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 | |
329 | ret = smalloc(sizeof(*ret)); |
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; |
419 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
420 | } |
9dda6459 |
421 | |
ee5c1422 |
422 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
423 | ret->keyblob_len += len; |
9dda6459 |
424 | |
ee5c1422 |
425 | memset(out, 0, sizeof(out)); |
426 | } |
9dda6459 |
427 | |
ee5c1422 |
428 | p++; |
9dda6459 |
429 | } |
430 | } |
431 | } |
432 | |
433 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
434 | errmsg = "Key body not present"; |
435 | goto error; |
436 | } |
437 | |
438 | if (ret->encrypted && ret->keyblob_len % 8 != 0) { |
439 | errmsg = "Encrypted key blob is not a multiple of cipher block size"; |
440 | goto error; |
441 | } |
442 | |
ee5c1422 |
443 | memset(buffer, 0, sizeof(buffer)); |
444 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
445 | return ret; |
446 | |
447 | error: |
ee5c1422 |
448 | memset(buffer, 0, sizeof(buffer)); |
449 | memset(base64_bit, 0, sizeof(base64_bit)); |
9dda6459 |
450 | if (ret) { |
ee5c1422 |
451 | if (ret->keyblob) { |
452 | memset(ret->keyblob, 0, ret->keyblob_size); |
453 | sfree(ret->keyblob); |
454 | } |
455 | memset(&ret, 0, sizeof(ret)); |
9dda6459 |
456 | sfree(ret); |
457 | } |
458 | return NULL; |
459 | } |
460 | |
9a30e26b |
461 | int openssh_encrypted(const Filename *filename) |
9dda6459 |
462 | { |
463 | struct openssh_key *key = load_openssh_key(filename); |
464 | int ret; |
465 | |
466 | if (!key) |
467 | return 0; |
468 | ret = key->encrypted; |
ee5c1422 |
469 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
470 | sfree(key->keyblob); |
ee5c1422 |
471 | memset(&key, 0, sizeof(key)); |
9dda6459 |
472 | sfree(key); |
473 | return ret; |
474 | } |
475 | |
9a30e26b |
476 | struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase) |
9dda6459 |
477 | { |
478 | struct openssh_key *key = load_openssh_key(filename); |
479 | struct ssh2_userkey *retkey; |
480 | unsigned char *p; |
481 | int ret, id, len, flags; |
482 | int i, num_integers; |
483 | struct ssh2_userkey *retval = NULL; |
484 | char *errmsg; |
485 | unsigned char *blob; |
ee5c1422 |
486 | int blobsize, blobptr, privptr; |
9dda6459 |
487 | char *modptr; |
488 | int modlen; |
489 | |
e3498db5 |
490 | blob = NULL; |
491 | |
9dda6459 |
492 | if (!key) |
493 | return NULL; |
494 | |
495 | if (key->encrypted) { |
496 | /* |
497 | * Derive encryption key from passphrase and iv/salt: |
498 | * |
499 | * - let block A equal MD5(passphrase || iv) |
500 | * - let block B equal MD5(A || passphrase || iv) |
501 | * - block C would be MD5(B || passphrase || iv) and so on |
502 | * - encryption key is the first N bytes of A || B |
503 | */ |
504 | struct MD5Context md5c; |
505 | unsigned char keybuf[32]; |
506 | |
507 | MD5Init(&md5c); |
201188af |
508 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
509 | MD5Update(&md5c, (unsigned char *)key->iv, 8); |
9dda6459 |
510 | MD5Final(keybuf, &md5c); |
511 | |
512 | MD5Init(&md5c); |
513 | MD5Update(&md5c, keybuf, 16); |
201188af |
514 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
515 | MD5Update(&md5c, (unsigned char *)key->iv, 8); |
9dda6459 |
516 | MD5Final(keybuf+16, &md5c); |
517 | |
518 | /* |
519 | * Now decrypt the key blob. |
520 | */ |
201188af |
521 | des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv, |
9dda6459 |
522 | key->keyblob, key->keyblob_len); |
ee5c1422 |
523 | |
524 | memset(&md5c, 0, sizeof(md5c)); |
525 | memset(keybuf, 0, sizeof(keybuf)); |
9dda6459 |
526 | } |
527 | |
528 | /* |
529 | * Now we have a decrypted key blob, which contains an ASN.1 |
530 | * encoded private key. We must now untangle the ASN.1. |
531 | * |
532 | * We expect the whole key blob to be formatted as a SEQUENCE |
533 | * (0x30 followed by a length code indicating that the rest of |
534 | * the blob is part of the sequence). Within that SEQUENCE we |
535 | * expect to see a bunch of INTEGERs. What those integers mean |
536 | * depends on the key type: |
537 | * |
538 | * - For RSA, we expect the integers to be 0, n, e, d, p, q, |
539 | * dmp1, dmq1, iqmp in that order. (The last three are d mod |
540 | * (p-1), d mod (q-1), inverse of q mod p respectively.) |
541 | * |
542 | * - For DSA, we expect them to be 0, p, q, g, y, x in that |
543 | * order. |
544 | */ |
545 | |
546 | p = key->keyblob; |
547 | |
548 | /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ |
549 | ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); |
550 | p += ret; |
551 | if (ret < 0 || id != 16) { |
552 | errmsg = "ASN.1 decoding failure"; |
553 | retval = SSH2_WRONG_PASSPHRASE; |
554 | goto error; |
555 | } |
556 | |
557 | /* Expect a load of INTEGERs. */ |
558 | if (key->type == OSSH_RSA) |
559 | num_integers = 9; |
560 | else if (key->type == OSSH_DSA) |
561 | num_integers = 6; |
562 | |
563 | /* |
564 | * Space to create key blob in. |
565 | */ |
ee5c1422 |
566 | blobsize = 256+key->keyblob_len; |
567 | blob = smalloc(blobsize); |
9dda6459 |
568 | PUT_32BIT(blob, 7); |
569 | if (key->type == OSSH_DSA) |
