authfile.c - security/openssh-library - Rivoreo Source Code Repositories

 /*
  * 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 "includes.h"
 RCSID("$OpenBSD: authfile.c,v 1.25 2001/01/21 19:05:44 markus Exp $");

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

 #include "cipher.h"
 #include "xmalloc.h"
 #include "buffer.h"
 #include "bufaux.h"
 #include "key.h"
 #include "ssh.h"
 #include "log.h"

 /* Version identification string for identity files. */
 #define 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.
  */

 int
 save_private_key_rsa1(const char *filename, const char *passphrase,
     RSA *key, const char *comment)
 {
 	Buffer buffer, encrypted;
 	char buf[100], *cp;
 	int fd, i;
 	CipherContext ciphercontext;
 	Cipher *cipher;
 	u_int32_t rand;

 	/*
 	 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
 	 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
 	 */
 	if (strcmp(passphrase, "") == 0)
 		cipher = cipher_by_number(SSH_CIPHER_NONE);
 	else
 		cipher = cipher_by_number(SSH_AUTHFILE_CIPHER);
 	if (cipher == 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. */
 	rand = arc4random();
 	buf[0] = rand & 0xff;
 	buf[1] = (rand >> 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->d);
 	buffer_put_bignum(&buffer, key->iqmp);
 	buffer_put_bignum(&buffer, key->q);	/* reverse from SSL p */
 	buffer_put_bignum(&buffer, key->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. */
 	cp = AUTHFILE_ID_STRING;
 	for (i = 0; cp[i]; i++)
 		buffer_put_char(&encrypted, cp[i]);
 	buffer_put_char(&encrypted, 0);

 	/* Store cipher type. */
 	buffer_put_char(&encrypted, cipher->number);
 	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->n));
 	buffer_put_bignum(&encrypted, key->n);
 	buffer_put_bignum(&encrypted, key->e);
 	buffer_put_string(&encrypted, comment, strlen(comment));

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

 	cipher_set_key_string(&ciphercontext, cipher, passphrase);
 	cipher_encrypt(&ciphercontext, (u_char *) cp,
 	    (u_char *) buffer_ptr(&buffer), buffer_len(&buffer));
 	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)
 		return 0;
 	if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
 	    buffer_len(&encrypted)) {
 		debug("Write to key file %.200s failed: %.100s", filename,
 		      strerror(errno));
 		buffer_free(&encrypted);
 		close(fd);
 		unlink(filename);
 		return 0;
 	}
 	close(fd);
 	buffer_free(&encrypted);
 	return 1;
 }

 /* save SSH2 key in OpenSSL PEM format */
 int
 save_private_key_ssh2(const char *filename, const char *_passphrase,
     Key *key, const char *comment)
 {
 	FILE *fp;
 	int fd;
 	int success = 0;
 	int len = strlen(_passphrase);
 	char *passphrase = (len > 0) ? (char *)_passphrase : NULL;
 	EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;

 	if (len > 0 && len <= 4) {
 		error("passphrase too short: %d bytes", len);
 		errno = 0;
 		return 0;
 	}
 	fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
 	if (fd < 0) {
 		debug("open %s failed", filename);
 		return 0;
 	}
 	fp = fdopen(fd, "w");
 	if (fp == NULL ) {
 		debug("fdopen %s failed", filename);
 		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_RSA:
 			success = PEM_write_RSAPrivateKey(fp, key->rsa,
 			    cipher, passphrase, len, NULL, NULL);
 			break;
 	}
 	fclose(fp);
 	return success;
 }

 int
 save_private_key(const char *filename, const char *passphrase, Key *key,
     const char *comment)
 {
 	switch (key->type) {
 	case KEY_RSA1:
 		return save_private_key_rsa1(filename, passphrase, key->rsa, comment);
 		break;
 	case KEY_DSA:
 	case KEY_RSA:
 		return save_private_key_ssh2(filename, passphrase, key, comment);
 		break;
 	default:
 		break;
 	}
 	return 0;
 }

