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); |
28 | |
7b4ef1ae |
29 | int sshcom_encrypted(char *filename, char **comment); |
30 | struct ssh2_userkey *sshcom_read(char *filename, char *passphrase); |
31 | |
9dda6459 |
32 | /* |
33 | * Given a key type, determine whether we know how to import it. |
34 | */ |
35 | int import_possible(int type) |
36 | { |
37 | if (type == SSH_KEYTYPE_OPENSSH) |
38 | return 1; |
7b4ef1ae |
39 | if (type == SSH_KEYTYPE_SSHCOM) |
40 | return 1; |
9dda6459 |
41 | return 0; |
42 | } |
43 | |
44 | /* |
45 | * Given a key type, determine what native key type |
46 | * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once |
47 | * we've imported it. |
48 | */ |
49 | int import_target_type(int type) |
50 | { |
51 | /* |
52 | * There are no known foreign SSH1 key formats. |
53 | */ |
54 | return SSH_KEYTYPE_SSH2; |
55 | } |
56 | |
57 | /* |
58 | * Determine whether a foreign key is encrypted. |
59 | */ |
60 | int import_encrypted(char *filename, int type, char **comment) |
61 | { |
62 | if (type == SSH_KEYTYPE_OPENSSH) { |
63 | *comment = filename; /* OpenSSH doesn't do key comments */ |
64 | return openssh_encrypted(filename); |
65 | } |
7b4ef1ae |
66 | if (type == SSH_KEYTYPE_SSHCOM) { |
67 | return sshcom_encrypted(filename, comment); |
68 | } |
9dda6459 |
69 | return 0; |
70 | } |
71 | |
72 | /* |
73 | * Import an SSH1 key. |
74 | */ |
75 | int import_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase) |
76 | { |
77 | return 0; |
78 | } |
79 | |
80 | /* |
81 | * Import an SSH2 key. |
82 | */ |
83 | struct ssh2_userkey *import_ssh2(char *filename, int type, char *passphrase) |
84 | { |
85 | if (type == SSH_KEYTYPE_OPENSSH) |
86 | return openssh_read(filename, passphrase); |
7b4ef1ae |
87 | if (type == SSH_KEYTYPE_SSHCOM) |
88 | return sshcom_read(filename, passphrase); |
9dda6459 |
89 | return NULL; |
90 | } |
91 | |
92 | /* ---------------------------------------------------------------------- |
93 | * Helper routines. (The base64 ones are defined in sshpubk.c.) |
94 | */ |
95 | |
96 | #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ |
97 | ((c) >= 'a' && (c) <= 'z') || \ |
98 | ((c) >= '0' && (c) <= '9') || \ |
99 | (c) == '+' || (c) == '/' || (c) == '=' \ |
100 | ) |
101 | |
102 | extern int base64_decode_atom(char *atom, unsigned char *out); |
103 | extern int base64_lines(int datalen); |
104 | extern void base64_encode_atom(unsigned char *data, int n, char *out); |
105 | extern void base64_encode(FILE * fp, unsigned char *data, int datalen); |
106 | |
107 | /* |
108 | * Read an ASN.1/BER identifier and length pair. |
109 | * |
110 | * Flags are a combination of the #defines listed below. |
111 | * |
112 | * Returns -1 if unsuccessful; otherwise returns the number of |
113 | * bytes used out of the source data. |
114 | */ |
115 | |
116 | /* ASN.1 tag classes. */ |
117 | #define ASN1_CLASS_UNIVERSAL (0 << 6) |
118 | #define ASN1_CLASS_APPLICATION (1 << 6) |
119 | #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6) |
120 | #define ASN1_CLASS_PRIVATE (3 << 6) |
121 | #define ASN1_CLASS_MASK (3 << 6) |
122 | |
123 | /* Primitive versus constructed bit. */ |
124 | #define ASN1_CONSTRUCTED (1 << 5) |
125 | |
126 | int ber_read_id_len(void *source, int sourcelen, |
127 | int *id, int *length, int *flags) |
128 | { |
129 | unsigned char *p = (unsigned char *) source; |
130 | |
131 | if (sourcelen == 0) |
132 | return -1; |
133 | |
134 | *flags = (*p & 0xE0); |
135 | if ((*p & 0x1F) == 0x1F) { |
136 | *id = 0; |
137 | while (*p & 0x80) { |
138 | *id = (*id << 7) | (*p & 0x7F); |
139 | p++, sourcelen--; |
140 | if (sourcelen == 0) |
141 | return -1; |
142 | } |
143 | *id = (*id << 7) | (*p & 0x7F); |
144 | p++, sourcelen--; |
145 | } else { |
146 | *id = *p & 0x1F; |
147 | p++, sourcelen--; |
148 | } |
149 | |
150 | if (sourcelen == 0) |
151 | return -1; |
152 | |
153 | if (*p & 0x80) { |
154 | int n = *p & 0x7F; |
155 | p++, sourcelen--; |
156 | if (sourcelen < n) |
157 | return -1; |
158 | *length = 0; |
159 | while (n--) |