570 | memcpy(blob+4, "ssh-dss", 7); |
571 | else if (key->type == OSSH_RSA) |
572 | memcpy(blob+4, "ssh-rsa", 7); |
573 | blobptr = 4+7; |
574 | privptr = -1; |
575 | |
576 | for (i = 0; i < num_integers; i++) { |
577 | ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, |
578 | &id, &len, &flags); |
579 | p += ret; |
580 | if (ret < 0 || id != 2 || |
581 | key->keyblob+key->keyblob_len-p < len) { |
582 | errmsg = "ASN.1 decoding failure"; |
583 | goto error; |
584 | } |
585 | |
586 | if (i == 0) { |
587 | /* |
588 | * The first integer should be zero always (I think |
589 | * this is some sort of version indication). |
590 | */ |
591 | if (len != 1 || p[0] != 0) { |
592 | errmsg = "Version number mismatch"; |
593 | goto error; |
594 | } |
595 | } else if (key->type == OSSH_RSA) { |
596 | /* |
597 | * Integers 1 and 2 go into the public blob but in the |
598 | * opposite order; integers 3, 4, 5 and 8 go into the |
599 | * private blob. The other two (6 and 7) are ignored. |
600 | */ |
601 | if (i == 1) { |
602 | /* Save the details for after we deal with number 2. */ |
201188af |
603 | modptr = (char *)p; |
9dda6459 |
604 | modlen = len; |
605 | } else if (i != 6 && i != 7) { |
606 | PUT_32BIT(blob+blobptr, len); |
607 | memcpy(blob+blobptr+4, p, len); |
608 | blobptr += 4+len; |
609 | if (i == 2) { |
610 | PUT_32BIT(blob+blobptr, modlen); |
611 | memcpy(blob+blobptr+4, modptr, modlen); |
612 | blobptr += 4+modlen; |
613 | privptr = blobptr; |
614 | } |
615 | } |
616 | } else if (key->type == OSSH_DSA) { |
617 | /* |
618 | * Integers 1-4 go into the public blob; integer 5 goes |
619 | * into the private blob. |
620 | */ |
621 | PUT_32BIT(blob+blobptr, len); |
622 | memcpy(blob+blobptr+4, p, len); |
623 | blobptr += 4+len; |
624 | if (i == 4) |
625 | privptr = blobptr; |
626 | } |
627 | |
628 | /* Skip past the number. */ |
629 | p += len; |
630 | } |
631 | |
632 | /* |
633 | * Now put together the actual key. Simplest way to do this is |
634 | * to assemble our own key blobs and feed them to the createkey |
635 | * functions; this is a bit faffy but it does mean we get all |
636 | * the sanity checks for free. |
637 | */ |
638 | assert(privptr > 0); /* should have bombed by now if not */ |
639 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
640 | retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss); |
641 | retkey->data = retkey->alg->createkey(blob, privptr, |
642 | blob+privptr, blobptr-privptr); |
643 | if (!retkey->data) { |
644 | sfree(retkey); |
645 | errmsg = "unable to create key data structure"; |
646 | goto error; |
647 | } |
648 | |
649 | retkey->comment = dupstr("imported-openssh-key"); |
ee5c1422 |
650 | errmsg = NULL; /* no error */ |
651 | retval = retkey; |
9dda6459 |
652 | |
653 | error: |
ee5c1422 |
654 | if (blob) { |
655 | memset(blob, 0, blobsize); |
656 | sfree(blob); |
657 | } |
658 | memset(key->keyblob, 0, key->keyblob_size); |
9dda6459 |
659 | sfree(key->keyblob); |
ee5c1422 |
660 | memset(&key, 0, sizeof(key)); |
9dda6459 |
661 | sfree(key); |
662 | return retval; |
663 | } |
7b4ef1ae |
664 | |
9a30e26b |
665 | int openssh_write(const Filename *filename, struct ssh2_userkey *key, |
666 | char *passphrase) |
d23a9b21 |
667 | { |
668 | unsigned char *pubblob, *privblob, *spareblob; |
669 | int publen, privlen, sparelen; |
670 | unsigned char *outblob; |
671 | int outlen; |
672 | struct mpint_pos numbers[9]; |
673 | int nnumbers, pos, len, seqlen, i; |
674 | char *header, *footer; |
675 | char zero[1]; |
676 | unsigned char iv[8]; |
677 | int ret = 0; |
678 | FILE *fp; |
679 | |
680 | /* |
681 | * Fetch the key blobs. |
682 | */ |
683 | pubblob = key->alg->public_blob(key->data, &publen); |
684 | privblob = key->alg->private_blob(key->data, &privlen); |
685 | spareblob = outblob = NULL; |
686 | |
687 | /* |
688 | * Find the sequence of integers to be encoded into the OpenSSH |
689 | * key blob, and also decide on the header line. |
690 | */ |
691 | if (key->alg == &ssh_rsa) { |
692 | int pos; |
693 | struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1; |
694 | Bignum bd, bp, bq, bdmp1, bdmq1; |
695 | |
696 | pos = 4 + GET_32BIT(pubblob); |
697 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
698 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
699 | pos = 0; |
700 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
701 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
702 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
703 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
704 | |
705 | assert(e.start && iqmp.start); /* can't go wrong */ |
706 | |
707 | /* We also need d mod (p-1) and d mod (q-1). */ |
708 | bd = bignum_from_bytes(d.start, d.bytes); |
709 | bp = bignum_from_bytes(p.start, p.bytes); |
710 | bq = bignum_from_bytes(q.start, q.bytes); |
711 | decbn(bp); |
712 | decbn(bq); |
713 | bdmp1 = bigmod(bd, bp); |
714 | bdmq1 = bigmod(bd, bq); |
715 | freebn(bd); |
716 | freebn(bp); |
717 | freebn(bq); |
718 | |
719 | dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8; |
720 | dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8; |
721 | sparelen = dmp1.bytes + dmq1.bytes; |
