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 | |
9a30e26b |
11 | #include "putty.h" |
9dda6459 |
12 | #include "ssh.h" |
13 | #include "misc.h" |
14 | |
15 | #define PUT_32BIT(cp, value) do { \ |
96d19bc9 |
16 | (cp)[3] = (unsigned char)(value); \ |
17 | (cp)[2] = (unsigned char)((value) >> 8); \ |
18 | (cp)[1] = (unsigned char)((value) >> 16); \ |
19 | (cp)[0] = (unsigned char)((value) >> 24); } while (0) |
9dda6459 |
20 | |
21 | #define GET_32BIT(cp) \ |
22 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
23 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
24 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
25 | ((unsigned long)(unsigned char)(cp)[3])) |
26 | |
9a30e26b |
27 | int openssh_encrypted(const Filename *filename); |
28 | struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase); |
29 | int openssh_write(const Filename *filename, struct ssh2_userkey *key, |
30 | char *passphrase); |
9dda6459 |
31 | |
9a30e26b |
32 | int sshcom_encrypted(const Filename *filename, char **comment); |
33 | struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase); |
34 | int sshcom_write(const Filename *filename, struct ssh2_userkey *key, |
35 | char *passphrase); |
7b4ef1ae |
36 | |
9dda6459 |
37 | /* |
38 | * Given a key type, determine whether we know how to import it. |
39 | */ |
40 | int import_possible(int type) |
41 | { |
42 | if (type == SSH_KEYTYPE_OPENSSH) |
43 | return 1; |
7b4ef1ae |
44 | if (type == SSH_KEYTYPE_SSHCOM) |
45 | return 1; |
9dda6459 |
46 | return 0; |
47 | } |
48 | |
49 | /* |
50 | * Given a key type, determine what native key type |
51 | * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once |
52 | * we've imported it. |
53 | */ |
54 | int import_target_type(int type) |
55 | { |
56 | /* |
57 | * There are no known foreign SSH1 key formats. |
58 | */ |
59 | return SSH_KEYTYPE_SSH2; |
60 | } |
61 | |
62 | /* |
63 | * Determine whether a foreign key is encrypted. |
64 | */ |
9a30e26b |
65 | int import_encrypted(const Filename *filename, int type, char **comment) |
9dda6459 |
66 | { |
67 | if (type == SSH_KEYTYPE_OPENSSH) { |
9a30e26b |
68 | /* OpenSSH doesn't do key comments */ |
9fab77dc |
69 | *comment = dupstr(filename_to_str(filename)); |
9dda6459 |
70 | return openssh_encrypted(filename); |
71 | } |
7b4ef1ae |
72 | if (type == SSH_KEYTYPE_SSHCOM) { |
73 | return sshcom_encrypted(filename, comment); |
74 | } |
9dda6459 |
75 | return 0; |
76 | } |
77 | |
78 | /* |
79 | * Import an SSH1 key. |
80 | */ |
9a30e26b |
81 | int import_ssh1(const Filename *filename, int type, |
82 | struct RSAKey *key, char *passphrase) |
9dda6459 |
83 | { |
84 | return 0; |
85 | } |
86 | |
87 | /* |
88 | * Import an SSH2 key. |
89 | */ |
9a30e26b |
90 | struct ssh2_userkey *import_ssh2(const Filename *filename, int type, |
91 | char *passphrase) |
9dda6459 |
92 | { |
93 | if (type == SSH_KEYTYPE_OPENSSH) |
94 | return openssh_read(filename, passphrase); |
7b4ef1ae |
95 | if (type == SSH_KEYTYPE_SSHCOM) |
96 | return sshcom_read(filename, passphrase); |
9dda6459 |
97 | return NULL; |
98 | } |
99 | |
4801c01c |
100 | /* |
101 | * Export an SSH1 key. |
102 | */ |
9a30e26b |
103 | int export_ssh1(const Filename *filename, int type, struct RSAKey *key, |
104 | char *passphrase) |
4801c01c |
105 | { |
106 | return 0; |
107 | } |
108 | |
109 | /* |
110 | * Export an SSH2 key. |
111 | */ |
9a30e26b |
112 | int export_ssh2(const Filename *filename, int type, |
4801c01c |
113 | struct ssh2_userkey *key, char *passphrase) |
114 | { |
4801c01c |
115 | if (type == SSH_KEYTYPE_OPENSSH) |
116 | return openssh_write(filename, key, passphrase); |
117 | if (type == SSH_KEYTYPE_SSHCOM) |
118 | return sshcom_write(filename, key, passphrase); |
4801c01c |
119 | return 0; |
120 | } |
121 | |
9dda6459 |
122 | /* ---------------------------------------------------------------------- |
123 | * Helper routines. (The base64 ones are defined in sshpubk.c.) |
124 | */ |
125 | |
126 | #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ |
127 | ((c) >= 'a' && (c) <= 'z') || \ |
128 | ((c) >= '0' && (c) <= '9') || \ |
129 | (c) == '+' || (c) == '/' || (c) == '=' \ |
130 | ) |
131 | |
9dda6459 |
132 | /* |
133 | * Read an ASN.1/BER identifier and length pair. |
134 | * |
135 | * Flags are a combination of the #defines listed below. |
136 | * |
137 | * Returns -1 if unsuccessful; otherwise returns the number of |
138 | * bytes used out of the source data. |
139 | */ |
140 | |
141 | /* ASN.1 tag classes. */ |
142 | #define ASN1_CLASS_UNIVERSAL (0 << 6) |
143 | #define ASN1_CLASS_APPLICATION (1 << 6) |
144 | #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6) |
145 | #define ASN1_CLASS_PRIVATE (3 << 6) |
146 | #define ASN1_CLASS_MASK (3 << 6) |
147 | |
148 | /* Primitive versus constructed bit. */ |
149 | #define ASN1_CONSTRUCTED (1 << 5) |
150 | |
d714d740 |
151 | static int ber_read_id_len(void *source, int sourcelen, |
152 | int *id, int *length, int *flags) |
9dda6459 |
153 | { |
154 | unsigned char *p = (unsigned char *) source; |
155 | |
156 | if (sourcelen == 0) |
157 | return -1; |
158 | |
159 | *flags = (*p & 0xE0); |
160 | if ((*p & 0x1F) == 0x1F) { |
161 | *id = 0; |
162 | while (*p & 0x80) { |
163 | *id = (*id << 7) | (*p & 0x7F); |
164 | p++, sourcelen--; |
165 | if (sourcelen == 0) |
166 | return -1; |
167 | } |
168 | *id = (*id << 7) | (*p & 0x7F); |
169 | p++, sourcelen--; |
170 | } else { |
171 | *id = *p & 0x1F; |
172 | p++, sourcelen--; |
173 | } |
174 | |
175 | if (sourcelen == 0) |
176 | return -1; |
177 | |
178 | if (*p & 0x80) { |
179 | int n = *p & 0x7F; |
180 | p++, sourcelen--; |
181 | if (sourcelen < n) |
182 | return -1; |
183 | *length = 0; |
184 | while (n--) |
185 | *length = (*length << 8) | (*p++); |
186 | sourcelen -= n; |
187 | } else { |
188 | *length = *p; |
189 | p++, sourcelen--; |
190 | } |
191 | |
192 | return p - (unsigned char *) source; |
193 | } |
194 | |
d23a9b21 |
195 | /* |
196 | * Write an ASN.1/BER identifier and length pair. Returns the |
197 | * number of bytes consumed. Assumes dest contains enough space. |
198 | * Will avoid writing anything if dest is NULL, but still return |
199 | * amount of space required. |
200 | */ |
d714d740 |
201 | static int ber_write_id_len(void *dest, int id, int length, int flags) |
d23a9b21 |
202 | { |
203 | unsigned char *d = (unsigned char *)dest; |
204 | int len = 0; |
205 | |
206 | if (id <= 30) { |
207 | /* |
208 | * Identifier is one byte. |
209 | */ |
210 | len++; |
211 | if (d) *d++ = id | flags; |
212 | } else { |
213 | int n; |
214 | /* |
215 | * Identifier is multiple bytes: the first byte is 11111 |
216 | * plus the flags, and subsequent bytes encode the value of |
217 | * the identifier, 7 bits at a time, with the top bit of |