 /*
  * Loads the public part of the key file.  Returns 0 if an error was
  * encountered (the file does not exist or is not readable), and non-zero
  * otherwise.
  */

 int
 load_public_key_rsa(const char *filename, RSA * pub, char **comment_return)
 {
 	int fd, i;
 	off_t len;
 	Buffer buffer;
 	char *cp;

 	fd = open(filename, O_RDONLY);
 	if (fd < 0)
 		return 0;
 	len = lseek(fd, (off_t) 0, SEEK_END);
 	lseek(fd, (off_t) 0, SEEK_SET);

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

 	if (read(fd, cp, (size_t) len) != (size_t) len) {
 		debug("Read from key file %.200s failed: %.100s", filename,
 		    strerror(errno));
 		buffer_free(&buffer);
 		close(fd);
 		return 0;
 	}
 	close(fd);

 	/* Check that it is at least big enought to contain the ID string. */
 	if (len < strlen(AUTHFILE_ID_STRING) + 1) {
 		debug3("Bad RSA1 key file %.200s.", filename);
 		buffer_free(&buffer);
 		return 0;
 	}
 	/*
 	 * Make sure it begins with the id string.  Consume the id string
 	 * from the buffer.
 	 */
 	for (i = 0; i < (u_int) strlen(AUTHFILE_ID_STRING) + 1; i++)
 		if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
 			debug3("Bad RSA1 key file %.200s.", filename);
 			buffer_free(&buffer);
 			return 0;
 		}
 	/* 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. */
 	buffer_get_int(&buffer);
 	/* XXX alloc */
 	if (pub->n == NULL)
 		pub->n = BN_new();
 	buffer_get_bignum(&buffer, pub->n);
 	/* XXX alloc */
 	if (pub->e == NULL)
 		pub->e = BN_new();
 	buffer_get_bignum(&buffer, pub->e);
 	if (comment_return)
 		*comment_return = buffer_get_string(&buffer, NULL);
 	/* The encrypted private part is not parsed by this function. */

 	buffer_free(&buffer);

 	return 1;
 }

 /* load public key from private-key file */
 int
 load_public_key(const char *filename, Key * key, char **comment_return)
 {
 	switch (key->type) {
 	case KEY_RSA1:
 		return load_public_key_rsa(filename, key->rsa, comment_return);
 		break;
 	case KEY_DSA:
 	case KEY_RSA:
 	default:
 		break;
 	}
 	return 0;
 }

 /*
  * 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.
  */

 int
 load_private_key_rsa1(int fd, const char *filename,
     const char *passphrase, RSA * prv, char **comment_return)
 {
 	int i, check1, check2, cipher_type;
 	off_t len;
 	Buffer buffer, decrypted;
 	char *cp;
 	CipherContext ciphercontext;
 	Cipher *cipher;
 	BN_CTX *ctx;
 	BIGNUM *aux;

 	len = lseek(fd, (off_t) 0, SEEK_END);
 	lseek(fd, (off_t) 0, SEEK_SET);

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

 	if (read(fd, cp, (size_t) len) != (size_t) len) {
 		debug("Read from key file %.200s failed: %.100s", filename,
 		    strerror(errno));
 		buffer_free(&buffer);
 		close(fd);
 		return 0;
 	}
 	close(fd);

 	/* Check that it is at least big enought to contain the ID string. */
 	if (len < strlen(AUTHFILE_ID_STRING) + 1) {
 		debug3("Bad RSA1 key file %.200s.", filename);
 		buffer_free(&buffer);
 		return 0;
 	}
 	/*
 	 * Make sure it begins with the id string.  Consume the id string
 	 * from the buffer.
 	 */
 	for (i = 0; i < (u_int) strlen(AUTHFILE_ID_STRING) + 1; i++)
 		if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
 			debug3("Bad RSA1 key file %.200s.", filename);
 			buffer_free(&buffer);
 			return 0;
 		}
 	/* Read cipher type. */
 	cipher_type = buffer_get_char(&buffer);
 	(void) buffer_get_int(&buffer);	/* Reserved data. */