722 | spareblob = smalloc(sparelen); |
723 | dmp1.start = spareblob; |
724 | dmq1.start = spareblob + dmp1.bytes; |
725 | for (i = 0; i < dmp1.bytes; i++) |
726 | spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i); |
727 | for (i = 0; i < dmq1.bytes; i++) |
728 | spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i); |
729 | freebn(bdmp1); |
730 | freebn(bdmq1); |
731 | |
732 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
733 | numbers[1] = n; |
734 | numbers[2] = e; |
735 | numbers[3] = d; |
736 | numbers[4] = p; |
737 | numbers[5] = q; |
738 | numbers[6] = dmp1; |
739 | numbers[7] = dmq1; |
740 | numbers[8] = iqmp; |
741 | |
742 | nnumbers = 9; |
743 | header = "-----BEGIN RSA PRIVATE KEY-----\n"; |
744 | footer = "-----END RSA PRIVATE KEY-----\n"; |
745 | } else if (key->alg == &ssh_dss) { |
746 | int pos; |
747 | struct mpint_pos p, q, g, y, x; |
748 | |
749 | pos = 4 + GET_32BIT(pubblob); |
750 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
751 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
752 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
753 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
754 | pos = 0; |
755 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
756 | |
757 | assert(y.start && x.start); /* can't go wrong */ |
758 | |
759 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; |
760 | numbers[1] = p; |
761 | numbers[2] = q; |
762 | numbers[3] = g; |
763 | numbers[4] = y; |
764 | numbers[5] = x; |
765 | |
766 | nnumbers = 6; |
767 | header = "-----BEGIN DSA PRIVATE KEY-----\n"; |
768 | footer = "-----END DSA PRIVATE KEY-----\n"; |
769 | } else { |
770 | assert(0); /* zoinks! */ |
771 | } |
772 | |
773 | /* |
774 | * Now count up the total size of the ASN.1 encoded integers, |
775 | * so as to determine the length of the containing SEQUENCE. |
776 | */ |
777 | len = 0; |
778 | for (i = 0; i < nnumbers; i++) { |
779 | len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); |
780 | len += numbers[i].bytes; |
781 | } |
782 | seqlen = len; |
783 | /* Now add on the SEQUENCE header. */ |
784 | len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); |
04627c33 |
785 | /* Round up to the cipher block size, ensuring we have at least one |
786 | * byte of padding (see below). */ |
787 | outlen = len; |
d23a9b21 |
788 | if (passphrase) |
04627c33 |
789 | outlen = (outlen+8) &~ 7; |
d23a9b21 |
790 | |
791 | /* |
792 | * Now we know how big outblob needs to be. Allocate it. |
793 | */ |
d23a9b21 |
794 | outblob = smalloc(outlen); |
795 | |
796 | /* |
797 | * And write the data into it. |
798 | */ |
799 | pos = 0; |
800 | pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); |
801 | for (i = 0; i < nnumbers; i++) { |
802 | pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); |
803 | memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); |
804 | pos += numbers[i].bytes; |
805 | } |
04627c33 |
806 | |
807 | /* |
808 | * Padding on OpenSSH keys is deterministic. The number of |
809 | * padding bytes is always more than zero, and always at most |
810 | * the cipher block length. The value of each padding byte is |
811 | * equal to the number of padding bytes. So a plaintext that's |
812 | * an exact multiple of the block size will be padded with 08 |
813 | * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a |
814 | * plaintext one byte less than a multiple of the block size |
815 | * will be padded with just 01. |
816 | * |
817 | * This enables the OpenSSL key decryption function to strip |
818 | * off the padding algorithmically and return the unpadded |
819 | * plaintext to the next layer: it looks at the final byte, and |
820 | * then expects to find that many bytes at the end of the data |
821 | * with the same value. Those are all removed and the rest is |
822 | * returned. |
823 | */ |
824 | assert(pos == len); |
d23a9b21 |
825 | while (pos < outlen) { |
04627c33 |
826 | outblob[pos++] = outlen - len; |
d23a9b21 |
827 | } |
828 | |
829 | /* |
830 | * Encrypt the key. |
831 | */ |
832 | if (passphrase) { |
833 | /* |
834 | * Invent an iv. Then derive encryption key from passphrase |
835 | * and iv/salt: |
836 | * |
837 | * - let block A equal MD5(passphrase || iv) |
838 | * - let block B equal MD5(A || passphrase || iv) |
839 | * - block C would be MD5(B || passphrase || iv) and so on |
840 | * - encryption key is the first N bytes of A || B |
841 | */ |
842 | struct MD5Context md5c; |
843 | unsigned char keybuf[32]; |
844 | |
845 | for (i = 0; i < 8; i++) iv[i] = random_byte(); |
846 | |
847 | MD5Init(&md5c); |
201188af |
848 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
d23a9b21 |
849 | MD5Update(&md5c, iv, 8); |
850 | MD5Final(keybuf, &md5c); |
851 | |
852 | MD5Init(&md5c); |
853 | MD5Update(&md5c, keybuf, 16); |
201188af |
854 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
d23a9b21 |
855 | MD5Update(&md5c, iv, 8); |
856 | MD5Final(keybuf+16, &md5c); |
857 | |
858 | /* |
859 | * Now encrypt the key blob. |
860 | */ |
861 | des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen); |
862 | |
863 | memset(&md5c, 0, sizeof(md5c)); |