160 | *length = (*length << 8) | (*p++); |
161 | sourcelen -= n; |
162 | } else { |
163 | *length = *p; |
164 | p++, sourcelen--; |
165 | } |
166 | |
167 | return p - (unsigned char *) source; |
168 | } |
169 | |
7b4ef1ae |
170 | static int put_string(void *target, void *data, int len) |
171 | { |
172 | unsigned char *d = (unsigned char *)target; |
173 | |
174 | PUT_32BIT(d, len); |
175 | memcpy(d+4, data, len); |
176 | return len+4; |
177 | } |
178 | |
179 | static int put_mp(void *target, void *data, int len) |
180 | { |
181 | unsigned char *d = (unsigned char *)target; |
182 | unsigned char *i = (unsigned char *)data; |
183 | |
184 | if (*i & 0x80) { |
185 | PUT_32BIT(d, len+1); |
186 | d[4] = 0; |
187 | memcpy(d+5, data, len); |
188 | return len+5; |
189 | } else { |
190 | PUT_32BIT(d, len); |
191 | memcpy(d+4, data, len); |
192 | return len+4; |
193 | } |
194 | } |
195 | |
9dda6459 |
196 | /* ---------------------------------------------------------------------- |
197 | * Code to read OpenSSH private keys. |
198 | */ |
199 | |
200 | enum { OSSH_DSA, OSSH_RSA }; |
201 | struct openssh_key { |
202 | int type; |
203 | int encrypted; |
204 | char iv[32]; |
205 | unsigned char *keyblob; |
206 | int keyblob_len, keyblob_size; |
207 | }; |
208 | |
209 | struct openssh_key *load_openssh_key(char *filename) |
210 | { |
211 | struct openssh_key *ret; |
212 | FILE *fp; |
213 | char buffer[256]; |
214 | char *errmsg, *p; |
215 | int headers_done; |
ee5c1422 |
216 | char base64_bit[4]; |
217 | int base64_chars = 0; |
9dda6459 |
218 | |
219 | ret = smalloc(sizeof(*ret)); |
220 | ret->keyblob = NULL; |
221 | ret->keyblob_len = ret->keyblob_size = 0; |
222 | ret->encrypted = 0; |
223 | memset(ret->iv, 0, sizeof(ret->iv)); |
224 | |
225 | fp = fopen(filename, "r"); |
226 | if (!fp) { |
227 | errmsg = "Unable to open key file"; |
228 | goto error; |
229 | } |
230 | if (!fgets(buffer, sizeof(buffer), fp) || |
231 | 0 != strncmp(buffer, "-----BEGIN ", 11) || |
232 | 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) { |
233 | errmsg = "File does not begin with OpenSSH key header"; |
234 | goto error; |
235 | } |
236 | if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n")) |
237 | ret->type = OSSH_RSA; |
238 | else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n")) |
239 | ret->type = OSSH_DSA; |
240 | else { |
241 | errmsg = "Unrecognised key type"; |
242 | goto error; |
243 | } |
244 | |
245 | headers_done = 0; |
246 | while (1) { |
247 | if (!fgets(buffer, sizeof(buffer), fp)) { |
248 | errmsg = "Unexpected end of file"; |
249 | goto error; |
250 | } |
251 | if (0 == strncmp(buffer, "-----END ", 9) && |
252 | 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) |
253 | break; /* done */ |
254 | if ((p = strchr(buffer, ':')) != NULL) { |
255 | if (headers_done) { |
256 | errmsg = "Header found in body of key data"; |
257 | goto error; |
258 | } |
259 | *p++ = '\0'; |
260 | while (*p && isspace((unsigned char)*p)) p++; |
261 | if (!strcmp(buffer, "Proc-Type")) { |
262 | if (p[0] != '4' || p[1] != ',') { |
263 | errmsg = "Proc-Type is not 4 (only 4 is supported)"; |
264 | goto error; |
265 | } |
266 | p += 2; |
267 | if (!strcmp(p, "ENCRYPTED\n")) |
268 | ret->encrypted = 1; |
269 | } else if (!strcmp(buffer, "DEK-Info")) { |
270 | int i, j; |
271 | |
272 | if (strncmp(p, "DES-EDE3-CBC,", 13)) { |
273 | errmsg = "Ciphers other than DES-EDE3-CBC not supported"; |
274 | goto error; |
275 | } |
276 | p += 13; |
277 | for (i = 0; i < 8; i++) { |
278 | if (1 != sscanf(p, "%2x", &j)) |
279 | break; |
280 | ret->iv[i] = j; |
281 | p += 2; |
282 | } |
283 | if (i < 8) { |
284 | errmsg = "Expected 16-digit iv in DEK-Info"; |
285 | goto error; |
286 | } |
287 | } |
288 | } else { |
289 | headers_done = 1; |
290 | |
291 | p = buffer; |
ee5c1422 |
292 | while (isbase64(*p)) { |
293 | base64_bit[base64_chars++] = *p; |
294 | if (base64_chars == 4) { |
295 | unsigned char out[3]; |
296 | int len; |
9dda6459 |
297 | |
ee5c1422 |
298 | base64_chars = 0; |
9dda6459 |
299 | |