 	/* Read the public key from the buffer. */
 	buffer_get_int(&buffer);
 	prv->n = BN_new();
 	buffer_get_bignum(&buffer, prv->n);
 	prv->e = BN_new();
 	buffer_get_bignum(&buffer, prv->e);
 	if (comment_return)
 		*comment_return = 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);
 	buffer_append_space(&decrypted, &cp, buffer_len(&buffer));

 	/* Rest of the buffer is encrypted.  Decrypt it using the passphrase. */
 	cipher_set_key_string(&ciphercontext, cipher, passphrase);
 	cipher_decrypt(&ciphercontext, (u_char *) cp,
 	    (u_char *) buffer_ptr(&buffer), buffer_len(&buffer));
 	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);
 fail:
 		BN_clear_free(prv->n);
 		prv->n = NULL;
 		BN_clear_free(prv->e);
 		prv->e = NULL;
 		if (comment_return)
 			xfree(*comment_return);
 		return 0;
 	}
 	/* Read the rest of the private key. */
 	prv->d = BN_new();
 	buffer_get_bignum(&decrypted, prv->d);
 	prv->iqmp = BN_new();
 	buffer_get_bignum(&decrypted, prv->iqmp);	/* u */
 	/* in SSL and SSH p and q are exchanged */
 	prv->q = BN_new();
 	buffer_get_bignum(&decrypted, prv->q);		/* p */
 	prv->p = BN_new();
 	buffer_get_bignum(&decrypted, prv->p);		/* q */

 	ctx = BN_CTX_new();
 	aux = BN_new();

 	BN_sub(aux, prv->q, BN_value_one());
 	prv->dmq1 = BN_new();
 	BN_mod(prv->dmq1, prv->d, aux, ctx);

 	BN_sub(aux, prv->p, BN_value_one());
 	prv->dmp1 = BN_new();
 	BN_mod(prv->dmp1, prv->d, aux, ctx);

 	BN_clear_free(aux);
 	BN_CTX_free(ctx);

 	buffer_free(&decrypted);

 	return 1;
 }

 int
 load_private_key_ssh2(int fd, const char *passphrase, Key *k, char **comment_return)
 {
 	FILE *fp;
 	int success = 0;
 	EVP_PKEY *pk = NULL;
 	char *name = "<no key>";

 	fp = fdopen(fd, "r");
 	if (fp == NULL) {
 		error("fdopen failed");
 		return 0;
 	}
 	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) {
 		/* replace k->rsa with loaded key */
 		if (k->type == KEY_RSA || k->type == KEY_UNSPEC) {
 			if (k->rsa != NULL)
 				RSA_free(k->rsa);
 			k->rsa = EVP_PKEY_get1_RSA(pk);
 			k->type = KEY_RSA;
 			name = "rsa w/o comment";
 			success = 1;
 #ifdef DEBUG_PK
 			RSA_print_fp(stderr, k->rsa, 8);
 #endif
 		}
 	} else if (pk->type == EVP_PKEY_DSA) {
 		/* replace k->dsa with loaded key */
 		if (k->type == KEY_DSA || k->type == KEY_UNSPEC) {
 			if (k->dsa != NULL)
 				DSA_free(k->dsa);
 			k->dsa = EVP_PKEY_get1_DSA(pk);
 			k->type = KEY_DSA;
 			name = "dsa w/o comment";
 #ifdef DEBUG_PK
 			DSA_print_fp(stderr, k->dsa, 8);
 #endif
 			success = 1;
 		}
 	} 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 (success && comment_return)
 		*comment_return = xstrdup(name);
 	debug("read SSH2 private key done: name %s success %d", name, success);
 	return success;
 }

 int
 load_private_key(const char *filename, const char *passphrase, Key *key,
     char **comment_return)
 {
 	int fd;
 	int ret = 0;
 	struct stat st;

 	fd = open(filename, O_RDONLY);
 	if (fd < 0)
 		return 0;

