication (private) key in a file, encrypting it with
 * passphrase.  The identification of the file (lowest 64 bits of n) will
 * precede the key to provide identification of the key without needing a
 * passphrase.
 */

static int
key_save_private_rsa1(Key *key, const char *filename, const char *passphrase,
    const char *comment)
{
	Buffer buffer, encrypted;
	u_char buf[100], *cp;
	int fd, i, cipher_num;
	CipherContext ciphercontext;
	Cipher *cipher;
	u_int32_t rnd;

	/*
	 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
	 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
	 */
	cipher_num = (strcmp(passphrase, "") == 0) ?
	    SSH_CIPHER_NONE : SSH_AUTHFILE_CIPHER;
	if ((cipher = cipher_by_number(cipher_num)) == NULL)
		fatal("save_private_key_rsa: bad cipher");

	/* This buffer is used to built the secret part of the private key. */
	buffer_init(&buffer);

	/* Put checkbytes for checking passphrase validity. */
	rnd = arc4random();
	buf[0] = rnd & 0xff;
	buf[1] = (rnd >> 8) & 0xff;
	buf[2] = buf[0];
	buf[3] = buf[1];
	buffer_append(&buffer, buf, 4);

	/*
	 * Store the private key (n and e will not be stored because they
	 * will be stored in plain text, and storing them also in encrypted
	 * format would just give known plaintext).
	 */
	buffer_put_bignum(&buffer, key->rsa->d);
	buffer_put_bignum(&buffer, key->rsa->iqmp);
	buffer_put_bignum(&buffer, key->rsa->q);	/* reverse from SSL p */
	buffer_put_bignum(&buffer, key->rsa->p);	/* reverse from SSL q */

	/* Pad the part to be encrypted until its size is a multiple of 8. */
	while (buffer_len(&buffer) % 8 != 0)
		buffer_put_char(&buffer, 0);

	/* This buffer will be used to contain the data in the file. */
	buffer_init(&encrypted);

	/* First store keyfile id string. */
	for (i = 0; authfile_id_string[i]; i++)
		buffer_put_char(&encrypted, authfile_id_string[i]);
	buffer_put_char(&encrypted, 0);

	/* Store cipher type. */
	buffer_put_char(&encrypted, cipher_num);
	buffer_put_int(&encrypted, 0);	/* For future extension */

	/* Store public key.  This will be in plain text. */
	buffer_put_int(&encrypted, BN_num_bits(key->rsa->n));
	buffer_put_bignum(&encrypted, key->rsa->n);
	buffer_put_bignum(&encrypted, key->rsa->e);
	buffer_put_cstring(&encrypted, comment);

	/* Allocate space for the private part of the key in the buffer. */
	cp = buffer_append_space(&encrypted, buffer_len(&buffer));

	cipher_set_key_string(&ciphercontext, cipher, passphrase,
	    CIPHER_ENCRYPT);
	cipher_crypt(&ciphercontext, cp,
	    buffer_ptr(&buffer), buffer_len(&buffer));
	cipher_cleanup(&ciphercontext);
	memset(&ciphercontext, 0, sizeof(ciphercontext));

	/* Destroy temporary data. */
	memset(buf, 0, sizeof(buf));
	buffer_free(&buffer);

	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
	if (fd < 0) {
		error("open %s failed: %s.", filename, strerror(errno));
		buffer_free(&encrypted);
		return 0;
	}
	if (atomicio(vwrite, fd, buffer_ptr(&encrypted),
	    buffer_len(&encrypted)) != buffer_len(&encrypted)) {
		error("write to key file %s failed: %s", filename,
		    strerror(errno));
		buffer_free(&encrypted);
		close(fd);
		unlink(filename);
		return 0;
	}
	close(fd);
	buffer_free(&encrypted);
	return 1;
}

