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 { \ |
96d19bc9 |
15 | (cp)[3] = (unsigned char)(value); \ |
16 | (cp)[2] = (unsigned char)((value) >> 8); \ |
17 | (cp)[1] = (unsigned char)((value) >> 16); \ |
18 | (cp)[0] = (unsigned char)((value) >> 24); } while (0) |
9dda6459 |
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); |
96d19bc9 |
32 | int sshcom_write(char *filename, struct ssh2_userkey *key, char *passphrase); |
7b4ef1ae |
33 | |
9dda6459 |
34 | /* |
35 | * Given a key type, determine whether we know how to import it. |
36 | */ |
37 | int import_possible(int type) |
38 | { |
39 | if (type == SSH_KEYTYPE_OPENSSH) |
40 | return 1; |
7b4ef1ae |
41 | if (type == SSH_KEYTYPE_SSHCOM) |
42 | return 1; |
9dda6459 |
43 | return 0; |
44 | } |
45 | |
46 | /* |
47 | * Given a key type, determine what native key type |
48 | * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once |
49 | * we've imported it. |
50 | */ |
51 | int import_target_type(int type) |
52 | { |
53 | /* |
54 | * There are no known foreign SSH1 key formats. |
55 | */ |
56 | return SSH_KEYTYPE_SSH2; |
57 | } |
58 | |
59 | /* |
60 | * Determine whether a foreign key is encrypted. |
61 | */ |
62 | int import_encrypted(char *filename, int type, char **comment) |
63 | { |
64 | if (type == SSH_KEYTYPE_OPENSSH) { |
c232b3e3 |
65 | *comment = dupstr(filename); /* OpenSSH doesn't do key comments */ |
9dda6459 |
66 | return openssh_encrypted(filename); |
67 | } |
7b4ef1ae |
68 | if (type == SSH_KEYTYPE_SSHCOM) { |
69 | return sshcom_encrypted(filename, comment); |
70 | } |
9dda6459 |
71 | return 0; |
72 | } |
73 | |
74 | /* |
75 | * Import an SSH1 key. |
76 | */ |
77 | int import_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase) |
78 | { |
79 | return 0; |
80 | } |
81 | |
82 | /* |
83 | * Import an SSH2 key. |
84 | */ |
85 | struct ssh2_userkey *import_ssh2(char *filename, int type, char *passphrase) |
86 | { |
87 | if (type == SSH_KEYTYPE_OPENSSH) |
88 | return openssh_read(filename, passphrase); |
7b4ef1ae |
89 | if (type == SSH_KEYTYPE_SSHCOM) |
90 | return sshcom_read(filename, passphrase); |
9dda6459 |
91 | return NULL; |
92 | } |
93 | |
4801c01c |
94 | /* |
95 | * Export an SSH1 key. |
96 | */ |
97 | int export_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase) |
98 | { |
99 | return 0; |
100 | } |
101 | |
102 | /* |
103 | * Export an SSH2 key. |
104 | */ |
105 | int export_ssh2(char *filename, int type, |
106 | struct ssh2_userkey *key, char *passphrase) |
107 | { |
4801c01c |
108 | if (type == SSH_KEYTYPE_OPENSSH) |
109 | return openssh_write(filename, key, passphrase); |
110 | if (type == SSH_KEYTYPE_SSHCOM) |
111 | return sshcom_write(filename, key, passphrase); |
4801c01c |
112 | return 0; |
113 | } |
114 | |
9dda6459 |
115 | /* ---------------------------------------------------------------------- |
116 | * Helper routines. (The base64 ones are defined in sshpubk.c.) |
117 | */ |
118 | |
119 | #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ |
120 | ((c) >= 'a' && (c) <= 'z') || \ |
121 | ((c) >= '0' && (c) <= '9') || \ |
122 | (c) == '+' || (c) == '/' || (c) == '=' \ |
123 | ) |
124 | |
125 | extern int base64_decode_atom(char *atom, unsigned char *out); |
126 | extern int base64_lines(int datalen); |
127 | extern void base64_encode_atom(unsigned char *data, int n, char *out); |
96d19bc9 |
128 | extern void base64_encode(FILE *fp, unsigned char *data, int datalen, int cpl); |
9dda6459 |
129 | |
130 | /* |
131 | * Read an ASN.1/BER identifier and length pair. |
132 | * |
133 | * Flags are a combination of the #defines listed below. |
134 | * |
135 | * Returns -1 if unsuccessful; otherwise returns the number of |
136 | * bytes used out of the source data. |
137 | */ |
138 | |
139 | /* ASN.1 tag classes. */ |
140 | #define ASN1_CLASS_UNIVERSAL (0 << 6) |
141 | #define ASN1_CLASS_APPLICATION (1 << 6) |
142 | #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6) |
143 | #define ASN1_CLASS_PRIVATE (3 << 6) |
144 | #define ASN1_CLASS_MASK (3 << 6) |
145 | |
146 | /* Primitive versus constructed bit. */ |
147 | #define ASN1_CONSTRUCTED (1 << 5) |
148 | |
149 | int ber_read_id_len(void *source, int sourcelen, |
150 | int *id, int *length, int *flags) |
151 | { |
152 | unsigned char *p = (unsigned char *) source; |
153 | |
154 | if (sourcelen == 0) |
155 | return -1; |
156 | |
157 | *flags = (*p & 0xE0); |
158 | if ((*p & 0x1F) == 0x1F) { |
159 | *id = 0; |
160 | while (*p & 0x80) { |
161 | *id = (*id << 7) | (*p & 0x7F); |
162 | p++, sourcelen--; |
163 | if (sourcelen == 0) |
164 | return -1; |
165 | } |
166 | *id = (*id << 7) | (*p & 0x7F); |
167 | p++, sourcelen--; |
168 | } else { |
169 | *id = *p & 0x1F; |
170 | p++, sourcelen--; |
171 | } |
172 | |
173 | if (sourcelen == 0) |
174 | return -1; |
175 | |
176 | if (*p & 0x80) { |
177 | int n = *p & 0x7F; |
178 | p++, sourcelen--; |
179 | if (sourcelen < n) |
180 | return -1; |
181 | *length = 0; |
182 | while (n--) |
183 | *length = (*length << 8) | (*p++); |
184 | sourcelen -= n; |
185 | } else { |
186 | *length = *p; |
187 | p++, sourcelen--; |
188 | } |
189 | |
190 | return p - (unsigned char *) source; |
191 | } |
192 | |
d23a9b21 |
193 | /* |
194 | * Write an ASN.1/BER identifier and length pair. Returns the |
195 | * number of bytes consumed. Assumes dest contains enough space. |
196 | * Will avoid writing anything if dest is NULL, but still return |
197 | * amount of space required. |
198 | */ |
199 | int ber_write_id_len(void *dest, int id, int length, int flags) |
200 | { |
201 | unsigned char *d = (unsigned char *)dest; |
202 | int len = 0; |
203 | |
204 | if (id <= 30) { |
205 | /* |
206 | * Identifier is one byte. |
207 | */ |
208 | len++; |
209 | if (d) *d++ = id | flags; |
210 | } else { |
211 | int n; |
212 | /* |
213 | * Identifier is multiple bytes: the first byte is 11111 |
214 | * plus the flags, and subsequent bytes encode the value of |
215 | * the identifier, 7 bits at a time, with the top bit of |
216 | * each byte 1 except the last one which is 0. |
217 | */ |
218 | len++; |
219 | if (d) *d++ = 0x1F | flags; |
220 | for (n = 1; (id >> (7*n)) > 0; n++) |
221 | continue; /* count the bytes */ |
222 | while (n--) { |
223 | len++; |
224 | if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F); |
225 | } |
226 | } |
227 | |
228 | if (length < 128) { |
229 | /* |
230 | * Length is one byte. |
231 | */ |
232 | len++; |
233 | if (d) *d++ = length; |
234 | } else { |
235 | int n; |
236 | /* |