 	/* check owner and modes */
 #ifdef HAVE_CYGWIN
 	if (check_ntsec(filename))
 #endif
 	if (fstat(fd, &st) < 0 ||
 	    (st.st_uid != 0 && getuid() != 0 && st.st_uid != getuid()) ||
 	    (st.st_mode & 077) != 0) {
 		close(fd);
 		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
 		error("@         WARNING: UNPROTECTED PRIVATE KEY FILE!          @");
 		error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
 		error("Bad ownership or mode(0%3.3o) for '%s'.",
 		      st.st_mode & 0777, filename);
 		error("It is recommended that your private key files are NOT accessible by others.");
 		return 0;
 	}
 	switch (key->type) {
 	case KEY_RSA1:
 		if (key->rsa->e != NULL) {
 			BN_clear_free(key->rsa->e);
 			key->rsa->e = NULL;
 		}
 		if (key->rsa->n != NULL) {
 			BN_clear_free(key->rsa->n);
 			key->rsa->n = NULL;
 		}
 		ret = load_private_key_rsa1(fd, filename, passphrase,
 		     key->rsa, comment_return);
 		break;
 	case KEY_DSA:
 	case KEY_RSA:
 	case KEY_UNSPEC:
 		ret = load_private_key_ssh2(fd, passphrase, key, comment_return);
 	default:
 		break;
 	}
 	close(fd);
 	return ret;
 }

 int
 do_load_public_key(const char *filename, Key *k, char **commentp)
 {
 	FILE *f;
 	char line[1024];
 	char *cp;

 	f = fopen(filename, "r");
 	if (f != NULL) {
 		while (fgets(line, sizeof(line), f)) {
 			line[sizeof(line)-1] = '\0';
 			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 pubkey file */
 int
 try_load_public_key(const char *filename, Key *k, char **commentp)
 {
 	char pub[MAXPATHLEN];

 	if (do_load_public_key(filename, k, commentp) == 1)
 		return 1;
 	if (strlcpy(pub, filename, sizeof pub) >= MAXPATHLEN)
 		return 0;
 	if (strlcat(pub, ".pub", sizeof pub) >= MAXPATHLEN)
 		return 0;
 	if (do_load_public_key(pub, k, commentp) == 1)
 		return 1;
 	return 0;
 }
	/*
	* 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 "includes.h"
	RCSID("$OpenBSD: authfile.c,v 1.25 2001/01/21 19:05:44 markus Exp $");

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

	#include "cipher.h"
	#include "xmalloc.h"
	#include "buffer.h"
	#include "bufaux.h"
	#include "key.h"
	#include "ssh.h"
	#include "log.h"

	/* Version identification string for identity files. */
	#define 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.
	*/

	int
	save_private_key_rsa1(const char filename, const char passphrase,
	RSA key, const char comment)
	{
	Buffer buffer, encrypted;
	char buf[100], *cp;
	int fd, i;
	CipherContext ciphercontext;
	Cipher *cipher;
	u_int32_t rand;

	/*
	* If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
	* to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
	*/
	if (strcmp(passphrase, "") == 0)
	cipher = cipher_by_number(SSH_CIPHER_NONE);
	else
	cipher = cipher_by_number(SSH_AUTHFILE_CIPHER);
	if (cipher == 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. */
	rand = arc4random();
	buf[0] = rand & 0xff;
	buf[1] = (rand >> 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->d);
	buffer_put_bignum(&buffer, key->iqmp);
	buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */
	buffer_put_bignum(&buffer, key->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. */
	cp = AUTHFILE_ID_STRING;
	for (i = 0; cp[i]; i++)
	buffer_put_char(&encrypted, cp[i]);
	buffer_put_char(&encrypted, 0);