218 | * each byte 1 except the last one which is 0. |
219 | */ |
220 | len++; |
221 | if (d) *d++ = 0x1F | flags; |
222 | for (n = 1; (id >> (7*n)) > 0; n++) |
223 | continue; /* count the bytes */ |
224 | while (n--) { |
225 | len++; |
226 | if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F); |
227 | } |
228 | } |
229 | |
230 | if (length < 128) { |
231 | /* |
232 | * Length is one byte. |
233 | */ |
234 | len++; |
235 | if (d) *d++ = length; |
236 | } else { |
237 | int n; |
238 | /* |
239 | * Length is multiple bytes. The first is 0x80 plus the |
240 | * number of subsequent bytes, and the subsequent bytes |
241 | * encode the actual length. |
242 | */ |
243 | for (n = 1; (length >> (8*n)) > 0; n++) |
244 | continue; /* count the bytes */ |
245 | len++; |
246 | if (d) *d++ = 0x80 | n; |
247 | while (n--) { |
248 | len++; |
249 | if (d) *d++ = (length >> (8*n)) & 0xFF; |
250 | } |
251 | } |
252 | |
253 | return len; |
254 | } |
255 | |
7b4ef1ae |
256 | static int put_string(void *target, void *data, int len) |
257 | { |
258 | unsigned char *d = (unsigned char *)target; |
259 | |
260 | PUT_32BIT(d, len); |
261 | memcpy(d+4, data, len); |
262 | return len+4; |
263 | } |
264 | |
265 | static int put_mp(void *target, void *data, int len) |
266 | { |
267 | unsigned char *d = (unsigned char *)target; |
268 | unsigned char *i = (unsigned char *)data; |
269 | |
270 | if (*i & 0x80) { |
271 | PUT_32BIT(d, len+1); |
272 | d[4] = 0; |
273 | memcpy(d+5, data, len); |
274 | return len+5; |
275 | } else { |
276 | PUT_32BIT(d, len); |
277 | memcpy(d+4, data, len); |
278 | return len+4; |
279 | } |
280 | } |
281 | |
d23a9b21 |
282 | /* Simple structure to point to an mp-int within a blob. */ |
283 | struct mpint_pos { void *start; int bytes; }; |
284 | |
d714d740 |
285 | static int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret) |
d23a9b21 |
286 | { |
287 | int bytes; |
288 | unsigned char *d = (unsigned char *) data; |
289 | |
290 | if (len < 4) |
291 | goto error; |
292 | bytes = GET_32BIT(d); |
293 | if (len < 4+bytes) |
294 | goto error; |
295 | |
296 | ret->start = d + 4; |
297 | ret->bytes = bytes; |
298 | return bytes+4; |
299 | |
300 | error: |
301 | ret->start = NULL; |
302 | ret->bytes = -1; |
303 | return len; /* ensure further calls fail as well */ |
304 | } |
305 | |
9dda6459 |
306 | /* ---------------------------------------------------------------------- |
d23a9b21 |
307 | * Code to read and write OpenSSH private keys. |
9dda6459 |
308 | */ |
309 | |
310 | enum { OSSH_DSA, OSSH_RSA }; |
311 | struct openssh_key { |
312 | int type; |
313 | int encrypted; |
314 | char iv[32]; |
315 | unsigned char *keyblob; |
316 | int keyblob_len, keyblob_size; |
317 | }; |
318 | |
d714d740 |
319 | static struct openssh_key *load_openssh_key(const Filename *filename) |
9dda6459 |
320 | { |
321 | struct openssh_key *ret; |
322 | FILE *fp; |
323 | char buffer[256]; |
324 | char *errmsg, *p; |
325 | int headers_done; |
ee5c1422 |
326 | char base64_bit[4]; |
327 | int base64_chars = 0; |
9dda6459 |
328 | |
3d88e64d |
329 | ret = snew(struct openssh_key); |
9dda6459 |
330 | ret->keyblob = NULL; |
331 | ret->keyblob_len = ret->keyblob_size = 0; |
332 | ret->encrypted = 0; |
333 | memset(ret->iv, 0, sizeof(ret->iv)); |
334 | |
9a30e26b |
335 | fp = f_open(*filename, "r"); |
9dda6459 |
336 | if (!fp) { |
337 | errmsg = "Unable to open key file"; |
338 | goto error; |
339 | } |
340 | if (!fgets(buffer, sizeof(buffer), fp) || |
341 | 0 != strncmp(buffer, "-----BEGIN ", 11) || |
342 | 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) { |
343 | errmsg = "File does not begin with OpenSSH key header"; |
344 | goto error; |
345 | } |
346 | if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n")) |
347 | ret->type = OSSH_RSA; |
348 | else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n")) |
349 | ret->type = OSSH_DSA; |
350 | else { |
351 | errmsg = "Unrecognised key type"; |
352 | goto error; |
353 | } |
354 | |
355 | headers_done = 0; |
356 | while (1) { |
357 | if (!fgets(buffer, sizeof(buffer), fp)) { |
358 | errmsg = "Unexpected end of file"; |
359 | goto error; |
360 | } |
361 | if (0 == strncmp(buffer, "-----END ", 9) && |
362 | 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) |
363 | break; /* done */ |
364 | if ((p = strchr(buffer, ':')) != NULL) { |
365 | if (headers_done) { |
366 | errmsg = "Header found in body of key data"; |
367 | goto error; |
368 | } |
369 | *p++ = '\0'; |
370 | while (*p && isspace((unsigned char)*p)) p++; |
371 | if (!strcmp(buffer, "Proc-Type")) { |
372 | if (p[0] != '4' || p[1] != ',') { |
373 | errmsg = "Proc-Type is not 4 (only 4 is supported)"; |
374 | goto error; |
375 | } |
376 | p += 2; |
377 | if (!strcmp(p, "ENCRYPTED\n")) |
378 | ret->encrypted = 1; |
379 | } else if (!strcmp(buffer, "DEK-Info")) { |
380 | int i, j; |
381 | |
382 | if (strncmp(p, "DES-EDE3-CBC,", 13)) { |
383 | errmsg = "Ciphers other than DES-EDE3-CBC not supported"; |
384 | goto error; |
385 | } |
386 | p += 13; |
387 | for (i = 0; i < 8; i++) { |
388 | if (1 != sscanf(p, "%2x", &j)) |
389 | break; |
390 | ret->iv[i] = j; |
391 | p += 2; |
392 | } |
393 | if (i < 8) { |
394 | errmsg = "Expected 16-digit iv in DEK-Info"; |
395 | goto error; |
396 | } |
397 | } |
398 | } else { |
399 | headers_done = 1; |
400 | |
401 | p = buffer; |
ee5c1422 |
402 | while (isbase64(*p)) { |
403 | base64_bit[base64_chars++] = *p; |
404 | if (base64_chars == 4) { |
405 | unsigned char out[3]; |
406 | int len; |
9dda6459 |
407 | |
ee5c1422 |
408 | base64_chars = 0; |
9dda6459 |
409 | |
ee5c1422 |
410 | len = base64_decode_atom(base64_bit, out); |
9dda6459 |
411 | |
ee5c1422 |
412 | if (len <= 0) { |
413 | errmsg = "Invalid base64 encoding"; |
414 | goto error; |
415 | } |
416 | |
417 | if (ret->keyblob_len + len > ret->keyblob_size) { |
418 | ret->keyblob_size = ret->keyblob_len + len + 256; |
3d88e64d |
419 | ret->keyblob = sresize(ret->keyblob, ret->keyblob_size, |
420 | unsigned char); |
ee5c1422 |
421 | } |
9dda6459 |
422 | |
ee5c1422 |
423 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
424 | ret->keyblob_len += len; |
9dda6459 |
425 | |
ee5c1422 |
426 | memset(out, 0, sizeof(out)); |
427 | } |
9dda6459 |
428 | |
ee5c1422 |
429 | p++; |
9dda6459 |
430 | } |
431 | } |
432 | } |
433 | |
434 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
435 | errmsg = "Key body not present"; |
436 | goto error; |
437 | } |
438 | |
439 | if (ret->encrypted && ret->keyblob_len % 8 != 0) { |
440 | errmsg = "Encrypted key blob is not a multiple of cipher block size"; |
441 | goto error; |
442 | } |
443 | |
ee5c1422 |
444 | memset(buffer, 0, sizeof(buffer)); |