237 | * Length is multiple bytes. The first is 0x80 plus the |
238 | * number of subsequent bytes, and the subsequent bytes |
239 | * encode the actual length. |
240 | */ |
241 | for (n = 1; (length >> (8*n)) > 0; n++) |
242 | continue; /* count the bytes */ |
243 | len++; |
244 | if (d) *d++ = 0x80 | n; |
245 | while (n--) { |
246 | len++; |
247 | if (d) *d++ = (length >> (8*n)) & 0xFF; |
248 | } |
249 | } |
250 | |
251 | return len; |
252 | } |
253 | |
7b4ef1ae |
254 | static int put_string(void *target, void *data, int len) |
255 | { |
256 | unsigned char *d = (unsigned char *)target; |
257 | |
258 | PUT_32BIT(d, len); |
259 | memcpy(d+4, data, len); |
260 | return len+4; |
261 | } |
262 | |
263 | static int put_mp(void *target, void *data, int len) |
264 | { |
265 | unsigned char *d = (unsigned char *)target; |
266 | unsigned char *i = (unsigned char *)data; |
267 | |
268 | if (*i & 0x80) { |
269 | PUT_32BIT(d, len+1); |
270 | d[4] = 0; |
271 | memcpy(d+5, data, len); |
272 | return len+5; |
273 | } else { |
274 | PUT_32BIT(d, len); |
275 | memcpy(d+4, data, len); |
276 | return len+4; |
277 | } |
278 | } |
279 | |
d23a9b21 |
280 | /* Simple structure to point to an mp-int within a blob. */ |
281 | struct mpint_pos { void *start; int bytes; }; |
282 | |
283 | int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret) |
284 | { |
285 | int bytes; |
286 | unsigned char *d = (unsigned char *) data; |
287 | |
288 | if (len < 4) |
289 | goto error; |
290 | bytes = GET_32BIT(d); |
291 | if (len < 4+bytes) |
292 | goto error; |
293 | |
294 | ret->start = d + 4; |
295 | ret->bytes = bytes; |
296 | return bytes+4; |
297 | |
298 | error: |
299 | ret->start = NULL; |
300 | ret->bytes = -1; |
301 | return len; /* ensure further calls fail as well */ |
302 | } |
303 | |
9dda6459 |
304 | /* ---------------------------------------------------------------------- |
d23a9b21 |
305 | * Code to read and write OpenSSH private keys. |
9dda6459 |
306 | */ |
307 | |
308 | enum { OSSH_DSA, OSSH_RSA }; |
309 | struct openssh_key { |
310 | int type; |
311 | int encrypted; |
312 | char iv[32]; |
313 | unsigned char *keyblob; |
314 | int keyblob_len, keyblob_size; |
315 | }; |
316 | |
317 | struct openssh_key *load_openssh_key(char *filename) |
318 | { |
319 | struct openssh_key *ret; |
320 | FILE *fp; |
321 | char buffer[256]; |
322 | char *errmsg, *p; |
323 | int headers_done; |
ee5c1422 |
324 | char base64_bit[4]; |
325 | int base64_chars = 0; |
9dda6459 |
326 | |
327 | ret = smalloc(sizeof(*ret)); |
328 | ret->keyblob = NULL; |
329 | ret->keyblob_len = ret->keyblob_size = 0; |
330 | ret->encrypted = 0; |
331 | memset(ret->iv, 0, sizeof(ret->iv)); |
332 | |
333 | fp = fopen(filename, "r"); |
334 | if (!fp) { |
335 | errmsg = "Unable to open key file"; |
336 | goto error; |
337 | } |
338 | if (!fgets(buffer, sizeof(buffer), fp) || |
339 | 0 != strncmp(buffer, "-----BEGIN ", 11) || |
340 | 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) { |
341 | errmsg = "File does not begin with OpenSSH key header"; |
342 | goto error; |
343 | } |
344 | if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n")) |
345 | ret->type = OSSH_RSA; |
346 | else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n")) |
347 | ret->type = OSSH_DSA; |
348 | else { |
349 | errmsg = "Unrecognised key type"; |
350 | goto error; |
351 | } |
352 | |
353 | headers_done = 0; |
354 | while (1) { |
355 | if (!fgets(buffer, sizeof(buffer), fp)) { |
356 | errmsg = "Unexpected end of file"; |
357 | goto error; |
358 | } |
359 | if (0 == strncmp(buffer, "-----END ", 9) && |
360 | 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) |
361 | break; /* done */ |
362 | if ((p = strchr(buffer, ':')) != NULL) { |
363 | if (headers_done) { |
364 | errmsg = "Header found in body of key data"; |
365 | goto error; |
366 | } |
367 | *p++ = '\0'; |
368 | while (*p && isspace((unsigned char)*p)) p++; |
369 | if (!strcmp(buffer, "Proc-Type")) { |
370 | if (p[0] != '4' || p[1] != ',') { |
371 | errmsg = "Proc-Type is not 4 (only 4 is supported)"; |
372 | goto error; |
373 | } |
374 | p += 2; |
375 | if (!strcmp(p, "ENCRYPTED\n")) |
376 | ret->encrypted = 1; |
377 | } else if (!strcmp(buffer, "DEK-Info")) { |
378 | int i, j; |
379 | |
380 | if (strncmp(p, "DES-EDE3-CBC,", 13)) { |
381 | errmsg = "Ciphers other than DES-EDE3-CBC not supported"; |
382 | goto error; |
383 | } |
384 | p += 13; |
385 | for (i = 0; i < 8; i++) { |
386 | if (1 != sscanf(p, "%2x", &j)) |
387 | break; |
388 | ret->iv[i] = j; |
389 | p += 2; |
390 | } |
391 | if (i < 8) { |
392 | errmsg = "Expected 16-digit iv in DEK-Info"; |
393 | goto error; |
394 | } |
395 | } |
396 | } else { |
397 | headers_done = 1; |
398 | |
399 | p = buffer; |
ee5c1422 |
400 | while (isbase64(*p)) { |
401 | base64_bit[base64_chars++] = *p; |
402 | if (base64_chars == 4) { |
403 | unsigned char out[3]; |
404 | int len; |
9dda6459 |
405 | |
ee5c1422 |
406 | base64_chars = 0; |
9dda6459 |
407 | |
ee5c1422 |
408 | len = base64_decode_atom(base64_bit, out); |
9dda6459 |
409 | |
ee5c1422 |
410 | if (len <= 0) { |
411 | errmsg = "Invalid base64 encoding"; |
412 | goto error; |
413 | } |
414 | |
415 | if (ret->keyblob_len + len > ret->keyblob_size) { |
416 | ret->keyblob_size = ret->keyblob_len + len + 256; |
417 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
418 | } |
9dda6459 |
419 | |
ee5c1422 |
420 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
421 | ret->keyblob_len += len; |
9dda6459 |
422 | |
ee5c1422 |
423 | memset(out, 0, sizeof(out)); |
424 | } |
9dda6459 |
425 | |
ee5c1422 |
426 | p++; |
9dda6459 |
427 | } |
428 | } |
429 | } |
430 | |
431 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
432 | errmsg = "Key body not present"; |
433 | goto error; |
434 | } |
435 | |
436 | if (ret->encrypted && ret->keyblob_len % 8 != 0) { |
437 | errmsg = "Encrypted key blob is not a multiple of cipher block size"; |
438 | goto error; |
439 | } |
440 | |
ee5c1422 |
441 | memset(buffer, 0, sizeof(buffer)); |
442 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
443 | return ret; |
444 | |
445 | error: |
ee5c1422 |
446 | memset(buffer, 0, sizeof(buffer)); |
447 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
448 | if (ret) { |
ee5c1422 |
449 | if (ret->keyblob) { |
450 | memset(ret->keyblob, 0, ret->keyblob_size); |
451 | sfree(ret->keyblob); |
452 | } |
453 | memset(&ret, 0, sizeof(ret)); |
9dda6459 |
454 | sfree(ret); |
455 | } |
456 | return NULL; |
457 | } |
458 | |