	/* Store cipher type. */
	buffer_put_char(&encrypted, cipher->number);
	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->n));
	buffer_put_bignum(&encrypted, key->n);
	buffer_put_bignum(&encrypted, key->e);
	buffer_put_string(&encrypted, comment, strlen(comment));

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

	cipher_set_key_string(&ciphercontext, cipher, passphrase);
	cipher_encrypt(&ciphercontext, (u_char *) cp,
	(u_char *) buffer_ptr(&buffer), buffer_len(&buffer));
	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)
	return 0;
	if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
	buffer_len(&encrypted)) {
	debug("Write to key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&encrypted);
	close(fd);
	unlink(filename);
	return 0;
	}
	close(fd);
	buffer_free(&encrypted);
	return 1;
	}

	/* save SSH2 key in OpenSSL PEM format */
	int
	save_private_key_ssh2(const char filename, const char _passphrase,
	Key key, const char comment)
	{
	FILE *fp;
	int fd;
	int success = 0;
	int len = strlen(_passphrase);
	char passphrase = (len > 0) ? (char )_passphrase : NULL;
	EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;

	if (len > 0 && len <= 4) {
	error("passphrase too short: %d bytes", len);
	errno = 0;
	return 0;
	}
	fd = open(filename, O_WRONLY \| O_CREAT \| O_TRUNC, 0600);
	if (fd < 0) {
	debug("open %s failed", filename);
	return 0;
	}
	fp = fdopen(fd, "w");
	if (fp == NULL ) {
	debug("fdopen %s failed", filename);
	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_RSA:
	success = PEM_write_RSAPrivateKey(fp, key->rsa,
	cipher, passphrase, len, NULL, NULL);
	break;
	}
	fclose(fp);
	return success;
	}

	int
	save_private_key(const char filename, const char passphrase, Key *key,
	const char *comment)
	{
	switch (key->type) {
	case KEY_RSA1:
	return save_private_key_rsa1(filename, passphrase, key->rsa, comment);
	break;
	case KEY_DSA:
	case KEY_RSA:
	return save_private_key_ssh2(filename, passphrase, key, comment);
	break;
	default:
	break;
	}
	return 0;
	}

	/*
	* Loads the public part of the key file. Returns 0 if an error was
	* encountered (the file does not exist or is not readable), and non-zero
	* otherwise.
	*/

	int
	load_public_key_rsa(const char filename, RSA pub, char **comment_return)
	{
	int fd, i;
	off_t len;
	Buffer buffer;
	char *cp;

	fd = open(filename, O_RDONLY);
	if (fd < 0)
	return 0;
	len = lseek(fd, (off_t) 0, SEEK_END);
	lseek(fd, (off_t) 0, SEEK_SET);

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

	if (read(fd, cp, (size_t) len) != (size_t) len) {
	debug("Read from key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&buffer);
	close(fd);
	return 0;
	}
	close(fd);

	/* Check that it is at least big enought to contain the ID string. */
	if (len < strlen(AUTHFILE_ID_STRING) + 1) {
	debug3("Bad RSA1 key file %.200s.", filename);
	buffer_free(&buffer);
	return 0;
	}
	/*
	* Make sure it begins with the id string. Consume the id string
	* from the buffer.
	*/
	for (i = 0; i < (u_int) strlen(AUTHFILE_ID_STRING) + 1; i++)
	if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
	debug3("Bad RSA1 key file %.200s.", filename);
	buffer_free(&buffer);
	return 0;
	}
	/* 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. */
	buffer_get_int(&buffer);
	/* XXX alloc */
	if (pub->n == NULL)
	pub->n = BN_new();
	buffer_get_bignum(&buffer, pub->n);
	/* XXX alloc */
	if (pub->e == NULL)
	pub->e = BN_new();
	buffer_get_bignum(&buffer, pub->e);
	if (comment_return)
	*comment_return = buffer_get_string(&buffer, NULL);
	/* The encrypted private part is not parsed by this function. */

