Return to authfile.c CVS log

Up to [local] / src / usr.bin / ssh

add encrypt-then-mac (EtM) modes to openssh by defining new mac algorithms
that change the packet format and compute the MAC over the encrypted
message (including the packet size) instead of the plaintext data;
these EtM modes are considered more secure and used by default.
feedback and ok djm@

/* $OpenBSD: authfile.c,v 1.94 2012/12/11 22:31:18 markus 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"

#define MAX_KEY_FILE_SIZE	(1024 * 1024)

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

/*
 * Serialises the authentication (private) key to a blob, encrypting it with
 * passphrase.  The identification of the blob (lowest 64 bits of n) will
 * precede the key to provide identification of the key without needing a
 * passphrase.
 */
static int
key_private_rsa1_to_blob(Key *key, Buffer *blob, const char *passphrase,
    const char *comment)
{
	Buffer buffer, encrypted;
	u_char buf[100], *cp;
	int 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), 0);
	cipher_cleanup(&ciphercontext);
	memset(&ciphercontext, 0, sizeof(ciphercontext));

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

	buffer_append(blob, buffer_ptr(&encrypted), buffer_len(&encrypted));
	buffer_free(&encrypted);

	return 1;
}

/* convert SSH v2 key in OpenSSL PEM format */
static int
key_private_pem_to_blob(Key *key, Buffer *blob, const char *_passphrase,
    const char *comment)
{
	int success = 0;
	int blen, len = strlen(_passphrase);
	u_char *passphrase = (len > 0) ? (u_char *)_passphrase : NULL;
	const EVP_CIPHER *cipher = (len > 0) ? EVP_aes_128_cbc() : NULL;
	const u_char *bptr;
	BIO *bio;

	if (len > 0 && len <= 4) {
		error("passphrase too short: have %d bytes, need > 4", len);
		return 0;
	}
	if ((bio = BIO_new(BIO_s_mem())) == NULL) {
		error("%s: BIO_new failed", __func__);
		return 0;
	}
	switch (key->type) {
	case KEY_DSA:
		success = PEM_write_bio_DSAPrivateKey(bio, key->dsa,
		    cipher, passphrase, len, NULL, NULL);
		break;
	case KEY_ECDSA:
		success = PEM_write_bio_ECPrivateKey(bio, key->ecdsa,
		    cipher, passphrase, len, NULL, NULL);
		break;
	case KEY_RSA:
		success = PEM_write_bio_RSAPrivateKey(bio, key->rsa,
		    cipher, passphrase, len, NULL, NULL);
		break;
	}
	if (success) {
		if ((blen = BIO_get_mem_data(bio, &bptr)) <= 0)
			success = 0;
		else
			buffer_append(blob, bptr, blen);
	}
	BIO_free(bio);
	return success;
}

/* Save a key blob to a file */
static int
key_save_private_blob(Buffer *keybuf, const char *filename)
{
	int fd;

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

/* Serialise "key" to buffer "blob" */
static int
key_private_to_blob(Key *key, Buffer *blob, const char *passphrase,
    const char *comment)
{
	switch (key->type) {
	case KEY_RSA1:
		return key_private_rsa1_to_blob(key, blob, passphrase, comment);
	case KEY_DSA:
	case KEY_ECDSA:
	case KEY_RSA:
		return key_private_pem_to_blob(key, blob, passphrase, comment);
	default:
		error("%s: cannot save key type %d", __func__, key->type);
		return 0;
	}
}

int
key_save_private(Key *key, const char *filename, const char *passphrase,
    const char *comment)
{
	Buffer keyblob;
	int success = 0;

	buffer_init(&keyblob);
	if (!key_private_to_blob(key, &keyblob, passphrase, comment))
		goto out;
	if (!key_save_private_blob(&keyblob, filename))
		goto out;
	success = 1;
 out:
	buffer_free(&keyblob);
	return success;
}

/*
 * Parse the public, unencrypted portion of a RSA1 key.
 */
static Key *
key_parse_public_rsa1(Buffer *blob, char **commentp)
{
	Key *pub;
	Buffer copy;

	/* Check that it is at least big enough to contain the ID string. */
	if (buffer_len(blob) < sizeof(authfile_id_string)) {
		debug3("Truncated RSA1 identifier");
		return NULL;
	}