459 | int openssh_encrypted(char *filename) |
460 | { |
461 | struct openssh_key *key = load_openssh_key(filename); |
462 | int ret; |
463 | |
464 | if (!key) |
465 | return 0; |
466 | ret = key->encrypted; |
ee5c1422 |
467 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
468 | sfree(key->keyblob); |
ee5c1422 |
469 | memset(&key, 0, sizeof(key)); |
9dda6459 |
470 | sfree(key); |
471 | return ret; |
472 | } |
473 | |
474 | struct ssh2_userkey *openssh_read(char *filename, char *passphrase) |
475 | { |
476 | struct openssh_key *key = load_openssh_key(filename); |
477 | struct ssh2_userkey *retkey; |
478 | unsigned char *p; |
479 | int ret, id, len, flags; |
480 | int i, num_integers; |
481 | struct ssh2_userkey *retval = NULL; |
482 | char *errmsg; |
483 | unsigned char *blob; |
ee5c1422 |
484 | int blobsize, blobptr, privptr; |
9dda6459 |
485 | char *modptr; |
486 | int modlen; |
487 | |
e3498db5 |
488 | blob = NULL; |
489 | |
9dda6459 |
490 | if (!key) |
491 | return NULL; |
492 | |
493 | if (key->encrypted) { |
494 | /* |
495 | * Derive encryption key from passphrase and iv/salt: |
496 | * |
497 | * - let block A equal MD5(passphrase || iv) |
498 | * - let block B equal MD5(A || passphrase || iv) |
499 | * - block C would be MD5(B || passphrase || iv) and so on |
500 | * - encryption key is the first N bytes of A || B |
501 | */ |
502 | struct MD5Context md5c; |
503 | unsigned char keybuf[32]; |
504 | |
505 | MD5Init(&md5c); |
506 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
507 | MD5Update(&md5c, key->iv, 8); |
508 | MD5Final(keybuf, &md5c); |
509 | |
510 | MD5Init(&md5c); |
511 | MD5Update(&md5c, keybuf, 16); |
512 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
513 | MD5Update(&md5c, key->iv, 8); |
514 | MD5Final(keybuf+16, &md5c); |
515 | |
516 | /* |
517 | * Now decrypt the key blob. |
518 | */ |
519 | des3_decrypt_pubkey_ossh(keybuf, key->iv, |
520 | key->keyblob, key->keyblob_len); |
ee5c1422 |
521 | |
522 | memset(&md5c, 0, sizeof(md5c)); |
523 | memset(keybuf, 0, sizeof(keybuf)); |
9dda6459 |
524 | } |
525 | |
526 | /* |
527 | * Now we have a decrypted key blob, which contains an ASN.1 |
528 | * encoded private key. We must now untangle the ASN.1. |
529 | * |
530 | * We expect the whole key blob to be formatted as a SEQUENCE |
531 | * (0x30 followed by a length code indicating that the rest of |
532 | * the blob is part of the sequence). Within that SEQUENCE we |
533 | * expect to see a bunch of INTEGERs. What those integers mean |
534 | * depends on the key type: |
535 | * |
536 | * - For RSA, we expect the integers to be 0, n, e, d, p, q, |
537 | * dmp1, dmq1, iqmp in that order. (The last three are d mod |
538 | * (p-1), d mod (q-1), inverse of q mod p respectively.) |
539 | * |
540 | * - For DSA, we expect them to be 0, p, q, g, y, x in that |
541 | * order. |
542 | */ |
543 | |
544 | p = key->keyblob; |
545 | |
546 | /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ |
547 | ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); |
548 | p += ret; |
549 | if (ret < 0 || id != 16) { |
550 | errmsg = "ASN.1 decoding failure"; |
551 | retval = SSH2_WRONG_PASSPHRASE; |
552 | goto error; |
553 | } |
554 | |
555 | /* Expect a load of INTEGERs. */ |
556 | if (key->type == OSSH_RSA) |
557 | num_integers = 9; |
558 | else if (key->type == OSSH_DSA) |
559 | num_integers = 6; |
560 | |
561 | /* |
562 | * Space to create key blob in. |
563 | */ |
ee5c1422 |
564 | blobsize = 256+key->keyblob_len; |
565 | blob = smalloc(blobsize); |
9dda6459 |
566 | PUT_32BIT(blob, 7); |
567 | if (key->type == OSSH_DSA) |
568 | memcpy(blob+4, "ssh-dss", 7); |
569 | else if (key->type == OSSH_RSA) |
570 | memcpy(blob+4, "ssh-rsa", 7); |
571 | blobptr = 4+7; |
572 | privptr = -1; |
573 | |
574 | for (i = 0; i < num_integers; i++) { |
575 | ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, |
576 | &id, &len, &flags); |
577 | p += ret; |
578 | if (ret < 0 || id != 2 || |
579 | key->keyblob+key->keyblob_len-p < len) { |
580 | errmsg = "ASN.1 decoding failure"; |
581 | goto error; |
582 | } |
583 | |
584 | if (i == 0) { |
585 | /* |
586 | * The first integer should be zero always (I think |
587 | * this is some sort of version indication). |
588 | */ |
589 | if (len != 1 || p[0] != 0) { |
590 | errmsg = "Version number mismatch"; |
591 | goto error; |
592 | } |
593 | } else if (key->type == OSSH_RSA) { |
594 | /* |
595 | * Integers 1 and 2 go into the public blob but in the |
596 | * opposite order; integers 3, 4, 5 and 8 go into the |
597 | * private blob. The other two (6 and 7) are ignored. |
598 | */ |
599 | if (i == 1) { |
600 | /* Save the details for after we deal with number 2. */ |
601 | modptr = p; |
602 | modlen = len; |
603 | } else if (i != 6 && i != 7) { |
604 | PUT_32BIT(blob+blobptr, len); |
605 | memcpy(blob+blobptr+4, p, len); |
606 | blobptr += 4+len; |
607 | if (i == 2) { |
608 | PUT_32BIT(blob+blobptr, modlen); |
609 | memcpy(blob+blobptr+4, modptr, modlen); |
610 | blobptr += 4+modlen; |
611 | privptr = blobptr; |
612 | } |
613 | } |
614 | } else if (key->type == OSSH_DSA) { |
615 | /* |
616 | * Integers 1-4 go into the public blob; integer 5 goes |
617 | * into the private blob. |
618 | */ |
619 | PUT_32BIT(blob+blobptr, len); |
620 | memcpy(blob+blobptr+4, p, len); |
621 | blobptr += 4+len; |
622 | if (i == 4) |
623 | privptr = blobptr; |
624 | } |
625 | |
626 | /* Skip past the number. */ |
627 | p += len; |
628 | } |
629 | |
630 | /* |
631 | * Now put together the actual key. Simplest way to do this is |
632 | * to assemble our own key blobs and feed them to the createkey |
633 | * functions; this is a bit faffy but it does mean we get all |
634 | * the sanity checks for free. |
635 | */ |
636 | assert(privptr > 0); /* should have bombed by now if not */ |
637 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
638 | retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss); |
639 | retkey->data = retkey->alg->createkey(blob, privptr, |
640 | blob+privptr, blobptr-privptr); |
641 | if (!retkey->data) { |
642 | sfree(retkey); |
643 | errmsg = "unable to create key data structure"; |
644 | goto error; |
645 | } |
646 | |
647 | retkey->comment = dupstr("imported-openssh-key"); |
ee5c1422 |
648 | errmsg = NULL; /* no error */ |
649 | retval = retkey; |
9dda6459 |
650 | |
651 | error: |
ee5c1422 |
652 | if (blob) { |
653 | memset(blob, 0, blobsize); |
654 | sfree(blob); |
655 | } |
656 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
657 | sfree(key->keyblob); |
