9dda6459 |
1 | /* |
2 | * Code for PuTTY to import and export private key files in other |
3 | * SSH clients' formats. |
4 | */ |
5 | |
6 | #include <stdio.h> |
7 | #include <stdlib.h> |
8 | #include <assert.h> |
9 | #include <ctype.h> |
10 | |
11 | #include "ssh.h" |
12 | #include "misc.h" |
13 | |
14 | #define PUT_32BIT(cp, value) do { \ |
15 | (cp)[3] = (value); \ |
16 | (cp)[2] = (value) >> 8; \ |
17 | (cp)[1] = (value) >> 16; \ |
18 | (cp)[0] = (value) >> 24; } while (0) |
19 | |
20 | #define GET_32BIT(cp) \ |
21 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
22 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
23 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
24 | ((unsigned long)(unsigned char)(cp)[3])) |
25 | |
26 | int openssh_encrypted(char *filename); |
27 | struct ssh2_userkey *openssh_read(char *filename, char *passphrase); |
d23a9b21 |
28 | int openssh_write(char *filename, struct ssh2_userkey *key, char *passphrase); |
9dda6459 |
29 | |
7b4ef1ae |
30 | int sshcom_encrypted(char *filename, char **comment); |
31 | struct ssh2_userkey *sshcom_read(char *filename, char *passphrase); |
32 | |
9dda6459 |
33 | /* |
34 | * Given a key type, determine whether we know how to import it. |
35 | */ |
36 | int import_possible(int type) |
37 | { |
38 | if (type == SSH_KEYTYPE_OPENSSH) |
39 | return 1; |
7b4ef1ae |
40 | if (type == SSH_KEYTYPE_SSHCOM) |
41 | return 1; |
9dda6459 |
42 | return 0; |
43 | } |
44 | |
45 | /* |
46 | * Given a key type, determine what native key type |
47 | * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once |
48 | * we've imported it. |
49 | */ |
50 | int import_target_type(int type) |
51 | { |
52 | /* |
53 | * There are no known foreign SSH1 key formats. |
54 | */ |
55 | return SSH_KEYTYPE_SSH2; |
56 | } |
57 | |
58 | /* |
59 | * Determine whether a foreign key is encrypted. |
60 | */ |
61 | int import_encrypted(char *filename, int type, char **comment) |
62 | { |
63 | if (type == SSH_KEYTYPE_OPENSSH) { |
64 | *comment = filename; /* OpenSSH doesn't do key comments */ |
65 | return openssh_encrypted(filename); |
66 | } |
7b4ef1ae |
67 | if (type == SSH_KEYTYPE_SSHCOM) { |
68 | return sshcom_encrypted(filename, comment); |
69 | } |
9dda6459 |
70 | return 0; |
71 | } |
72 | |
73 | /* |
74 | * Import an SSH1 key. |
75 | */ |
76 | int import_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase) |
77 | { |
78 | return 0; |
79 | } |
80 | |
81 | /* |
82 | * Import an SSH2 key. |
83 | */ |
84 | struct ssh2_userkey *import_ssh2(char *filename, int type, char *passphrase) |
85 | { |
86 | if (type == SSH_KEYTYPE_OPENSSH) |
87 | return openssh_read(filename, passphrase); |
7b4ef1ae |
88 | if (type == SSH_KEYTYPE_SSHCOM) |
89 | return sshcom_read(filename, passphrase); |
9dda6459 |
90 | return NULL; |
91 | } |
92 | |
4801c01c |
93 | /* |
94 | * Export an SSH1 key. |
95 | */ |
96 | int export_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase) |
97 | { |
98 | return 0; |
99 | } |
100 | |
101 | /* |
102 | * Export an SSH2 key. |
103 | */ |
104 | int export_ssh2(char *filename, int type, |
105 | struct ssh2_userkey *key, char *passphrase) |
106 | { |
4801c01c |
107 | if (type == SSH_KEYTYPE_OPENSSH) |
108 | return openssh_write(filename, key, passphrase); |
d23a9b21 |
109 | #if 0 |
4801c01c |
110 | if (type == SSH_KEYTYPE_SSHCOM) |
111 | return sshcom_write(filename, key, passphrase); |
112 | #endif |
113 | return 0; |
114 | } |
115 | |
9dda6459 |
116 | /* ---------------------------------------------------------------------- |
117 | * Helper routines. (The base64 ones are defined in sshpubk.c.) |
118 | */ |
119 | |
120 | #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ |
121 | ((c) >= 'a' && (c) <= 'z') || \ |
122 | ((c) >= '0' && (c) <= '9') || \ |
123 | (c) == '+' || (c) == '/' || (c) == '=' \ |
124 | ) |
125 | |
126 | extern int base64_decode_atom(char *atom, unsigned char *out); |
127 | extern int base64_lines(int datalen); |
128 | extern void base64_encode_atom(unsigned char *data, int n, char *out); |
d23a9b21 |
129 | extern void base64_encode(FILE *fp, unsigned char *data, int datalen); |
9dda6459 |
130 | |
131 | /* |
132 | * Read an ASN.1/BER identifier and length pair. |
133 | * |
134 | * Flags are a combination of the #defines listed below. |
135 | * |
136 | * Returns -1 if unsuccessful; otherwise returns the number of |
137 | * bytes used out of the source data. |
138 | */ |
139 | |
140 | /* ASN.1 tag classes. */ |
141 | #define ASN1_CLASS_UNIVERSAL (0 << 6) |
142 | #define ASN1_CLASS_APPLICATION (1 << 6) |
143 | #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6) |
144 | #define ASN1_CLASS_PRIVATE (3 << 6) |
145 | #define ASN1_CLASS_MASK (3 << 6) |
146 | |
147 | /* Primitive versus constructed bit. */ |
148 | #define ASN1_CONSTRUCTED (1 << 5) |
149 | |
150 | int ber_read_id_len(void *source, int sourcelen, |
151 | int *id, int *length, int *flags) |
152 | { |
153 | unsigned char *p = (unsigned char *) source; |
154 | |
155 | if (sourcelen == 0) |
156 | return -1; |
157 | |
158 | *flags = (*p & 0xE0); |
159 | if ((*p & 0x1F) == 0x1F) { |
160 | *id = 0; |
161 | while (*p & 0x80) { |
162 | *id = (*id << 7) | (*p & 0x7F); |
163 | p++, sourcelen--; |
164 | if (sourcelen == 0) |
165 | return -1; |
166 | } |
167 | *id = (*id << 7) | (*p & 0x7F); |
168 | p++, sourcelen--; |
169 | } else { |
170 | *id = *p & 0x1F; |
171 | p++, sourcelen--; |
172 | } |
173 | |
174 | if (sourcelen == 0) |
175 | return -1; |