	buffer_free(&buffer);

	return 1;
	}

	/* load public key from private-key file */
	int
	load_public_key(const char filename, Key key, char **comment_return)
	{
	switch (key->type) {
	case KEY_RSA1:
	return load_public_key_rsa(filename, key->rsa, comment_return);
	break;
	case KEY_DSA:
	case KEY_RSA:
	default:
	break;
	}
	return 0;
	}

	/*
	* 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.
	*/

	int
	load_private_key_rsa1(int fd, const char *filename,
	const char passphrase, RSA prv, char **comment_return)
	{
	int i, check1, check2, cipher_type;
	off_t len;
	Buffer buffer, decrypted;
	char *cp;
	CipherContext ciphercontext;
	Cipher *cipher;
	BN_CTX *ctx;
	BIGNUM *aux;

	len = lseek(fd, (off_t) 0, SEEK_END);
	lseek(fd, (off_t) 0, SEEK_SET);

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

	if (read(fd, cp, (size_t) len) != (size_t) len) {
	debug("Read from key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&buffer);
	close(fd);
	return 0;
	}
	close(fd);

	/* Check that it is at least big enought to contain the ID string. */
	if (len < strlen(AUTHFILE_ID_STRING) + 1) {
	debug3("Bad RSA1 key file %.200s.", filename);
	buffer_free(&buffer);
	return 0;
	}
	/*
	* Make sure it begins with the id string. Consume the id string
	* from the buffer.
	*/
	for (i = 0; i < (u_int) strlen(AUTHFILE_ID_STRING) + 1; i++)
	if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
	debug3("Bad RSA1 key file %.200s.", filename);
	buffer_free(&buffer);
	return 0;
	}
	/* Read cipher type. */
	cipher_type = buffer_get_char(&buffer);
	(void) buffer_get_int(&buffer); /* Reserved data. */

	/* Read the public key from the buffer. */
	buffer_get_int(&buffer);
	prv->n = BN_new();
	buffer_get_bignum(&buffer, prv->n);
	prv->e = BN_new();
	buffer_get_bignum(&buffer, prv->e);
	if (comment_return)
	*comment_return = 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);
	buffer_append_space(&decrypted, &cp, buffer_len(&buffer));

	/* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
	cipher_set_key_string(&ciphercontext, cipher, passphrase);
	cipher_decrypt(&ciphercontext, (u_char *) cp,
	(u_char *) buffer_ptr(&buffer), buffer_len(&buffer));
	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);
	fail:
	BN_clear_free(prv->n);
	prv->n = NULL;
	BN_clear_free(prv->e);
	prv->e = NULL;
	if (comment_return)
	xfree(*comment_return);
	return 0;
	}
	/* Read the rest of the private key. */
	prv->d = BN_new();
	buffer_get_bignum(&decrypted, prv->d);
	prv->iqmp = BN_new();
	buffer_get_bignum(&decrypted, prv->iqmp); /* u */
	/* in SSL and SSH p and q are exchanged */
	prv->q = BN_new();
	buffer_get_bignum(&decrypted, prv->q); /* p */
	prv->p = BN_new();
	buffer_get_bignum(&decrypted, prv->p); /* q */

	ctx = BN_CTX_new();
	aux = BN_new();

	BN_sub(aux, prv->q, BN_value_one());
	prv->dmq1 = BN_new();
	BN_mod(prv->dmq1, prv->d, aux, ctx);

	BN_sub(aux, prv->p, BN_value_one());
	prv->dmp1 = BN_new();
	BN_mod(prv->dmp1, prv->d, aux, ctx);

