[openssh.git] / authfile.c

/*

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("$Id$");

#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;
}
Commit	Line	Data
8efc0c15	1	/*
	2
	3	authfile.c
	4
	5	Author: Tatu Ylonen <ylo@cs.hut.fi>
	6
	7	Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
	8	All rights reserved
	9
	10	Created: Mon Mar 27 03:52:05 1995 ylo
	11
	12	This file contains functions for reading and writing identity files, and
	13	for reading the passphrase from the user.
	14
	15	*/
	16
	17	#include "includes.h"
	18	RCSID("$Id$");
	19
	20	#include <openssl/bn.h>
	21	#include "xmalloc.h"
	22	#include "buffer.h"
	23	#include "bufaux.h"
	24	#include "cipher.h"
	25	#include "ssh.h"
	26
	27	/* Version identification string for identity files. */
	28	#define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
	29
	30	/* Saves the authentication (private) key in a file, encrypting it with
	31	passphrase. The identification of the file (lowest 64 bits of n)
	32	will precede the key to provide identification of the key without
	33	needing a passphrase. */
	34
	35	int
	36	save_private_key(const char filename, const char passphrase,
	37	RSA key, const char comment)
	38	{
	39	Buffer buffer, encrypted;
	40	char buf[100], *cp;
	41	int f, i;
	42	CipherContext cipher;
	43	int cipher_type;
	44	u_int32_t rand;
	45
	46	/* If the passphrase is empty, use SSH_CIPHER_NONE to ease converting to
	47	another cipher; otherwise use SSH_AUTHFILE_CIPHER. */
	48	if (strcmp(passphrase, "") == 0)
	49	cipher_type = SSH_CIPHER_NONE;
	50	else
	51	cipher_type = SSH_AUTHFILE_CIPHER;
	52
	53	/* This buffer is used to built the secret part of the private key. */
	54	buffer_init(&buffer);
	55
	56	/* Put checkbytes for checking passphrase validity. */
	57	rand = arc4random();
	58	buf[0] = rand & 0xff;
	59	buf[1] = (rand >> 8) & 0xff;
	60	buf[2] = buf[0];
	61	buf[3] = buf[1];
	62	buffer_append(&buffer, buf, 4);
	63
	64	/* Store the private key (n and e will not be stored because they will
65	be stored in plain text, and storing them also in encrypted format
66	would just give known plaintext). */
67	buffer_put_bignum(&buffer, key->d);
68	buffer_put_bignum(&buffer, key->iqmp);
69	buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */
70	buffer_put_bignum(&buffer, key->p); /* reverse from SSL q */
71
72	/* Pad the part to be encrypted until its size is a multiple of 8. */
73	while (buffer_len(&buffer) % 8 != 0)
74	buffer_put_char(&buffer, 0);
75
76	/* This buffer will be used to contain the data in the file. */
77	buffer_init(&encrypted);
78
79	/* First store keyfile id string. */
80	cp = AUTHFILE_ID_STRING;
81	for (i = 0; cp[i]; i++)
82	buffer_put_char(&encrypted, cp[i]);
83	buffer_put_char(&encrypted, 0);
84
85	/* Store cipher type. */
86	buffer_put_char(&encrypted, cipher_type);
87	buffer_put_int(&encrypted, 0); /* For future extension */
88
89	/* Store public key. This will be in plain text. */
90	buffer_put_int(&encrypted, BN_num_bits(key->n));
91	buffer_put_bignum(&encrypted, key->n);
92	buffer_put_bignum(&encrypted, key->e);
93	buffer_put_string(&encrypted, comment, strlen(comment));
94
95	/* Allocate space for the private part of the key in the buffer. */
96	buffer_append_space(&encrypted, &cp, buffer_len(&buffer));
97
98	cipher_set_key_string(&cipher, cipher_type, passphrase, 1);
99	cipher_encrypt(&cipher, (unsigned char *)cp,
100	(unsigned char *)buffer_ptr(&buffer),
101	buffer_len(&buffer));
102	memset(&cipher, 0, sizeof(cipher));
103