ee5c1422 |
300 | len = base64_decode_atom(base64_bit, out); |
9dda6459 |
301 | |
ee5c1422 |
302 | if (len <= 0) { |
303 | errmsg = "Invalid base64 encoding"; |
304 | goto error; |
305 | } |
306 | |
307 | if (ret->keyblob_len + len > ret->keyblob_size) { |
308 | ret->keyblob_size = ret->keyblob_len + len + 256; |
309 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
310 | } |
9dda6459 |
311 | |
ee5c1422 |
312 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
313 | ret->keyblob_len += len; |
9dda6459 |
314 | |
ee5c1422 |
315 | memset(out, 0, sizeof(out)); |
316 | } |
9dda6459 |
317 | |
ee5c1422 |
318 | p++; |
9dda6459 |
319 | } |
320 | } |
321 | } |
322 | |
323 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
324 | errmsg = "Key body not present"; |
325 | goto error; |
326 | } |
327 | |
328 | if (ret->encrypted && ret->keyblob_len % 8 != 0) { |
329 | errmsg = "Encrypted key blob is not a multiple of cipher block size"; |
330 | goto error; |
331 | } |
332 | |
ee5c1422 |
333 | memset(buffer, 0, sizeof(buffer)); |
334 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
335 | return ret; |
336 | |
337 | error: |
ee5c1422 |
338 | memset(buffer, 0, sizeof(buffer)); |
339 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
340 | if (ret) { |
ee5c1422 |
341 | if (ret->keyblob) { |
342 | memset(ret->keyblob, 0, ret->keyblob_size); |
343 | sfree(ret->keyblob); |
344 | } |
345 | memset(&ret, 0, sizeof(ret)); |
9dda6459 |
346 | sfree(ret); |
347 | } |
348 | return NULL; |
349 | } |
350 | |
351 | int openssh_encrypted(char *filename) |
352 | { |
353 | struct openssh_key *key = load_openssh_key(filename); |
354 | int ret; |
355 | |
356 | if (!key) |
357 | return 0; |
358 | ret = key->encrypted; |
ee5c1422 |
359 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
360 | sfree(key->keyblob); |
ee5c1422 |
361 | memset(&key, 0, sizeof(key)); |
9dda6459 |
362 | sfree(key); |
363 | return ret; |
364 | } |
365 | |
366 | struct ssh2_userkey *openssh_read(char *filename, char *passphrase) |
367 | { |
368 | struct openssh_key *key = load_openssh_key(filename); |
369 | struct ssh2_userkey *retkey; |
370 | unsigned char *p; |
371 | int ret, id, len, flags; |
372 | int i, num_integers; |
373 | struct ssh2_userkey *retval = NULL; |
374 | char *errmsg; |
375 | unsigned char *blob; |
ee5c1422 |
376 | int blobsize, blobptr, privptr; |
9dda6459 |
377 | char *modptr; |
378 | int modlen; |
379 | |
380 | if (!key) |
381 | return NULL; |
382 | |
383 | if (key->encrypted) { |
384 | /* |
385 | * Derive encryption key from passphrase and iv/salt: |
386 | * |
387 | * - let block A equal MD5(passphrase || iv) |
388 | * - let block B equal MD5(A || passphrase || iv) |
389 | * - block C would be MD5(B || passphrase || iv) and so on |
390 | * - encryption key is the first N bytes of A || B |
391 | */ |
392 | struct MD5Context md5c; |
393 | unsigned char keybuf[32]; |
394 | |
395 | MD5Init(&md5c); |
396 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
397 | MD5Update(&md5c, key->iv, 8); |
398 | MD5Final(keybuf, &md5c); |
399 | |
400 | MD5Init(&md5c); |
401 | MD5Update(&md5c, keybuf, 16); |
402 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
403 | MD5Update(&md5c, key->iv, 8); |
404 | MD5Final(keybuf+16, &md5c); |
405 | |
406 | /* |
407 | * Now decrypt the key blob. |
408 | */ |
409 | des3_decrypt_pubkey_ossh(keybuf, key->iv, |
410 | key->keyblob, key->keyblob_len); |
ee5c1422 |
411 | |
412 | memset(&md5c, 0, sizeof(md5c)); |
413 | memset(keybuf, 0, sizeof(keybuf)); |
9dda6459 |
414 | } |
415 | |
416 | /* |
417 | * Now we have a decrypted key blob, which contains an ASN.1 |
418 | * encoded private key. We must now untangle the ASN.1. |
419 | * |
420 | * We expect the whole key blob to be formatted as a SEQUENCE |
421 | * (0x30 followed by a length code indicating that the rest of |
422 | * the blob is part of the sequence). Within that SEQUENCE we |
423 | * expect to see a bunch of INTEGERs. What those integers mean |
424 | * depends on the key type: |
425 | * |