176 | |
177 | if (*p & 0x80) { |
178 | int n = *p & 0x7F; |
179 | p++, sourcelen--; |
180 | if (sourcelen < n) |
181 | return -1; |
182 | *length = 0; |
183 | while (n--) |
184 | *length = (*length << 8) | (*p++); |
185 | sourcelen -= n; |
186 | } else { |
187 | *length = *p; |
188 | p++, sourcelen--; |
189 | } |
190 | |
191 | return p - (unsigned char *) source; |
192 | } |
193 | |
d23a9b21 |
194 | /* |
195 | * Write an ASN.1/BER identifier and length pair. Returns the |
196 | * number of bytes consumed. Assumes dest contains enough space. |
197 | * Will avoid writing anything if dest is NULL, but still return |
198 | * amount of space required. |
199 | */ |
200 | int ber_write_id_len(void *dest, int id, int length, int flags) |
201 | { |
202 | unsigned char *d = (unsigned char *)dest; |
203 | int len = 0; |
204 | |
205 | if (id <= 30) { |
206 | /* |
207 | * Identifier is one byte. |
208 | */ |
209 | len++; |
210 | if (d) *d++ = id | flags; |
211 | } else { |
212 | int n; |
213 | /* |
214 | * Identifier is multiple bytes: the first byte is 11111 |
215 | * plus the flags, and subsequent bytes encode the value of |
216 | * the identifier, 7 bits at a time, with the top bit of |
217 | * each byte 1 except the last one which is 0. |
218 | */ |
219 | len++; |
220 | if (d) *d++ = 0x1F | flags; |
221 | for (n = 1; (id >> (7*n)) > 0; n++) |
222 | continue; /* count the bytes */ |
223 | while (n--) { |
224 | len++; |
225 | if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F); |
226 | } |
227 | } |
228 | |
229 | if (length < 128) { |
230 | /* |
231 | * Length is one byte. |
232 | */ |
233 | len++; |
234 | if (d) *d++ = length; |
235 | } else { |
236 | int n; |
237 | /* |
238 | * Length is multiple bytes. The first is 0x80 plus the |
239 | * number of subsequent bytes, and the subsequent bytes |
240 | * encode the actual length. |
241 | */ |
242 | for (n = 1; (length >> (8*n)) > 0; n++) |
243 | continue; /* count the bytes */ |
244 | len++; |
245 | if (d) *d++ = 0x80 | n; |
246 | while (n--) { |
247 | len++; |
248 | if (d) *d++ = (length >> (8*n)) & 0xFF; |
249 | } |
250 | } |
251 | |
252 | return len; |
253 | } |
254 | |
7b4ef1ae |
255 | static int put_string(void *target, void *data, int len) |
256 | { |
257 | unsigned char *d = (unsigned char *)target; |
258 | |
259 | PUT_32BIT(d, len); |
260 | memcpy(d+4, data, len); |
261 | return len+4; |
262 | } |
263 | |
264 | static int put_mp(void *target, void *data, int len) |
265 | { |
266 | unsigned char *d = (unsigned char *)target; |
267 | unsigned char *i = (unsigned char *)data; |
268 | |
269 | if (*i & 0x80) { |
270 | PUT_32BIT(d, len+1); |
271 | d[4] = 0; |
272 | memcpy(d+5, data, len); |
273 | return len+5; |
274 | } else { |
275 | PUT_32BIT(d, len); |
276 | memcpy(d+4, data, len); |
277 | return len+4; |
278 | } |
279 | } |
280 | |
d23a9b21 |
281 | /* Simple structure to point to an mp-int within a blob. */ |
282 | struct mpint_pos { void *start; int bytes; }; |
283 | |
284 | int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret) |
285 | { |
286 | int bytes; |
287 | unsigned char *d = (unsigned char *) data; |
288 | |
289 | if (len < 4) |
290 | goto error; |
291 | bytes = GET_32BIT(d); |
292 | if (len < 4+bytes) |
293 | goto error; |
294 | |
295 | ret->start = d + 4; |
296 | ret->bytes = bytes; |
297 | return bytes+4; |
298 | |
299 | error: |
300 | ret->start = NULL; |
301 | ret->bytes = -1; |
302 | return len; /* ensure further calls fail as well */ |
303 | } |
304 | |
9dda6459 |
305 | /* ---------------------------------------------------------------------- |
d23a9b21 |
306 | * Code to read and write OpenSSH private keys. |
9dda6459 |
307 | */ |
308 | |
309 | enum { OSSH_DSA, OSSH_RSA }; |
310 | struct openssh_key { |
311 | int type; |
312 | int encrypted; |
313 | char iv[32]; |
314 | unsigned char *keyblob; |
315 | int keyblob_len, keyblob_size; |
316 | }; |
317 | |
318 | struct openssh_key *load_openssh_key(char *filename) |
319 | { |
320 | struct openssh_key *ret; |
321 | FILE *fp; |
322 | char buffer[256]; |
323 | char *errmsg, *p; |
324 | int headers_done; |
ee5c1422 |
325 | char base64_bit[4]; |
326 | int base64_chars = 0; |
9dda6459 |
327 | |
328 | ret = smalloc(sizeof(*ret)); |
329 | ret->keyblob = NULL; |
330 | ret->keyblob_len = ret->keyblob_size = 0; |
331 | ret->encrypted = 0; |
332 | memset(ret->iv, 0, sizeof(ret->iv)); |
333 | |
334 | fp = fopen(filename, "r"); |
335 | if (!fp) { |
336 | errmsg = "Unable to open key file"; |
337 | goto error; |
338 | } |
339 | if (!fgets(buffer, sizeof(buffer), fp) || |
340 | 0 != strncmp(buffer, "-----BEGIN ", 11) || |
341 | 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) { |
342 | errmsg = "File does not begin with OpenSSH key header"; |
343 | goto error; |
344 | } |
345 | if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n")) |
346 | ret->type = OSSH_RSA; |
347 | else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n")) |
348 | ret->type = OSSH_DSA; |
349 | else { |
350 | errmsg = "Unrecognised key type"; |
351 | goto error; |
352 | } |
353 | |
354 | headers_done = 0; |
355 | while (1) { |
356 | if (!fgets(buffer, sizeof(buffer), fp)) { |
357 | errmsg = "Unexpected end of file"; |
358 | goto error; |
359 | } |
360 | if (0 == strncmp(buffer, "-----END ", 9) && |
361 | 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) |
362 | break; /* done */ |
363 | if ((p = strchr(buffer, ':')) != NULL) { |
364 | if (headers_done) { |