445 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
446 | return ret; |
447 | |
448 | error: |
ee5c1422 |
449 | memset(buffer, 0, sizeof(buffer)); |
450 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
451 | if (ret) { |
ee5c1422 |
452 | if (ret->keyblob) { |
453 | memset(ret->keyblob, 0, ret->keyblob_size); |
454 | sfree(ret->keyblob); |
455 | } |
456 | memset(&ret, 0, sizeof(ret)); |
9dda6459 |
457 | sfree(ret); |
458 | } |
459 | return NULL; |
460 | } |
461 | |
9a30e26b |
462 | int openssh_encrypted(const Filename *filename) |
9dda6459 |
463 | { |
464 | struct openssh_key *key = load_openssh_key(filename); |
465 | int ret; |
466 | |
467 | if (!key) |
468 | return 0; |
469 | ret = key->encrypted; |
ee5c1422 |
470 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
471 | sfree(key->keyblob); |
ee5c1422 |
472 | memset(&key, 0, sizeof(key)); |
9dda6459 |
473 | sfree(key); |
474 | return ret; |
475 | } |
476 | |
9a30e26b |
477 | struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase) |
9dda6459 |
478 | { |
479 | struct openssh_key *key = load_openssh_key(filename); |
480 | struct ssh2_userkey *retkey; |
481 | unsigned char *p; |
482 | int ret, id, len, flags; |
483 | int i, num_integers; |
484 | struct ssh2_userkey *retval = NULL; |
485 | char *errmsg; |
486 | unsigned char *blob; |
ee5c1422 |
487 | int blobsize, blobptr, privptr; |
9dda6459 |
488 | char *modptr; |
489 | int modlen; |
490 | |
e3498db5 |
491 | blob = NULL; |
492 | |
9dda6459 |
493 | if (!key) |
494 | return NULL; |
495 | |
496 | if (key->encrypted) { |
497 | /* |
498 | * Derive encryption key from passphrase and iv/salt: |
499 | * |
500 | * - let block A equal MD5(passphrase || iv) |
501 | * - let block B equal MD5(A || passphrase || iv) |
502 | * - block C would be MD5(B || passphrase || iv) and so on |
503 | * - encryption key is the first N bytes of A || B |
504 | */ |
505 | struct MD5Context md5c; |
506 | unsigned char keybuf[32]; |
507 | |
508 | MD5Init(&md5c); |
201188af |
509 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
510 | MD5Update(&md5c, (unsigned char *)key->iv, 8); |
9dda6459 |
511 | MD5Final(keybuf, &md5c); |
512 | |
513 | MD5Init(&md5c); |
514 | MD5Update(&md5c, keybuf, 16); |
201188af |
515 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
516 | MD5Update(&md5c, (unsigned char *)key->iv, 8); |
9dda6459 |
517 | MD5Final(keybuf+16, &md5c); |
518 | |
519 | /* |
520 | * Now decrypt the key blob. |
521 | */ |
201188af |
522 | des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv, |
9dda6459 |
523 | key->keyblob, key->keyblob_len); |
ee5c1422 |
524 | |
525 | memset(&md5c, 0, sizeof(md5c)); |
526 | memset(keybuf, 0, sizeof(keybuf)); |
9dda6459 |
527 | } |
528 | |
529 | /* |
530 | * Now we have a decrypted key blob, which contains an ASN.1 |
531 | * encoded private key. We must now untangle the ASN.1. |
532 | * |
533 | * We expect the whole key blob to be formatted as a SEQUENCE |
534 | * (0x30 followed by a length code indicating that the rest of |
535 | * the blob is part of the sequence). Within that SEQUENCE we |
536 | * expect to see a bunch of INTEGERs. What those integers mean |
537 | * depends on the key type: |
538 | * |
539 | * - For RSA, we expect the integers to be 0, n, e, d, p, q, |
540 | * dmp1, dmq1, iqmp in that order. (The last three are d mod |
541 | * (p-1), d mod (q-1), inverse of q mod p respectively.) |
542 | * |
543 | * - For DSA, we expect them to be 0, p, q, g, y, x in that |
544 | * order. |
545 | */ |
546 | |
547 | p = key->keyblob; |
548 | |
549 | /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ |
550 | ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); |
551 | p += ret; |
552 | if (ret < 0 || id != 16) { |
553 | errmsg = "ASN.1 decoding failure"; |
554 | retval = SSH2_WRONG_PASSPHRASE; |
555 | goto error; |
556 | } |
557 | |
558 | /* Expect a load of INTEGERs. */ |
559 | if (key->type == OSSH_RSA) |
560 | num_integers = 9; |
561 | else if (key->type == OSSH_DSA) |
562 | num_integers = 6; |
563 | |
564 | /* |
565 | * Space to create key blob in. |
566 | */ |
ee5c1422 |
567 | blobsize = 256+key->keyblob_len; |
3d88e64d |
568 | blob = snewn(blobsize, unsigned char); |
9dda6459 |
569 | PUT_32BIT(blob, 7); |
570 | if (key->type == OSSH_DSA) |
571 | memcpy(blob+4, "ssh-dss", 7); |
572 | else if (key->type == OSSH_RSA) |
573 | memcpy(blob+4, "ssh-rsa", 7); |
574 | blobptr = 4+7; |
575 | privptr = -1; |
576 | |
577 | for (i = 0; i < num_integers; i++) { |
578 | ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, |
579 | &id, &len, &flags); |
580 | p += ret; |
581 | if (ret < 0 || id != 2 || |
582 | key->keyblob+key->keyblob_len-p < len) { |
583 | errmsg = "ASN.1 decoding failure"; |
584 | goto error; |
585 | } |
586 | |
587 | if (i == 0) { |
588 | /* |
589 | * The first integer should be zero always (I think |
590 | * this is some sort of version indication). |
591 | */ |
592 | if (len != 1 || p[0] != 0) { |
593 | errmsg = "Version number mismatch"; |
594 | goto error; |
595 | } |
596 | } else if (key->type == OSSH_RSA) { |
597 | /* |
598 | * Integers 1 and 2 go into the public blob but in the |
599 | * opposite order; integers 3, 4, 5 and 8 go into the |
600 | * private blob. The other two (6 and 7) are ignored. |
601 | */ |
602 | if (i == 1) { |
603 | /* Save the details for after we deal with number 2. */ |
201188af |
604 | modptr = (char *)p; |
9dda6459 |
605 | modlen = len; |
606 | } else if (i != 6 && i != 7) { |
607 | PUT_32BIT(blob+blobptr, len); |
608 | memcpy(blob+blobptr+4, p, len); |
609 | blobptr += 4+len; |
610 | if (i == 2) { |
611 | PUT_32BIT(blob+blobptr, modlen); |
612 | memcpy(blob+blobptr+4, modptr, modlen); |
613 | blobptr += 4+modlen; |
614 | privptr = blobptr; |
615 | } |
616 | } |
617 | } else if (key->type == OSSH_DSA) { |
618 | /* |
619 | * Integers 1-4 go into the public blob; integer 5 goes |
620 | * into the private blob. |
621 | */ |
622 | PUT_32BIT(blob+blobptr, len); |
623 | memcpy(blob+blobptr+4, p, len); |
624 | blobptr += 4+len; |
625 | if (i == 4) |
626 | privptr = blobptr; |
627 | } |
628 | |
629 | /* Skip past the number. */ |
630 | p += len; |
631 | } |
632 | |
633 | /* |
634 | * Now put together the actual key. Simplest way to do this is |
635 | * to assemble our own key blobs and feed them to the createkey |
636 | * functions; this is a bit faffy but it does mean we get all |
637 | * the sanity checks for free. |
638 | */ |
639 | assert(privptr > 0); /* should have bombed by now if not */ |
3d88e64d |
640 | retkey = snew(struct ssh2_userkey); |
9dda6459 |
641 | retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss); |
642 | retkey->data = retkey->alg->createkey(blob, privptr, |
643 | blob+privptr, blobptr-privptr); |