864 | memset(keybuf, 0, sizeof(keybuf)); |
865 | } |
866 | |
867 | /* |
868 | * And save it. We'll use Unix line endings just in case it's |
869 | * subsequently transferred in binary mode. |
870 | */ |
9a30e26b |
871 | fp = f_open(*filename, "wb"); /* ensure Unix line endings */ |
d23a9b21 |
872 | if (!fp) |
873 | goto error; |
874 | fputs(header, fp); |
875 | if (passphrase) { |
876 | fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,"); |
877 | for (i = 0; i < 8; i++) |
878 | fprintf(fp, "%02X", iv[i]); |
879 | fprintf(fp, "\n\n"); |
880 | } |
96d19bc9 |
881 | base64_encode(fp, outblob, outlen, 64); |
d23a9b21 |
882 | fputs(footer, fp); |
883 | fclose(fp); |
884 | ret = 1; |
885 | |
886 | error: |
887 | if (outblob) { |
888 | memset(outblob, 0, outlen); |
889 | sfree(outblob); |
890 | } |
891 | if (spareblob) { |
892 | memset(spareblob, 0, sparelen); |
893 | sfree(spareblob); |
894 | } |
895 | if (privblob) { |
896 | memset(privblob, 0, privlen); |
897 | sfree(privblob); |
898 | } |
899 | if (pubblob) { |
900 | memset(pubblob, 0, publen); |
901 | sfree(pubblob); |
902 | } |
903 | return ret; |
904 | } |
905 | |
7b4ef1ae |
906 | /* ---------------------------------------------------------------------- |
907 | * Code to read ssh.com private keys. |
908 | */ |
909 | |
910 | /* |
911 | * The format of the base64 blob is largely ssh2-packet-formatted, |
912 | * except that mpints are a bit different: they're more like the |
913 | * old ssh1 mpint. You have a 32-bit bit count N, followed by |
914 | * (N+7)/8 bytes of data. |
915 | * |
916 | * So. The blob contains: |
917 | * |
918 | * - uint32 0x3f6ff9eb (magic number) |
919 | * - uint32 size (total blob size) |
920 | * - string key-type (see below) |
921 | * - string cipher-type (tells you if key is encrypted) |
922 | * - string encrypted-blob |
923 | * |
924 | * (The first size field includes the size field itself and the |
925 | * magic number before it. All other size fields are ordinary ssh2 |
926 | * strings, so the size field indicates how much data is to |
927 | * _follow_.) |
928 | * |
929 | * The encrypted blob, once decrypted, contains a single string |
930 | * which in turn contains the payload. (This allows padding to be |
931 | * added after that string while still making it clear where the |
932 | * real payload ends. Also it probably makes for a reasonable |
933 | * decryption check.) |
934 | * |
935 | * The payload blob, for an RSA key, contains: |
936 | * - mpint e |
937 | * - mpint d |
938 | * - mpint n (yes, the public and private stuff is intermixed) |
939 | * - mpint u (presumably inverse of p mod q) |
940 | * - mpint p (p is the smaller prime) |
941 | * - mpint q (q is the larger) |
942 | * |
943 | * For a DSA key, the payload blob contains: |
944 | * - uint32 0 |
945 | * - mpint p |
946 | * - mpint g |
947 | * - mpint q |
948 | * - mpint y |
949 | * - mpint x |
950 | * |
951 | * Alternatively, if the parameters are `predefined', that |
952 | * (0,p,g,q) sequence can be replaced by a uint32 1 and a string |
953 | * containing some predefined parameter specification. *shudder*, |
954 | * but I doubt we'll encounter this in real life. |
955 | * |
956 | * The key type strings are ghastly. The RSA key I looked at had a |
957 | * type string of |
958 | * |
959 | * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}' |
960 | * |
961 | * and the DSA key wasn't much better: |
962 | * |
963 | * `dl-modp{sign{dsa-nist-sha1},dh{plain}}' |
964 | * |
965 | * It isn't clear that these will always be the same. I think it |
966 | * might be wise just to look at the `if-modn{sign{rsa' and |
967 | * `dl-modp{sign{dsa' prefixes. |
968 | * |
969 | * Finally, the encryption. The cipher-type string appears to be |
970 | * either `none' or `3des-cbc'. Looks as if this is SSH2-style |
971 | * 3des-cbc (i.e. outer cbc rather than inner). The key is created |
972 | * from the passphrase by means of yet another hashing faff: |
973 | * |
974 | * - first 16 bytes are MD5(passphrase) |
975 | * - next 16 bytes are MD5(passphrase || first 16 bytes) |
976 | * - if there were more, they'd be MD5(passphrase || first 32), |
977 | * and so on. |
978 | */ |
979 | |
96d19bc9 |
980 | #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb |
981 | |
7b4ef1ae |
982 | struct sshcom_key { |
983 | char comment[256]; /* allowing any length is overkill */ |
984 | unsigned char *keyblob; |
985 | int keyblob_len, keyblob_size; |
986 | }; |
987 | |
d714d740 |
988 | static struct sshcom_key *load_sshcom_key(const Filename *filename) |
7b4ef1ae |
989 | { |
990 | struct sshcom_key *ret; |
991 | FILE *fp; |
992 | char buffer[256]; |
993 | int len; |
994 | char *errmsg, *p; |
995 | int headers_done; |
996 | char base64_bit[4]; |
997 | int base64_chars = 0; |
998 | |
999 | ret = smalloc(sizeof(*ret)); |
1000 | ret->comment[0] = '\0'; |
1001 | ret->keyblob = NULL; |
1002 | ret->keyblob_len = ret->keyblob_size = 0; |
1003 | |
9a30e26b |
1004 | fp = f_open(*filename, "r"); |
7b4ef1ae |
1005 | if (!fp) { |
1006 | errmsg = "Unable to open key file"; |
1007 | goto error; |
1008 | } |
1009 | if (!fgets(buffer, sizeof(buffer), fp) || |
