2 * Author: Tatu Ylonen <ylo@cs.hut.fi>
3 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 * This file contains functions for reading and writing identity files, and
6 * for reading the passphrase from the user.
8 * As far as I am concerned, the code I have written for this software
9 * can be used freely for any purpose. Any derived versions of this
10 * software must be clearly marked as such, and if the derived work is
11 * incompatible with the protocol description in the RFC file, it must be
12 * called by a name other than "ssh" or "Secure Shell".
15 * Copyright (c) 2000 Markus Friedl. All rights reserved.
17 * Redistribution and use in source and binary forms, with or without
18 * modification, are permitted provided that the following conditions
20 * 1. Redistributions of source code must retain the above copyright
21 * notice, this list of conditions and the following disclaimer.
22 * 2. Redistributions in binary form must reproduce the above copyright
23 * notice, this list of conditions and the following disclaimer in the
24 * documentation and/or other materials provided with the distribution.
26 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
27 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
28 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
29 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
30 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
31 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
39 RCSID("$OpenBSD: authfile.c,v 1.39 2001/10/07 10:29:52 markus Exp $");
41 #include <openssl/err.h>
42 #include <openssl/evp.h>
43 #include <openssl/pem.h>
54 /* Version identification string for SSH v1 identity files. */
55 static const char authfile_id_string[] =
56 "SSH PRIVATE KEY FILE FORMAT 1.1\n";
59 * Saves the authentication (private) key in a file, encrypting it with
60 * passphrase. The identification of the file (lowest 64 bits of n) will
61 * precede the key to provide identification of the key without needing a
66 key_save_private_rsa1(Key *key, const char *filename, const char *passphrase,
69 Buffer buffer, encrypted;
72 CipherContext ciphercontext;
77 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
78 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
80 if (strcmp(passphrase, "") == 0)
81 cipher = cipher_by_number(SSH_CIPHER_NONE);
83 cipher = cipher_by_number(SSH_AUTHFILE_CIPHER);
85 fatal("save_private_key_rsa: bad cipher");
87 /* This buffer is used to built the secret part of the private key. */
90 /* Put checkbytes for checking passphrase validity. */
93 buf[1] = (rand >> 8) & 0xff;
96 buffer_append(&buffer, buf, 4);
99 * Store the private key (n and e will not be stored because they
100 * will be stored in plain text, and storing them also in encrypted
101 * format would just give known plaintext).
103 buffer_put_bignum(&buffer, key->rsa->d);
104 buffer_put_bignum(&buffer, key->rsa->iqmp);
105 buffer_put_bignum(&buffer, key->rsa->q); /* reverse from SSL p */
106 buffer_put_bignum(&buffer, key->rsa->p); /* reverse from SSL q */
108 /* Pad the part to be encrypted until its size is a multiple of 8. */
109 while (buffer_len(&buffer) % 8 != 0)
110 buffer_put_char(&buffer, 0);
112 /* This buffer will be used to contain the data in the file. */
113 buffer_init(&encrypted);
115 /* First store keyfile id string. */
116 for (i = 0; authfile_id_string[i]; i++)
117 buffer_put_char(&encrypted, authfile_id_string[i]);
118 buffer_put_char(&encrypted, 0);
120 /* Store cipher type. */
121 buffer_put_char(&encrypted, cipher->number);
122 buffer_put_int(&encrypted, 0); /* For future extension */
124 /* Store public key. This will be in plain text. */
125 buffer_put_int(&encrypted, BN_num_bits(key->rsa->n));
126 buffer_put_bignum(&encrypted, key->rsa->n);
127 buffer_put_bignum(&encrypted, key->rsa->e);