365 | errmsg = "Header found in body of key data"; |
366 | goto error; |
367 | } |
368 | *p++ = '\0'; |
369 | while (*p && isspace((unsigned char)*p)) p++; |
370 | if (!strcmp(buffer, "Proc-Type")) { |
371 | if (p[0] != '4' || p[1] != ',') { |
372 | errmsg = "Proc-Type is not 4 (only 4 is supported)"; |
373 | goto error; |
374 | } |
375 | p += 2; |
376 | if (!strcmp(p, "ENCRYPTED\n")) |
377 | ret->encrypted = 1; |
378 | } else if (!strcmp(buffer, "DEK-Info")) { |
379 | int i, j; |
380 | |
381 | if (strncmp(p, "DES-EDE3-CBC,", 13)) { |
382 | errmsg = "Ciphers other than DES-EDE3-CBC not supported"; |
383 | goto error; |
384 | } |
385 | p += 13; |
386 | for (i = 0; i < 8; i++) { |
387 | if (1 != sscanf(p, "%2x", &j)) |
388 | break; |
389 | ret->iv[i] = j; |
390 | p += 2; |
391 | } |
392 | if (i < 8) { |
393 | errmsg = "Expected 16-digit iv in DEK-Info"; |
394 | goto error; |
395 | } |
396 | } |
397 | } else { |
398 | headers_done = 1; |
399 | |
400 | p = buffer; |
ee5c1422 |
401 | while (isbase64(*p)) { |
402 | base64_bit[base64_chars++] = *p; |
403 | if (base64_chars == 4) { |
404 | unsigned char out[3]; |
405 | int len; |
9dda6459 |
406 | |
ee5c1422 |
407 | base64_chars = 0; |
9dda6459 |
408 | |
ee5c1422 |
409 | len = base64_decode_atom(base64_bit, out); |
9dda6459 |
410 | |
ee5c1422 |
411 | if (len <= 0) { |
412 | errmsg = "Invalid base64 encoding"; |
413 | goto error; |
414 | } |
415 | |
416 | if (ret->keyblob_len + len > ret->keyblob_size) { |
417 | ret->keyblob_size = ret->keyblob_len + len + 256; |
418 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
419 | } |
9dda6459 |
420 | |
ee5c1422 |
421 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
422 | ret->keyblob_len += len; |
9dda6459 |
423 | |
ee5c1422 |
424 | memset(out, 0, sizeof(out)); |
425 | } |
9dda6459 |
426 | |
ee5c1422 |
427 | p++; |
9dda6459 |
428 | } |
429 | } |
430 | } |
431 | |
432 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
433 | errmsg = "Key body not present"; |
434 | goto error; |
435 | } |
436 | |
437 | if (ret->encrypted && ret->keyblob_len % 8 != 0) { |
438 | errmsg = "Encrypted key blob is not a multiple of cipher block size"; |
439 | goto error; |
440 | } |
441 | |
ee5c1422 |
442 | memset(buffer, 0, sizeof(buffer)); |
443 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
444 | return ret; |
445 | |
446 | error: |
ee5c1422 |
447 | memset(buffer, 0, sizeof(buffer)); |
448 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
449 | if (ret) { |
ee5c1422 |
450 | if (ret->keyblob) { |
451 | memset(ret->keyblob, 0, ret->keyblob_size); |
452 | sfree(ret->keyblob); |
453 | } |
454 | memset(&ret, 0, sizeof(ret)); |
9dda6459 |
455 | sfree(ret); |
456 | } |
457 | return NULL; |
458 | } |
459 | |
460 | int openssh_encrypted(char *filename) |
461 | { |
462 | struct openssh_key *key = load_openssh_key(filename); |
463 | int ret; |
464 | |
465 | if (!key) |
466 | return 0; |
467 | ret = key->encrypted; |
ee5c1422 |
468 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
469 | sfree(key->keyblob); |
ee5c1422 |
470 | memset(&key, 0, sizeof(key)); |
9dda6459 |
471 | sfree(key); |
472 | return ret; |
473 | } |
474 | |
475 | struct ssh2_userkey *openssh_read(char *filename, char *passphrase) |
476 | { |
477 | struct openssh_key *key = load_openssh_key(filename); |
478 | struct ssh2_userkey *retkey; |
479 | unsigned char *p; |
480 | int ret, id, len, flags; |
481 | int i, num_integers; |
482 | struct ssh2_userkey *retval = NULL; |
483 | char *errmsg; |
484 | unsigned char *blob; |
ee5c1422 |
485 | int blobsize, blobptr, privptr; |
9dda6459 |
486 | char *modptr; |
487 | int modlen; |
488 | |
489 | if (!key) |
490 | return NULL; |
491 | |
492 | if (key->encrypted) { |
493 | /* |
494 | * Derive encryption key from passphrase and iv/salt: |
495 | * |
496 | * - let block A equal MD5(passphrase || iv) |
497 | * - let block B equal MD5(A || passphrase || iv) |
498 | * - block C would be MD5(B || passphrase || iv) and so on |
499 | * - encryption key is the first N bytes of A || B |
500 | */ |
501 | struct MD5Context md5c; |
502 | unsigned char keybuf[32]; |
503 | |
504 | MD5Init(&md5c); |
505 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
506 | MD5Update(&md5c, key->iv, 8); |
507 | MD5Final(keybuf, &md5c); |
508 | |
509 | MD5Init(&md5c); |
510 | MD5Update(&md5c, keybuf, 16); |
511 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
512 | MD5Update(&md5c, key->iv, 8); |
513 | MD5Final(keybuf+16, &md5c); |
514 | |
515 | /* |
516 | * Now decrypt the key blob. |
517 | */ |
518 | des3_decrypt_pubkey_ossh(keybuf, key->iv, |
519 | key->keyblob, key->keyblob_len); |
ee5c1422 |
520 | |
521 | memset(&md5c, 0, sizeof(md5c)); |
522 | memset(keybuf, 0, sizeof(keybuf)); |
9dda6459 |
523 | } |
524 | |
525 | /* |
526 | * Now we have a decrypted key blob, which contains an ASN.1 |
527 | * encoded private key. We must now untangle the ASN.1. |
528 | * |
529 | * We expect the whole key blob to be formatted as a SEQUENCE |
530 | * (0x30 followed by a length code indicating that the rest of |
531 | * the blob is part of the sequence). Within that SEQUENCE we |
532 | * expect to see a bunch of INTEGERs. What those integers mean |
533 | * depends on the key type: |
534 | * |
535 | * - For RSA, we expect the integers to be 0, n, e, d, p, q, |
536 | * dmp1, dmq1, iqmp in that order. (The last three are d mod |
537 | * (p-1), d mod (q-1), inverse of q mod p respectively.) |
538 | * |
539 | * - For DSA, we expect them to be 0, p, q, g, y, x in that |