/* save SSH v2 key in OpenSSL PEM format */
static int
key_save_private_pem(Key *key, const char *filename, const char *_passphrase,
    const char *comment)
{
	FILE *fp;
	int fd;
	int success = 0;
	int len = strlen(_passphrase);
	u_char *passphrase = (len > 0) ? (u_char *)_passphrase : NULL;
	const EVP_CIPHER *cipher = (len > 0) ? EVP_aes_128_cbc() : NULL;

	if (len > 0 && len <= 4) {
		error("passphrase too short: have %d bytes, need > 4", len);
		return 0;
	}
	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
	if (fd < 0) {
		error("open %s failed: %s.", filename, strerror(errno));
		return 0;
	}
	fp = fdopen(fd, "w");
	if (fp == NULL) {
		error("fdopen %s failed: %s.", filename, strerror(errno));
		close(fd);
		return 0;
	}
	switch (key->type) {
	case KEY_DSA:
		success = PEM_write_DSAPrivateKey(fp, key->dsa,
		    cipher, passphrase, len, NULL, NULL);
		break;
	case KEY_ECDSA:
		success = PEM_write_ECPrivateKey(fp, key->ecdsa,
		    cipher, passphrase, len, NULL, NULL);
		break;
	case KEY_RSA:
		success = PEM_write_RSAPrivateKey(fp, key->rsa,
		    cipher, passphrase, len, NULL, NULL);
		break;
	}
	fclose(fp);
	return success;
}

int
key_save_private(Key *key, const char *filename, const char *passphrase,
    const char *comment)
{
	switch (key->type) {
	case KEY_RSA1:
		return key_save_private_rsa1(key, filename, passphrase,
		    comment);
	case KEY_DSA:
	case KEY_ECDSA:
	case KEY_RSA:
		return key_save_private_pem(key, filename, passphrase,
		    comment);
	default:
		break;
	}
	error("key_save_private: cannot save key type %d", key->type);
	return 0;
}

/*
 * Loads the public part of the ssh v1 key file.  Returns NULL if an error was
 * encountered (the file does not exist or is not readable), and the key
 * otherwise.
 */

static Key *
key_load_public_rsa1(int fd, const char *filename, char **commentp)
{
	Buffer buffer;
	Key *pub;
	struct stat st;
	char *cp;
	u_int i;
	size_t len;

	if (fstat(fd, &st) < 0) {
		error("fstat for key file %.200s failed: %.100s",
		    filename, strerror(errno));
		return NULL;
	}
	if (st.st_size > 1*1024*1024) {
		error("key file %.200s too large", filename);
		return NULL;
	}
	len = (size_t)st.st_size;		/* truncated */

	buffer_init(&buffer);
	cp = buffer_append_space(&buffer, len);

	if (atomicio(read, fd, cp, len) != len) {
		debug("Read from key file %.200s failed: %.100s", filename,
		    strerror(errno));
		buffer_free(&buffer);
		return NULL;
	}

	/* Check that it is at least big enough to contain the ID string. */
	if (len < sizeof(authfile_id_string)) {
		debug3("Not a RSA1 key file %.200s.", filename);
		buffer_free(&buffer);
		return NULL;
	}
	/*
	 * Make sure it begins with the id string.  Consume the id string
	 * from the buffer.
	 */
	for (i = 0; i < sizeof(authfile_id_string); i++)
		if (buffer_get_char(&buffer) != authfile_id_string[i]) {
			debug3("Not a RSA1 key file %.200s.", filename);
			buffer_free(&buffer);
			return NULL;
		}
	/* Skip cipher type and reserved data. */
	(void) buffer_get_char(&buffer);	/* cipher type */
	(void) buffer_get_int(&buffer);		/* reserved */