426 | * - For RSA, we expect the integers to be 0, n, e, d, p, q, |
427 | * dmp1, dmq1, iqmp in that order. (The last three are d mod |
428 | * (p-1), d mod (q-1), inverse of q mod p respectively.) |
429 | * |
430 | * - For DSA, we expect them to be 0, p, q, g, y, x in that |
431 | * order. |
432 | */ |
433 | |
434 | p = key->keyblob; |
435 | |
436 | /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ |
437 | ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); |
438 | p += ret; |
439 | if (ret < 0 || id != 16) { |
440 | errmsg = "ASN.1 decoding failure"; |
441 | retval = SSH2_WRONG_PASSPHRASE; |
442 | goto error; |
443 | } |
444 | |
445 | /* Expect a load of INTEGERs. */ |
446 | if (key->type == OSSH_RSA) |
447 | num_integers = 9; |
448 | else if (key->type == OSSH_DSA) |
449 | num_integers = 6; |
450 | |
451 | /* |
452 | * Space to create key blob in. |
453 | */ |
ee5c1422 |
454 | blobsize = 256+key->keyblob_len; |
455 | blob = smalloc(blobsize); |
9dda6459 |
456 | PUT_32BIT(blob, 7); |
457 | if (key->type == OSSH_DSA) |
458 | memcpy(blob+4, "ssh-dss", 7); |
459 | else if (key->type == OSSH_RSA) |
460 | memcpy(blob+4, "ssh-rsa", 7); |
461 | blobptr = 4+7; |
462 | privptr = -1; |
463 | |
464 | for (i = 0; i < num_integers; i++) { |
465 | ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, |
466 | &id, &len, &flags); |
467 | p += ret; |
468 | if (ret < 0 || id != 2 || |
469 | key->keyblob+key->keyblob_len-p < len) { |
470 | errmsg = "ASN.1 decoding failure"; |
471 | goto error; |
472 | } |
473 | |
474 | if (i == 0) { |
475 | /* |
476 | * The first integer should be zero always (I think |
477 | * this is some sort of version indication). |
478 | */ |
479 | if (len != 1 || p[0] != 0) { |
480 | errmsg = "Version number mismatch"; |
481 | goto error; |
482 | } |
483 | } else if (key->type == OSSH_RSA) { |
484 | /* |
485 | * Integers 1 and 2 go into the public blob but in the |
486 | * opposite order; integers 3, 4, 5 and 8 go into the |
487 | * private blob. The other two (6 and 7) are ignored. |
488 | */ |
489 | if (i == 1) { |
490 | /* Save the details for after we deal with number 2. */ |
491 | modptr = p; |
492 | modlen = len; |
493 | } else if (i != 6 && i != 7) { |
494 | PUT_32BIT(blob+blobptr, len); |
495 | memcpy(blob+blobptr+4, p, len); |
496 | blobptr += 4+len; |
497 | if (i == 2) { |
498 | PUT_32BIT(blob+blobptr, modlen); |
499 | memcpy(blob+blobptr+4, modptr, modlen); |
500 | blobptr += 4+modlen; |
501 | privptr = blobptr; |
502 | } |
503 | } |
504 | } else if (key->type == OSSH_DSA) { |
505 | /* |
506 | * Integers 1-4 go into the public blob; integer 5 goes |
507 | * into the private blob. |
508 | */ |
509 | PUT_32BIT(blob+blobptr, len); |
510 | memcpy(blob+blobptr+4, p, len); |
511 | blobptr += 4+len; |
512 | if (i == 4) |
513 | privptr = blobptr; |
514 | } |
515 | |
516 | /* Skip past the number. */ |
517 | p += len; |
518 | } |
519 | |
520 | /* |
521 | * Now put together the actual key. Simplest way to do this is |
522 | * to assemble our own key blobs and feed them to the createkey |
523 | * functions; this is a bit faffy but it does mean we get all |
524 | * the sanity checks for free. |
525 | */ |
526 | assert(privptr > 0); /* should have bombed by now if not */ |
527 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
528 | retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss); |
529 | retkey->data = retkey->alg->createkey(blob, privptr, |
530 | blob+privptr, blobptr-privptr); |
531 | if (!retkey->data) { |
532 | sfree(retkey); |
533 | errmsg = "unable to create key data structure"; |
534 | goto error; |
535 | } |
536 | |
537 | retkey->comment = dupstr("imported-openssh-key"); |
ee5c1422 |
538 | errmsg = NULL; /* no error */ |
539 | retval = retkey; |
9dda6459 |
540 | |
541 | error: |
ee5c1422 |
542 | if (blob) { |
543 | memset(blob, 0, blobsize); |
544 | sfree(blob); |
545 | } |
546 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
547 | sfree(key->keyblob); |
ee5c1422 |
548 | memset(&key, 0, sizeof(key)); |
9dda6459 |
549 | sfree(key); |
550 | return retval; |