540 | * order. |
541 | */ |
542 | |
543 | p = key->keyblob; |
544 | |
545 | /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ |
546 | ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); |
547 | p += ret; |
548 | if (ret < 0 || id != 16) { |
549 | errmsg = "ASN.1 decoding failure"; |
550 | retval = SSH2_WRONG_PASSPHRASE; |
551 | goto error; |
552 | } |
553 | |
554 | /* Expect a load of INTEGERs. */ |
555 | if (key->type == OSSH_RSA) |
556 | num_integers = 9; |
557 | else if (key->type == OSSH_DSA) |
558 | num_integers = 6; |
559 | |
560 | /* |
561 | * Space to create key blob in. |
562 | */ |
ee5c1422 |
563 | blobsize = 256+key->keyblob_len; |
564 | blob = smalloc(blobsize); |
9dda6459 |
565 | PUT_32BIT(blob, 7); |
566 | if (key->type == OSSH_DSA) |
567 | memcpy(blob+4, "ssh-dss", 7); |
568 | else if (key->type == OSSH_RSA) |
569 | memcpy(blob+4, "ssh-rsa", 7); |
570 | blobptr = 4+7; |
571 | privptr = -1; |
572 | |
573 | for (i = 0; i < num_integers; i++) { |
574 | ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, |
575 | &id, &len, &flags); |
576 | p += ret; |
577 | if (ret < 0 || id != 2 || |
578 | key->keyblob+key->keyblob_len-p < len) { |
579 | errmsg = "ASN.1 decoding failure"; |
580 | goto error; |
581 | } |
582 | |
583 | if (i == 0) { |
584 | /* |
585 | * The first integer should be zero always (I think |
586 | * this is some sort of version indication). |
587 | */ |
588 | if (len != 1 || p[0] != 0) { |
589 | errmsg = "Version number mismatch"; |
590 | goto error; |
591 | } |
592 | } else if (key->type == OSSH_RSA) { |
593 | /* |
594 | * Integers 1 and 2 go into the public blob but in the |
595 | * opposite order; integers 3, 4, 5 and 8 go into the |
596 | * private blob. The other two (6 and 7) are ignored. |
597 | */ |
598 | if (i == 1) { |
599 | /* Save the details for after we deal with number 2. */ |
600 | modptr = p; |
601 | modlen = len; |
602 | } else if (i != 6 && i != 7) { |
603 | PUT_32BIT(blob+blobptr, len); |
604 | memcpy(blob+blobptr+4, p, len); |
605 | blobptr += 4+len; |
606 | if (i == 2) { |
607 | PUT_32BIT(blob+blobptr, modlen); |
608 | memcpy(blob+blobptr+4, modptr, modlen); |
609 | blobptr += 4+modlen; |
610 | privptr = blobptr; |
611 | } |
612 | } |
613 | } else if (key->type == OSSH_DSA) { |
614 | /* |
615 | * Integers 1-4 go into the public blob; integer 5 goes |
616 | * into the private blob. |
617 | */ |
618 | PUT_32BIT(blob+blobptr, len); |
619 | memcpy(blob+blobptr+4, p, len); |
620 | blobptr += 4+len; |
621 | if (i == 4) |
622 | privptr = blobptr; |
623 | } |
624 | |
625 | /* Skip past the number. */ |
626 | p += len; |
627 | } |
628 | |
629 | /* |
630 | * Now put together the actual key. Simplest way to do this is |
631 | * to assemble our own key blobs and feed them to the createkey |
632 | * functions; this is a bit faffy but it does mean we get all |
633 | * the sanity checks for free. |
634 | */ |
635 | assert(privptr > 0); /* should have bombed by now if not */ |
636 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
637 | retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss); |
638 | retkey->data = retkey->alg->createkey(blob, privptr, |
639 | blob+privptr, blobptr-privptr); |
640 | if (!retkey->data) { |
641 | sfree(retkey); |
642 | errmsg = "unable to create key data structure"; |
643 | goto error; |
644 | } |
645 | |
646 | retkey->comment = dupstr("imported-openssh-key"); |
ee5c1422 |
647 | errmsg = NULL; /* no error */ |
648 | retval = retkey; |
9dda6459 |
649 | |
650 | error: |
ee5c1422 |
651 | if (blob) { |
652 | memset(blob, 0, blobsize); |
653 | sfree(blob); |
654 | } |
655 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
656 | sfree(key->keyblob); |
ee5c1422 |
657 | memset(&key, 0, sizeof(key)); |
9dda6459 |
658 | sfree(key); |
659 | return retval; |
660 | } |
7b4ef1ae |
661 | |
d23a9b21 |
662 | int openssh_write(char *filename, struct ssh2_userkey *key, char *passphrase) |
663 | { |
664 | unsigned char *pubblob, *privblob, *spareblob; |
665 | int publen, privlen, sparelen; |
666 | unsigned char *outblob; |
667 | int outlen; |
668 | struct mpint_pos numbers[9]; |
669 | int nnumbers, pos, len, seqlen, i; |
670 | char *header, *footer; |
671 | char zero[1]; |
672 | unsigned char iv[8]; |
673 | int ret = 0; |
674 | FILE *fp; |
675 | |
676 | /* |
677 | * Fetch the key blobs. |
678 | */ |
679 | pubblob = key->alg->public_blob(key->data, &publen); |
680 | privblob = key->alg->private_blob(key->data, &privlen); |
681 | spareblob = outblob = NULL; |
682 | |
683 | /* |
684 | * Find the sequence of integers to be encoded into the OpenSSH |
685 | * key blob, and also decide on the header line. |
686 | */ |
687 | if (key->alg == &ssh_rsa) { |
688 | int pos; |
689 | struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1; |
690 | Bignum bd, bp, bq, bdmp1, bdmq1; |
691 | |
692 | pos = 4 + GET_32BIT(pubblob); |
693 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
694 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
695 | pos = 0; |
696 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
697 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
698 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
699 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
700 | |
701 | assert(e.start && iqmp.start); /* can't go wrong */ |
702 | |
703 | /* We also need d mod (p-1) and d mod (q-1). */ |
704 | bd = bignum_from_bytes(d.start, d.bytes); |
705 | bp = bignum_from_bytes(p.start, p.bytes); |