	/*
	 * Make sure it begins with the id string.  Consume the id string
	 * from the buffer.
	 */
	if (memcmp(buffer_ptr(blob), authfile_id_string,
	    sizeof(authfile_id_string)) != 0) {
		debug3("Incorrect RSA1 identifier");
		return NULL;
	}
	buffer_init(&copy);
	buffer_append(&copy, buffer_ptr(blob), buffer_len(blob));
	buffer_consume(&copy, sizeof(authfile_id_string));

	/* Skip cipher type and reserved data. */
	(void) buffer_get_char(&copy);		/* cipher type */
	(void) buffer_get_int(&copy);		/* reserved */

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

	return pub;
}

/* Load a key from a fd into a buffer */
int
key_load_file(int fd, const char *filename, Buffer *blob)
{
	u_char buf[1024];
	size_t len;
	struct stat st;

	if (fstat(fd, &st) < 0) {
		error("%s: fstat of key file %.200s%sfailed: %.100s", __func__,
		    filename == NULL ? "" : filename,
		    filename == NULL ? "" : " ",
		    strerror(errno));
		return 0;
	}
	if ((st.st_mode & (S_IFSOCK|S_IFCHR|S_IFIFO)) == 0 &&
	    st.st_size > MAX_KEY_FILE_SIZE) {
 toobig:
		error("%s: key file %.200s%stoo large", __func__,
		    filename == NULL ? "" : filename,
		    filename == NULL ? "" : " ");
		return 0;
	}
	buffer_clear(blob);
	for (;;) {
		if ((len = atomicio(read, fd, buf, sizeof(buf))) == 0) {
			if (errno == EPIPE)
				break;
			debug("%s: read from key file %.200s%sfailed: %.100s",
			    __func__, filename == NULL ? "" : filename,
			    filename == NULL ? "" : " ", strerror(errno));
			buffer_clear(blob);
			bzero(buf, sizeof(buf));
			return 0;
		}
		buffer_append(blob, buf, len);
		if (buffer_len(blob) > MAX_KEY_FILE_SIZE) {
			buffer_clear(blob);
			bzero(buf, sizeof(buf));
			goto toobig;
		}
	}
	bzero(buf, sizeof(buf));
	if ((st.st_mode & (S_IFSOCK|S_IFCHR|S_IFIFO)) == 0 &&
	    st.st_size != buffer_len(blob)) {
		debug("%s: key file %.200s%schanged size while reading",
		    __func__, filename == NULL ? "" : filename,
		    filename == NULL ? "" : " ");
		buffer_clear(blob);
		return 0;
	}

	return 1;
}

/*
 * 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;

	buffer_init(&buffer);
	if (!key_load_file(fd, filename, &buffer)) {
		buffer_free(&buffer);
		return NULL;
	}

	pub = key_parse_public_rsa1(&buffer, commentp);
	if (pub == NULL)
		debug3("Could not load \"%s\" as a RSA1 public key", filename);
	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;
}

static Key *
key_parse_private_rsa1(Buffer *blob, const char *passphrase, char **commentp)
{
	int check1, check2, cipher_type;
	Buffer decrypted;
	u_char *cp;
	CipherContext ciphercontext;
	Cipher *cipher;
	Key *prv = NULL;
	Buffer copy;

	/* Check that it is at least big enough to contain the ID string. */
	if (buffer_len(blob) < sizeof(authfile_id_string)) {
		debug3("Truncated RSA1 identifier");
		return NULL;
	}

	/*
	 * Make sure it begins with the id string.  Consume the id string
	 * from the buffer.
	 */
	if (memcmp(buffer_ptr(blob), authfile_id_string,
	    sizeof(authfile_id_string)) != 0) {
		debug3("Incorrect RSA1 identifier");
		return NULL;
	}
	buffer_init(&copy);
	buffer_append(&copy, buffer_ptr(blob), buffer_len(blob));
	buffer_consume(&copy, sizeof(authfile_id_string));

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

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

	buffer_get_bignum(&copy, prv->rsa->n);
	buffer_get_bignum(&copy, prv->rsa->e);
	if (commentp)
		*commentp = buffer_get_string(&copy, NULL);
	else
		(void)buffer_get_string_ptr(&copy, NULL);

	/* Check that it is a supported cipher. */
	cipher = cipher_by_number(cipher_type);
	if (cipher == NULL) {
		debug("Unsupported RSA1 cipher %d", cipher_type);
		buffer_free(&copy);
		goto fail;
	}
	/* Initialize space for decrypted data. */
	buffer_init(&decrypted);
	cp = buffer_append_space(&decrypted, buffer_len(&copy));