	/* Read the public key from the buffer. */
	(void) buffer_get_int(&buffer);
	pub = key_new(KEY_RSA1);
	buffer_get_bignum(&buffer, pub->rsa->n);
	buffer_get_bignum(&buffer, pub->rsa->e);
	if (commentp)
		*commentp = buffer_get_string(&buffer, NULL);
	/* The encrypted private part is not parsed by this function. */

	buffer_free(&buffer);
	return pub;
}

/* load public key from private-key file, works only for SSH v1 */
Key *
key_load_public_type(int type, const char *filename, char **commentp)
{
	Key *pub;
	int fd;

	if (type == KEY_RSA1) {
		fd = open(filename, O_RDONLY);
		if (fd < 0)
			return NULL;
		pub = key_load_public_rsa1(fd, filename, commentp);
		close(fd);
		return pub;
	}
	return NULL;
}

/*
 * Loads the private key from the file.  Returns 0 if an error is encountered
 * (file does not exist or is not readable, or passphrase is bad). This
 * initializes the private key.
 * Assumes we are called under uid of the owner of the file.
 */

static Key *
key_load_private_rsa1(int fd, const char *filename, const char *passphrase,
    char **commentp)
{
	u_int i;
	int check1, check2, cipher_type;
	size_t len;
	Buffer buffer, decrypted;
	u_char *cp;
	CipherContext ciphercontext;
	Cipher *cipher;
	Key *prv = NULL;
	struct stat st;

	if (fstat(fd, &st) < 0) {
		error("fstat for key file %.200s failed: %.100s",
		    filename, strerror(errno));
		close(fd);
		return NULL;
	}
	if (st.st_size > 1*1024*1024) {
		error("key file %.200s too large", filename);
		close(fd);
		return (NULL);
	}
	len = (size_t)st.st_size;		/* truncated */

	buffer_init(&buffer);
	cp = buffer_append_space(&buffer, len);

	if (atomicio(read, fd, cp, len) != len) {
		debug("Read from key file %.200s failed: %.100s", filename,
		    strerror(errno));
		buffer_free(&buffer);
		close(fd);
		return NULL;
	}

	/* Check that it is at least big enough to contain the ID string. */
	if (len < sizeof(authfile_id_string)) {
		debug3("Not a RSA1 key file %.200s.", filename);
		buffer_free(&buffer);
		close(fd);
		return NULL;
	}
	/*
	 * Make sure it begins with the id string.  Consume the id string
	 * from the buffer.
	 */
	for (i = 0; i < sizeof(authfile_id_string); i++)
		if (buffer_get_char(&buffer) != authfile_id_string[i]) {
			debug3("Not a RSA1 key file %.200s.", filename);
			buffer_free(&buffer);
			close(fd);
			return NULL;
		}

	/* Read cipher type. */
	cipher_type = buffer_get_char(&buffer);
	(void) buffer_get_int(&buffer);	/* Reserved data. */

	/* Read the public key from the buffer. */
	(void) buffer_get_int(&buffer);
	prv = key_new_private(KEY_RSA1);

	buffer_get_bignum(&buffer, prv->rsa->n);
	buffer_get_bignum(&buffer, prv->rsa->e);
	if (commentp)
		*commentp = buffer_get_string(&buffer, NULL);
	else
		xfree(buffer_get_string(&buffer, NULL));

	/* Check that it is a supported cipher. */
	cipher = cipher_by_number(cipher_type);
	if (cipher == NULL) {
		debug("Unsupported cipher %d used in key file %.200s.",
		    cipher_type, filename);
		buffer_free(&buffer);
		goto fail;
	}
	/* Initialize space for decrypted data. */
	buffer_init(&decrypted);
	cp = buffer_append_space(&decrypted, buffer_len(&buffer));

	/* Rest of the buffer is encrypted.  Decrypt it using the passphrase. */
	cipher_set_key_string(&ciphercontext, cipher, passphrase,
	    CIPHER_DECRYPT);
	cipher_crypt(&ciphercontext, cp,
	    buffer_ptr(&buffer), buffer_len(&buffer));
	cipher_cleanup(&ciphercontext);
	memset(&ciphercontext, 0, sizeof(ciphercontext));
	buffer_free(&buffer);

