5 * Author: Tatu Ylonen <ylo@cs.hut.fi>
7 * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
10 * Created: Mon Mar 27 03:52:05 1995 ylo
12 * This file contains functions for reading and writing identity files, and
13 * for reading the passphrase from the user.
20 #include <openssl/bn.h>
27 /* Version identification string for identity files. */
28 #define AUTHFILE_ID_STRING "SSH PRIVATE KEY FILE FORMAT 1.1\n"
31 * Saves the authentication (private) key in a file, encrypting it with
32 * passphrase. The identification of the file (lowest 64 bits of n) will
33 * precede the key to provide identification of the key without needing a
38 save_private_key(const char *filename, const char *passphrase,
39 RSA *key, const char *comment)
41 Buffer buffer, encrypted;
49 * If the passphrase is empty, use SSH_CIPHER_NONE to ease converting
50 * to another cipher; otherwise use SSH_AUTHFILE_CIPHER.
52 if (strcmp(passphrase, "") == 0)
53 cipher_type = SSH_CIPHER_NONE;
55 cipher_type = SSH_AUTHFILE_CIPHER;
57 /* This buffer is used to built the secret part of the private key. */
60 /* Put checkbytes for checking passphrase validity. */
63 buf[1] = (rand >> 8) & 0xff;
66 buffer_append(&buffer, buf, 4);
69 * Store the private key (n and e will not be stored because they
70 * will be stored in plain text, and storing them also in encrypted
71 * format would just give known plaintext).
73 buffer_put_bignum(&buffer, key->d);
74 buffer_put_bignum(&buffer, key->iqmp);
75 buffer_put_bignum(&buffer, key->q); /* reverse from SSL p */
76 buffer_put_bignum(&buffer, key->p); /* reverse from SSL q */
78 /* Pad the part to be encrypted until its size is a multiple of 8. */
79 while (buffer_len(&buffer) % 8 != 0)
80 buffer_put_char(&buffer, 0);
82 /* This buffer will be used to contain the data in the file. */
83 buffer_init(&encrypted);
85 /* First store keyfile id string. */
86 cp = AUTHFILE_ID_STRING;
87 for (i = 0; cp[i]; i++)
88 buffer_put_char(&encrypted, cp[i]);
89 buffer_put_char(&encrypted, 0);
91 /* Store cipher type. */
92 buffer_put_char(&encrypted, cipher_type);
93 buffer_put_int(&encrypted, 0); /* For future extension */
95 /* Store public key. This will be in plain text. */
96 buffer_put_int(&encrypted, BN_num_bits(key->n));
97 buffer_put_bignum(&encrypted, key->n);
98 buffer_put_bignum(&encrypted, key->e);
99 buffer_put_string(&encrypted, comment, strlen(comment));
101 /* Allocate space for the private part of the key in the buffer. */
102 buffer_append_space(&encrypted, &cp, buffer_len(&buffer));
104 cipher_set_key_string(&cipher, cipher_type, passphrase);
105 cipher_encrypt(&cipher, (unsigned char *) cp,
106 (unsigned char *) buffer_ptr(&buffer),
107 buffer_len(&buffer));
108 memset(&cipher, 0, sizeof(cipher));
110 /* Destroy temporary data. */
111 memset(buf, 0, sizeof(buf));
112 buffer_free(&buffer);
114 fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
117 if (write(fd, buffer_ptr(&encrypted), buffer_len(&encrypted)) !=
118 buffer_len(&encrypted)) {
119 debug("Write to key file %.200s failed: %.100s", filename,
121 buffer_free(&encrypted);
127 buffer_free(&encrypted);
132 * Loads the public part of the key file. Returns 0 if an error was
133 * encountered (the file does not exist or is not readable), and non-zero
138 load_public_key(const char *filename, RSA * pub,
139 char **comment_return)
146 fd = open(filename, O_RDONLY);
149 len = lseek(fd, (off_t) 0, SEEK_END);
150 lseek(fd, (off_t) 0, SEEK_SET);
152 buffer_init(&buffer);
153 buffer_append_space(&buffer, &cp, len);
155 if (read(fd, cp, (size_t) len) != (size_t) len) {
156 debug("Read from key file %.200s failed: %.100s", filename,
158 buffer_free(&buffer);
164 /* Check that it is at least big enought to contain the ID string. */
165 if (len < strlen(AUTHFILE_ID_STRING) + 1) {
166 debug("Bad key file %.200s.", filename);
167 buffer_free(&buffer);
171 * Make sure it begins with the id string. Consume the id string
174 for (i = 0; i < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++)
175 if (buffer_get_char(&buffer) != (u_char) AUTHFILE_ID_STRING[i]) {
176 debug("Bad key file %.200s.", filename);
177 buffer_free(&buffer);
180 /* Skip cipher type and reserved data. */
181 (void) buffer_get_char(&buffer); /* cipher type */
182 (void) buffer_get_int(&buffer); /* reserved */
184 /* Read the public key from the buffer. */
185 buffer_get_int(&buffer);
187 buffer_get_bignum(&buffer, pub->n);
189 buffer_get_bignum(&buffer, pub->e);
191 *comment_return = buffer_get_string(&buffer, NULL);
192 /* The encrypted private part is not parsed by this function. */
194 buffer_free(&buffer);
200 * Loads the private key from the file. Returns 0 if an error is encountered
201 * (file does not exist or is not readable, or passphrase is bad). This
202 * initializes the private key.