104	/* Destroy temporary data. */
105	memset(buf, 0, sizeof(buf));
106	buffer_free(&buffer);
107
108	/* Write to a file. */
109	f = open(filename, O_WRONLY\|O_CREAT\|O_TRUNC, 0600);
110	if (f < 0)
111	return 0;
112
113	if (write(f, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
114	buffer_len(&encrypted))
115	{
116	debug("Write to key file %.200s failed: %.100s", filename,
117	strerror(errno));
118	buffer_free(&encrypted);
119	close(f);
120	remove(filename);
121	return 0;
122	}
123	close(f);
124	buffer_free(&encrypted);
125	return 1;
126	}
127
128	/* Loads the public part of the key file. Returns 0 if an error
129	was encountered (the file does not exist or is not readable), and
130	non-zero otherwise. */
131
132	int
133	load_public_key(const char filename, RSA pub,
134	char **comment_return)
135	{
136	int f, i;
137	off_t len;
138	Buffer buffer;
139	char *cp;
140
141	/* Read data from the file into the buffer. */
142	f = open(filename, O_RDONLY);
143	if (f < 0)
144	return 0;
145
146	len = lseek(f, (off_t)0, SEEK_END);
147	lseek(f, (off_t)0, SEEK_SET);
148
149	buffer_init(&buffer);
150	buffer_append_space(&buffer, &cp, len);
151
152	if (read(f, cp, (size_t)len) != (size_t)len)
153	{
154	debug("Read from key file %.200s failed: %.100s", filename,
155	strerror(errno));
156	buffer_free(&buffer);
157	close(f);
158	return 0;
159	}
160	close(f);
161
162	/* Check that it is at least big enought to contain the ID string. */
163	if (len < strlen(AUTHFILE_ID_STRING) + 1)
164	{
165	debug("Bad key file %.200s.", filename);
166	buffer_free(&buffer);
167	return 0;
168	}
169
170	/* Make sure it begins with the id string. Consume the id string from
171	the buffer. */
172	for (i = 0; i < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++)
173	if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i])
174	{
175	debug("Bad key file %.200s.", filename);
176	buffer_free(&buffer);
177	return 0;
178	}
179
180	/* Skip cipher type and reserved data. */
181	(void)buffer_get_char(&buffer); /* cipher type */
182	(void)buffer_get_int(&buffer); /* reserved */
183
184	/* Read the public key from the buffer. */
185	buffer_get_int(&buffer);
186	pub->n = BN_new();
187	buffer_get_bignum(&buffer, pub->n);
188	pub->e = BN_new();
189	buffer_get_bignum(&buffer, pub->e);
190	if (comment_return)
191	*comment_return = buffer_get_string(&buffer, NULL);
192	/* The encrypted private part is not parsed by this function. */
193
194	buffer_free(&buffer);
195
196	return 1;
197	}
198
199	/* Loads the private key from the file. Returns 0 if an error is encountered
200	(file does not exist or is not readable, or passphrase is bad).
201	This initializes the private key. */
202
203	int
204	load_private_key(const char filename, const char passphrase,
205	RSA prv, char *comment_return)
206	{
207	int f, i, check1, check2, cipher_type;
208	off_t len;
209	Buffer buffer, decrypted;
210	char *cp;
211	CipherContext cipher;
212	BN_CTX *ctx;
213	BIGNUM *aux;
214	struct stat st;
215
216	/* Read the file into the buffer. */
217	f = open(filename, O_RDONLY);
218	if (f < 0)
219	return 0;
220
221	/* We assume we are called under uid of the owner of the file */
222	if (fstat(f, &st) < 0 \|\|
223	(st.st_uid != 0 && st.st_uid != getuid()) \|\|
224	(st.st_mode & 077) != 0) {
225	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
226	error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
227	error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
228	error("Bad ownership or mode(0%3.3o) for '%s'.",