644 | if (!retkey->data) { |
645 | sfree(retkey); |
646 | errmsg = "unable to create key data structure"; |
647 | goto error; |
648 | } |
649 | |
650 | retkey->comment = dupstr("imported-openssh-key"); |
ee5c1422 |
651 | errmsg = NULL; /* no error */ |
652 | retval = retkey; |
9dda6459 |
653 | |
654 | error: |
ee5c1422 |
655 | if (blob) { |
656 | memset(blob, 0, blobsize); |
657 | sfree(blob); |
658 | } |
659 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
660 | sfree(key->keyblob); |
ee5c1422 |
661 | memset(&key, 0, sizeof(key)); |
9dda6459 |
662 | sfree(key); |
663 | return retval; |
664 | } |
7b4ef1ae |
665 | |
9a30e26b |
666 | int openssh_write(const Filename *filename, struct ssh2_userkey *key, |
667 | char *passphrase) |
d23a9b21 |
668 | { |
669 | unsigned char *pubblob, *privblob, *spareblob; |
670 | int publen, privlen, sparelen; |
671 | unsigned char *outblob; |
672 | int outlen; |
673 | struct mpint_pos numbers[9]; |
674 | int nnumbers, pos, len, seqlen, i; |
675 | char *header, *footer; |
676 | char zero[1]; |
677 | unsigned char iv[8]; |
678 | int ret = 0; |
679 | FILE *fp; |
680 | |
681 | /* |
682 | * Fetch the key blobs. |
683 | */ |
684 | pubblob = key->alg->public_blob(key->data, &publen); |
685 | privblob = key->alg->private_blob(key->data, &privlen); |
686 | spareblob = outblob = NULL; |
687 | |
688 | /* |
689 | * Find the sequence of integers to be encoded into the OpenSSH |
690 | * key blob, and also decide on the header line. |
691 | */ |
692 | if (key->alg == &ssh_rsa) { |
693 | int pos; |
694 | struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1; |
695 | Bignum bd, bp, bq, bdmp1, bdmq1; |
696 | |
697 | pos = 4 + GET_32BIT(pubblob); |
698 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
699 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
700 | pos = 0; |
701 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
702 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
703 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
704 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
705 | |
706 | assert(e.start && iqmp.start); /* can't go wrong */ |
707 | |
708 | /* We also need d mod (p-1) and d mod (q-1). */ |
709 | bd = bignum_from_bytes(d.start, d.bytes); |
710 | bp = bignum_from_bytes(p.start, p.bytes); |
711 | bq = bignum_from_bytes(q.start, q.bytes); |
712 | decbn(bp); |
713 | decbn(bq); |
714 | bdmp1 = bigmod(bd, bp); |
715 | bdmq1 = bigmod(bd, bq); |
716 | freebn(bd); |
717 | freebn(bp); |
718 | freebn(bq); |
719 | |
720 | dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8; |
721 | dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8; |
722 | sparelen = dmp1.bytes + dmq1.bytes; |
3d88e64d |
723 | spareblob = snewn(sparelen, unsigned char); |
d23a9b21 |
724 | dmp1.start = spareblob; |
725 | dmq1.start = spareblob + dmp1.bytes; |
726 | for (i = 0; i < dmp1.bytes; i++) |
727 | spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i); |
728 | for (i = 0; i < dmq1.bytes; i++) |
729 | spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i); |
730 | freebn(bdmp1); |
731 | freebn(bdmq1); |
732 | |
733 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
734 | numbers[1] = n; |
735 | numbers[2] = e; |
736 | numbers[3] = d; |
737 | numbers[4] = p; |
738 | numbers[5] = q; |
739 | numbers[6] = dmp1; |
740 | numbers[7] = dmq1; |
741 | numbers[8] = iqmp; |
742 | |
743 | nnumbers = 9; |
744 | header = "-----BEGIN RSA PRIVATE KEY-----\n"; |
745 | footer = "-----END RSA PRIVATE KEY-----\n"; |
746 | } else if (key->alg == &ssh_dss) { |
747 | int pos; |
748 | struct mpint_pos p, q, g, y, x; |
749 | |
750 | pos = 4 + GET_32BIT(pubblob); |
751 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
752 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
753 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
754 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
755 | pos = 0; |
756 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
757 | |
758 | assert(y.start && x.start); /* can't go wrong */ |
759 | |
760 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
761 | numbers[1] = p; |
762 | numbers[2] = q; |
763 | numbers[3] = g; |
764 | numbers[4] = y; |
765 | numbers[5] = x; |
766 | |
767 | nnumbers = 6; |
768 | header = "-----BEGIN DSA PRIVATE KEY-----\n"; |
769 | footer = "-----END DSA PRIVATE KEY-----\n"; |
770 | } else { |
771 | assert(0); /* zoinks! */ |
772 | } |
773 | |
774 | /* |
775 | * Now count up the total size of the ASN.1 encoded integers, |
776 | * so as to determine the length of the containing SEQUENCE. |
777 | */ |
778 | len = 0; |
779 | for (i = 0; i < nnumbers; i++) { |
780 | len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); |
781 | len += numbers[i].bytes; |
782 | } |
783 | seqlen = len; |
784 | /* Now add on the SEQUENCE header. */ |
785 | len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); |
04627c33 |
786 | /* Round up to the cipher block size, ensuring we have at least one |
787 | * byte of padding (see below). */ |
788 | outlen = len; |
d23a9b21 |
789 | if (passphrase) |
04627c33 |
790 | outlen = (outlen+8) &~ 7; |
d23a9b21 |
791 | |
792 | /* |
793 | * Now we know how big outblob needs to be. Allocate it. |
794 | */ |
3d88e64d |
795 | outblob = snewn(outlen, unsigned char); |
d23a9b21 |
796 | |
797 | /* |
798 | * And write the data into it. |
799 | */ |
800 | pos = 0; |
801 | pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); |
802 | for (i = 0; i < nnumbers; i++) { |
803 | pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); |
804 | memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); |
805 | pos += numbers[i].bytes; |
806 | } |
04627c33 |
807 | |
808 | /* |
809 | * Padding on OpenSSH keys is deterministic. The number of |
810 | * padding bytes is always more than zero, and always at most |
811 | * the cipher block length. The value of each padding byte is |
812 | * equal to the number of padding bytes. So a plaintext that's |
813 | * an exact multiple of the block size will be padded with 08 |
814 | * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a |
815 | * plaintext one byte less than a multiple of the block size |
816 | * will be padded with just 01. |
817 | * |
818 | * This enables the OpenSSL key decryption function to strip |
819 | * off the padding algorithmically and return the unpadded |
820 | * plaintext to the next layer: it looks at the final byte, and |
821 | * then expects to find that many bytes at the end of the data |
822 | * with the same value. Those are all removed and the rest is |
823 | * returned. |
824 | */ |
825 | assert(pos == len); |
d23a9b21 |
826 | while (pos < outlen) { |
04627c33 |
827 | outblob[pos++] = outlen - len; |
d23a9b21 |
828 | } |
829 | |
830 | /* |