1010 | 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) { |
1011 | errmsg = "File does not begin with ssh.com key header"; |
1012 | goto error; |
1013 | } |
1014 | |
1015 | headers_done = 0; |
1016 | while (1) { |
1017 | if (!fgets(buffer, sizeof(buffer), fp)) { |
1018 | errmsg = "Unexpected end of file"; |
1019 | goto error; |
1020 | } |
1021 | if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n")) |
1022 | break; /* done */ |
1023 | if ((p = strchr(buffer, ':')) != NULL) { |
1024 | if (headers_done) { |
1025 | errmsg = "Header found in body of key data"; |
1026 | goto error; |
1027 | } |
1028 | *p++ = '\0'; |
1029 | while (*p && isspace((unsigned char)*p)) p++; |
1030 | /* |
1031 | * Header lines can end in a trailing backslash for |
1032 | * continuation. |
1033 | */ |
6ef15436 |
1034 | while ((len = strlen(p)) > (int)(sizeof(buffer) - (p-buffer) -1) || |
7b4ef1ae |
1035 | p[len-1] != '\n' || p[len-2] == '\\') { |
6ef15436 |
1036 | if (len > (int)((p-buffer) + sizeof(buffer)-2)) { |
7b4ef1ae |
1037 | errmsg = "Header line too long to deal with"; |
1038 | goto error; |
1039 | } |
1040 | if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) { |
1041 | errmsg = "Unexpected end of file"; |
1042 | goto error; |
1043 | } |
1044 | } |
1045 | p[strcspn(p, "\n")] = '\0'; |
1046 | if (!strcmp(buffer, "Comment")) { |
1047 | /* Strip quotes in comment if present. */ |
1048 | if (p[0] == '"' && p[strlen(p)-1] == '"') { |
1049 | p++; |
1050 | p[strlen(p)-1] = '\0'; |
1051 | } |
1052 | strncpy(ret->comment, p, sizeof(ret->comment)); |
1053 | ret->comment[sizeof(ret->comment)-1] = '\0'; |
1054 | } |
1055 | } else { |
1056 | headers_done = 1; |
1057 | |
1058 | p = buffer; |
1059 | while (isbase64(*p)) { |
1060 | base64_bit[base64_chars++] = *p; |
1061 | if (base64_chars == 4) { |
1062 | unsigned char out[3]; |
1063 | |
1064 | base64_chars = 0; |
1065 | |
1066 | len = base64_decode_atom(base64_bit, out); |
1067 | |
1068 | if (len <= 0) { |
1069 | errmsg = "Invalid base64 encoding"; |
1070 | goto error; |
1071 | } |
1072 | |
1073 | if (ret->keyblob_len + len > ret->keyblob_size) { |
1074 | ret->keyblob_size = ret->keyblob_len + len + 256; |
1075 | ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size); |
1076 | } |
1077 | |
1078 | memcpy(ret->keyblob + ret->keyblob_len, out, len); |
1079 | ret->keyblob_len += len; |
1080 | } |
1081 | |
1082 | p++; |
1083 | } |
1084 | } |
1085 | } |
1086 | |
1087 | if (ret->keyblob_len == 0 || !ret->keyblob) { |
1088 | errmsg = "Key body not present"; |
1089 | goto error; |
1090 | } |
1091 | |
1092 | return ret; |
1093 | |
1094 | error: |
1095 | if (ret) { |
ee5c1422 |
1096 | if (ret->keyblob) { |
1097 | memset(ret->keyblob, 0, ret->keyblob_size); |
1098 | sfree(ret->keyblob); |
1099 | } |
1100 | memset(&ret, 0, sizeof(ret)); |
7b4ef1ae |
1101 | sfree(ret); |
1102 | } |
1103 | return NULL; |
1104 | } |
1105 | |
9a30e26b |
1106 | int sshcom_encrypted(const Filename *filename, char **comment) |
7b4ef1ae |
1107 | { |
1108 | struct sshcom_key *key = load_sshcom_key(filename); |
1109 | int pos, len, answer; |
1110 | |
1111 | *comment = NULL; |
1112 | if (!key) |
1113 | return 0; |
1114 | |
1115 | /* |
1116 | * Check magic number. |
1117 | */ |
1118 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) |
1119 | return 0; /* key is invalid */ |
1120 | |
1121 | /* |
1122 | * Find the cipher-type string. |
1123 | */ |
1124 | answer = 0; |
1125 | pos = 8; |
1126 | if (key->keyblob_len < pos+4) |
1127 | goto done; /* key is far too short */ |
1128 | pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ |
1129 | if (key->keyblob_len < pos+4) |
1130 | goto done; /* key is far too short */ |
1131 | len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ |
1132 | if (key->keyblob_len < pos+4+len) |
1133 | goto done; /* cipher type string is incomplete */ |
1134 | if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) |
1135 | answer = 1; |
1136 | |
1137 | done: |
1138 | *comment = dupstr(key->comment); |
ee5c1422 |
1139 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1140 | sfree(key->keyblob); |
ee5c1422 |
1141 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1142 | sfree(key); |
1143 | return answer; |
1144 | } |
1145 | |
d714d740 |
1146 | static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) |
7b4ef1ae |
1147 | { |
1148 | int bits; |
1149 | int bytes; |
1150 | unsigned char *d = (unsigned char *) data; |
1151 | |
1152 | if (len < 4) |
1153 | goto error; |
1154 | bits = GET_32BIT(d); |
1155 | |
1156 | bytes = (bits + 7) / 8; |
1157 | if (len < 4+bytes) |
1158 | goto error; |
1159 | |
1160 | ret->start = d + 4; |
1161 | ret->bytes = bytes; |
1162 | return bytes+4; |
1163 | |
1164 | error: |
1165 | ret->start = NULL; |
1166 | ret->bytes = -1; |
1167 | return len; /* ensure further calls fail as well */ |
1168 | } |
1169 | |
96d19bc9 |
1170 | static int sshcom_put_mpint(void *target, void *data, int len) |
1171 | { |
1172 | unsigned char *d = (unsigned char *)target; |
1173 | unsigned char *i = (unsigned char *)data; |
1174 | int bits = len * 8 - 1; |
1175 | |
1176 | while (bits > 0) { |
1177 | if (*i & (1 << (bits & 7))) |