706 | bq = bignum_from_bytes(q.start, q.bytes); |
707 | decbn(bp); |
708 | decbn(bq); |
709 | bdmp1 = bigmod(bd, bp); |
710 | bdmq1 = bigmod(bd, bq); |
711 | freebn(bd); |
712 | freebn(bp); |
713 | freebn(bq); |
714 | |
715 | dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8; |
716 | dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8; |
717 | sparelen = dmp1.bytes + dmq1.bytes; |
718 | spareblob = smalloc(sparelen); |
719 | dmp1.start = spareblob; |
720 | dmq1.start = spareblob + dmp1.bytes; |
721 | for (i = 0; i < dmp1.bytes; i++) |
722 | spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i); |
723 | for (i = 0; i < dmq1.bytes; i++) |
724 | spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i); |
725 | freebn(bdmp1); |
726 | freebn(bdmq1); |
727 | |
728 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
729 | numbers[1] = n; |
730 | numbers[2] = e; |
731 | numbers[3] = d; |
732 | numbers[4] = p; |
733 | numbers[5] = q; |
734 | numbers[6] = dmp1; |
735 | numbers[7] = dmq1; |
736 | numbers[8] = iqmp; |
737 | |
738 | nnumbers = 9; |
739 | header = "-----BEGIN RSA PRIVATE KEY-----\n"; |
740 | footer = "-----END RSA PRIVATE KEY-----\n"; |
741 | } else if (key->alg == &ssh_dss) { |
742 | int pos; |
743 | struct mpint_pos p, q, g, y, x; |
744 | |
745 | pos = 4 + GET_32BIT(pubblob); |
746 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
747 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
748 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
749 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
750 | pos = 0; |
751 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
752 | |
753 | assert(y.start && x.start); /* can't go wrong */ |
754 | |
755 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
756 | numbers[1] = p; |
757 | numbers[2] = q; |
758 | numbers[3] = g; |
759 | numbers[4] = y; |
760 | numbers[5] = x; |
761 | |
762 | nnumbers = 6; |
763 | header = "-----BEGIN DSA PRIVATE KEY-----\n"; |
764 | footer = "-----END DSA PRIVATE KEY-----\n"; |
765 | } else { |
766 | assert(0); /* zoinks! */ |
767 | } |
768 | |
769 | /* |
770 | * Now count up the total size of the ASN.1 encoded integers, |
771 | * so as to determine the length of the containing SEQUENCE. |
772 | */ |
773 | len = 0; |
774 | for (i = 0; i < nnumbers; i++) { |
775 | len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); |
776 | len += numbers[i].bytes; |
777 | } |
778 | seqlen = len; |
779 | /* Now add on the SEQUENCE header. */ |
780 | len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); |
781 | /* And round up to the cipher block size. */ |
782 | if (passphrase) |
783 | len = (len+7) &~ 7; |
784 | |
785 | /* |
786 | * Now we know how big outblob needs to be. Allocate it. |
787 | */ |
788 | outlen = len; |
789 | outblob = smalloc(outlen); |
790 | |
791 | /* |
792 | * And write the data into it. |
793 | */ |
794 | pos = 0; |
795 | pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); |
796 | for (i = 0; i < nnumbers; i++) { |
797 | pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); |
798 | memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); |
799 | pos += numbers[i].bytes; |
800 | } |
801 | while (pos < outlen) { |
802 | outblob[pos++] = random_byte(); |
803 | } |
804 | |
805 | /* |
806 | * Encrypt the key. |
807 | */ |
808 | if (passphrase) { |
809 | /* |
810 | * Invent an iv. Then derive encryption key from passphrase |
811 | * and iv/salt: |
812 | * |
813 | * - let block A equal MD5(passphrase || iv) |
814 | * - let block B equal MD5(A || passphrase || iv) |
815 | * - block C would be MD5(B || passphrase || iv) and so on |
816 | * - encryption key is the first N bytes of A || B |
817 | */ |
818 | struct MD5Context md5c; |
819 | unsigned char keybuf[32]; |
820 | |
821 | for (i = 0; i < 8; i++) iv[i] = random_byte(); |
822 | |
823 | MD5Init(&md5c); |
824 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
825 | MD5Update(&md5c, iv, 8); |
826 | MD5Final(keybuf, &md5c); |
827 | |
828 | MD5Init(&md5c); |
829 | MD5Update(&md5c, keybuf, 16); |
830 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
831 | MD5Update(&md5c, iv, 8); |
832 | MD5Final(keybuf+16, &md5c); |
833 | |
834 | /* |
835 | * Now encrypt the key blob. |
836 | */ |
837 | des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen); |
838 | |
839 | memset(&md5c, 0, sizeof(md5c)); |
840 | memset(keybuf, 0, sizeof(keybuf)); |
841 | } |
842 | |
843 | /* |
844 | * And save it. We'll use Unix line endings just in case it's |
845 | * subsequently transferred in binary mode. |
846 | */ |
847 | fp = fopen(filename, "wb"); /* ensure Unix line endings */ |
848 | if (!fp) |
849 | goto error; |
850 | fputs(header, fp); |
851 | if (passphrase) { |
852 | fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,"); |
853 | for (i = 0; i < 8; i++) |
854 | fprintf(fp, "%02X", iv[i]); |
855 | fprintf(fp, "\n\n"); |
856 | } |
857 | base64_encode(fp, outblob, outlen); |
858 | fputs(footer, fp); |
859 | fclose(fp); |
860 | ret = 1; |
861 | |
862 | error: |
863 | if (outblob) { |
864 | memset(outblob, 0, outlen); |
865 | sfree(outblob); |
866 | } |
867 | if (spareblob) { |
868 | memset(spareblob, 0, sparelen); |
869 | sfree(spareblob); |
870 | } |
871 | if (privblob) { |
872 | memset(privblob, 0, privlen); |
873 | sfree(privblob); |
874 | } |
875 | if (pubblob) { |
876 | memset(pubblob, 0, publen); |
877 | sfree(pubblob); |
878 | } |
879 | return ret; |
880 | } |
881 | |
7b4ef1ae |