	BN_clear_free(aux);
	BN_CTX_free(ctx);

	buffer_free(&decrypted);

	return 1;
	}

	int
	load_private_key_ssh2(int fd, const char passphrase, Key k, char **comment_return)
	{
	FILE *fp;
	int success = 0;
	EVP_PKEY *pk = NULL;
	char *name = "<no key>";

	fp = fdopen(fd, "r");
	if (fp == NULL) {
	error("fdopen failed");
	return 0;
	}
	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) {
	/* replace k->rsa with loaded key */
	if (k->type == KEY_RSA \|\| k->type == KEY_UNSPEC) {
	if (k->rsa != NULL)
	RSA_free(k->rsa);
	k->rsa = EVP_PKEY_get1_RSA(pk);
	k->type = KEY_RSA;
	name = "rsa w/o comment";
	success = 1;
	#ifdef DEBUG_PK
	RSA_print_fp(stderr, k->rsa, 8);
	#endif
	}
	} else if (pk->type == EVP_PKEY_DSA) {
	/* replace k->dsa with loaded key */
	if (k->type == KEY_DSA \|\| k->type == KEY_UNSPEC) {
	if (k->dsa != NULL)
	DSA_free(k->dsa);
	k->dsa = EVP_PKEY_get1_DSA(pk);
	k->type = KEY_DSA;
	name = "dsa w/o comment";
	#ifdef DEBUG_PK
	DSA_print_fp(stderr, k->dsa, 8);
	#endif
	success = 1;
	}
	} 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 (success && comment_return)
	*comment_return = xstrdup(name);
	debug("read SSH2 private key done: name %s success %d", name, success);
	return success;
	}

	int
	load_private_key(const char filename, const char passphrase, Key *key,
	char **comment_return)
	{
	int fd;
	int ret = 0;
	struct stat st;

	fd = open(filename, O_RDONLY);
	if (fd < 0)
	return 0;

	/* check owner and modes */
	#ifdef HAVE_CYGWIN
	if (check_ntsec(filename))
	#endif
	if (fstat(fd, &st) < 0 \|\|
	(st.st_uid != 0 && getuid() != 0 && st.st_uid != getuid()) \|\|
	(st.st_mode & 077) != 0) {
	close(fd);
	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
	error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
	error("Bad ownership or mode(0%3.3o) for '%s'.",
	st.st_mode & 0777, filename);
	error("It is recommended that your private key files are NOT accessible by others.");
	return 0;
	}
	switch (key->type) {
	case KEY_RSA1:
	if (key->rsa->e != NULL) {
	BN_clear_free(key->rsa->e);
	key->rsa->e = NULL;
	}
	if (key->rsa->n != NULL) {
	BN_clear_free(key->rsa->n);
	key->rsa->n = NULL;
	}
	ret = load_private_key_rsa1(fd, filename, passphrase,
	key->rsa, comment_return);
	break;
	case KEY_DSA:
	case KEY_RSA:
	case KEY_UNSPEC:
	ret = load_private_key_ssh2(fd, passphrase, key, comment_return);
	default:
	break;
	}
	close(fd);
	return ret;
	}

	int
	do_load_public_key(const char filename, Key k, char **commentp)
	{
	FILE *f;
	char line[1024];
	char *cp;

	f = fopen(filename, "r");
	if (f != NULL) {
	while (fgets(line, sizeof(line), f)) {
	line[sizeof(line)-1] = '\0';
	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 pubkey file */
	int
	try_load_public_key(const char filename, Key k, char **commentp)
	{
	char pub[MAXPATHLEN];

	if (do_load_public_key(filename, k, commentp) == 1)
	return 1;
	if (strlcpy(pub, filename, sizeof pub) >= MAXPATHLEN)
	return 0;
	if (strlcat(pub, ".pub", sizeof pub) >= MAXPATHLEN)
	return 0;
	if (do_load_public_key(pub, k, commentp) == 1)
	return 1;
	return 0;
	}