	check1 = buffer_get_char(&decrypted);
	check2 = buffer_get_char(&decrypted);
	if (check1 != buffer_get_char(&decrypted) ||
	    check2 != buffer_get_char(&decrypted)) {
		if (strcmp(passphrase, "") != 0)
			debug("Bad passphrase supplied for key file %.200s.",
			    filename);
		/* Bad passphrase. */
		buffer_free(&decrypted);
		goto fail;
	}
	/* Read the rest of the private key. */
	buffer_get_bignum(&decrypted, prv->rsa->d);
	buffer_get_bignum(&decrypted, prv->rsa->iqmp);		/* u */
	/* in SSL and SSH v1 p and q are exchanged */
	buffer_get_bignum(&decrypted, prv->rsa->q);		/* p */
	buffer_get_bignum(&decrypted, prv->rsa->p);		/* q */

	/* calculate p-1 and q-1 */
	rsa_generate_additional_parameters(prv->rsa);

	buffer_free(&decrypted);

	/* enable blinding */
	if (RSA_blinding_on(prv->rsa, NULL) != 1) {
		error("key_load_private_rsa1: RSA_blinding_on failed");
		goto fail;
	}
	close(fd);
	return prv;

fail:
	if (commentp)
		xfree(*commentp);
	close(fd);
	key_free(prv);
	return NULL;
}

Key *
key_load_private_pem(int fd, int type, const char *passphrase,
    char **commentp)
{
	FILE *fp;
	EVP_PKEY *pk = NULL;
	Key *prv = NULL;
	char *name = "<no key>";

	fp = fdopen(fd, "r");
	if (fp == NULL) {
		error("fdopen failed: %s", strerror(errno));
		close(fd);
		return NULL;
	}
	pk = PEM_read_PrivateKey(fp, NULL, NULL, (char *)passphrase);
	if (pk == NULL) {
		debug("PEM_read_PrivateKey failed");
		(void)ERR_get_error();
	} else if (pk->type == EVP_PKEY_RSA &&
	    (type == KEY_UNSPEC||type==KEY_RSA)) {
		prv = key_new(KEY_UNSPEC);
		prv->rsa = EVP_PKEY_get1_RSA(pk);
		prv->type = KEY_RSA;
		name = "rsa w/o comment";
#ifdef DEBUG_PK
		RSA_print_fp(stderr, prv->rsa, 8);
#endif
		if (RSA_blinding_on(prv->rsa, NULL) != 1) {
			error("key_load_private_pem: RSA_blinding_on failed");
			key_free(prv);
			prv = NULL;
		}
	} else if (pk->type == EVP_PKEY_DSA &&
	    (type == KEY_UNSPEC||type==KEY_DSA)) {
		prv = key_new(KEY_UNSPEC);
		prv->dsa = EVP_PKEY_get1_DSA(pk);
		prv->type = KEY_DSA;
		name = "dsa w/o comment";
#ifdef DEBUG_PK
		DSA_print_fp(stderr, prv->dsa, 8);
#endif
	} else if (pk->type == EVP_PKEY_EC &&
	    (type == KEY_UNSPEC||type==KEY_ECDSA)) {
		prv = key_new(KEY_UNSPEC);
		prv->ecdsa = EVP_PKEY_get1_EC_KEY(pk);
		prv->type = KEY_ECDSA;
		prv->ecdsa_nid = key_ecdsa_group_to_nid(
		    EC_KEY_get0_group(prv->ecdsa));
		if (key_curve_nid_to_name(prv->ecdsa_nid) == NULL) {
			key_free(prv);
			prv = NULL;
		}
		if (key_ec_validate_public(EC_KEY_get0_group(prv->ecdsa),
		    EC_KEY_get0_public_key(prv->ecdsa)) != 0 ||
		    key_ec_validate_private(prv->ecdsa) != 0) {
			error("%s: bad ECDSA key", __func__);
			key_free(prv);
			prv = NULL;
		}
		name = "dsa w/o comment";
#ifdef DEBUG_PK
		if (prv->ecdsa != NULL)
			key_dump_ec_key(prv->ecdsa);
#endif
	} else {
		error("PEM_read_PrivateKey: mismatch or "
		    "unknown EVP_PKEY save_type %d", pk->save_type);
	}
	fclose(fp);
	if (pk != NULL)
		EVP_PKEY_free(pk);
	if (prv != NULL && commentp)
		*commentp = xstrdup(name);
	debug("read PEM private key done: type %s",
	    prv ? key_type(prv) : "<unknown>");
	return prv;
}