882 | /* ---------------------------------------------------------------------- |
883 | * Code to read ssh.com private keys. |
884 | */ |
885 | |
886 | /* |
887 | * The format of the base64 blob is largely ssh2-packet-formatted, |
888 | * except that mpints are a bit different: they're more like the |
889 | * old ssh1 mpint. You have a 32-bit bit count N, followed by |
890 | * (N+7)/8 bytes of data. |
891 | * |
892 | * So. The blob contains: |
893 | * |
894 | * - uint32 0x3f6ff9eb (magic number) |
895 | * - uint32 size (total blob size) |
896 | * - string key-type (see below) |
897 | * - string cipher-type (tells you if key is encrypted) |
898 | * - string encrypted-blob |
899 | * |
900 | * (The first size field includes the size field itself and the |
901 | * magic number before it. All other size fields are ordinary ssh2 |
902 | * strings, so the size field indicates how much data is to |
903 | * _follow_.) |
904 | * |
905 | * The encrypted blob, once decrypted, contains a single string |
906 | * which in turn contains the payload. (This allows padding to be |
907 | * added after that string while still making it clear where the |
908 | * real payload ends. Also it probably makes for a reasonable |
909 | * decryption check.) |
910 | * |
911 | * The payload blob, for an RSA key, contains: |
912 | * - mpint e |
913 | * - mpint d |
914 | * - mpint n (yes, the public and private stuff is intermixed) |
915 | * - mpint u (presumably inverse of p mod q) |
916 | * - mpint p (p is the smaller prime) |
917 | * - mpint q (q is the larger) |
918 | * |
919 | * For a DSA key, the payload blob contains: |
920 | * - uint32 0 |
921 | * - mpint p |
922 | * - mpint g |
923 | * - mpint q |
924 | * - mpint y |
925 | * - mpint x |
926 | * |
927 | * Alternatively, if the parameters are `predefined', that |
928 | * (0,p,g,q) sequence can be replaced by a uint32 1 and a string |
929 | * containing some predefined parameter specification. *shudder*, |
930 | * but I doubt we'll encounter this in real life. |
931 | * |
932 | * The key type strings are ghastly. The RSA key I looked at had a |
933 | * type string of |
934 | * |
935 | * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}' |
936 | * |
937 | * and the DSA key wasn't much better: |
938 | * |
939 | * `dl-modp{sign{dsa-nist-sha1},dh{plain}}' |
940 | * |
941 | * It isn't clear that these will always be the same. I think it |
942 | * might be wise just to look at the `if-modn{sign{rsa' and |
943 | * `dl-modp{sign{dsa' prefixes. |
944 | * |
945 | * Finally, the encryption. The cipher-type string appears to be |
946 | * either `none' or `3des-cbc'. Looks as if this is SSH2-style |
947 | * 3des-cbc (i.e. outer cbc rather than inner). The key is created |
948 | * from the passphrase by means of yet another hashing faff: |
949 | * |
950 | * - first 16 bytes are MD5(passphrase) |
951 | * - next 16 bytes are MD5(passphrase || first 16 bytes) |
952 | * - if there were more, they'd be MD5(passphrase || first 32), |
953 | * and so on. |
954 | */ |
955 | |
956 | struct sshcom_key { |
957 | char comment[256]; /* allowing any length is overkill */ |
958 | unsigned char *keyblob; |
959 | int keyblob_len, keyblob_size; |
960 | }; |
961 | |
962 | struct sshcom_key *load_sshcom_key(char *filename) |
963 | { |
964 | struct sshcom_key *ret; |
965 | FILE *fp; |
966 | char buffer[256]; |
967 | int len; |
968 | char *errmsg, *p; |
969 | int headers_done; |
970 | char base64_bit[4]; |
971 | int base64_chars = 0; |
972 | |
973 | ret = smalloc(sizeof(*ret)); |
974 | ret->comment[0] = '\0'; |
975 | ret->keyblob = NULL; |
976 | ret->keyblob_len = ret->keyblob_size = 0; |
977 | |
978 | fp = fopen(filename, "r"); |
979 | if (!fp) { |
980 | errmsg = "Unable to open key file"; |
981 | goto error; |
982 | } |
983 | if (!fgets(buffer, sizeof(buffer), fp) || |
984 | 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { |
985 | errmsg = "File does not begin with ssh.com key header"; |
986 | goto error; |
987 | } |
988 | |
989 | headers_done = 0; |
990 | while (1) { |
991 | if (!fgets(buffer, sizeof(buffer), fp)) { |
992 | errmsg = "Unexpected end of file"; |
993 | goto error; |
994 | } |
995 | if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) |
996 | break; /* done */ |
997 | if ((p = strchr(buffer, ':')) != NULL) { |
998 | if (headers_done) { |
999 | errmsg = "Header found in body of key data"; |
1000 | goto error; |
1001 | } |
1002 | *p++ = '\0'; |
1003 | while (*p && isspace((unsigned char)*p)) p++; |
1004 | /* |
1005 | * Header lines can end in a trailing backslash for |
1006 | * continuation. |
1007 | */ |
1008 | while ((len = strlen(p)) > sizeof(buffer) - (p-buffer) -1 || |
1009 | p[len-1] != '\n' || p[len-2] == '\\') { |
1010 | if (len > (p-buffer) + sizeof(buffer)-2) { |
1011 | errmsg = "Header line too long to deal with"; |
1012 | goto error; |
1013 | } |
1014 | if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { |
1015 | errmsg = "Unexpected end of file"; |
1016 | goto error; |
1017 | } |
1018 | } |
1019 | p[strcspn(p, "\n")] = '\0'; |
1020 | if (!strcmp(buffer, "Comment")) { |
1021 | /* Strip quotes in comment if present. */ |
1022 | if (p[0] == '"' && p[strlen(p)-1] == '"') { |
1023 | p++; |
1024 | p[strlen(p)-1] = '\0'; |
1025 | } |
1026 | strncpy(ret->comment, p, sizeof(ret->comment)); |
1027 | ret->comment[sizeof(ret->comment)-1] = '\0'; |
1028 | } |
1029 | } else { |
1030 | headers_done = 1; |
1031 | |
1032 | p = buffer; |
