authfile.c - third_party/openssh-portable - Git at Google

 /*

 authfile.c

 Author: Tatu Ylonen <ylo@cs.hut.fi>

 Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
                    All rights reserved

 Created: Mon Mar 27 03:52:05 1995 ylo

 This file contains functions for reading and writing identity files, and
 for reading the passphrase from the user.

 */

 #include "includes.h"
 RCSID("$Id: authfile.c,v 1.1.1.1 1999/10/27 03:42:43 damien Exp $");

 #include <openssl/bn.h>
 #include "xmalloc.h"
 #include "buffer.h"
 #include "bufaux.h"
 #include "cipher.h"
 #include "ssh.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(const char *filename, const char *passphrase,
 		 RSA *key, const char *comment)
 {
   Buffer buffer, encrypted;
   char buf[100], *cp;
   int f, i;
   CipherContext cipher;
   int cipher_type;
   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_type = SSH_CIPHER_NONE;
   else
     cipher_type = SSH_AUTHFILE_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_type);
   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(&cipher, cipher_type, passphrase, 1);
   cipher_encrypt(&cipher, (unsigned char *)cp,
 		 (unsigned char *)buffer_ptr(&buffer),
 		 buffer_len(&buffer));
   memset(&cipher, 0, sizeof(cipher));

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

   /* Write to a file. */
   f = open(filename, O_WRONLY|O_CREAT|O_TRUNC, 0600);
   if (f < 0)
     return 0;

   if (write(f, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
       buffer_len(&encrypted))
     {
       debug("Write to key file %.200s failed: %.100s", filename,
 	    strerror(errno));
       buffer_free(&encrypted);
       close(f);
       remove(filename);
       return 0;
     }
   close(f);
   buffer_free(&encrypted);
   return 1;
 }

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

   /* Read data from the file into the buffer. */
   f = open(filename, O_RDONLY);
   if (f < 0)
     return 0;

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

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

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

   /* Check that it is at least big enought to contain the ID string. */
   if (len < strlen(AUTHFILE_ID_STRING) + 1)
     {
       debug("Bad 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 < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++)
     if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i])
       {
 	debug("Bad 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);
   pub->n = BN_new();
   buffer_get_bignum(&buffer, pub->n);
   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;
 }

 /* 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. */

 int
 load_private_key(const char *filename, const char *passphrase,
 		 RSA *prv, char **comment_return)
 {
   int f, i, check1, check2, cipher_type;
   off_t len;
   Buffer buffer, decrypted;
   char *cp;
   CipherContext cipher;
   BN_CTX *ctx;
   BIGNUM *aux;
   struct stat st;

   /* Read the file into the buffer. */
   f = open(filename, O_RDONLY);
   if (f < 0)
     return 0;

   /* We assume we are called under uid of the owner of the file */
   if (fstat(f, &st) < 0 ||
       (st.st_uid != 0 && st.st_uid != getuid()) ||
       (st.st_mode & 077) != 0) {
     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;
   }

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

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

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

   /* Check that it is at least big enought to contain the ID string. */
   if (len < strlen(AUTHFILE_ID_STRING) + 1)
     {
       debug("Bad 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 < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++)
     if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i])
       {
 	debug("Bad 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. */
   if (((cipher_mask() | SSH_CIPHER_NONE | SSH_AUTHFILE_CIPHER) &
 	(1 << cipher_type)) == 0)
     {
       debug("Unsupported cipher %.100s used in key file %.200s.",
 	    cipher_name(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(&cipher, cipher_type, passphrase, 0);
   cipher_decrypt(&cipher, (unsigned char *)cp,
 		 (unsigned char *)buffer_ptr(&buffer),
 		 buffer_len(&buffer));

   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);
       BN_clear_free(prv->e);
       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;
 }
	/*

	authfile.c

	Author: Tatu Ylonen <ylo@cs.hut.fi>

	Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	All rights reserved

	Created: Mon Mar 27 03:52:05 1995 ylo

	This file contains functions for reading and writing identity files, and
	for reading the passphrase from the user.

	*/

	#include "includes.h"
	RCSID("$Id: authfile.c,v 1.1.1.1 1999/10/27 03:42:43 damien Exp $");

	#include <openssl/bn.h>
	#include "xmalloc.h"
	#include "buffer.h"
	#include "bufaux.h"
	#include "cipher.h"
	#include "ssh.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(const char filename, const char passphrase,
	RSA key, const char comment)
	{
	Buffer buffer, encrypted;
	char buf[100], *cp;
	int f, i;
	CipherContext cipher;
	int cipher_type;
	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_type = SSH_CIPHER_NONE;
	else
	cipher_type = SSH_AUTHFILE_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_type);
	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(&cipher, cipher_type, passphrase, 1);
	cipher_encrypt(&cipher, (unsigned char *)cp,
	(unsigned char *)buffer_ptr(&buffer),
	buffer_len(&buffer));
	memset(&cipher, 0, sizeof(cipher));

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

	/* Write to a file. */
	f = open(filename, O_WRONLY\|O_CREAT\|O_TRUNC, 0600);
	if (f < 0)
	return 0;

	if (write(f, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
	buffer_len(&encrypted))
	{
	debug("Write to key file %.200s failed: %.100s", filename,
	strerror(errno));
	buffer_free(&encrypted);
	close(f);
	remove(filename);
	return 0;
	}
	close(f);
	buffer_free(&encrypted);
	return 1;
	}

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

	/* Read data from the file into the buffer. */
	f = open(filename, O_RDONLY);
	if (f < 0)
	return 0;

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

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

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

	/* Check that it is at least big enought to contain the ID string. */
	if (len < strlen(AUTHFILE_ID_STRING) + 1)
	{
	debug("Bad 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 < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++)
	if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i])
	{
	debug("Bad 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);
	pub->n = BN_new();
	buffer_get_bignum(&buffer, pub->n);
	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;
	}

	/* 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. */

	int
	load_private_key(const char filename, const char passphrase,
	RSA prv, char *comment_return)
	{
	int f, i, check1, check2, cipher_type;
	off_t len;
	Buffer buffer, decrypted;
	char *cp;
	CipherContext cipher;
	BN_CTX *ctx;
	BIGNUM *aux;
	struct stat st;

	/* Read the file into the buffer. */
	f = open(filename, O_RDONLY);
	if (f < 0)
	return 0;

	/* We assume we are called under uid of the owner of the file */
	if (fstat(f, &st) < 0 \|\|
	(st.st_uid != 0 && st.st_uid != getuid()) \|\|
	(st.st_mode & 077) != 0) {
	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;
	}

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

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

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

	/* Check that it is at least big enought to contain the ID string. */
	if (len < strlen(AUTHFILE_ID_STRING) + 1)
	{
	debug("Bad 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 < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++)
	if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i])
	{
	debug("Bad 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. */
	if (((cipher_mask() \| SSH_CIPHER_NONE \| SSH_AUTHFILE_CIPHER) &
	(1 << cipher_type)) == 0)
	{
	debug("Unsupported cipher %.100s used in key file %.200s.",
	cipher_name(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(&cipher, cipher_type, passphrase, 0);
	cipher_decrypt(&cipher, (unsigned char *)cp,
	(unsigned char *)buffer_ptr(&buffer),
	buffer_len(&buffer));

	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);
	BN_clear_free(prv->e);
	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;
	}