831 | * Encrypt the key. |
832 | */ |
833 | if (passphrase) { |
834 | /* |
835 | * Invent an iv. Then derive encryption key from passphrase |
836 | * and iv/salt: |
837 | * |
838 | * - let block A equal MD5(passphrase || iv) |
839 | * - let block B equal MD5(A || passphrase || iv) |
840 | * - block C would be MD5(B || passphrase || iv) and so on |
841 | * - encryption key is the first N bytes of A || B |
842 | */ |
843 | struct MD5Context md5c; |
844 | unsigned char keybuf[32]; |
845 | |
846 | for (i = 0; i < 8; i++) iv[i] = random_byte(); |
847 | |
848 | MD5Init(&md5c); |
201188af |
849 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
d23a9b21 |
850 | MD5Update(&md5c, iv, 8); |
851 | MD5Final(keybuf, &md5c); |
852 | |
853 | MD5Init(&md5c); |
854 | MD5Update(&md5c, keybuf, 16); |
201188af |
855 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
d23a9b21 |
856 | MD5Update(&md5c, iv, 8); |
857 | MD5Final(keybuf+16, &md5c); |
858 | |
859 | /* |
860 | * Now encrypt the key blob. |
861 | */ |
862 | des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen); |
863 | |
864 | memset(&md5c, 0, sizeof(md5c)); |
865 | memset(keybuf, 0, sizeof(keybuf)); |
866 | } |
867 | |
868 | /* |
869 | * And save it. We'll use Unix line endings just in case it's |
870 | * subsequently transferred in binary mode. |
871 | */ |
9a30e26b |
872 | fp = f_open(*filename, "wb"); /* ensure Unix line endings */ |
d23a9b21 |
873 | if (!fp) |
874 | goto error; |
875 | fputs(header, fp); |
876 | if (passphrase) { |
877 | fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,"); |
878 | for (i = 0; i < 8; i++) |
879 | fprintf(fp, "%02X", iv[i]); |
880 | fprintf(fp, "\n\n"); |
881 | } |
96d19bc9 |
882 | base64_encode(fp, outblob, outlen, 64); |
d23a9b21 |
883 | fputs(footer, fp); |
884 | fclose(fp); |
885 | ret = 1; |
886 | |
887 | error: |
888 | if (outblob) { |
889 | memset(outblob, 0, outlen); |
890 | sfree(outblob); |
891 | } |
892 | if (spareblob) { |
893 | memset(spareblob, 0, sparelen); |
894 | sfree(spareblob); |
895 | } |
896 | if (privblob) { |
897 | memset(privblob, 0, privlen); |
898 | sfree(privblob); |
899 | } |
900 | if (pubblob) { |
901 | memset(pubblob, 0, publen); |
902 | sfree(pubblob); |
903 | } |
904 | return ret; |
905 | } |
906 | |
7b4ef1ae |
907 | /* ---------------------------------------------------------------------- |
908 | * Code to read ssh.com private keys. |
909 | */ |
910 | |
911 | /* |
912 | * The format of the base64 blob is largely ssh2-packet-formatted, |
913 | * except that mpints are a bit different: they're more like the |
914 | * old ssh1 mpint. You have a 32-bit bit count N, followed by |
915 | * (N+7)/8 bytes of data. |
916 | * |
917 | * So. The blob contains: |
918 | * |
919 | * - uint32 0x3f6ff9eb (magic number) |
920 | * - uint32 size (total blob size) |
921 | * - string key-type (see below) |
922 | * - string cipher-type (tells you if key is encrypted) |
923 | * - string encrypted-blob |
924 | * |
925 | * (The first size field includes the size field itself and the |
926 | * magic number before it. All other size fields are ordinary ssh2 |
927 | * strings, so the size field indicates how much data is to |
928 | * _follow_.) |
929 | * |
930 | * The encrypted blob, once decrypted, contains a single string |
931 | * which in turn contains the payload. (This allows padding to be |
932 | * added after that string while still making it clear where the |
933 | * real payload ends. Also it probably makes for a reasonable |
934 | * decryption check.) |
935 | * |
936 | * The payload blob, for an RSA key, contains: |
937 | * - mpint e |
938 | * - mpint d |
939 | * - mpint n (yes, the public and private stuff is intermixed) |
940 | * - mpint u (presumably inverse of p mod q) |
941 | * - mpint p (p is the smaller prime) |
942 | * - mpint q (q is the larger) |
943 | * |
944 | * For a DSA key, the payload blob contains: |
945 | * - uint32 0 |
946 | * - mpint p |
947 | * - mpint g |
948 | * - mpint q |
949 | * - mpint y |
950 | * - mpint x |
951 | * |
952 | * Alternatively, if the parameters are `predefined', that |
953 | * (0,p,g,q) sequence can be replaced by a uint32 1 and a string |
954 | * containing some predefined parameter specification. *shudder*, |
955 | * but I doubt we'll encounter this in real life. |
956 | * |
957 | * The key type strings are ghastly. The RSA key I looked at had a |
958 | * type string of |
959 | * |
960 | * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}' |
961 | * |
962 | * and the DSA key wasn't much better: |
963 | * |
964 | * `dl-modp{sign{dsa-nist-sha1},dh{plain}}' |
965 | * |
966 | * It isn't clear that these will always be the same. I think it |
967 | * might be wise just to look at the `if-modn{sign{rsa' and |
968 | * `dl-modp{sign{dsa' prefixes. |
969 | * |
970 | * Finally, the encryption. The cipher-type string appears to be |
971 | * either `none' or `3des-cbc'. Looks as if this is SSH2-style |
972 | * 3des-cbc (i.e. outer cbc rather than inner). The key is created |
973 | * from the passphrase by means of yet another hashing faff: |
974 | * |
975 | * - first 16 bytes are MD5(passphrase) |
976 | * - next 16 bytes are MD5(passphrase || first 16 bytes) |
977 | * - if there were more, they'd be MD5(passphrase || first 32), |
978 | * and so on. |
979 | */ |
980 | |
96d19bc9 |
981 | #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb |
982 | |
7b4ef1ae |
983 | struct sshcom_key { |
984 | char comment[256]; /* allowing any length is overkill */ |
985 | unsigned char *keyblob; |
986 | int keyblob_len, keyblob_size; |
987 | }; |
988 | |
d714d740 |
989 | static struct sshcom_key *load_sshcom_key(const Filename *filename) |
7b4ef1ae |
990 | { |
991 | struct sshcom_key *ret; |
992 | FILE *fp; |
993 | char buffer[256]; |
994 | int len; |
995 | char *errmsg, *p; |
996 | int headers_done; |
997 | char base64_bit[4]; |
998 | int base64_chars = 0; |
999 | |
3d88e64d |
1000 | ret = snew(struct sshcom_key); |
7b4ef1ae |
1001 | ret->comment[0] = '\0'; |
1002 | ret->keyblob = NULL; |
1003 | ret->keyblob_len = ret->keyblob_size = 0; |
1004 | |
9a30e26b |
1005 | fp = f_open(*filename, "r"); |
7b4ef1ae |
1006 | if (!fp) { |
1007 | errmsg = "Unable to open key file"; |
1008 | goto error; |
1009 | } |
1010 | if (!fgets(buffer, sizeof(buffer), fp) || |
1011 | 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { |
1012 | errmsg = "File does not begin with ssh.com key header"; |
1013 | goto error; |
1014 | } |
1015 | |
1016 | headers_done = 0; |
1017 | while (1) { |
1018 | if (!fgets(buffer, sizeof(buffer), fp)) { |
1019 | errmsg = "Unexpected end of file"; |
1020 | goto error; |
1021 | } |
1022 | if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) |
1023 | break; /* done */ |