551 | } |
7b4ef1ae |
552 | |
553 | /* ---------------------------------------------------------------------- |
554 | * Code to read ssh.com private keys. |
555 | */ |
556 | |
557 | /* |
558 | * The format of the base64 blob is largely ssh2-packet-formatted, |
559 | * except that mpints are a bit different: they're more like the |
560 | * old ssh1 mpint. You have a 32-bit bit count N, followed by |
561 | * (N+7)/8 bytes of data. |
562 | * |
563 | * So. The blob contains: |
564 | * |
565 | * - uint32 0x3f6ff9eb (magic number) |
566 | * - uint32 size (total blob size) |
567 | * - string key-type (see below) |
568 | * - string cipher-type (tells you if key is encrypted) |
569 | * - string encrypted-blob |
570 | * |
571 | * (The first size field includes the size field itself and the |
572 | * magic number before it. All other size fields are ordinary ssh2 |
573 | * strings, so the size field indicates how much data is to |
574 | * _follow_.) |
575 | * |
576 | * The encrypted blob, once decrypted, contains a single string |
577 | * which in turn contains the payload. (This allows padding to be |
578 | * added after that string while still making it clear where the |
579 | * real payload ends. Also it probably makes for a reasonable |
580 | * decryption check.) |
581 | * |
582 | * The payload blob, for an RSA key, contains: |
583 | * - mpint e |
584 | * - mpint d |
585 | * - mpint n (yes, the public and private stuff is intermixed) |
586 | * - mpint u (presumably inverse of p mod q) |
587 | * - mpint p (p is the smaller prime) |
588 | * - mpint q (q is the larger) |
589 | * |
590 | * For a DSA key, the payload blob contains: |
591 | * - uint32 0 |
592 | * - mpint p |
593 | * - mpint g |
594 | * - mpint q |
595 | * - mpint y |
596 | * - mpint x |
597 | * |
598 | * Alternatively, if the parameters are `predefined', that |
599 | * (0,p,g,q) sequence can be replaced by a uint32 1 and a string |
600 | * containing some predefined parameter specification. *shudder*, |
601 | * but I doubt we'll encounter this in real life. |
602 | * |
603 | * The key type strings are ghastly. The RSA key I looked at had a |
604 | * type string of |
605 | * |
606 | * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}' |
607 | * |
608 | * and the DSA key wasn't much better: |
609 | * |
610 | * `dl-modp{sign{dsa-nist-sha1},dh{plain}}' |
611 | * |
612 | * It isn't clear that these will always be the same. I think it |
613 | * might be wise just to look at the `if-modn{sign{rsa' and |
614 | * `dl-modp{sign{dsa' prefixes. |
615 | * |
616 | * Finally, the encryption. The cipher-type string appears to be |
617 | * either `none' or `3des-cbc'. Looks as if this is SSH2-style |
618 | * 3des-cbc (i.e. outer cbc rather than inner). The key is created |
619 | * from the passphrase by means of yet another hashing faff: |
620 | * |
621 | * - first 16 bytes are MD5(passphrase) |
622 | * - next 16 bytes are MD5(passphrase || first 16 bytes) |
623 | * - if there were more, they'd be MD5(passphrase || first 32), |
624 | * and so on. |
625 | */ |
626 | |
627 | struct sshcom_key { |
628 | char comment[256]; /* allowing any length is overkill */ |
629 | unsigned char *keyblob; |
630 | int keyblob_len, keyblob_size; |
631 | }; |
632 | |
633 | struct sshcom_key *load_sshcom_key(char *filename) |
634 | { |
635 | struct sshcom_key *ret; |
636 | FILE *fp; |
637 | char buffer[256]; |
638 | int len; |
639 | char *errmsg, *p; |
640 | int headers_done; |
641 | char base64_bit[4]; |
642 | int base64_chars = 0; |
643 | |
644 | ret = smalloc(sizeof(*ret)); |
645 | ret->comment[0] = '\0'; |
646 | ret->keyblob = NULL; |
647 | ret->keyblob_len = ret->keyblob_size = 0; |
648 | |
649 | fp = fopen(filename, "r"); |
650 | if (!fp) { |
651 | errmsg = "Unable to open key file"; |
652 | goto error; |
653 | } |
654 | if (!fgets(buffer, sizeof(buffer), fp) || |
655 | 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { |
656 | errmsg = "File does not begin with ssh.com key header"; |
657 | goto error; |
658 | } |
659 | |