128 buffer_put_cstring(&encrypted, comment);
130 /* Allocate space for the private part of the key in the buffer. */
131 buffer_append_space(&encrypted, &cp, buffer_len(&buffer));
133 cipher_set_key_string(&ciphercontext, cipher, passphrase);
134 cipher_encrypt(&ciphercontext, (u_char *) cp,
135 (u_char *) buffer_ptr(&buffer), buffer_len(&buffer));
136 memset(&ciphercontext, 0, sizeof(ciphercontext));
138 /* Destroy temporary data. */
139 memset(buf, 0, sizeof(buf));
140 buffer_free(&buffer);
142 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
144 error("open %s failed: %s.", filename, strerror(errno));
147 if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
148 buffer_len(&encrypted)) {
149 error("write to key file %s failed: %s", filename,
151 buffer_free(&encrypted);
157 buffer_free(&encrypted);
161 /* save SSH v2 key in OpenSSL PEM format */
163 key_save_private_pem(Key *key, const char *filename, const char *_passphrase,
169 int len = strlen(_passphrase);
170 char *passphrase = (len > 0) ? (char *)_passphrase : NULL;
171 EVP_CIPHER *cipher = (len > 0) ? EVP_des_ede3_cbc() : NULL;
173 if (len > 0 && len <= 4) {
174 error("passphrase too short: have %d bytes, need > 4", len);
177 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
179 error("open %s failed: %s.", filename, strerror(errno));
182 fp = fdopen(fd, "w");
184 error("fdopen %s failed: %s.", filename, strerror(errno));
190 success = PEM_write_DSAPrivateKey(fp, key->dsa,
191 cipher, passphrase, len, NULL, NULL);
194 success = PEM_write_RSAPrivateKey(fp, key->rsa,
195 cipher, passphrase, len, NULL, NULL);
203 key_save_private(Key *key, const char *filename, const char *passphrase,
208 return key_save_private_rsa1(key, filename, passphrase,
213 return key_save_private_pem(key, filename, passphrase,
219 error("key_save_private: cannot save key type %d", key->type);
224 * Loads the public part of the ssh v1 key file. Returns NULL if an error was
225 * encountered (the file does not exist or is not readable), and the key
230 key_load_public_rsa1(int fd, const char *filename, char **commentp)
238 len = lseek(fd, (off_t) 0, SEEK_END);
239 lseek(fd, (off_t) 0, SEEK_SET);
241 buffer_init(&buffer);
242 buffer_append_space(&buffer, &cp, len);
244 if (read(fd, cp, (size_t) len) != (size_t) len) {
245 debug("Read from key file %.200s failed: %.100s", filename,
247 buffer_free(&buffer);
251 /* Check that it is at least big enough to contain the ID string. */
252 if (len < sizeof(authfile_id_string)) {
253 debug3("Not a RSA1 key file %.200s.", filename);
254 buffer_free(&buffer);
258 * Make sure it begins with the id string. Consume the id string
261 for (i = 0; i < sizeof(authfile_id_string); i++)
262 if (buffer_get_char(&buffer) != authfile_id_string[i]) {
263 debug3("Not a RSA1 key file %.200s.", filename);
264 buffer_free(&buffer);
267 /* Skip cipher type and reserved data. */
268 (void) buffer_get_char(&buffer); /* cipher type */
269 (void) buffer_get_int(&buffer); /* reserved */
271 /* Read the public key from the buffer. */
272 buffer_get_int(&buffer);
273 pub = key_new(KEY_RSA1);
274 buffer_get_bignum(&buffer, pub->rsa->n);
275 buffer_get_bignum(&buffer, pub->rsa->e);
277 *commentp = buffer_get_string(&buffer, NULL);
278 /* The encrypted private part is not parsed by this function. */
280 buffer_free(&buffer);
284 /* load public key from private-key file, works only for SSH v1 */
286 key_load_public_type(int type, const char *filename, char **commentp)
291 if (type == KEY_RSA1) {
292 fd = open(filename, O_RDONLY);
295 pub = key_load_public_rsa1(fd, filename, commentp);
303 * Loads the private key from the file. Returns 0 if an error is encountered
304 * (file does not exist or is not readable, or passphrase is bad). This
305 * initializes the private key.