1178 | break; |
1179 | if (!(bits-- & 7)) |
1180 | i++, len--; |
1181 | } |
1182 | |
1183 | PUT_32BIT(d, bits+1); |
1184 | memcpy(d+4, i, len); |
1185 | return len+4; |
1186 | } |
1187 | |
9a30e26b |
1188 | struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase) |
7b4ef1ae |
1189 | { |
1190 | struct sshcom_key *key = load_sshcom_key(filename); |
1191 | char *errmsg; |
1192 | int pos, len; |
1193 | const char prefix_rsa[] = "if-modn{sign{rsa"; |
1194 | const char prefix_dsa[] = "dl-modp{sign{dsa"; |
1195 | enum { RSA, DSA } type; |
1196 | int encrypted; |
1197 | char *ciphertext; |
1198 | int cipherlen; |
1199 | struct ssh2_userkey *ret = NULL, *retkey; |
1200 | const struct ssh_signkey *alg; |
1201 | unsigned char *blob = NULL; |
ee5c1422 |
1202 | int blobsize, publen, privlen; |
7b4ef1ae |
1203 | |
1204 | if (!key) |
1205 | return NULL; |
1206 | |
1207 | /* |
1208 | * Check magic number. |
1209 | */ |
96d19bc9 |
1210 | if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) { |
7b4ef1ae |
1211 | errmsg = "Key does not begin with magic number"; |
1212 | goto error; |
1213 | } |
1214 | |
1215 | /* |
1216 | * Determine the key type. |
1217 | */ |
1218 | pos = 8; |
1219 | if (key->keyblob_len < pos+4 || |
1220 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1221 | errmsg = "Key blob does not contain a key type string"; |
1222 | goto error; |
1223 | } |
1224 | if (len > sizeof(prefix_rsa) - 1 && |
1225 | !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { |
1226 | type = RSA; |
1227 | } else if (len > sizeof(prefix_dsa) - 1 && |
1228 | !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { |
1229 | type = DSA; |
1230 | } else { |
1231 | errmsg = "Key is of unknown type"; |
1232 | goto error; |
1233 | } |
1234 | pos += 4+len; |
1235 | |
1236 | /* |
1237 | * Determine the cipher type. |
1238 | */ |
1239 | if (key->keyblob_len < pos+4 || |
1240 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1241 | errmsg = "Key blob does not contain a cipher type string"; |
1242 | goto error; |
1243 | } |
1244 | if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) |
1245 | encrypted = 0; |
1246 | else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) |
1247 | encrypted = 1; |
1248 | else { |
1249 | errmsg = "Key encryption is of unknown type"; |
1250 | goto error; |
1251 | } |
1252 | pos += 4+len; |
1253 | |
1254 | /* |
1255 | * Get hold of the encrypted part of the key. |
1256 | */ |
1257 | if (key->keyblob_len < pos+4 || |
1258 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { |
1259 | errmsg = "Key blob does not contain actual key data"; |
1260 | goto error; |
1261 | } |
201188af |
1262 | ciphertext = (char *)key->keyblob + pos + 4; |
7b4ef1ae |
1263 | cipherlen = len; |
1264 | if (cipherlen == 0) { |
1265 | errmsg = "Length of key data is zero"; |
1266 | goto error; |
1267 | } |
1268 | |
1269 | /* |
1270 | * Decrypt it if necessary. |
1271 | */ |
1272 | if (encrypted) { |
1273 | /* |
1274 | * Derive encryption key from passphrase and iv/salt: |
1275 | * |
1276 | * - let block A equal MD5(passphrase) |
1277 | * - let block B equal MD5(passphrase || A) |
1278 | * - block C would be MD5(passphrase || A || B) and so on |
1279 | * - encryption key is the first N bytes of A || B |
1280 | */ |
1281 | struct MD5Context md5c; |
1282 | unsigned char keybuf[32], iv[8]; |
1283 | |
1284 | if (cipherlen % 8 != 0) { |
1285 | errmsg = "Encrypted part of key is not a multiple of cipher block" |
1286 | " size"; |
1287 | goto error; |
1288 | } |
1289 | |
1290 | MD5Init(&md5c); |
201188af |
1291 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
7b4ef1ae |
1292 | MD5Final(keybuf, &md5c); |
1293 | |
1294 | MD5Init(&md5c); |
201188af |
1295 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
7b4ef1ae |
1296 | MD5Update(&md5c, keybuf, 16); |
1297 | MD5Final(keybuf+16, &md5c); |
1298 | |
1299 | /* |
1300 | * Now decrypt the key blob. |
1301 | */ |
ee5c1422 |
1302 | memset(iv, 0, sizeof(iv)); |
201188af |
1303 | des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, |
1304 | cipherlen); |
7b4ef1ae |
1305 | |
ee5c1422 |
1306 | memset(&md5c, 0, sizeof(md5c)); |
1307 | memset(keybuf, 0, sizeof(keybuf)); |
1308 | |
7b4ef1ae |
1309 | /* |
1310 | * Hereafter we return WRONG_PASSPHRASE for any parsing |
ee5c1422 |
1311 | * error. (But only if we've just tried to decrypt it! |
1312 | * Returning WRONG_PASSPHRASE for an unencrypted key is |
1313 | * automatic doom.) |
7b4ef1ae |
1314 | */ |
1315 | if (encrypted) |
1316 | ret = SSH2_WRONG_PASSPHRASE; |
1317 | } |
1318 | |
1319 | /* |
1320 | * Strip away the containing string to get to the real meat. |
1321 | */ |
1322 | len = GET_32BIT(ciphertext); |
1323 | if (len > cipherlen-4) { |
1324 | errmsg = "containing string was ill-formed"; |
1325 | goto error; |
1326 | } |
1327 | ciphertext += 4; |
1328 | cipherlen = len; |
1329 | |
1330 | /* |
1331 | * Now we break down into RSA versus DSA. In either case we'll |
1332 | * construct public and private blobs in our own format, and |
1333 | * end up feeding them to alg->createkey(). |
1334 | */ |
ee5c1422 |
1335 | blobsize = cipherlen + 256; |