ee5c1422 |
658 | memset(&key, 0, sizeof(key)); |
9dda6459 |
659 | sfree(key); |
660 | return retval; |
661 | } |
7b4ef1ae |
662 | |
d23a9b21 |
663 | int openssh_write(char *filename, struct ssh2_userkey *key, char *passphrase) |
664 | { |
665 | unsigned char *pubblob, *privblob, *spareblob; |
666 | int publen, privlen, sparelen; |
667 | unsigned char *outblob; |
668 | int outlen; |
669 | struct mpint_pos numbers[9]; |
670 | int nnumbers, pos, len, seqlen, i; |
671 | char *header, *footer; |
672 | char zero[1]; |
673 | unsigned char iv[8]; |
674 | int ret = 0; |
675 | FILE *fp; |
676 | |
677 | /* |
678 | * Fetch the key blobs. |
679 | */ |
680 | pubblob = key->alg->public_blob(key->data, &publen); |
681 | privblob = key->alg->private_blob(key->data, &privlen); |
682 | spareblob = outblob = NULL; |
683 | |
684 | /* |
685 | * Find the sequence of integers to be encoded into the OpenSSH |
686 | * key blob, and also decide on the header line. |
687 | */ |
688 | if (key->alg == &ssh_rsa) { |
689 | int pos; |
690 | struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1; |
691 | Bignum bd, bp, bq, bdmp1, bdmq1; |
692 | |
693 | pos = 4 + GET_32BIT(pubblob); |
694 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
695 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
696 | pos = 0; |
697 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
698 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
699 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
700 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
701 | |
702 | assert(e.start && iqmp.start); /* can't go wrong */ |
703 | |
704 | /* We also need d mod (p-1) and d mod (q-1). */ |
705 | bd = bignum_from_bytes(d.start, d.bytes); |
706 | bp = bignum_from_bytes(p.start, p.bytes); |
707 | bq = bignum_from_bytes(q.start, q.bytes); |
708 | decbn(bp); |
709 | decbn(bq); |
710 | bdmp1 = bigmod(bd, bp); |
711 | bdmq1 = bigmod(bd, bq); |
712 | freebn(bd); |
713 | freebn(bp); |
714 | freebn(bq); |
715 | |
716 | dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8; |
717 | dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8; |
718 | sparelen = dmp1.bytes + dmq1.bytes; |
719 | spareblob = smalloc(sparelen); |
720 | dmp1.start = spareblob; |
721 | dmq1.start = spareblob + dmp1.bytes; |
722 | for (i = 0; i < dmp1.bytes; i++) |
723 | spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i); |
724 | for (i = 0; i < dmq1.bytes; i++) |
725 | spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i); |
726 | freebn(bdmp1); |
727 | freebn(bdmq1); |
728 | |
729 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
730 | numbers[1] = n; |
731 | numbers[2] = e; |
732 | numbers[3] = d; |
733 | numbers[4] = p; |
734 | numbers[5] = q; |
735 | numbers[6] = dmp1; |
736 | numbers[7] = dmq1; |
737 | numbers[8] = iqmp; |
738 | |
739 | nnumbers = 9; |
740 | header = "-----BEGIN RSA PRIVATE KEY-----\n"; |
741 | footer = "-----END RSA PRIVATE KEY-----\n"; |
742 | } else if (key->alg == &ssh_dss) { |
743 | int pos; |
744 | struct mpint_pos p, q, g, y, x; |
745 | |
746 | pos = 4 + GET_32BIT(pubblob); |
747 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
748 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
749 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
750 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
751 | pos = 0; |
752 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
753 | |
754 | assert(y.start && x.start); /* can't go wrong */ |
755 | |
756 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
757 | numbers[1] = p; |
758 | numbers[2] = q; |
759 | numbers[3] = g; |
760 | numbers[4] = y; |
761 | numbers[5] = x; |
762 | |
763 | nnumbers = 6; |
764 | header = "-----BEGIN DSA PRIVATE KEY-----\n"; |
765 | footer = "-----END DSA PRIVATE KEY-----\n"; |
766 | } else { |
767 | assert(0); /* zoinks! */ |
768 | } |
769 | |
770 | /* |
771 | * Now count up the total size of the ASN.1 encoded integers, |
772 | * so as to determine the length of the containing SEQUENCE. |
773 | */ |
774 | len = 0; |
775 | for (i = 0; i < nnumbers; i++) { |
776 | len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); |
777 | len += numbers[i].bytes; |
778 | } |
779 | seqlen = len; |
780 | /* Now add on the SEQUENCE header. */ |
781 | len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); |
04627c33 |
782 | /* Round up to the cipher block size, ensuring we have at least one |
783 | * byte of padding (see below). */ |
784 | outlen = len; |
d23a9b21 |
785 | if (passphrase) |
04627c33 |
786 | outlen = (outlen+8) &~ 7; |
d23a9b21 |
787 | |
788 | /* |
789 | * Now we know how big outblob needs to be. Allocate it. |
790 | */ |
d23a9b21 |
791 | outblob = smalloc(outlen); |
792 | |
793 | /* |
794 | * And write the data into it. |
795 | */ |
796 | pos = 0; |
797 | pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); |
798 | for (i = 0; i < nnumbers; i++) { |
799 | pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); |
800 | memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); |
801 | pos += numbers[i].bytes; |
802 | } |
04627c33 |
803 | |
804 | /* |
805 | * Padding on OpenSSH keys is deterministic. The number of |
806 | * padding bytes is always more than zero, and always at most |
807 | * the cipher block length. The value of each padding byte is |
808 | * equal to the number of padding bytes. So a plaintext that's |
809 | * an exact multiple of the block size will be padded with 08 |
810 | * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a |
811 | * plaintext one byte less than a multiple of the block size |
812 | * will be padded with just 01. |
813 | * |
814 | * This enables the OpenSSL key decryption function to strip |
815 | * off the padding algorithmically and return the unpadded |
816 | * plaintext to the next layer: it looks at the final byte, and |
817 | * then expects to find that many bytes at the end of the data |
818 | * with the same value. Those are all removed and the rest is |
819 | * returned. |
820 | */ |
821 | assert(pos == len); |
d23a9b21 |
822 | while (pos < outlen) { |
04627c33 |
823 | outblob[pos++] = outlen - len; |
d23a9b21 |
824 | } |
825 | |
826 | /* |
827 | * Encrypt the key. |
828 | */ |
829 | if (passphrase) { |
830 | /* |
831 | * Invent an iv. Then derive encryption key from passphrase |
832 | * and iv/salt: |
833 | * |
834 | * - let block A equal MD5(passphrase || iv) |
835 | * - let block B equal MD5(A || passphrase || iv) |
836 | * - block C would be MD5(B || passphrase || iv) and so on |