int
key_perm_ok(int fd, const char *filename)
{
	struct stat st;

	if (fstat(fd, &st) < 0)
		return 0;
	/*
	 * if a key owned by the user is accessed, then we check the
	 * permissions of the file. if the key owned by a different user,
	 * then we don't care.
	 */
	if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) {
		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
		error("@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @");
		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
		error("Permissions 0%3.3o for '%s' are too open.",
		    (u_int)st.st_mode & 0777, filename);
		error("It is recommended that your private key files are NOT accessible by others.");
		error("This private key will be ignored.");
		return 0;
	}
	return 1;
}

Key *
key_load_private_type(int type, const char *filename, const char *passphrase,
    char **commentp, int *perm_ok)
{
	int fd;

	fd = open(filename, O_RDONLY);
	if (fd < 0) {
		debug("could not open key file '%s': %s", filename,
		    strerror(errno));
		if (perm_ok != NULL)
			*perm_ok = 0;
		return NULL;
	}
	if (!key_perm_ok(fd, filename)) {
		if (perm_ok != NULL)
			*perm_ok = 0;
		error("bad permissions: ignore key: %s", filename);
		close(fd);
		return NULL;
	}
	if (perm_ok != NULL)
		*perm_ok = 1;
	switch (type) {
	case KEY_RSA1:
		return key_load_private_rsa1(fd, filename, passphrase,
		    commentp);
		/* closes fd */
	case KEY_DSA:
	case KEY_ECDSA:
	case KEY_RSA:
	case KEY_UNSPEC:
		return key_load_private_pem(fd, type, passphrase, commentp);
		/* closes fd */
	default:
		close(fd);
		break;
	}
	return NULL;
}

Key *
key_load_private(const char *filename, const char *passphrase,
    char **commentp)
{
	Key *pub, *prv;
	int fd;

	fd = open(filename, O_RDONLY);
	if (fd < 0) {
		debug("could not open key file '%s': %s", filename,
		    strerror(errno));
		return NULL;
	}
	if (!key_perm_ok(fd, filename)) {
		error("bad permissions: ignore key: %s", filename);
		close(fd);
		return NULL;
	}
	pub = key_load_public_rsa1(fd, filename, commentp);
	lseek(fd, (off_t) 0, SEEK_SET);		/* rewind */
	if (pub == NULL) {
		/* closes fd */
		prv = key_load_private_pem(fd, KEY_UNSPEC, passphrase, NULL);
		/* use the filename as a comment for PEM */
		if (commentp && prv)
			*commentp = xstrdup(filename);
	} else {
		/* it's a SSH v1 key if the public key part is readable */
		key_free(pub);
		/* closes fd */
		prv = key_load_private_rsa1(fd, filename, passphrase, NULL);
	}
	return prv;
}

static int
key_try_load_public(Key *k, const char *filename, char **commentp)
{
	FILE *f;
	char line[SSH_MAX_PUBKEY_BYTES];
	char *cp;
	u_long linenum = 0;

	f = fopen(filename, "r");
	if (f != NULL) {
		while (read_keyfile_line(f, filename, line, sizeof(line),
			    &linenum) != -1) {
			cp = line;
			switch (*cp) {
			case '#':
			case '\n':
			case '\0':
				continue;
			}
			/* Skip leading whitespace. */
			for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
				;
			if (*cp) {
				if (key_read(k, &cp) == 1) {
					if (commentp)
						*commentp=xstrdup(filename);
					fclose(f);
					return 1;
				}
			}
		}
		fclose(f);
	}
	return 0;
}