1024 | if ((p = strchr(buffer, ':')) != NULL) { |
1025 | if (headers_done) { |
1026 | errmsg = "Header found in body of key data"; |
1027 | goto error; |
1028 | } |
1029 | *p++ = '\0'; |
1030 | while (*p && isspace((unsigned char)*p)) p++; |
1031 | /* |
1032 | * Header lines can end in a trailing backslash for |
1033 | * continuation. |
1034 | */ |
6ef15436 |
1035 | while ((len = strlen(p)) > (int)(sizeof(buffer) - (p-buffer) -1) || |
7b4ef1ae |
1036 | p[len-1] != '\n' || p[len-2] == '\\') { |
6ef15436 |
1037 | if (len > (int)((p-buffer) + sizeof(buffer)-2)) { |
7b4ef1ae |
1038 | errmsg = "Header line too long to deal with"; |
1039 | goto error; |
1040 | } |
1041 | if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { |
1042 | errmsg = "Unexpected end of file"; |
1043 | goto error; |
1044 | } |
1045 | } |
1046 | p[strcspn(p, "\n")] = '\0'; |
1047 | if (!strcmp(buffer, "Comment")) { |
1048 | /* Strip quotes in comment if present. */ |
1049 | if (p[0] == '"' && p[strlen(p)-1] == '"') { |
1050 | p++; |
1051 | p[strlen(p)-1] = '\0'; |
1052 | } |
1053 | strncpy(ret->comment, p, sizeof(ret->comment)); |
1054 | ret->comment[sizeof(ret->comment)-1] = '\0'; |
1055 | } |
1056 | } else { |
1057 | headers_done = 1; |
1058 | |
1059 | p = buffer; |
1060 | while (isbase64(*p)) { |
1061 | base64_bit[base64_chars++] = *p; |
1062 | if (base64_chars == 4) { |
1063 | unsigned char out[3]; |
1064 | |
1065 | base64_chars = 0; |
1066 | |
1067 | len = base64_decode_atom(base64_bit, out); |
1068 | |
1069 | if (len <= 0) { |
1070 | errmsg = "Invalid base64 encoding"; |
1071 | goto error; |
1072 | } |
1073 | |
1074 | if (ret->keyblob_len + len > ret->keyblob_size) { |
1075 | ret->keyblob_size = ret->keyblob_len + len + 256; |
3d88e64d |
1076 | ret->keyblob = sresize(ret->keyblob, ret->keyblob_size, |
1077 | unsigned char); |
7b4ef1ae |
1078 | } |
1079 | |
1080 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
1081 | ret->keyblob_len += len; |
1082 | } |
1083 | |
1084 | p++; |
1085 | } |
1086 | } |
1087 | } |
1088 | |
1089 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
1090 | errmsg = "Key body not present"; |
1091 | goto error; |
1092 | } |
1093 | |
1094 | return ret; |
1095 | |
1096 | error: |
1097 | if (ret) { |
ee5c1422 |
1098 | if (ret->keyblob) { |
1099 | memset(ret->keyblob, 0, ret->keyblob_size); |
1100 | sfree(ret->keyblob); |
1101 | } |
1102 | memset(&ret, 0, sizeof(ret)); |
7b4ef1ae |
1103 | sfree(ret); |
1104 | } |
1105 | return NULL; |
1106 | } |
1107 | |
9a30e26b |
1108 | int sshcom_encrypted(const Filename *filename, char **comment) |
7b4ef1ae |
1109 | { |
1110 | struct sshcom_key *key = load_sshcom_key(filename); |
1111 | int pos, len, answer; |
1112 | |
1113 | *comment = NULL; |
1114 | if (!key) |
1115 | return 0; |
1116 | |
1117 | /* |
1118 | * Check magic number. |
1119 | */ |
1120 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) |
1121 | return 0; /* key is invalid */ |
1122 | |
1123 | /* |
1124 | * Find the cipher-type string. |
1125 | */ |
1126 | answer = 0; |
1127 | pos = 8; |
1128 | if (key->keyblob_len < pos+4) |
1129 | goto done; /* key is far too short */ |
1130 | pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ |
1131 | if (key->keyblob_len < pos+4) |
1132 | goto done; /* key is far too short */ |
1133 | len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ |
1134 | if (key->keyblob_len < pos+4+len) |
1135 | goto done; /* cipher type string is incomplete */ |
1136 | if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) |
1137 | answer = 1; |
1138 | |
1139 | done: |
1140 | *comment = dupstr(key->comment); |
ee5c1422 |
1141 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1142 | sfree(key->keyblob); |
ee5c1422 |
1143 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1144 | sfree(key); |
1145 | return answer; |
1146 | } |
1147 | |
d714d740 |
1148 | static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) |
7b4ef1ae |
1149 | { |
1150 | int bits; |
1151 | int bytes; |
1152 | unsigned char *d = (unsigned char *) data; |
1153 | |
1154 | if (len < 4) |
1155 | goto error; |
1156 | bits = GET_32BIT(d); |
1157 | |
1158 | bytes = (bits + 7) / 8; |
1159 | if (len < 4+bytes) |
1160 | goto error; |
1161 | |
1162 | ret->start = d + 4; |
1163 | ret->bytes = bytes; |
1164 | return bytes+4; |
1165 | |
1166 | error: |
1167 | ret->start = NULL; |
1168 | ret->bytes = -1; |
1169 | return len; /* ensure further calls fail as well */ |
1170 | } |
1171 | |
96d19bc9 |
1172 | static int sshcom_put_mpint(void *target, void *data, int len) |
1173 | { |
1174 | unsigned char *d = (unsigned char *)target; |
1175 | unsigned char *i = (unsigned char *)data; |
1176 | int bits = len * 8 - 1; |
1177 | |
1178 | while (bits > 0) { |
1179 | if (*i & (1 << (bits & 7))) |
1180 | break; |
1181 | if (!(bits-- & 7)) |
1182 | i++, len--; |
1183 | } |
1184 | |
1185 | PUT_32BIT(d, bits+1); |
1186 | memcpy(d+4, i, len); |
1187 | return len+4; |
1188 | } |
1189 | |
9a30e26b |
1190 | struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase) |
7b4ef1ae |
1191 | { |
1192 | struct sshcom_key *key = load_sshcom_key(filename); |
1193 | char *errmsg; |
1194 | int pos, len; |
1195 | const char prefix_rsa[] = "if-modn{sign{rsa"; |
1196 | const char prefix_dsa[] = "dl-modp{sign{dsa"; |
1197 | enum { RSA, DSA } type; |
1198 | int encrypted; |
1199 | char *ciphertext; |
1200 | int cipherlen; |
1201 | struct ssh2_userkey *ret = NULL, *retkey; |
1202 | const struct ssh_signkey *alg; |
1203 | unsigned char *blob = NULL; |
ee5c1422 |
1204 | int blobsize, publen, privlen; |
7b4ef1ae |
1205 | |
1206 | if (!key) |
1207 | return NULL; |
1208 | |
1209 | /* |
1210 | * Check magic number. |
1211 | */ |
96d19bc9 |
1212 | if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) { |
7b4ef1ae |
1213 | errmsg = "Key does not begin with magic number"; |
1214 | goto error; |
1215 | } |
1216 | |
1217 | /* |
1218 | * Determine the key type. |
1219 | */ |
1220 | pos = 8; |
1221 | if (key->keyblob_len < pos+4 || |
1222 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1223 | errmsg = "Key blob does not contain a key type string"; |
1224 | goto error; |
1225 | } |
1226 | if (len > sizeof(prefix_rsa) - 1 && |
1227 | !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { |
1228 | type = RSA; |
1229 | } else if (len > sizeof(prefix_dsa) - 1 && |
1230 | !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { |
1231 | type = DSA; |
1232 | } else { |
1233 | errmsg = "Key is of unknown type"; |
1234 | goto error; |
1235 | } |
1236 | pos += 4+len; |
1237 | |
1238 | /* |
1239 | * Determine the cipher type. |
1240 | */ |
1241 | if (key->keyblob_len < pos+4 || |
1242 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1243 | errmsg = "Key blob does not contain a cipher type string"; |