837 | * - encryption key is the first N bytes of A || B |
838 | */ |
839 | struct MD5Context md5c; |
840 | unsigned char keybuf[32]; |
841 | |
842 | for (i = 0; i < 8; i++) iv[i] = random_byte(); |
843 | |
844 | MD5Init(&md5c); |
845 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
846 | MD5Update(&md5c, iv, 8); |
847 | MD5Final(keybuf, &md5c); |
848 | |
849 | MD5Init(&md5c); |
850 | MD5Update(&md5c, keybuf, 16); |
851 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
852 | MD5Update(&md5c, iv, 8); |
853 | MD5Final(keybuf+16, &md5c); |
854 | |
855 | /* |
856 | * Now encrypt the key blob. |
857 | */ |
858 | des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen); |
859 | |
860 | memset(&md5c, 0, sizeof(md5c)); |
861 | memset(keybuf, 0, sizeof(keybuf)); |
862 | } |
863 | |
864 | /* |
865 | * And save it. We'll use Unix line endings just in case it's |
866 | * subsequently transferred in binary mode. |
867 | */ |
868 | fp = fopen(filename, "wb"); /* ensure Unix line endings */ |
869 | if (!fp) |
870 | goto error; |
871 | fputs(header, fp); |
872 | if (passphrase) { |
873 | fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,"); |
874 | for (i = 0; i < 8; i++) |
875 | fprintf(fp, "%02X", iv[i]); |
876 | fprintf(fp, "\n\n"); |
877 | } |
96d19bc9 |
878 | base64_encode(fp, outblob, outlen, 64); |
d23a9b21 |
879 | fputs(footer, fp); |
880 | fclose(fp); |
881 | ret = 1; |
882 | |
883 | error: |
884 | if (outblob) { |
885 | memset(outblob, 0, outlen); |
886 | sfree(outblob); |
887 | } |
888 | if (spareblob) { |
889 | memset(spareblob, 0, sparelen); |
890 | sfree(spareblob); |
891 | } |
892 | if (privblob) { |
893 | memset(privblob, 0, privlen); |
894 | sfree(privblob); |
895 | } |
896 | if (pubblob) { |
897 | memset(pubblob, 0, publen); |
898 | sfree(pubblob); |
899 | } |
900 | return ret; |
901 | } |
902 | |
7b4ef1ae |
903 | /* ---------------------------------------------------------------------- |
904 | * Code to read ssh.com private keys. |
905 | */ |
906 | |
907 | /* |
908 | * The format of the base64 blob is largely ssh2-packet-formatted, |
909 | * except that mpints are a bit different: they're more like the |
910 | * old ssh1 mpint. You have a 32-bit bit count N, followed by |
911 | * (N+7)/8 bytes of data. |
912 | * |
913 | * So. The blob contains: |
914 | * |
915 | * - uint32 0x3f6ff9eb (magic number) |
916 | * - uint32 size (total blob size) |
917 | * - string key-type (see below) |
918 | * - string cipher-type (tells you if key is encrypted) |
919 | * - string encrypted-blob |
920 | * |
921 | * (The first size field includes the size field itself and the |
922 | * magic number before it. All other size fields are ordinary ssh2 |
923 | * strings, so the size field indicates how much data is to |
924 | * _follow_.) |
925 | * |
926 | * The encrypted blob, once decrypted, contains a single string |
927 | * which in turn contains the payload. (This allows padding to be |
928 | * added after that string while still making it clear where the |
929 | * real payload ends. Also it probably makes for a reasonable |
930 | * decryption check.) |
931 | * |
932 | * The payload blob, for an RSA key, contains: |
933 | * - mpint e |
934 | * - mpint d |
935 | * - mpint n (yes, the public and private stuff is intermixed) |
936 | * - mpint u (presumably inverse of p mod q) |
937 | * - mpint p (p is the smaller prime) |
938 | * - mpint q (q is the larger) |
939 | * |
940 | * For a DSA key, the payload blob contains: |
941 | * - uint32 0 |
942 | * - mpint p |
943 | * - mpint g |
944 | * - mpint q |
945 | * - mpint y |
946 | * - mpint x |
947 | * |
948 | * Alternatively, if the parameters are `predefined', that |
949 | * (0,p,g,q) sequence can be replaced by a uint32 1 and a string |
950 | * containing some predefined parameter specification. *shudder*, |
951 | * but I doubt we'll encounter this in real life. |
952 | * |
953 | * The key type strings are ghastly. The RSA key I looked at had a |
954 | * type string of |
955 | * |
956 | * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}' |
957 | * |
958 | * and the DSA key wasn't much better: |
959 | * |
960 | * `dl-modp{sign{dsa-nist-sha1},dh{plain}}' |
961 | * |
962 | * It isn't clear that these will always be the same. I think it |
963 | * might be wise just to look at the `if-modn{sign{rsa' and |
964 | * `dl-modp{sign{dsa' prefixes. |
965 | * |
966 | * Finally, the encryption. The cipher-type string appears to be |
967 | * either `none' or `3des-cbc'. Looks as if this is SSH2-style |
968 | * 3des-cbc (i.e. outer cbc rather than inner). The key is created |
969 | * from the passphrase by means of yet another hashing faff: |
970 | * |
971 | * - first 16 bytes are MD5(passphrase) |
972 | * - next 16 bytes are MD5(passphrase || first 16 bytes) |
973 | * - if there were more, they'd be MD5(passphrase || first 32), |
974 | * and so on. |
975 | */ |
976 | |
96d19bc9 |
977 | #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb |
978 | |
7b4ef1ae |
979 | struct sshcom_key { |
980 | char comment[256]; /* allowing any length is overkill */ |
981 | unsigned char *keyblob; |
982 | int keyblob_len, keyblob_size; |
983 | }; |
984 | |
985 | struct sshcom_key *load_sshcom_key(char *filename) |
986 | { |
987 | struct sshcom_key *ret; |
988 | FILE *fp; |
989 | char buffer[256]; |
990 | int len; |
991 | char *errmsg, *p; |
992 | int headers_done; |
993 | char base64_bit[4]; |
994 | int base64_chars = 0; |
995 | |
996 | ret = smalloc(sizeof(*ret)); |
997 | ret->comment[0] = '\0'; |
998 | ret->keyblob = NULL; |
999 | ret->keyblob_len = ret->keyblob_size = 0; |
1000 | |
1001 | fp = fopen(filename, "r"); |
1002 | if (!fp) { |
1003 | errmsg = "Unable to open key file"; |
1004 | goto error; |
1005 | } |
1006 | if (!fgets(buffer, sizeof(buffer), fp) || |
1007 | 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { |
1008 | errmsg = "File does not begin with ssh.com key header"; |
1009 | goto error; |
1010 | } |
1011 | |
1012 | headers_done = 0; |
1013 | while (1) { |
1014 | if (!fgets(buffer, sizeof(buffer), fp)) { |
1015 | errmsg = "Unexpected end of file"; |
1016 | goto error; |
1017 | } |
1018 | if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) |
1019 | break; /* done */ |
1020 | if ((p = strchr(buffer, ':')) != NULL) { |
1021 | if (headers_done) { |
1022 | errmsg = "Header found in body of key data"; |
1023 | goto error; |
1024 | } |
1025 | *p++ = '\0'; |
1026 | while (*p && isspace((unsigned char)*p)) p++; |