660 | headers_done = 0; |
661 | while (1) { |
662 | if (!fgets(buffer, sizeof(buffer), fp)) { |
663 | errmsg = "Unexpected end of file"; |
664 | goto error; |
665 | } |
666 | if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) |
667 | break; /* done */ |
668 | if ((p = strchr(buffer, ':')) != NULL) { |
669 | if (headers_done) { |
670 | errmsg = "Header found in body of key data"; |
671 | goto error; |
672 | } |
673 | *p++ = '\0'; |
674 | while (*p && isspace((unsigned char)*p)) p++; |
675 | /* |
676 | * Header lines can end in a trailing backslash for |
677 | * continuation. |
678 | */ |
679 | while ((len = strlen(p)) > sizeof(buffer) - (p-buffer) -1 || |
680 | p[len-1] != '\n' || p[len-2] == '\\') { |
681 | if (len > (p-buffer) + sizeof(buffer)-2) { |
682 | errmsg = "Header line too long to deal with"; |
683 | goto error; |
684 | } |
685 | if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { |
686 | errmsg = "Unexpected end of file"; |
687 | goto error; |
688 | } |
689 | } |
690 | p[strcspn(p, "\n")] = '\0'; |
691 | if (!strcmp(buffer, "Comment")) { |
692 | /* Strip quotes in comment if present. */ |
693 | if (p[0] == '"' && p[strlen(p)-1] == '"') { |
694 | p++; |
695 | p[strlen(p)-1] = '\0'; |
696 | } |
697 | strncpy(ret->comment, p, sizeof(ret->comment)); |
698 | ret->comment[sizeof(ret->comment)-1] = '\0'; |
699 | } |
700 | } else { |
701 | headers_done = 1; |
702 | |
703 | p = buffer; |
704 | while (isbase64(*p)) { |
705 | base64_bit[base64_chars++] = *p; |
706 | if (base64_chars == 4) { |
707 | unsigned char out[3]; |
708 | |
709 | base64_chars = 0; |
710 | |
711 | len = base64_decode_atom(base64_bit, out); |
712 | |
713 | if (len <= 0) { |
714 | errmsg = "Invalid base64 encoding"; |
715 | goto error; |
716 | } |
717 | |
718 | if (ret->keyblob_len + len > ret->keyblob_size) { |
719 | ret->keyblob_size = ret->keyblob_len + len + 256; |
720 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
721 | } |
722 | |
723 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
724 | ret->keyblob_len += len; |
725 | } |
726 | |
727 | p++; |
728 | } |
729 | } |
730 | } |
731 | |
732 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
733 | errmsg = "Key body not present"; |
734 | goto error; |
735 | } |
736 | |
737 | return ret; |
738 | |
739 | error: |
740 | if (ret) { |
ee5c1422 |
741 | if (ret->keyblob) { |
742 | memset(ret->keyblob, 0, ret->keyblob_size); |
743 | sfree(ret->keyblob); |
744 | } |
745 | memset(&ret, 0, sizeof(ret)); |
7b4ef1ae |
746 | sfree(ret); |
747 | } |
748 | return NULL; |
749 | } |
750 | |
751 | int sshcom_encrypted(char *filename, char **comment) |
752 | { |
753 | struct sshcom_key *key = load_sshcom_key(filename); |
754 | int pos, len, answer; |
755 | |
756 | *comment = NULL; |
757 | if (!key) |
758 | return 0; |
759 | |
760 | /* |
761 | * Check magic number. |
762 | */ |
763 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) |
764 | return 0; /* key is invalid */ |
765 | |
766 | /* |
767 | * Find the cipher-type string. |
768 | */ |
769 | answer = 0; |
770 | pos = 8; |
771 | if (key->keyblob_len < pos+4) |
772 | goto done; /* key is far too short */ |
773 | pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ |
774 | if (key->keyblob_len < pos+4) |
775 | goto done; /* key is far too short */ |
776 | len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ |
777 | if (key->keyblob_len < pos+4+len) |
778 | goto done; /* cipher type string is incomplete */ |
779 | if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) |
780 | answer = 1; |
781 | |
782 | done: |
783 | *comment = dupstr(key->comment); |
ee5c1422 |
784 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
785 | sfree(key->keyblob); |
ee5c1422 |
786 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
787 | sfree(key); |
788 | return answer; |
789 | } |
790 | |
791 | struct mpint_pos { void *start; int bytes; }; |
792 | |
793 | int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) |
794 | { |
795 | int bits; |
796 | int bytes; |
797 | unsigned char *d = (unsigned char *) data; |