1244 | goto error; |
1245 | } |
1246 | if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) |
1247 | encrypted = 0; |
1248 | else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) |
1249 | encrypted = 1; |
1250 | else { |
1251 | errmsg = "Key encryption is of unknown type"; |
1252 | goto error; |
1253 | } |
1254 | pos += 4+len; |
1255 | |
1256 | /* |
1257 | * Get hold of the encrypted part of the key. |
1258 | */ |
1259 | if (key->keyblob_len < pos+4 || |
1260 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1261 | errmsg = "Key blob does not contain actual key data"; |
1262 | goto error; |
1263 | } |
201188af |
1264 | ciphertext = (char *)key->keyblob + pos + 4; |
7b4ef1ae |
1265 | cipherlen = len; |
1266 | if (cipherlen == 0) { |
1267 | errmsg = "Length of key data is zero"; |
1268 | goto error; |
1269 | } |
1270 | |
1271 | /* |
1272 | * Decrypt it if necessary. |
1273 | */ |
1274 | if (encrypted) { |
1275 | /* |
1276 | * Derive encryption key from passphrase and iv/salt: |
1277 | * |
1278 | * - let block A equal MD5(passphrase) |
1279 | * - let block B equal MD5(passphrase || A) |
1280 | * - block C would be MD5(passphrase || A || B) and so on |
1281 | * - encryption key is the first N bytes of A || B |
1282 | */ |
1283 | struct MD5Context md5c; |
1284 | unsigned char keybuf[32], iv[8]; |
1285 | |
1286 | if (cipherlen % 8 != 0) { |
1287 | errmsg = "Encrypted part of key is not a multiple of cipher block" |
1288 | " size"; |
1289 | goto error; |
1290 | } |
1291 | |
1292 | MD5Init(&md5c); |
201188af |
1293 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
7b4ef1ae |
1294 | MD5Final(keybuf, &md5c); |
1295 | |
1296 | MD5Init(&md5c); |
201188af |
1297 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
7b4ef1ae |
1298 | MD5Update(&md5c, keybuf, 16); |
1299 | MD5Final(keybuf+16, &md5c); |
1300 | |
1301 | /* |
1302 | * Now decrypt the key blob. |
1303 | */ |
ee5c1422 |
1304 | memset(iv, 0, sizeof(iv)); |
201188af |
1305 | des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, |
1306 | cipherlen); |
7b4ef1ae |
1307 | |
ee5c1422 |
1308 | memset(&md5c, 0, sizeof(md5c)); |
1309 | memset(keybuf, 0, sizeof(keybuf)); |
1310 | |
7b4ef1ae |
1311 | /* |
1312 | * Hereafter we return WRONG_PASSPHRASE for any parsing |
ee5c1422 |
1313 | * error. (But only if we've just tried to decrypt it! |
1314 | * Returning WRONG_PASSPHRASE for an unencrypted key is |
1315 | * automatic doom.) |
7b4ef1ae |
1316 | */ |
1317 | if (encrypted) |
1318 | ret = SSH2_WRONG_PASSPHRASE; |
1319 | } |
1320 | |
1321 | /* |
1322 | * Strip away the containing string to get to the real meat. |
1323 | */ |
1324 | len = GET_32BIT(ciphertext); |
1325 | if (len > cipherlen-4) { |
1326 | errmsg = "containing string was ill-formed"; |
1327 | goto error; |
1328 | } |
1329 | ciphertext += 4; |
1330 | cipherlen = len; |
1331 | |
1332 | /* |
1333 | * Now we break down into RSA versus DSA. In either case we'll |
1334 | * construct public and private blobs in our own format, and |
1335 | * end up feeding them to alg->createkey(). |
1336 | */ |
ee5c1422 |
1337 | blobsize = cipherlen + 256; |
3d88e64d |
1338 | blob = snewn(blobsize, unsigned char); |
7b4ef1ae |
1339 | privlen = 0; |
1340 | if (type == RSA) { |
1341 | struct mpint_pos n, e, d, u, p, q; |
1342 | int pos = 0; |
1343 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); |
1344 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); |
1345 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); |
1346 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); |
1347 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
1348 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1349 | if (!q.start) { |
1350 | errmsg = "key data did not contain six integers"; |
1351 | goto error; |
1352 | } |
1353 | |
1354 | alg = &ssh_rsa; |
1355 | pos = 0; |
1356 | pos += put_string(blob+pos, "ssh-rsa", 7); |
1357 | pos += put_mp(blob+pos, e.start, e.bytes); |
1358 | pos += put_mp(blob+pos, n.start, n.bytes); |
1359 | publen = pos; |
1360 | pos += put_string(blob+pos, d.start, d.bytes); |
1361 | pos += put_mp(blob+pos, q.start, q.bytes); |
1362 | pos += put_mp(blob+pos, p.start, p.bytes); |
1363 | pos += put_mp(blob+pos, u.start, u.bytes); |
1364 | privlen = pos - publen; |
1365 | } else if (type == DSA) { |
1366 | struct mpint_pos p, q, g, x, y; |
1367 | int pos = 4; |
1368 | if (GET_32BIT(ciphertext) != 0) { |
1369 | errmsg = "predefined DSA parameters not supported"; |
1370 | goto error; |
1371 | } |
1372 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
1373 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); |
1374 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1375 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); |
1376 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); |
1377 | if (!x.start) { |
1378 | errmsg = "key data did not contain five integers"; |
1379 | goto error; |
1380 | } |
1381 | |
1382 | alg = &ssh_dss; |
1383 | pos = 0; |
1384 | pos += put_string(blob+pos, "ssh-dss", 7); |
1385 | pos += put_mp(blob+pos, p.start, p.bytes); |
1386 | pos += put_mp(blob+pos, q.start, q.bytes); |
1387 | pos += put_mp(blob+pos, g.start, g.bytes); |
1388 | pos += put_mp(blob+pos, y.start, y.bytes); |
1389 | publen = pos; |
1390 | pos += put_mp(blob+pos, x.start, x.bytes); |
1391 | privlen = pos - publen; |
1392 | } |
1393 | |
1394 | assert(privlen > 0); /* should have bombed by now if not */ |
1395 | |
3d88e64d |
1396 | retkey = snew(struct ssh2_userkey); |
7b4ef1ae |
1397 | retkey->alg = alg; |
1398 | retkey->data = alg->createkey(blob, publen, blob+publen, privlen); |
1399 | if (!retkey->data) { |
1400 | sfree(retkey); |
1401 | errmsg = "unable to create key data structure"; |
1402 | goto error; |
1403 | } |
1404 | retkey->comment = dupstr(key->comment); |
1405 | |
1406 | errmsg = NULL; /* no error */ |
1407 | ret = retkey; |
1408 | |
1409 | error: |
ee5c1422 |
1410 | if (blob) { |
1411 | memset(blob, 0, blobsize); |
1412 | sfree(blob); |
1413 | } |
1414 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1415 | sfree(key->keyblob); |
ee5c1422 |
1416 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1417 | sfree(key); |
1418 | return ret; |
1419 | } |
96d19bc9 |
1420 | |
9a30e26b |
1421 | int sshcom_write(const Filename *filename, struct ssh2_userkey *key, |
1422 | char *passphrase) |
96d19bc9 |
1423 | { |
1424 | unsigned char *pubblob, *privblob; |
1425 | int publen, privlen; |
1426 | unsigned char *outblob; |
1427 | int outlen; |
1428 | struct mpint_pos numbers[6]; |
1429 | int nnumbers, initial_zero, pos, lenpos, i; |
1430 | char *type; |
1431 | char *ciphertext; |
1432 | int cipherlen; |
1433 | int ret = 0; |