1027 | /* |
1028 | * Header lines can end in a trailing backslash for |
1029 | * continuation. |
1030 | */ |
6ef15436 |
1031 | while ((len = strlen(p)) > (int)(sizeof(buffer) - (p-buffer) -1) || |
7b4ef1ae |
1032 | p[len-1] != '\n' || p[len-2] == '\\') { |
6ef15436 |
1033 | if (len > (int)((p-buffer) + sizeof(buffer)-2)) { |
7b4ef1ae |
1034 | errmsg = "Header line too long to deal with"; |
1035 | goto error; |
1036 | } |
1037 | if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { |
1038 | errmsg = "Unexpected end of file"; |
1039 | goto error; |
1040 | } |
1041 | } |
1042 | p[strcspn(p, "\n")] = '\0'; |
1043 | if (!strcmp(buffer, "Comment")) { |
1044 | /* Strip quotes in comment if present. */ |
1045 | if (p[0] == '"' && p[strlen(p)-1] == '"') { |
1046 | p++; |
1047 | p[strlen(p)-1] = '\0'; |
1048 | } |
1049 | strncpy(ret->comment, p, sizeof(ret->comment)); |
1050 | ret->comment[sizeof(ret->comment)-1] = '\0'; |
1051 | } |
1052 | } else { |
1053 | headers_done = 1; |
1054 | |
1055 | p = buffer; |
1056 | while (isbase64(*p)) { |
1057 | base64_bit[base64_chars++] = *p; |
1058 | if (base64_chars == 4) { |
1059 | unsigned char out[3]; |
1060 | |
1061 | base64_chars = 0; |
1062 | |
1063 | len = base64_decode_atom(base64_bit, out); |
1064 | |
1065 | if (len <= 0) { |
1066 | errmsg = "Invalid base64 encoding"; |
1067 | goto error; |
1068 | } |
1069 | |
1070 | if (ret->keyblob_len + len > ret->keyblob_size) { |
1071 | ret->keyblob_size = ret->keyblob_len + len + 256; |
1072 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
1073 | } |
1074 | |
1075 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
1076 | ret->keyblob_len += len; |
1077 | } |
1078 | |
1079 | p++; |
1080 | } |
1081 | } |
1082 | } |
1083 | |
1084 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
1085 | errmsg = "Key body not present"; |
1086 | goto error; |
1087 | } |
1088 | |
1089 | return ret; |
1090 | |
1091 | error: |
1092 | if (ret) { |
ee5c1422 |
1093 | if (ret->keyblob) { |
1094 | memset(ret->keyblob, 0, ret->keyblob_size); |
1095 | sfree(ret->keyblob); |
1096 | } |
1097 | memset(&ret, 0, sizeof(ret)); |
7b4ef1ae |
1098 | sfree(ret); |
1099 | } |
1100 | return NULL; |
1101 | } |
1102 | |
1103 | int sshcom_encrypted(char *filename, char **comment) |
1104 | { |
1105 | struct sshcom_key *key = load_sshcom_key(filename); |
1106 | int pos, len, answer; |
1107 | |
1108 | *comment = NULL; |
1109 | if (!key) |
1110 | return 0; |
1111 | |
1112 | /* |
1113 | * Check magic number. |
1114 | */ |
1115 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) |
1116 | return 0; /* key is invalid */ |
1117 | |
1118 | /* |
1119 | * Find the cipher-type string. |
1120 | */ |
1121 | answer = 0; |
1122 | pos = 8; |
1123 | if (key->keyblob_len < pos+4) |
1124 | goto done; /* key is far too short */ |
1125 | pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ |
1126 | if (key->keyblob_len < pos+4) |
1127 | goto done; /* key is far too short */ |
1128 | len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ |
1129 | if (key->keyblob_len < pos+4+len) |
1130 | goto done; /* cipher type string is incomplete */ |
1131 | if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) |
1132 | answer = 1; |
1133 | |
1134 | done: |
1135 | *comment = dupstr(key->comment); |
ee5c1422 |
1136 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1137 | sfree(key->keyblob); |
ee5c1422 |
1138 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1139 | sfree(key); |
1140 | return answer; |
1141 | } |
1142 | |
7b4ef1ae |
1143 | int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) |
1144 | { |
1145 | int bits; |
1146 | int bytes; |
1147 | unsigned char *d = (unsigned char *) data; |
1148 | |
1149 | if (len < 4) |
1150 | goto error; |
1151 | bits = GET_32BIT(d); |
1152 | |
1153 | bytes = (bits + 7) / 8; |
1154 | if (len < 4+bytes) |
1155 | goto error; |
1156 | |
1157 | ret->start = d + 4; |
1158 | ret->bytes = bytes; |
1159 | return bytes+4; |
1160 | |
1161 | error: |
1162 | ret->start = NULL; |
1163 | ret->bytes = -1; |
1164 | return len; /* ensure further calls fail as well */ |
1165 | } |
1166 | |
96d19bc9 |
1167 | static int sshcom_put_mpint(void *target, void *data, int len) |
1168 | { |
1169 | unsigned char *d = (unsigned char *)target; |
1170 | unsigned char *i = (unsigned char *)data; |
1171 | int bits = len * 8 - 1; |
1172 | |
1173 | while (bits > 0) { |
1174 | if (*i & (1 << (bits & 7))) |
1175 | break; |
1176 | if (!(bits-- & 7)) |
1177 | i++, len--; |
1178 | } |
1179 | |
1180 | PUT_32BIT(d, bits+1); |
1181 | memcpy(d+4, i, len); |
1182 | return len+4; |
1183 | } |
1184 | |
7b4ef1ae |
1185 | struct ssh2_userkey *sshcom_read(char *filename, char *passphrase) |
1186 | { |
1187 | struct sshcom_key *key = load_sshcom_key(filename); |
1188 | char *errmsg; |
1189 | int pos, len; |
1190 | const char prefix_rsa[] = "if-modn{sign{rsa"; |
1191 | const char prefix_dsa[] = "dl-modp{sign{dsa"; |
1192 | enum { RSA, DSA } type; |
1193 | int encrypted; |
1194 | char *ciphertext; |
1195 | int cipherlen; |
1196 | struct ssh2_userkey *ret = NULL, *retkey; |
1197 | const struct ssh_signkey *alg; |
1198 | unsigned char *blob = NULL; |
ee5c1422 |
1199 | int blobsize, publen, privlen; |
7b4ef1ae |
1200 | |
1201 | if (!key) |
1202 | return NULL; |
1203 | |
1204 | /* |
1205 | * Check magic number. |
1206 | */ |
96d19bc9 |
1207 | if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) { |
7b4ef1ae |
1208 | errmsg = "Key does not begin with magic number"; |
1209 | goto error; |
1210 | } |
1211 | |
1212 | /* |
1213 | * Determine the key type. |
1214 | */ |
1215 | pos = 8; |
1216 | if (key->keyblob_len < pos+4 || |
1217 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1218 | errmsg = "Key blob does not contain a key type string"; |
1219 | goto error; |
1220 | } |
1221 | if (len > sizeof(prefix_rsa) - 1 && |
1222 | !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { |
1223 | type = RSA; |
1224 | } else if (len > sizeof(prefix_dsa) - 1 && |
1225 | !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { |
1226 | type = DSA; |
1227 | } else { |
1228 | errmsg = "Key is of unknown type"; |
1229 | goto error; |
1230 | } |
1231 | pos += 4+len; |
1232 | |
1233 | /* |
1234 | * Determine the cipher type. |
1235 | */ |
1236 | if (key->keyblob_len < pos+4 || |
1237 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1238 | errmsg = "Key blob does not contain a cipher type string"; |
1239 | goto error; |
1240 | } |
1241 | if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) |