798 | |
799 | if (len < 4) |
800 | goto error; |
801 | bits = GET_32BIT(d); |
802 | |
803 | bytes = (bits + 7) / 8; |
804 | if (len < 4+bytes) |
805 | goto error; |
806 | |
807 | ret->start = d + 4; |
808 | ret->bytes = bytes; |
809 | return bytes+4; |
810 | |
811 | error: |
812 | ret->start = NULL; |
813 | ret->bytes = -1; |
814 | return len; /* ensure further calls fail as well */ |
815 | } |
816 | |
817 | struct ssh2_userkey *sshcom_read(char *filename, char *passphrase) |
818 | { |
819 | struct sshcom_key *key = load_sshcom_key(filename); |
820 | char *errmsg; |
821 | int pos, len; |
822 | const char prefix_rsa[] = "if-modn{sign{rsa"; |
823 | const char prefix_dsa[] = "dl-modp{sign{dsa"; |
824 | enum { RSA, DSA } type; |
825 | int encrypted; |
826 | char *ciphertext; |
827 | int cipherlen; |
828 | struct ssh2_userkey *ret = NULL, *retkey; |
829 | const struct ssh_signkey *alg; |
830 | unsigned char *blob = NULL; |
ee5c1422 |
831 | int blobsize, publen, privlen; |
7b4ef1ae |
832 | |
833 | if (!key) |
834 | return NULL; |
835 | |
836 | /* |
837 | * Check magic number. |
838 | */ |
839 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) { |
840 | errmsg = "Key does not begin with magic number"; |
841 | goto error; |
842 | } |
843 | |
844 | /* |
845 | * Determine the key type. |
846 | */ |
847 | pos = 8; |
848 | if (key->keyblob_len < pos+4 || |
849 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
850 | errmsg = "Key blob does not contain a key type string"; |
851 | goto error; |
852 | } |
853 | if (len > sizeof(prefix_rsa) - 1 && |
854 | !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { |
855 | type = RSA; |
856 | } else if (len > sizeof(prefix_dsa) - 1 && |
857 | !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { |
858 | type = DSA; |
859 | } else { |
860 | errmsg = "Key is of unknown type"; |
861 | goto error; |
862 | } |
863 | pos += 4+len; |
864 | |
865 | /* |
866 | * Determine the cipher type. |
867 | */ |
868 | if (key->keyblob_len < pos+4 || |
869 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
870 | errmsg = "Key blob does not contain a cipher type string"; |
871 | goto error; |
872 | } |
873 | if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) |
874 | encrypted = 0; |
875 | else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) |
876 | encrypted = 1; |
877 | else { |
878 | errmsg = "Key encryption is of unknown type"; |
879 | goto error; |
880 | } |
881 | pos += 4+len; |
882 | |
883 | /* |
884 | * Get hold of the encrypted part of the key. |
885 | */ |
886 | if (key->keyblob_len < pos+4 || |
887 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
888 | errmsg = "Key blob does not contain actual key data"; |
889 | goto error; |
890 | } |
891 | ciphertext = key->keyblob + pos + 4; |
892 | cipherlen = len; |
893 | if (cipherlen == 0) { |
894 | errmsg = "Length of key data is zero"; |
895 | goto error; |
896 | } |
897 | |
898 | /* |
899 | * Decrypt it if necessary. |
900 | */ |
901 | if (encrypted) { |
902 | /* |
903 | * Derive encryption key from passphrase and iv/salt: |
904 | * |
905 | * - let block A equal MD5(passphrase) |
906 | * - let block B equal MD5(passphrase || A) |
907 | * - block C would be MD5(passphrase || A || B) and so on |
908 | * - encryption key is the first N bytes of A || B |
909 | */ |
910 | struct MD5Context md5c; |
911 | unsigned char keybuf[32], iv[8]; |
912 | |
913 | if (cipherlen % 8 != 0) { |
914 | errmsg = "Encrypted part of key is not a multiple of cipher block" |
915 | " size"; |
916 | goto error; |
917 | } |
918 | |
919 | MD5Init(&md5c); |
920 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
921 | MD5Final(keybuf, &md5c); |
922 | |
923 | MD5Init(&md5c); |
924 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
925 | MD5Update(&md5c, keybuf, 16); |
926 | MD5Final(keybuf+16, &md5c); |
927 | |
928 | /* |
929 | * Now decrypt the key blob. |
930 | */ |
ee5c1422 |
931 | memset(iv, 0, sizeof(iv)); |
7b4ef1ae |
932 | des3_decrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen); |