203 * Assumes we are called under uid of the owner of the file.
207 load_private_key(const char *filename, const char *passphrase,
208 RSA * prv, char **comment_return)
210 int fd, i, check1, check2, cipher_type;
212 Buffer buffer, decrypted;
214 CipherContext cipher;
219 fd = open(filename, O_RDONLY);
223 /* check owner and modes */
224 if (fstat(fd, &st) < 0 ||
225 (st.st_uid != 0 && getuid() != 0 && st.st_uid != getuid()) ||
226 (st.st_mode & 077) != 0) {
228 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
229 error("@ WARNING: UNPROTECTED PRIVATE KEY FILE! @");
230 error("@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@");
231 error("Bad ownership or mode(0%3.3o) for '%s'.",
232 st.st_mode & 0777, filename);
233 error("It is recommended that your private key files are NOT accessible by others.");
236 len = lseek(fd, (off_t) 0, SEEK_END);
237 lseek(fd, (off_t) 0, SEEK_SET);
239 buffer_init(&buffer);
240 buffer_append_space(&buffer, &cp, len);
242 if (read(fd, cp, (size_t) len) != (size_t) len) {
243 debug("Read from key file %.200s failed: %.100s", filename,
245 buffer_free(&buffer);
251 /* Check that it is at least big enought to contain the ID string. */
252 if (len < strlen(AUTHFILE_ID_STRING) + 1) {
253 debug("Bad 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 < (unsigned int) strlen(AUTHFILE_ID_STRING) + 1; i++)
262 if (buffer_get_char(&buffer) != (unsigned char) AUTHFILE_ID_STRING[i]) {
263 debug("Bad key file %.200s.", filename);
264 buffer_free(&buffer);
267 /* Read cipher type. */
268 cipher_type = buffer_get_char(&buffer);
269 (void) buffer_get_int(&buffer); /* Reserved data. */
271 /* Read the public key from the buffer. */
272 buffer_get_int(&buffer);
274 buffer_get_bignum(&buffer, prv->n);
276 buffer_get_bignum(&buffer, prv->e);
278 *comment_return = buffer_get_string(&buffer, NULL);
280 xfree(buffer_get_string(&buffer, NULL));
282 /* Check that it is a supported cipher. */
283 if (((cipher_mask1() | SSH_CIPHER_NONE | SSH_AUTHFILE_CIPHER) &
284 (1 << cipher_type)) == 0) {
285 debug("Unsupported cipher %.100s used in key file %.200s.",
286 cipher_name(cipher_type), filename);
287 buffer_free(&buffer);
290 /* Initialize space for decrypted data. */
291 buffer_init(&decrypted);
292 buffer_append_space(&decrypted, &cp, buffer_len(&buffer));
294 /* Rest of the buffer is encrypted. Decrypt it using the passphrase. */
295 cipher_set_key_string(&cipher, cipher_type, passphrase);
296 cipher_decrypt(&cipher, (unsigned char *) cp,
297 (unsigned char *) buffer_ptr(&buffer),
298 buffer_len(&buffer));
300 buffer_free(&buffer);
302 check1 = buffer_get_char(&decrypted);
303 check2 = buffer_get_char(&decrypted);
304 if (check1 != buffer_get_char(&decrypted) ||
305 check2 != buffer_get_char(&decrypted)) {
306 if (strcmp(passphrase, "") != 0)
307 debug("Bad passphrase supplied for key file %.200s.", filename);
308 /* Bad passphrase. */
309 buffer_free(&decrypted);
311 BN_clear_free(prv->n);
312 BN_clear_free(prv->e);
314 xfree(*comment_return);
317 /* Read the rest of the private key. */
319 buffer_get_bignum(&decrypted, prv->d);
320 prv->iqmp = BN_new();
321 buffer_get_bignum(&decrypted, prv->iqmp); /* u */
322 /* in SSL and SSH p and q are exchanged */
324 buffer_get_bignum(&decrypted, prv->q); /* p */
326 buffer_get_bignum(&decrypted, prv->p); /* q */
331 BN_sub(aux, prv->q, BN_value_one());
332 prv->dmq1 = BN_new();
333 BN_mod(prv->dmq1, prv->d, aux, ctx);
335 BN_sub(aux, prv->p, BN_value_one());
336 prv->dmp1 = BN_new();
337 BN_mod(prv->dmp1, prv->d, aux, ctx);
342 buffer_free(&decrypted);