1336 | blob = smalloc(blobsize); |
7b4ef1ae |
1337 | privlen = 0; |
1338 | if (type == RSA) { |
1339 | struct mpint_pos n, e, d, u, p, q; |
1340 | int pos = 0; |
1341 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); |
1342 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); |
1343 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); |
1344 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); |
1345 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
1346 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1347 | if (!q.start) { |
1348 | errmsg = "key data did not contain six integers"; |
1349 | goto error; |
1350 | } |
1351 | |
1352 | alg = &ssh_rsa; |
1353 | pos = 0; |
1354 | pos += put_string(blob+pos, "ssh-rsa", 7); |
1355 | pos += put_mp(blob+pos, e.start, e.bytes); |
1356 | pos += put_mp(blob+pos, n.start, n.bytes); |
1357 | publen = pos; |
1358 | pos += put_string(blob+pos, d.start, d.bytes); |
1359 | pos += put_mp(blob+pos, q.start, q.bytes); |
1360 | pos += put_mp(blob+pos, p.start, p.bytes); |
1361 | pos += put_mp(blob+pos, u.start, u.bytes); |
1362 | privlen = pos - publen; |
1363 | } else if (type == DSA) { |
1364 | struct mpint_pos p, q, g, x, y; |
1365 | int pos = 4; |
1366 | if (GET_32BIT(ciphertext) != 0) { |
1367 | errmsg = "predefined DSA parameters not supported"; |
1368 | goto error; |
1369 | } |
1370 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); |
1371 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); |
1372 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); |
1373 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); |
1374 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); |
1375 | if (!x.start) { |
1376 | errmsg = "key data did not contain five integers"; |
1377 | goto error; |
1378 | } |
1379 | |
1380 | alg = &ssh_dss; |
1381 | pos = 0; |
1382 | pos += put_string(blob+pos, "ssh-dss", 7); |
1383 | pos += put_mp(blob+pos, p.start, p.bytes); |
1384 | pos += put_mp(blob+pos, q.start, q.bytes); |
1385 | pos += put_mp(blob+pos, g.start, g.bytes); |
1386 | pos += put_mp(blob+pos, y.start, y.bytes); |
1387 | publen = pos; |
1388 | pos += put_mp(blob+pos, x.start, x.bytes); |
1389 | privlen = pos - publen; |
1390 | } |
1391 | |
1392 | assert(privlen > 0); /* should have bombed by now if not */ |
1393 | |
1394 | retkey = smalloc(sizeof(struct ssh2_userkey)); |
1395 | retkey->alg = alg; |
1396 | retkey->data = alg->createkey(blob, publen, blob+publen, privlen); |
1397 | if (!retkey->data) { |
1398 | sfree(retkey); |
1399 | errmsg = "unable to create key data structure"; |
1400 | goto error; |
1401 | } |
1402 | retkey->comment = dupstr(key->comment); |
1403 | |
1404 | errmsg = NULL; /* no error */ |
1405 | ret = retkey; |
1406 | |
1407 | error: |
ee5c1422 |
1408 | if (blob) { |
1409 | memset(blob, 0, blobsize); |
1410 | sfree(blob); |
1411 | } |
1412 | memset(key->keyblob, 0, key->keyblob_size); |
7b4ef1ae |
1413 | sfree(key->keyblob); |
ee5c1422 |
1414 | memset(&key, 0, sizeof(key)); |
7b4ef1ae |
1415 | sfree(key); |
1416 | return ret; |
1417 | } |
96d19bc9 |
1418 | |
9a30e26b |
1419 | int sshcom_write(const Filename *filename, struct ssh2_userkey *key, |
1420 | char *passphrase) |
96d19bc9 |
1421 | { |
1422 | unsigned char *pubblob, *privblob; |
1423 | int publen, privlen; |
1424 | unsigned char *outblob; |
1425 | int outlen; |
1426 | struct mpint_pos numbers[6]; |
1427 | int nnumbers, initial_zero, pos, lenpos, i; |
1428 | char *type; |
1429 | char *ciphertext; |
1430 | int cipherlen; |
1431 | int ret = 0; |
1432 | FILE *fp; |
1433 | |
1434 | /* |
1435 | * Fetch the key blobs. |
1436 | */ |
1437 | pubblob = key->alg->public_blob(key->data, &publen); |
1438 | privblob = key->alg->private_blob(key->data, &privlen); |
1439 | outblob = NULL; |
1440 | |
1441 | /* |
1442 | * Find the sequence of integers to be encoded into the OpenSSH |
1443 | * key blob, and also decide on the header line. |
1444 | */ |
1445 | if (key->alg == &ssh_rsa) { |
1446 | int pos; |
1447 | struct mpint_pos n, e, d, p, q, iqmp; |
1448 | |
1449 | pos = 4 + GET_32BIT(pubblob); |
1450 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); |
1451 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); |
1452 | pos = 0; |
1453 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); |
1454 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); |
1455 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); |
1456 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); |
1457 | |
1458 | assert(e.start && iqmp.start); /* can't go wrong */ |
1459 | |
1460 | numbers[0] = e; |
1461 | numbers[1] = d; |
1462 | numbers[2] = n; |
1463 | numbers[3] = iqmp; |
1464 | numbers[4] = q; |
1465 | numbers[5] = p; |
1466 | |
1467 | nnumbers = 6; |
1468 | initial_zero = 0; |
1469 | type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}"; |
1470 | } else if (key->alg == &ssh_dss) { |
1471 | int pos; |
1472 | struct mpint_pos p, q, g, y, x; |
1473 | |
1474 | pos = 4 + GET_32BIT(pubblob); |
1475 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); |
1476 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); |