	/* 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(&copy), buffer_len(&copy), 0);
	cipher_cleanup(&ciphercontext);
	memset(&ciphercontext, 0, sizeof(ciphercontext));
	buffer_free(&copy);

	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 RSA1 key");
		/* 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("%s: RSA_blinding_on failed", __func__);
		goto fail;
	}
	return prv;

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

static Key *
key_parse_private_pem(Buffer *blob, int type, const char *passphrase,
    char **commentp)
{
	EVP_PKEY *pk = NULL;
	Key *prv = NULL;
	char *name = "<no key>";
	BIO *bio;

	if ((bio = BIO_new_mem_buf(buffer_ptr(blob),
	    buffer_len(blob))) == NULL) {
		error("%s: BIO_new_mem_buf failed", __func__);
		return NULL;
	}
	
	pk = PEM_read_bio_PrivateKey(bio, NULL, NULL, (char *)passphrase);
	BIO_free(bio);
	if (pk == NULL) {
		debug("%s: PEM_read_PrivateKey failed", __func__);
		(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("%s: RSA_blinding_on failed", __func__);
			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;
		if ((prv->ecdsa_nid = key_ecdsa_key_to_nid(prv->ecdsa)) == -1 ||
		    key_curve_nid_to_name(prv->ecdsa_nid) == NULL ||
		    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 = "ecdsa w/o comment";
#ifdef DEBUG_PK
		if (prv != NULL && prv->ecdsa != NULL)
			key_dump_ec_key(prv->ecdsa);
#endif
	} else {
		error("%s: PEM_read_PrivateKey: mismatch or "
		    "unknown EVP_PKEY save_type %d", __func__, pk->save_type);
	}
	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;
}

Key *
key_load_private_pem(int fd, int type, const char *passphrase,
    char **commentp)
{
	Buffer buffer;
	Key *prv;

	buffer_init(&buffer);
	if (!key_load_file(fd, NULL, &buffer)) {
		buffer_free(&buffer);
		return NULL;
	}
	prv = key_parse_private_pem(&buffer, type, passphrase, commentp);
	buffer_free(&buffer);
	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;
}

static Key *
key_parse_private_type(Buffer *blob, int type, const char *passphrase,
    char **commentp)
{
	switch (type) {
	case KEY_RSA1:
		return key_parse_private_rsa1(blob, passphrase, commentp);
	case KEY_DSA:
	case KEY_ECDSA:
	case KEY_RSA:
	case KEY_UNSPEC:
		return key_parse_private_pem(blob, type, passphrase, commentp);
	default:
		error("%s: cannot parse key type %d", __func__, type);
		break;
	}
	return NULL;
}

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

	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;

	buffer_init(&buffer);
	if (!key_load_file(fd, filename, &buffer)) {
		buffer_free(&buffer);
		close(fd);
		return NULL;
	}
	close(fd);
	ret = key_parse_private_type(&buffer, type, passphrase, commentp);
	buffer_free(&buffer);
	return ret;
}

Key *
key_parse_private(Buffer *buffer, const char *filename,
    const char *passphrase, char **commentp)
{
	Key *pub, *prv;

	/* it's a SSH v1 key if the public key part is readable */
	pub = key_parse_public_rsa1(buffer, commentp);
	if (pub == NULL) {
		prv = key_parse_private_type(buffer, KEY_UNSPEC,
		    passphrase, NULL);
		/* use the filename as a comment for PEM */
		if (commentp && prv)
			*commentp = xstrdup(filename);
	} else {
		key_free(pub);
		/* key_parse_public_rsa1() has already loaded the comment */
		prv = key_parse_private_type(buffer, KEY_RSA1, passphrase,
		    NULL);
	}
	return prv;
}

Key *
key_load_private(const char *filename, const char *passphrase,
    char **commentp)
{
	Key *prv;
	Buffer buffer;
	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;
	}

	buffer_init(&buffer);
	if (!key_load_file(fd, filename, &buffer)) {
		buffer_free(&buffer);
		close(fd);
		return NULL;
	}
	close(fd);

	prv = key_parse_private(&buffer, filename, passphrase, commentp);
	buffer_free(&buffer);
	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;
			}
			/* Abort loading if this looks like a private key */
			if (strncmp(cp, "-----BEGIN", 10) == 0)
				break;
			/* Skip leading whitespace. */
			for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
				;
			if (*cp) {
				if (key_read(k, &cp) == 1) {
					cp[strcspn(cp, "\r\n")] = '\0';
					if (commentp) {
						*commentp = xstrdup(*cp ?
						    cp : 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;
}