1434 | FILE *fp; |
1435 | |
1436 | /* |
1437 | * Fetch the key blobs. |
1438 | */ |
1439 | pubblob = key->alg->public_blob(key->data, &publen); |
1440 | privblob = key->alg->private_blob(key->data, &privlen); |
1441 | outblob = NULL; |
1442 | |
1443 | /* |
1444 | * Find the sequence of integers to be encoded into the OpenSSH |
1445 | * key blob, and also decide on the header line. |
1446 | */ |
1447 | if (key->alg == &ssh_rsa) { |
1448 | int pos; |
1449 | struct mpint_pos n, e, d, p, q, iqmp; |
1450 | |
1451 | pos = 4 + GET_32BIT(pubblob); |
1452 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
1453 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
1454 | pos = 0; |
1455 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
1456 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
1457 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
1458 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
1459 | |
1460 | assert(e.start && iqmp.start); /* can't go wrong */ |
1461 | |
1462 | numbers[0] = e; |
1463 | numbers[1] = d; |
1464 | numbers[2] = n; |
1465 | numbers[3] = iqmp; |
1466 | numbers[4] = q; |
1467 | numbers[5] = p; |
1468 | |
1469 | nnumbers = 6; |
1470 | initial_zero = 0; |
1471 | type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}"; |
1472 | } else if (key->alg == &ssh_dss) { |
1473 | int pos; |
1474 | struct mpint_pos p, q, g, y, x; |
1475 | |
1476 | pos = 4 + GET_32BIT(pubblob); |
1477 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
1478 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
1479 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
1480 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
1481 | pos = 0; |
1482 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
1483 | |
1484 | assert(y.start && x.start); /* can't go wrong */ |
1485 | |
1486 | numbers[0] = p; |
1487 | numbers[1] = g; |
1488 | numbers[2] = q; |
1489 | numbers[3] = y; |
1490 | numbers[4] = x; |
1491 | |
1492 | nnumbers = 5; |
1493 | initial_zero = 1; |
1494 | type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}"; |
1495 | } else { |
1496 | assert(0); /* zoinks! */ |
1497 | } |
1498 | |
1499 | /* |
1500 | * Total size of key blob will be somewhere under 512 plus |
1501 | * combined length of integers. We'll calculate the more |
1502 | * precise size as we construct the blob. |
1503 | */ |
1504 | outlen = 512; |
1505 | for (i = 0; i < nnumbers; i++) |
1506 | outlen += 4 + numbers[i].bytes; |
3d88e64d |
1507 | outblob = snewn(outlen, unsigned char); |
96d19bc9 |
1508 | |
1509 | /* |
1510 | * Create the unencrypted key blob. |
1511 | */ |
1512 | pos = 0; |
1513 | PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4; |
1514 | pos += 4; /* length field, fill in later */ |
1515 | pos += put_string(outblob+pos, type, strlen(type)); |
1516 | { |
1517 | char *ciphertype = passphrase ? "3des-cbc" : "none"; |
1518 | pos += put_string(outblob+pos, ciphertype, strlen(ciphertype)); |
1519 | } |
1520 | lenpos = pos; /* remember this position */ |
1521 | pos += 4; /* encrypted-blob size */ |
1522 | pos += 4; /* encrypted-payload size */ |
1523 | if (initial_zero) { |
1524 | PUT_32BIT(outblob+pos, 0); |
1525 | pos += 4; |
1526 | } |
1527 | for (i = 0; i < nnumbers; i++) |
1528 | pos += sshcom_put_mpint(outblob+pos, |
1529 | numbers[i].start, numbers[i].bytes); |
1530 | /* Now wrap up the encrypted payload. */ |
1531 | PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8)); |
1532 | /* Pad encrypted blob to a multiple of cipher block size. */ |
1533 | if (passphrase) { |
1534 | int padding = -(pos - (lenpos+4)) & 7; |
1535 | while (padding--) |
1536 | outblob[pos++] = random_byte(); |
1537 | } |
201188af |
1538 | ciphertext = (char *)outblob+lenpos+4; |
96d19bc9 |
1539 | cipherlen = pos - (lenpos+4); |
1540 | assert(!passphrase || cipherlen % 8 == 0); |
1541 | /* Wrap up the encrypted blob string. */ |
1542 | PUT_32BIT(outblob+lenpos, cipherlen); |
1543 | /* And finally fill in the total length field. */ |
1544 | PUT_32BIT(outblob+4, pos); |
1545 | |
1546 | assert(pos < outlen); |
1547 | |
1548 | /* |
1549 | * Encrypt the key. |
1550 | */ |
1551 | if (passphrase) { |
1552 | /* |
1553 | * Derive encryption key from passphrase and iv/salt: |
1554 | * |
1555 | * - let block A equal MD5(passphrase) |
1556 | * - let block B equal MD5(passphrase || A) |
1557 | * - block C would be MD5(passphrase || A || B) and so on |
1558 | * - encryption key is the first N bytes of A || B |
1559 | */ |
1560 | struct MD5Context md5c; |
1561 | unsigned char keybuf[32], iv[8]; |
1562 | |
1563 | MD5Init(&md5c); |
201188af |
1564 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
96d19bc9 |
1565 | MD5Final(keybuf, &md5c); |
1566 | |
1567 | MD5Init(&md5c); |
201188af |
1568 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
96d19bc9 |
1569 | MD5Update(&md5c, keybuf, 16); |
1570 | MD5Final(keybuf+16, &md5c); |
1571 | |
1572 | /* |
1573 | * Now decrypt the key blob. |
1574 | */ |
1575 | memset(iv, 0, sizeof(iv)); |
201188af |
1576 | des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, |
1577 | cipherlen); |
96d19bc9 |
1578 | |
1579 | memset(&md5c, 0, sizeof(md5c)); |
1580 | memset(keybuf, 0, sizeof(keybuf)); |
1581 | } |
1582 | |
1583 | /* |
1584 | * And save it. We'll use Unix line endings just in case it's |
1585 | * subsequently transferred in binary mode. |
1586 | */ |
9a30e26b |
1587 | fp = f_open(*filename, "wb"); /* ensure Unix line endings */ |
96d19bc9 |
1588 | if (!fp) |
1589 | goto error; |
1590 | fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); |
1591 | fprintf(fp, "Comment: \""); |
1592 | /* |
1593 | * Comment header is broken with backslash-newline if it goes |
1594 | * over 70 chars. Although it's surrounded by quotes, it |
1595 | * _doesn't_ escape backslashes or quotes within the string. |
1596 | * Don't ask me, I didn't design it. |
1597 | */ |
1598 | { |
1599 | int slen = 60; /* starts at 60 due to "Comment: " */ |
1600 | char *c = key->comment; |
6ef15436 |
1601 | while ((int)strlen(c) > slen) { |
96d19bc9 |
1602 | fprintf(fp, "%.*s\\\n", slen, c); |
1603 | c += slen; |
1604 | slen = 70; /* allow 70 chars on subsequent lines */ |
1605 | } |
1606 | fprintf(fp, "%s\"\n", c); |
1607 | } |
1608 | base64_encode(fp, outblob, pos, 70); |
1609 | fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); |
1610 | fclose(fp); |
1611 | ret = 1; |
1612 | |
1613 | error: |
1614 | if (outblob) { |
1615 | memset(outblob, 0, outlen); |
1616 | sfree(outblob); |
1617 | } |
1618 | if (privblob) { |
1619 | memset(privblob, 0, privlen); |
1620 | sfree(privblob); |
1621 | } |
1622 | if (pubblob) { |
1623 | memset(pubblob, 0, publen); |
1624 | sfree(pubblob); |
1625 | } |
1626 | return ret; |
1627 | } |