1033 | while (isbase64(*p)) { |
1034 | base64_bit[base64_chars++] = *p; |
1035 | if (base64_chars == 4) { |
1036 | unsigned char out[3]; |
1037 | |
1038 | base64_chars = 0; |
1039 | |
1040 | len = base64_decode_atom(base64_bit, out); |
1041 | |
1042 | if (len <= 0) { |
1043 | errmsg = "Invalid base64 encoding"; |
1044 | goto error; |
1045 | } |
1046 | |
1047 | if (ret->keyblob_len + len > ret->keyblob_size) { |
1048 | ret->keyblob_size = ret->keyblob_len + len + 256; |
1049 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
1050 | } |
1051 | |
1052 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
1053 | ret->keyblob_len += len; |
1054 | } |
1055 | |
1056 | p++; |
1057 | } |
1058 | } |
1059 | } |
1060 | |
1061 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
1062 | errmsg = "Key body not present"; |
1063 | goto error; |
1064 | } |
1065 | |
1066 | return ret; |
1067 | |
1068 | error: |
1069 | if (ret) { |
ee5c1422 |
1070 | if (ret->keyblob) { |
1071 | memset(ret->keyblob, 0, ret->keyblob_size); |
1072 | sfree(ret->keyblob); |
1073 | } |
1074 | memset(&ret, 0, sizeof(ret)); |
7b4ef1ae |
1075 | sfree(ret); |
1076 | } |
1077 | return NULL; |
1078 | } |
1079 | |
1080 | int sshcom_encrypted(char *filename, char **comment) |
1081 | { |
1082 | struct sshcom_key *key = load_sshcom_key(filename); |
1083 | int pos, len, answer; |
1084 | |
1085 | *comment = NULL; |
1086 | if (!key) |
1087 | return 0; |
1088 | |
1089 | /* |
1090 | * Check magic number. |
1091 | */ |
1092 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) |
1093 | return 0; /* key is invalid */ |
1094 | |
1095 | /* |
1096 | * Find the cipher-type string. |
1097 | */ |
1098 | answer = 0; |
1099 | pos = 8; |
1100 | if (key->keyblob_len < pos+4) |
1101 | goto done; /* key is far too short */ |
1102 | pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ |
1103 | if (key->keyblob_len < pos+4) |
1104 | goto done; /* key is far too short */ |
1105 | len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ |
1106 | if (key->keyblob_len < pos+4+len) |
1107 | goto done; /* cipher type string is incomplete */ |
1108 | if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) |
1109 | answer = 1; |
1110 | |
1111 | done: |
1112 | *comment = dupstr(key->comment); |
ee5c1422 |
1113 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1114 | sfree(key->keyblob); |
ee5c1422 |
1115 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1116 | sfree(key); |
1117 | return answer; |
1118 | } |
1119 | |
7b4ef1ae |
1120 | int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) |
1121 | { |
1122 | int bits; |
1123 | int bytes; |
1124 | unsigned char *d = (unsigned char *) data; |
1125 | |
1126 | if (len < 4) |
1127 | goto error; |
1128 | bits = GET_32BIT(d); |
1129 | |
1130 | bytes = (bits + 7) / 8; |
1131 | if (len < 4+bytes) |
1132 | goto error; |
1133 | |
1134 | ret->start = d + 4; |
1135 | ret->bytes = bytes; |
1136 | return bytes+4; |
1137 | |
1138 | error: |
1139 | ret->start = NULL; |
1140 | ret->bytes = -1; |
1141 | return len; /* ensure further calls fail as well */ |
1142 | } |
1143 | |
1144 | struct ssh2_userkey *sshcom_read(char *filename, char *passphrase) |
1145 | { |
1146 | struct sshcom_key *key = load_sshcom_key(filename); |
1147 | char *errmsg; |
1148 | int pos, len; |
1149 | const char prefix_rsa[] = "if-modn{sign{rsa"; |
1150 | const char prefix_dsa[] = "dl-modp{sign{dsa"; |
1151 | enum { RSA, DSA } type; |
1152 | int encrypted; |
1153 | char *ciphertext; |
1154 | int cipherlen; |
1155 | struct ssh2_userkey *ret = NULL, *retkey; |
1156 | const struct ssh_signkey *alg; |
1157 | unsigned char *blob = NULL; |
ee5c1422 |
1158 | int blobsize, publen, privlen; |
7b4ef1ae |
1159 | |
1160 | if (!key) |
1161 | return NULL; |
1162 | |
1163 | /* |
1164 | * Check magic number. |
1165 | */ |
1166 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) { |
1167 | errmsg = "Key does not begin with magic number"; |
1168 | goto error; |
1169 | } |
1170 | |
1171 | /* |
1172 | * Determine the key type. |
1173 | */ |
1174 | pos = 8; |
1175 | if (key->keyblob_len < pos+4 || |
1176 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1177 | errmsg = "Key blob does not contain a key type string"; |
1178 | goto error; |
1179 | } |
1180 | if (len > sizeof(prefix_rsa) - 1 && |
1181 | !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { |
1182 | type = RSA; |
1183 | } else if (len > sizeof(prefix_dsa) - 1 && |
1184 | !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { |
1185 | type = DSA; |
1186 | } else { |
1187 | errmsg = "Key is of unknown type"; |
1188 | goto error; |
1189 | } |
1190 | pos += 4+len; |
1191 | |
1192 | /* |
1193 | * Determine the cipher type. |
1194 | */ |
1195 | if (key->keyblob_len < pos+4 || |
1196 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1197 | errmsg = "Key blob does not contain a cipher type string"; |
1198 | goto error; |
1199 | } |
1200 | if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) |
1201 | encrypted = 0; |
1202 | else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) |
1203 | encrypted = 1; |
1204 | else { |
1205 | errmsg = "Key encryption is of unknown type"; |
1206 | goto error; |
1207 | } |
1208 | pos += 4+len; |
1209 | |
1210 | /* |
1211 | * Get hold of the encrypted part of the key. |
1212 | */ |
1213 | if (key->keyblob_len < pos+4 || |
1214 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1215 | errmsg = "Key blob does not contain actual key data"; |
1216 | goto error; |