/* load public key from ssh v1 private or any pubkey file */
Key *
key_load_public(const char *filename, char **commentp)
{
	Key *pub;
	char file[MAXPATHLEN];

	/* try rsa1 private key */
	pub = key_load_public_type(KEY_RSA1, filename, commentp);
	if (pub != NULL)
		return pub;

	/* try rsa1 public key */
	pub = key_new(KEY_RSA1);
	if (key_try_load_public(pub, filename, commentp) == 1)
		return pub;
	key_free(pub);

	/* try ssh2 public key */
	pub = key_new(KEY_UNSPEC);
	if (key_try_load_public(pub, filename, commentp) == 1)
		return pub;
	if ((strlcpy(file, filename, sizeof file) < sizeof(file)) &&
	    (strlcat(file, ".pub", sizeof file) < sizeof(file)) &&
	    (key_try_load_public(pub, file, commentp) == 1))
		return pub;
	key_free(pub);
	return NULL;
}

/* Load the certificate associated with the named private key */
Key *
key_load_cert(const char *filename)
{
	Key *pub;
	char *file;

	pub = key_new(KEY_UNSPEC);
	xasprintf(&file, "%s-cert.pub", filename);
	if (key_try_load_public(pub, file, NULL) == 1) {
		xfree(file);
		return pub;
	}
	xfree(file);
	key_free(pub);
	return NULL;
}

/* Load private key and certificate */
Key *
key_load_private_cert(int type, const char *filename, const char *passphrase,
    int *perm_ok)
{
	Key *key, *pub;

	switch (type) {
	case KEY_RSA:
	case KEY_DSA:
	case KEY_ECDSA:
		break;
	default:
		error("%s: unsupported key type", __func__);
		return NULL;
	}

	if ((key = key_load_private_type(type, filename, 
	    passphrase, NULL, perm_ok)) == NULL)
		return NULL;

	if ((pub = key_load_cert(filename)) == NULL) {
		key_free(key);
		return NULL;
	}

	/* Make sure the private key matches the certificate */
	if (key_equal_public(key, pub) == 0) {
		error("%s: certificate does not match private key %s",
		    __func__, filename);
	} else if (key_to_certified(key, key_cert_is_legacy(pub)) != 0) {
		error("%s: key_to_certified failed", __func__);
	} else {
		key_cert_copy(pub, key);
		key_free(pub);
		return key;
	}

	key_free(key);
	key_free(pub);
	return NULL;
}

/*
 * Returns 1 if the specified "key" is listed in the file "filename",
 * 0 if the key is not listed or -1 on error.
 * If strict_type is set then the key type must match exactly,
 * otherwise a comparison that ignores certficiate data is performed.
 */
int
key_in_file(Key *key, const char *filename, int strict_type)
{
	FILE *f;
	char line[SSH_MAX_PUBKEY_BYTES];
	char *cp;
	u_long linenum = 0;
	int ret = 0;
	Key *pub;
	int (*key_compare)(const Key *, const Key *) = strict_type ?
	    key_equal : key_equal_public;

	if ((f = fopen(filename, "r")) == NULL) {
		if (errno == ENOENT) {
			debug("%s: keyfile \"%s\" missing", __func__, filename);
			return 0;
		} else {
			error("%s: could not open keyfile \"%s\": %s", __func__,
			    filename, strerror(errno));
			return -1;
		}
	}

	while (read_keyfile_line(f, filename, line, sizeof(line),
		    &linenum) != -1) {
		cp = line;

		/* Skip leading whitespace. */
		for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
			;

		/* Skip comments and empty lines */
		switch (*cp) {
		case '#':
		case '\n':
		case '\0':
			continue;
		}

		pub = key_new(KEY_UNSPEC);
		if (key_read(pub, &cp) != 1) {
			key_free(pub);
			continue;
		}
		if (key_compare(key, pub)) {
			ret = 1;
			key_free(pub);
			break;
		}
		key_free(pub);
	}
	fclose(f);
	return ret;
}