306 * Assumes we are called under uid of the owner of the file.
310 key_load_private_rsa1(int fd, const char *filename, const char *passphrase,
313 int i, check1, check2, cipher_type;
315 Buffer buffer, decrypted;
317 CipherContext ciphercontext;
323 len = lseek(fd, (off_t) 0, SEEK_END);
324 lseek(fd, (off_t) 0, SEEK_SET);
326 buffer_init(&buffer);
327 buffer_append_space(&buffer, &cp, len);
329 if (read(fd, cp, (size_t) len) != (size_t) len) {
330 debug("Read from key file %.200s failed: %.100s", filename,
332 buffer_free(&buffer);
337 /* Check that it is at least big enough to contain the ID string. */
338 if (len < sizeof(authfile_id_string)) {
339 debug3("Not a RSA1 key file %.200s.", filename);
340 buffer_free(&buffer);
345 * Make sure it begins with the id string. Consume the id string
348 for (i = 0; i < sizeof(authfile_id_string); i++)
349 if (buffer_get_char(&buffer) != authfile_id_string[i]) {
350 debug3("Not a RSA1 key file %.200s.", filename);
351 buffer_free(&buffer);
356 /* Read cipher type. */
357 cipher_type = buffer_get_char(&buffer);
358 (void) buffer_get_int(&buffer); /* Reserved data. */
360 /* Read the public key from the buffer. */
361 buffer_get_int(&buffer);
362 prv = key_new_private(KEY_RSA1);
364 buffer_get_bignum(&buffer, prv->rsa->n);
365 buffer_get_bignum(&buffer, prv->rsa->e);
367 *commentp = buffer_get_string(&buffer, NULL);
369 xfree(buffer_get_string(&buffer, NULL));
371 /* Check that it is a supported cipher. */
372 cipher = cipher_by_number(cipher_type);
373 if (cipher == NULL) {
374 debug("Unsupported cipher %d used in key file %.200s.",
375 cipher_type, filename);
376 buffer_free(&buffer);
379 /* Initialize space for decrypted data. */
380 buffer_init(&decrypted);
381 buffer_append_space(&decrypted, &cp, buffer_len(&buffer));
383 /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
384 cipher_set_key_string(&ciphercontext, cipher, passphrase);
385 cipher_decrypt(&ciphercontext, (u_char *) cp,
386 (u_char *) buffer_ptr(&buffer), buffer_len(&buffer));
387 memset(&ciphercontext, 0, sizeof(ciphercontext));
388 buffer_free(&buffer);
390 check1 = buffer_get_char(&decrypted);
391 check2 = buffer_get_char(&decrypted);
392 if (check1 != buffer_get_char(&decrypted) ||
393 check2 != buffer_get_char(&decrypted)) {
394 if (strcmp(passphrase, "") != 0)
395 debug("Bad passphrase supplied for key file %.200s.",
397 /* Bad passphrase. */
398 buffer_free(&decrypted);
401 /* Read the rest of the private key. */
402 buffer_get_bignum(&decrypted, prv->rsa->d);
403 buffer_get_bignum(&decrypted, prv->rsa->iqmp); /* u */
404 /* in SSL and SSH v1 p and q are exchanged */
405 buffer_get_bignum(&decrypted, prv->rsa->q); /* p */
406 buffer_get_bignum(&decrypted, prv->rsa->p); /* q */
408 /* calculate p-1 and q-1 */
412 BN_sub(aux, prv->rsa->q, BN_value_one());
413 BN_mod(prv->rsa->dmq1, prv->rsa->d, aux, ctx);
415 BN_sub(aux, prv->rsa->p, BN_value_one());
416 BN_mod(prv->rsa->dmp1, prv->rsa->d, aux, ctx);
421 buffer_free(&decrypted);
434 key_load_private_pem(int fd, int type, const char *passphrase,
440 char *name = "<no key>";
442 fp = fdopen(fd, "r");
444 error("fdopen failed: %s", strerror(errno));
448 pk = PEM_read_PrivateKey(fp, NULL, NULL, (char *)passphrase);