1217 | } |
1218 | ciphertext = key->keyblob + pos + 4; |
1219 | cipherlen = len; |
1220 | if (cipherlen == 0) { |
1221 | errmsg = "Length of key data is zero"; |
1222 | goto error; |
1223 | } |
1224 | |
1225 | /* |
1226 | * Decrypt it if necessary. |
1227 | */ |
1228 | if (encrypted) { |
1229 | /* |
1230 | * Derive encryption key from passphrase and iv/salt: |
1231 | * |
1232 | * - let block A equal MD5(passphrase) |
1233 | * - let block B equal MD5(passphrase || A) |
1234 | * - block C would be MD5(passphrase || A || B) and so on |
1235 | * - encryption key is the first N bytes of A || B |
1236 | */ |
1237 | struct MD5Context md5c; |
1238 | unsigned char keybuf[32], iv[8]; |
1239 | |
1240 | if (cipherlen % 8 != 0) { |
1241 | errmsg = "Encrypted part of key is not a multiple of cipher block" |
1242 | " size"; |
1243 | goto error; |
1244 | } |
1245 | |
1246 | MD5Init(&md5c); |
1247 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
1248 | MD5Final(keybuf, &md5c); |
1249 | |
1250 | MD5Init(&md5c); |
1251 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
1252 | MD5Update(&md5c, keybuf, 16); |
1253 | MD5Final(keybuf+16, &md5c); |
1254 | |
1255 | /* |
1256 | * Now decrypt the key blob. |
1257 | */ |
ee5c1422 |
1258 | memset(iv, 0, sizeof(iv)); |
7b4ef1ae |
1259 | des3_decrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen); |
1260 | |
ee5c1422 |
1261 | memset(&md5c, 0, sizeof(md5c)); |
1262 | memset(keybuf, 0, sizeof(keybuf)); |
1263 | |
7b4ef1ae |
1264 | /* |
1265 | * Hereafter we return WRONG_PASSPHRASE for any parsing |
ee5c1422 |
1266 | * error. (But only if we've just tried to decrypt it! |
1267 | * Returning WRONG_PASSPHRASE for an unencrypted key is |
1268 | * automatic doom.) |
7b4ef1ae |
1269 | */ |
1270 | if (encrypted) |
1271 | ret = SSH2_WRONG_PASSPHRASE; |
1272 | } |
1273 | |
1274 | /* |
1275 | * Strip away the containing string to get to the real meat. |
1276 | */ |
1277 | len = GET_32BIT(ciphertext); |
1278 | if (len > cipherlen-4) { |
1279 | errmsg = "containing string was ill-formed"; |
1280 | goto error; |
1281 | } |
1282 | ciphertext += 4; |
1283 | cipherlen = len; |
1284 | |
1285 | /* |
1286 | * Now we break down into RSA versus DSA. In either case we'll |
1287 | * construct public and private blobs in our own format, and |
1288 | * end up feeding them to alg->createkey(). |
1289 | */ |
ee5c1422 |
1290 | blobsize = cipherlen + 256; |
1291 | blob = smalloc(blobsize); |
7b4ef1ae |
1292 | privlen = 0; |
1293 | if (type == RSA) { |
1294 | struct mpint_pos n, e, d, u, p, q; |
1295 | int pos = 0; |
1296 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); |
1297 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); |
1298 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); |
1299 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); |
1300 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
1301 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1302 | if (!q.start) { |
1303 | errmsg = "key data did not contain six integers"; |
1304 | goto error; |
1305 | } |
1306 | |
1307 | alg = &ssh_rsa; |
1308 | pos = 0; |
1309 | pos += put_string(blob+pos, "ssh-rsa", 7); |
1310 | pos += put_mp(blob+pos, e.start, e.bytes); |
1311 | pos += put_mp(blob+pos, n.start, n.bytes); |
1312 | publen = pos; |
1313 | pos += put_string(blob+pos, d.start, d.bytes); |
1314 | pos += put_mp(blob+pos, q.start, q.bytes); |
1315 | pos += put_mp(blob+pos, p.start, p.bytes); |
1316 | pos += put_mp(blob+pos, u.start, u.bytes); |
1317 | privlen = pos - publen; |
1318 | } else if (type == DSA) { |
1319 | struct mpint_pos p, q, g, x, y; |
1320 | int pos = 4; |
1321 | if (GET_32BIT(ciphertext) != 0) { |
1322 | errmsg = "predefined DSA parameters not supported"; |
1323 | goto error; |
1324 | } |
1325 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
1326 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); |
1327 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1328 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); |
1329 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); |
1330 | if (!x.start) { |
1331 | errmsg = "key data did not contain five integers"; |
1332 | goto error; |
1333 | } |
1334 | |
1335 | alg = &ssh_dss; |
1336 | pos = 0; |
1337 | pos += put_string(blob+pos, "ssh-dss", 7); |
1338 | pos += put_mp(blob+pos, p.start, p.bytes); |
1339 | pos += put_mp(blob+pos, q.start, q.bytes); |
1340 | pos += put_mp(blob+pos, g.start, g.bytes); |
1341 | pos += put_mp(blob+pos, y.start, y.bytes); |
1342 | publen = pos; |
1343 | pos += put_mp(blob+pos, x.start, x.bytes); |
1344 | privlen = pos - publen; |
1345 | } |
1346 | |
1347 | assert(privlen > 0); /* should have bombed by now if not */ |
1348 | |
1349 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
1350 | retkey->alg = alg; |
1351 | retkey->data = alg->createkey(blob, publen, blob+publen, privlen); |
1352 | if (!retkey->data) { |
1353 | sfree(retkey); |
1354 | errmsg = "unable to create key data structure"; |
1355 | goto error; |
1356 | } |
1357 | retkey->comment = dupstr(key->comment); |
1358 | |
1359 | errmsg = NULL; /* no error */ |
1360 | ret = retkey; |
1361 | |
1362 | error: |
ee5c1422 |
1363 | if (blob) { |
1364 | memset(blob, 0, blobsize); |
1365 | sfree(blob); |
1366 | } |
1367 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1368 | sfree(key->keyblob); |
ee5c1422 |
1369 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1370 | sfree(key); |
1371 | return ret; |
1372 | } |