229	st.st_mode & 0777, filename);
230	error("It is recommended that your private key files are NOT accessible by others.");
231	return 0;
232	}
233
234	len = lseek(f, (off_t)0, SEEK_END);
235	lseek(f, (off_t)0, SEEK_SET);
236
237	buffer_init(&buffer);
238	buffer_append_space(&buffer, &cp, len);
239
240	if (read(f, cp, (size_t)len) != (size_t)len)
241	{
242	debug("Read from key file %.200s failed: %.100s", filename,
243	strerror(errno));
244	buffer_free(&buffer);
245	close(f);
246	return 0;
247	}
248	close(f);
249
250	/* Check that it is at least big enought to contain the ID string. */
251	if (len < strlen(AUTHFILE_ID_STRING) + 1)
252	{
253	debug("Bad key file %.200s.", filename);
254	buffer_free(&buffer);
255	return 0;
256	}
257
258	/* Make sure it begins with the id string. Consume the id string from
259	the buffer. */
260	for (i = 0; i < (unsigned int)strlen(AUTHFILE_ID_STRING) + 1; i++)
261	if (buffer_get_char(&buffer) != (unsigned char)AUTHFILE_ID_STRING[i])
262	{
263	debug("Bad key file %.200s.", filename);
264	buffer_free(&buffer);
265	return 0;
266	}
267
268	/* Read cipher type. */
269	cipher_type = buffer_get_char(&buffer);
270	(void)buffer_get_int(&buffer); /* Reserved data. */
271
272	/* Read the public key from the buffer. */
273	buffer_get_int(&buffer);
274	prv->n = BN_new();
275	buffer_get_bignum(&buffer, prv->n);
276	prv->e = BN_new();
277	buffer_get_bignum(&buffer, prv->e);
278	if (comment_return)
279	*comment_return = buffer_get_string(&buffer, NULL);
280	else
281	xfree(buffer_get_string(&buffer, NULL));
282
283	/* Check that it is a supported cipher. */
284	if (((cipher_mask() \| SSH_CIPHER_NONE \| SSH_AUTHFILE_CIPHER) &
285	(1 << cipher_type)) == 0)
286	{
287	debug("Unsupported cipher %.100s used in key file %.200s.",
288	cipher_name(cipher_type), filename);
289	buffer_free(&buffer);
290	goto fail;
291	}
292
293	/* Initialize space for decrypted data. */
294	buffer_init(&decrypted);
295	buffer_append_space(&decrypted, &cp, buffer_len(&buffer));
296
297	/* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
298	cipher_set_key_string(&cipher, cipher_type, passphrase, 0);
299	cipher_decrypt(&cipher, (unsigned char *)cp,
300	(unsigned char *)buffer_ptr(&buffer),
301	buffer_len(&buffer));
302
303	buffer_free(&buffer);
304
305	check1 = buffer_get_char(&decrypted);
306	check2 = buffer_get_char(&decrypted);
307	if (check1 != buffer_get_char(&decrypted) \|\|
308	check2 != buffer_get_char(&decrypted))
309	{
310	if (strcmp(passphrase, "") != 0)
311	debug("Bad passphrase supplied for key file %.200s.", filename);
312	/* Bad passphrase. */
313	buffer_free(&decrypted);
314	fail:
315	BN_clear_free(prv->n);
316	BN_clear_free(prv->e);
317	if (comment_return)
318	xfree(*comment_return);
319	return 0;
320	}
321
322	/* Read the rest of the private key. */
323	prv->d = BN_new();
324	buffer_get_bignum(&decrypted, prv->d);
325	prv->iqmp = BN_new();
326	buffer_get_bignum(&decrypted, prv->iqmp); /* u */
327	/* in SSL and SSH p and q are exchanged */
328	prv->q = BN_new();
329	buffer_get_bignum(&decrypted, prv->q); /* p */
330	prv->p = BN_new();
331	buffer_get_bignum(&decrypted, prv->p); /* q */
332
333	ctx = BN_CTX_new();
334	aux = BN_new();
335
336	BN_sub(aux, prv->q, BN_value_one());
337	prv->dmq1 = BN_new();
338	BN_mod(prv->dmq1, prv->d, aux, ctx);
339
340	BN_sub(aux, prv->p, BN_value_one());
341	prv->dmp1 = BN_new();
342	BN_mod(prv->dmp1, prv->d, aux, ctx);
343
344	BN_clear_free(aux);
345	BN_CTX_free(ctx);
346
347	buffer_free(&decrypted);
348
349	return 1;
350	}