1242 | encrypted = 0; |
1243 | else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) |
1244 | encrypted = 1; |
1245 | else { |
1246 | errmsg = "Key encryption is of unknown type"; |
1247 | goto error; |
1248 | } |
1249 | pos += 4+len; |
1250 | |
1251 | /* |
1252 | * Get hold of the encrypted part of the key. |
1253 | */ |
1254 | if (key->keyblob_len < pos+4 || |
1255 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1256 | errmsg = "Key blob does not contain actual key data"; |
1257 | goto error; |
1258 | } |
1259 | ciphertext = key->keyblob + pos + 4; |
1260 | cipherlen = len; |
1261 | if (cipherlen == 0) { |
1262 | errmsg = "Length of key data is zero"; |
1263 | goto error; |
1264 | } |
1265 | |
1266 | /* |
1267 | * Decrypt it if necessary. |
1268 | */ |
1269 | if (encrypted) { |
1270 | /* |
1271 | * Derive encryption key from passphrase and iv/salt: |
1272 | * |
1273 | * - let block A equal MD5(passphrase) |
1274 | * - let block B equal MD5(passphrase || A) |
1275 | * - block C would be MD5(passphrase || A || B) and so on |
1276 | * - encryption key is the first N bytes of A || B |
1277 | */ |
1278 | struct MD5Context md5c; |
1279 | unsigned char keybuf[32], iv[8]; |
1280 | |
1281 | if (cipherlen % 8 != 0) { |
1282 | errmsg = "Encrypted part of key is not a multiple of cipher block" |
1283 | " size"; |
1284 | goto error; |
1285 | } |
1286 | |
1287 | MD5Init(&md5c); |
1288 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
1289 | MD5Final(keybuf, &md5c); |
1290 | |
1291 | MD5Init(&md5c); |
1292 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
1293 | MD5Update(&md5c, keybuf, 16); |
1294 | MD5Final(keybuf+16, &md5c); |
1295 | |
1296 | /* |
1297 | * Now decrypt the key blob. |
1298 | */ |
ee5c1422 |
1299 | memset(iv, 0, sizeof(iv)); |
7b4ef1ae |
1300 | des3_decrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen); |
1301 | |
ee5c1422 |
1302 | memset(&md5c, 0, sizeof(md5c)); |
1303 | memset(keybuf, 0, sizeof(keybuf)); |
1304 | |
7b4ef1ae |
1305 | /* |
1306 | * Hereafter we return WRONG_PASSPHRASE for any parsing |
ee5c1422 |
1307 | * error. (But only if we've just tried to decrypt it! |
1308 | * Returning WRONG_PASSPHRASE for an unencrypted key is |
1309 | * automatic doom.) |
7b4ef1ae |
1310 | */ |
1311 | if (encrypted) |
1312 | ret = SSH2_WRONG_PASSPHRASE; |
1313 | } |
1314 | |
1315 | /* |
1316 | * Strip away the containing string to get to the real meat. |
1317 | */ |
1318 | len = GET_32BIT(ciphertext); |
1319 | if (len > cipherlen-4) { |
1320 | errmsg = "containing string was ill-formed"; |
1321 | goto error; |
1322 | } |
1323 | ciphertext += 4; |
1324 | cipherlen = len; |
1325 | |
1326 | /* |
1327 | * Now we break down into RSA versus DSA. In either case we'll |
1328 | * construct public and private blobs in our own format, and |
1329 | * end up feeding them to alg->createkey(). |
1330 | */ |
ee5c1422 |
1331 | blobsize = cipherlen + 256; |
1332 | blob = smalloc(blobsize); |
7b4ef1ae |
1333 | privlen = 0; |
1334 | if (type == RSA) { |
1335 | struct mpint_pos n, e, d, u, p, q; |
1336 | int pos = 0; |
1337 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); |
1338 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); |
1339 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); |
1340 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); |
1341 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
1342 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1343 | if (!q.start) { |
1344 | errmsg = "key data did not contain six integers"; |
1345 | goto error; |
1346 | } |
1347 | |
1348 | alg = &ssh_rsa; |
1349 | pos = 0; |
1350 | pos += put_string(blob+pos, "ssh-rsa", 7); |
1351 | pos += put_mp(blob+pos, e.start, e.bytes); |
1352 | pos += put_mp(blob+pos, n.start, n.bytes); |
1353 | publen = pos; |
1354 | pos += put_string(blob+pos, d.start, d.bytes); |
1355 | pos += put_mp(blob+pos, q.start, q.bytes); |
1356 | pos += put_mp(blob+pos, p.start, p.bytes); |
1357 | pos += put_mp(blob+pos, u.start, u.bytes); |
1358 | privlen = pos - publen; |
1359 | } else if (type == DSA) { |
1360 | struct mpint_pos p, q, g, x, y; |
1361 | int pos = 4; |
1362 | if (GET_32BIT(ciphertext) != 0) { |
1363 | errmsg = "predefined DSA parameters not supported"; |
1364 | goto error; |
1365 | } |
1366 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
1367 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); |
1368 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1369 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); |
1370 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); |
1371 | if (!x.start) { |
1372 | errmsg = "key data did not contain five integers"; |
1373 | goto error; |
1374 | } |
1375 | |
1376 | alg = &ssh_dss; |
1377 | pos = 0; |
1378 | pos += put_string(blob+pos, "ssh-dss", 7); |
1379 | pos += put_mp(blob+pos, p.start, p.bytes); |
1380 | pos += put_mp(blob+pos, q.start, q.bytes); |
1381 | pos += put_mp(blob+pos, g.start, g.bytes); |
1382 | pos += put_mp(blob+pos, y.start, y.bytes); |
1383 | publen = pos; |
1384 | pos += put_mp(blob+pos, x.start, x.bytes); |
1385 | privlen = pos - publen; |
1386 | } |
1387 | |
1388 | assert(privlen > 0); /* should have bombed by now if not */ |
1389 | |
1390 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
1391 | retkey->alg = alg; |
1392 | retkey->data = alg->createkey(blob, publen, blob+publen, privlen); |
1393 | if (!retkey->data) { |
1394 | sfree(retkey); |
1395 | errmsg = "unable to create key data structure"; |
1396 | goto error; |
1397 | } |
1398 | retkey->comment = dupstr(key->comment); |
1399 | |
1400 | errmsg = NULL; /* no error */ |
1401 | ret = retkey; |
1402 | |
1403 | error: |
ee5c1422 |
1404 | if (blob) { |
1405 | memset(blob, 0, blobsize); |
1406 | sfree(blob); |
1407 | } |
1408 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1409 | sfree(key->keyblob); |
ee5c1422 |
1410 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1411 | sfree(key); |
1412 | return ret; |
1413 | } |
96d19bc9 |
1414 | |
1415 | int sshcom_write(char *filename, struct ssh2_userkey *key, char *passphrase) |
1416 | { |
1417 | unsigned char *pubblob, *privblob; |
1418 | int publen, privlen; |
1419 | unsigned char *outblob; |
1420 | int outlen; |
1421 | struct mpint_pos numbers[6]; |
1422 | int nnumbers, initial_zero, pos, lenpos, i; |
1423 | char *type; |
1424 | char *ciphertext; |
1425 | int cipherlen; |
1426 | int ret = 0; |
1427 | FILE *fp; |
1428 | |
1429 | /* |
1430 | * Fetch the key blobs. |