933 | |
ee5c1422 |
934 | memset(&md5c, 0, sizeof(md5c)); |
935 | memset(keybuf, 0, sizeof(keybuf)); |
936 | |
7b4ef1ae |
937 | /* |
938 | * Hereafter we return WRONG_PASSPHRASE for any parsing |
ee5c1422 |
939 | * error. (But only if we've just tried to decrypt it! |
940 | * Returning WRONG_PASSPHRASE for an unencrypted key is |
941 | * automatic doom.) |
7b4ef1ae |
942 | */ |
943 | if (encrypted) |
944 | ret = SSH2_WRONG_PASSPHRASE; |
945 | } |
946 | |
947 | /* |
948 | * Strip away the containing string to get to the real meat. |
949 | */ |
950 | len = GET_32BIT(ciphertext); |
951 | if (len > cipherlen-4) { |
952 | errmsg = "containing string was ill-formed"; |
953 | goto error; |
954 | } |
955 | ciphertext += 4; |
956 | cipherlen = len; |
957 | |
958 | /* |
959 | * Now we break down into RSA versus DSA. In either case we'll |
960 | * construct public and private blobs in our own format, and |
961 | * end up feeding them to alg->createkey(). |
962 | */ |
ee5c1422 |
963 | blobsize = cipherlen + 256; |
964 | blob = smalloc(blobsize); |
7b4ef1ae |
965 | privlen = 0; |
966 | if (type == RSA) { |
967 | struct mpint_pos n, e, d, u, p, q; |
968 | int pos = 0; |
969 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); |
970 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); |
971 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); |
972 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); |
973 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
974 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
975 | if (!q.start) { |
976 | errmsg = "key data did not contain six integers"; |
977 | goto error; |
978 | } |
979 | |
980 | alg = &ssh_rsa; |
981 | pos = 0; |
982 | pos += put_string(blob+pos, "ssh-rsa", 7); |
983 | pos += put_mp(blob+pos, e.start, e.bytes); |
984 | pos += put_mp(blob+pos, n.start, n.bytes); |
985 | publen = pos; |
986 | pos += put_string(blob+pos, d.start, d.bytes); |
987 | pos += put_mp(blob+pos, q.start, q.bytes); |
988 | pos += put_mp(blob+pos, p.start, p.bytes); |
989 | pos += put_mp(blob+pos, u.start, u.bytes); |
990 | privlen = pos - publen; |
991 | } else if (type == DSA) { |
992 | struct mpint_pos p, q, g, x, y; |
993 | int pos = 4; |
994 | if (GET_32BIT(ciphertext) != 0) { |
995 | errmsg = "predefined DSA parameters not supported"; |
996 | goto error; |
997 | } |
998 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
999 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); |
1000 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1001 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); |
1002 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); |
1003 | if (!x.start) { |
1004 | errmsg = "key data did not contain five integers"; |
1005 | goto error; |
1006 | } |
1007 | |
1008 | alg = &ssh_dss; |
1009 | pos = 0; |
1010 | pos += put_string(blob+pos, "ssh-dss", 7); |
1011 | pos += put_mp(blob+pos, p.start, p.bytes); |
1012 | pos += put_mp(blob+pos, q.start, q.bytes); |
1013 | pos += put_mp(blob+pos, g.start, g.bytes); |
1014 | pos += put_mp(blob+pos, y.start, y.bytes); |
1015 | publen = pos; |
1016 | pos += put_mp(blob+pos, x.start, x.bytes); |
1017 | privlen = pos - publen; |
1018 | } |
1019 | |
1020 | assert(privlen > 0); /* should have bombed by now if not */ |
1021 | |
1022 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
1023 | retkey->alg = alg; |
1024 | retkey->data = alg->createkey(blob, publen, blob+publen, privlen); |
1025 | if (!retkey->data) { |
1026 | sfree(retkey); |
1027 | errmsg = "unable to create key data structure"; |
1028 | goto error; |
1029 | } |
1030 | retkey->comment = dupstr(key->comment); |
1031 | |
1032 | errmsg = NULL; /* no error */ |
1033 | ret = retkey; |
1034 | |
1035 | error: |
ee5c1422 |
1036 | if (blob) { |
1037 | memset(blob, 0, blobsize); |
1038 | sfree(blob); |
1039 | } |
1040 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1041 | sfree(key->keyblob); |
ee5c1422 |
1042 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1043 | sfree(key); |
1044 | return ret; |
1045 | } |