450 debug("PEM_read_PrivateKey failed");
451 (void)ERR_get_error();
452 } else if (pk->type == EVP_PKEY_RSA &&
453 (type == KEY_UNSPEC||type==KEY_RSA)) {
454 prv = key_new(KEY_UNSPEC);
455 prv->rsa = EVP_PKEY_get1_RSA(pk);
457 name = "rsa w/o comment";
459 RSA_print_fp(stderr, prv->rsa, 8);
461 } else if (pk->type == EVP_PKEY_DSA &&
462 (type == KEY_UNSPEC||type==KEY_DSA)) {
463 prv = key_new(KEY_UNSPEC);
464 prv->dsa = EVP_PKEY_get1_DSA(pk);
466 name = "dsa w/o comment";
468 DSA_print_fp(stderr, prv->dsa, 8);
471 error("PEM_read_PrivateKey: mismatch or "
472 "unknown EVP_PKEY save_type %d", pk->save_type);
477 if (prv != NULL && commentp)
478 *commentp = xstrdup(name);
479 debug("read PEM private key done: type %s",
480 prv ? key_type(prv) : "<unknown>");
485 key_perm_ok(int fd, const char *filename)
489 if (fstat(fd, &st) < 0)
492 * if a key owned by the user is accessed, then we check the
493 * permissions of the file. if the key owned by a different user,
494 * then we don't care.
497 if (check_ntsec(filename))
499 if ((st.st_uid == getuid()) && (st.st_mode & 077) != 0) {
500 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
501 error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
502 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
503 error("Permissions 0%3.3o for '%s' are too open.",
504 st.st_mode & 0777, filename);
505 error("It is recommended that your private key files are NOT accessible by others.");
506 error("This private key will be ignored.");
513 key_load_private_type(int type, const char *filename, const char *passphrase,
518 fd = open(filename, O_RDONLY);
521 if (!key_perm_ok(fd, filename)) {
522 error("bad permissions: ignore key: %s", filename);
528 return key_load_private_rsa1(fd, filename, passphrase,
535 return key_load_private_pem(fd, type, passphrase, commentp);
546 key_load_private(const char *filename, const char *passphrase,
552 fd = open(filename, O_RDONLY);
555 if (!key_perm_ok(fd, filename)) {
556 error("bad permissions: ignore key: %s", filename);
560 pub = key_load_public_rsa1(fd, filename, commentp);
561 lseek(fd, (off_t) 0, SEEK_SET); /* rewind */
564 prv = key_load_private_pem(fd, KEY_UNSPEC, passphrase, NULL);
565 /* use the filename as a comment for PEM */
567 *commentp = xstrdup(filename);
569 /* it's a SSH v1 key if the public key part is readable */
572 prv = key_load_private_rsa1(fd, filename, passphrase, NULL);
578 key_try_load_public(Key *k, const char *filename, char **commentp)
584 f = fopen(filename, "r");
586 while (fgets(line, sizeof(line), f)) {
587 line[sizeof(line)-1] = '\0';
595 /* Skip leading whitespace. */
596 for (; *cp && (*cp == ' ' || *cp == '\t'); cp++)
599 if (key_read(k, &cp) == 1) {
601 *commentp=xstrdup(filename);
612 /* load public key from ssh v1 private or any pubkey file */
614 key_load_public(const char *filename, char **commentp)
617 char file[MAXPATHLEN];
619 pub = key_load_public_type(KEY_RSA1, filename, commentp);
622 pub = key_new(KEY_UNSPEC);
623 if (key_try_load_public(pub, filename, commentp) == 1)
625 if ((strlcpy(file, filename, sizeof file) < sizeof(file)) &&
626 (strlcat(file, ".pub", sizeof file) < sizeof(file)) &&
627 (key_try_load_public(pub, file, commentp) == 1))