1477 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); |
1478 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); |
1479 | pos = 0; |
1480 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); |
1481 | |
1482 | assert(y.start && x.start); /* can't go wrong */ |
1483 | |
1484 | numbers[0] = p; |
1485 | numbers[1] = g; |
1486 | numbers[2] = q; |
1487 | numbers[3] = y; |
1488 | numbers[4] = x; |
1489 | |
1490 | nnumbers = 5; |
1491 | initial_zero = 1; |
1492 | type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}"; |
1493 | } else { |
1494 | assert(0); /* zoinks! */ |
1495 | } |
1496 | |
1497 | /* |
1498 | * Total size of key blob will be somewhere under 512 plus |
1499 | * combined length of integers. We'll calculate the more |
1500 | * precise size as we construct the blob. |
1501 | */ |
1502 | outlen = 512; |
1503 | for (i = 0; i < nnumbers; i++) |
1504 | outlen += 4 + numbers[i].bytes; |
1505 | outblob = smalloc(outlen); |
1506 | |
1507 | /* |
1508 | * Create the unencrypted key blob. |
1509 | */ |
1510 | pos = 0; |
1511 | PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4; |
1512 | pos += 4; /* length field, fill in later */ |
1513 | pos += put_string(outblob+pos, type, strlen(type)); |
1514 | { |
1515 | char *ciphertype = passphrase ? "3des-cbc" : "none"; |
1516 | pos += put_string(outblob+pos, ciphertype, strlen(ciphertype)); |
1517 | } |
1518 | lenpos = pos; /* remember this position */ |
1519 | pos += 4; /* encrypted-blob size */ |
1520 | pos += 4; /* encrypted-payload size */ |
1521 | if (initial_zero) { |
1522 | PUT_32BIT(outblob+pos, 0); |
1523 | pos += 4; |
1524 | } |
1525 | for (i = 0; i < nnumbers; i++) |
1526 | pos += sshcom_put_mpint(outblob+pos, |
1527 | numbers[i].start, numbers[i].bytes); |
1528 | /* Now wrap up the encrypted payload. */ |
1529 | PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8)); |
1530 | /* Pad encrypted blob to a multiple of cipher block size. */ |
1531 | if (passphrase) { |
1532 | int padding = -(pos - (lenpos+4)) & 7; |
1533 | while (padding--) |
1534 | outblob[pos++] = random_byte(); |
1535 | } |
201188af |
1536 | ciphertext = (char *)outblob+lenpos+4; |
96d19bc9 |
1537 | cipherlen = pos - (lenpos+4); |
1538 | assert(!passphrase || cipherlen % 8 == 0); |
1539 | /* Wrap up the encrypted blob string. */ |
1540 | PUT_32BIT(outblob+lenpos, cipherlen); |
1541 | /* And finally fill in the total length field. */ |
1542 | PUT_32BIT(outblob+4, pos); |
1543 | |
1544 | assert(pos < outlen); |
1545 | |
1546 | /* |
1547 | * Encrypt the key. |
1548 | */ |
1549 | if (passphrase) { |
1550 | /* |
1551 | * Derive encryption key from passphrase and iv/salt: |
1552 | * |
1553 | * - let block A equal MD5(passphrase) |
1554 | * - let block B equal MD5(passphrase || A) |
1555 | * - block C would be MD5(passphrase || A || B) and so on |
1556 | * - encryption key is the first N bytes of A || B |
1557 | */ |
1558 | struct MD5Context md5c; |
1559 | unsigned char keybuf[32], iv[8]; |
1560 | |
1561 | MD5Init(&md5c); |
201188af |
1562 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
96d19bc9 |
1563 | MD5Final(keybuf, &md5c); |
1564 | |
1565 | MD5Init(&md5c); |
201188af |
1566 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); |
96d19bc9 |
1567 | MD5Update(&md5c, keybuf, 16); |
1568 | MD5Final(keybuf+16, &md5c); |
1569 | |
1570 | /* |
1571 | * Now decrypt the key blob. |
1572 | */ |
1573 | memset(iv, 0, sizeof(iv)); |
201188af |
1574 | des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, |
1575 | cipherlen); |
96d19bc9 |
1576 | |
1577 | memset(&md5c, 0, sizeof(md5c)); |
1578 | memset(keybuf, 0, sizeof(keybuf)); |
1579 | } |
1580 | |
1581 | /* |
1582 | * And save it. We'll use Unix line endings just in case it's |
1583 | * subsequently transferred in binary mode. |
1584 | */ |
9a30e26b |
1585 | fp = f_open(*filename, "wb"); /* ensure Unix line endings */ |
96d19bc9 |
1586 | if (!fp) |
1587 | goto error; |
1588 | fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); |
1589 | fprintf(fp, "Comment: \""); |
1590 | /* |
1591 | * Comment header is broken with backslash-newline if it goes |
1592 | * over 70 chars. Although it's surrounded by quotes, it |
1593 | * _doesn't_ escape backslashes or quotes within the string. |
1594 | * Don't ask me, I didn't design it. |
1595 | */ |
1596 | { |
1597 | int slen = 60; /* starts at 60 due to "Comment: " */ |
1598 | char *c = key->comment; |
6ef15436 |
1599 | while ((int)strlen(c) > slen) { |
96d19bc9 |
1600 | fprintf(fp, "%.*s\\\n", slen, c); |
1601 | c += slen; |
1602 | slen = 70; /* allow 70 chars on subsequent lines */ |
1603 | } |
1604 | fprintf(fp, "%s\"\n", c); |
1605 | } |
1606 | base64_encode(fp, outblob, pos, 70); |
1607 | fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); |
1608 | fclose(fp); |
1609 | ret = 1; |
1610 | |
1611 | error: |
1612 | if (outblob) { |
1613 | memset(outblob, 0, outlen); |
1614 | sfree(outblob); |
1615 | } |
1616 | if (privblob) { |
1617 | memset(privblob, 0, privlen); |
1618 | sfree(privblob); |
1619 | } |
1620 | if (pubblob) { |
1621 | memset(pubblob, 0, publen); |
1622 | sfree(pubblob); |
1623 | } |
1624 | return ret; |
1625 | } |