1431 | */ |
1432 | pubblob = key->alg->public_blob(key->data, &publen); |
1433 | privblob = key->alg->private_blob(key->data, &privlen); |
1434 | outblob = NULL; |
1435 | |
1436 | /* |
1437 | * Find the sequence of integers to be encoded into the OpenSSH |
1438 | * key blob, and also decide on the header line. |
1439 | */ |
1440 | if (key->alg == &ssh_rsa) { |
1441 | int pos; |
1442 | struct mpint_pos n, e, d, p, q, iqmp; |
1443 | |
1444 | pos = 4 + GET_32BIT(pubblob); |
1445 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
1446 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
1447 | pos = 0; |
1448 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
1449 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
1450 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
1451 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
1452 | |
1453 | assert(e.start && iqmp.start); /* can't go wrong */ |
1454 | |
1455 | numbers[0] = e; |
1456 | numbers[1] = d; |
1457 | numbers[2] = n; |
1458 | numbers[3] = iqmp; |
1459 | numbers[4] = q; |
1460 | numbers[5] = p; |
1461 | |
1462 | nnumbers = 6; |
1463 | initial_zero = 0; |
1464 | type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}"; |
1465 | } else if (key->alg == &ssh_dss) { |
1466 | int pos; |
1467 | struct mpint_pos p, q, g, y, x; |
1468 | |
1469 | pos = 4 + GET_32BIT(pubblob); |
1470 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
1471 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
1472 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
1473 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
1474 | pos = 0; |
1475 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
1476 | |
1477 | assert(y.start && x.start); /* can't go wrong */ |
1478 | |
1479 | numbers[0] = p; |
1480 | numbers[1] = g; |
1481 | numbers[2] = q; |
1482 | numbers[3] = y; |
1483 | numbers[4] = x; |
1484 | |
1485 | nnumbers = 5; |
1486 | initial_zero = 1; |
1487 | type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}"; |
1488 | } else { |
1489 | assert(0); /* zoinks! */ |
1490 | } |
1491 | |
1492 | /* |
1493 | * Total size of key blob will be somewhere under 512 plus |
1494 | * combined length of integers. We'll calculate the more |
1495 | * precise size as we construct the blob. |
1496 | */ |
1497 | outlen = 512; |
1498 | for (i = 0; i < nnumbers; i++) |
1499 | outlen += 4 + numbers[i].bytes; |
1500 | outblob = smalloc(outlen); |
1501 | |
1502 | /* |
1503 | * Create the unencrypted key blob. |
1504 | */ |
1505 | pos = 0; |
1506 | PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4; |
1507 | pos += 4; /* length field, fill in later */ |
1508 | pos += put_string(outblob+pos, type, strlen(type)); |
1509 | { |
1510 | char *ciphertype = passphrase ? "3des-cbc" : "none"; |
1511 | pos += put_string(outblob+pos, ciphertype, strlen(ciphertype)); |
1512 | } |
1513 | lenpos = pos; /* remember this position */ |
1514 | pos += 4; /* encrypted-blob size */ |
1515 | pos += 4; /* encrypted-payload size */ |
1516 | if (initial_zero) { |
1517 | PUT_32BIT(outblob+pos, 0); |
1518 | pos += 4; |
1519 | } |
1520 | for (i = 0; i < nnumbers; i++) |
1521 | pos += sshcom_put_mpint(outblob+pos, |
1522 | numbers[i].start, numbers[i].bytes); |
1523 | /* Now wrap up the encrypted payload. */ |
1524 | PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8)); |
1525 | /* Pad encrypted blob to a multiple of cipher block size. */ |
1526 | if (passphrase) { |
1527 | int padding = -(pos - (lenpos+4)) & 7; |
1528 | while (padding--) |
1529 | outblob[pos++] = random_byte(); |
1530 | } |
1531 | ciphertext = outblob+lenpos+4; |
1532 | cipherlen = pos - (lenpos+4); |
1533 | assert(!passphrase || cipherlen % 8 == 0); |
1534 | /* Wrap up the encrypted blob string. */ |
1535 | PUT_32BIT(outblob+lenpos, cipherlen); |
1536 | /* And finally fill in the total length field. */ |
1537 | PUT_32BIT(outblob+4, pos); |
1538 | |
1539 | assert(pos < outlen); |
1540 | |
1541 | /* |
1542 | * Encrypt the key. |
1543 | */ |
1544 | if (passphrase) { |
1545 | /* |
1546 | * Derive encryption key from passphrase and iv/salt: |
1547 | * |
1548 | * - let block A equal MD5(passphrase) |
1549 | * - let block B equal MD5(passphrase || A) |
1550 | * - block C would be MD5(passphrase || A || B) and so on |
1551 | * - encryption key is the first N bytes of A || B |
1552 | */ |
1553 | struct MD5Context md5c; |
1554 | unsigned char keybuf[32], iv[8]; |
1555 | |
1556 | MD5Init(&md5c); |
1557 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
1558 | MD5Final(keybuf, &md5c); |
1559 | |
1560 | MD5Init(&md5c); |
1561 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
1562 | MD5Update(&md5c, keybuf, 16); |
1563 | MD5Final(keybuf+16, &md5c); |
1564 | |
1565 | /* |
1566 | * Now decrypt the key blob. |
1567 | */ |
1568 | memset(iv, 0, sizeof(iv)); |
1569 | des3_encrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen); |
1570 | |
1571 | memset(&md5c, 0, sizeof(md5c)); |
1572 | memset(keybuf, 0, sizeof(keybuf)); |
1573 | } |
1574 | |
1575 | /* |
1576 | * And save it. We'll use Unix line endings just in case it's |
1577 | * subsequently transferred in binary mode. |
1578 | */ |
1579 | fp = fopen(filename, "wb"); /* ensure Unix line endings */ |
1580 | if (!fp) |
1581 | goto error; |
1582 | fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); |
1583 | fprintf(fp, "Comment: \""); |
1584 | /* |
1585 | * Comment header is broken with backslash-newline if it goes |
1586 | * over 70 chars. Although it's surrounded by quotes, it |
1587 | * _doesn't_ escape backslashes or quotes within the string. |
1588 | * Don't ask me, I didn't design it. |
1589 | */ |
1590 | { |
1591 | int slen = 60; /* starts at 60 due to "Comment: " */ |
1592 | char *c = key->comment; |
6ef15436 |
1593 | while ((int)strlen(c) > slen) { |
96d19bc9 |
1594 | fprintf(fp, "%.*s\\\n", slen, c); |
1595 | c += slen; |
1596 | slen = 70; /* allow 70 chars on subsequent lines */ |
1597 | } |
1598 | fprintf(fp, "%s\"\n", c); |
1599 | } |
1600 | base64_encode(fp, outblob, pos, 70); |
1601 | fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); |
1602 | fclose(fp); |
1603 | ret = 1; |
1604 | |
1605 | error: |
1606 | if (outblob) { |
1607 | memset(outblob, 0, outlen); |
1608 | sfree(outblob); |
1609 | } |
1610 | if (privblob) { |
1611 | memset(privblob, 0, privlen); |
1612 | sfree(privblob); |
1613 | } |
1614 | if (pubblob) { |
1615 | memset(pubblob, 0, publen); |
1616 | sfree(pubblob); |
1617 | } |
1618 | return ret; |
1619 | } |