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Commit | Line | Data |
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1c1af145 | 1 | /* |
2 | * Code for PuTTY to import and export private key files in other | |
3 | * SSH clients' formats. | |
4 | */ | |
5 | ||
6 | #include <stdio.h> | |
7 | #include <stdlib.h> | |
8 | #include <assert.h> | |
9 | #include <ctype.h> | |
10 | ||
11 | #include "putty.h" | |
12 | #include "ssh.h" | |
13 | #include "misc.h" | |
14 | ||
15 | int openssh_encrypted(const Filename *filename); | |
16 | struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase, | |
17 | const char **errmsg_p); | |
18 | int openssh_write(const Filename *filename, struct ssh2_userkey *key, | |
19 | char *passphrase); | |
20 | ||
21 | int sshcom_encrypted(const Filename *filename, char **comment); | |
22 | struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase, | |
23 | const char **errmsg_p); | |
24 | int sshcom_write(const Filename *filename, struct ssh2_userkey *key, | |
25 | char *passphrase); | |
26 | ||
27 | /* | |
28 | * Given a key type, determine whether we know how to import it. | |
29 | */ | |
30 | int import_possible(int type) | |
31 | { | |
32 | if (type == SSH_KEYTYPE_OPENSSH) | |
33 | return 1; | |
34 | if (type == SSH_KEYTYPE_SSHCOM) | |
35 | return 1; | |
36 | return 0; | |
37 | } | |
38 | ||
39 | /* | |
40 | * Given a key type, determine what native key type | |
41 | * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once | |
42 | * we've imported it. | |
43 | */ | |
44 | int import_target_type(int type) | |
45 | { | |
46 | /* | |
47 | * There are no known foreign SSH-1 key formats. | |
48 | */ | |
49 | return SSH_KEYTYPE_SSH2; | |
50 | } | |
51 | ||
52 | /* | |
53 | * Determine whether a foreign key is encrypted. | |
54 | */ | |
55 | int import_encrypted(const Filename *filename, int type, char **comment) | |
56 | { | |
57 | if (type == SSH_KEYTYPE_OPENSSH) { | |
58 | /* OpenSSH doesn't do key comments */ | |
59 | *comment = dupstr(filename_to_str(filename)); | |
60 | return openssh_encrypted(filename); | |
61 | } | |
62 | if (type == SSH_KEYTYPE_SSHCOM) { | |
63 | return sshcom_encrypted(filename, comment); | |
64 | } | |
65 | return 0; | |
66 | } | |
67 | ||
68 | /* | |
69 | * Import an SSH-1 key. | |
70 | */ | |
71 | int import_ssh1(const Filename *filename, int type, | |
72 | struct RSAKey *key, char *passphrase, const char **errmsg_p) | |
73 | { | |
74 | return 0; | |
75 | } | |
76 | ||
77 | /* | |
78 | * Import an SSH-2 key. | |
79 | */ | |
80 | struct ssh2_userkey *import_ssh2(const Filename *filename, int type, | |
81 | char *passphrase, const char **errmsg_p) | |
82 | { | |
83 | if (type == SSH_KEYTYPE_OPENSSH) | |
84 | return openssh_read(filename, passphrase, errmsg_p); | |
85 | if (type == SSH_KEYTYPE_SSHCOM) | |
86 | return sshcom_read(filename, passphrase, errmsg_p); | |
87 | return NULL; | |
88 | } | |
89 | ||
90 | /* | |
91 | * Export an SSH-1 key. | |
92 | */ | |
93 | int export_ssh1(const Filename *filename, int type, struct RSAKey *key, | |
94 | char *passphrase) | |
95 | { | |
96 | return 0; | |
97 | } | |
98 | ||
99 | /* | |
100 | * Export an SSH-2 key. | |
101 | */ | |
102 | int export_ssh2(const Filename *filename, int type, | |
103 | struct ssh2_userkey *key, char *passphrase) | |
104 | { | |
105 | if (type == SSH_KEYTYPE_OPENSSH) | |
106 | return openssh_write(filename, key, passphrase); | |
107 | if (type == SSH_KEYTYPE_SSHCOM) | |
108 | return sshcom_write(filename, key, passphrase); | |
109 | return 0; | |
110 | } | |
111 | ||
112 | /* | |
113 | * Strip trailing CRs and LFs at the end of a line of text. | |
114 | */ | |
115 | void strip_crlf(char *str) | |
116 | { | |
117 | char *p = str + strlen(str); | |
118 | ||
119 | while (p > str && (p[-1] == '\r' || p[-1] == '\n')) | |
120 | *--p = '\0'; | |
121 | } | |
122 | ||
123 | /* ---------------------------------------------------------------------- | |
124 | * Helper routines. (The base64 ones are defined in sshpubk.c.) | |
125 | */ | |
126 | ||
127 | #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \ | |
128 | ((c) >= 'a' && (c) <= 'z') || \ | |
129 | ((c) >= '0' && (c) <= '9') || \ | |
130 | (c) == '+' || (c) == '/' || (c) == '=' \ | |
131 | ) | |
132 | ||
133 | /* | |
134 | * Read an ASN.1/BER identifier and length pair. | |
135 | * | |
136 | * Flags are a combination of the #defines listed below. | |
137 | * | |
138 | * Returns -1 if unsuccessful; otherwise returns the number of | |
139 | * bytes used out of the source data. | |
140 | */ | |
141 | ||
142 | /* ASN.1 tag classes. */ | |
143 | #define ASN1_CLASS_UNIVERSAL (0 << 6) | |
144 | #define ASN1_CLASS_APPLICATION (1 << 6) | |
145 | #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6) | |
146 | #define ASN1_CLASS_PRIVATE (3 << 6) | |
147 | #define ASN1_CLASS_MASK (3 << 6) | |
148 | ||
149 | /* Primitive versus constructed bit. */ | |
150 | #define ASN1_CONSTRUCTED (1 << 5) | |
151 | ||
152 | static int ber_read_id_len(void *source, int sourcelen, | |
153 | int *id, int *length, int *flags) | |
154 | { | |
155 | unsigned char *p = (unsigned char *) source; | |
156 | ||
157 | if (sourcelen == 0) | |
158 | return -1; | |
159 | ||
160 | *flags = (*p & 0xE0); | |
161 | if ((*p & 0x1F) == 0x1F) { | |
162 | *id = 0; | |
163 | while (*p & 0x80) { | |
164 | p++, sourcelen--; | |
165 | if (sourcelen == 0) | |
166 | return -1; | |
167 | *id = (*id << 7) | (*p & 0x7F); | |
168 | } | |
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 | ||
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 | */ | |
201 | static int ber_write_id_len(void *dest, int id, int length, int flags) | |
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 | ||
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 | ||
282 | /* Simple structure to point to an mp-int within a blob. */ | |
283 | struct mpint_pos { void *start; int bytes; }; | |
284 | ||
285 | static int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret) | |
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 | ||
306 | /* ---------------------------------------------------------------------- | |
307 | * Code to read and write OpenSSH private keys. | |
308 | */ | |
309 | ||
310 | enum { OSSH_DSA, OSSH_RSA }; | |
311 | enum { OSSH_ENC_3DES, OSSH_ENC_AES }; | |
312 | struct openssh_key { | |
313 | int type; | |
314 | int encrypted, encryption; | |
315 | char iv[32]; | |
316 | unsigned char *keyblob; | |
317 | int keyblob_len, keyblob_size; | |
318 | }; | |
319 | ||
320 | static struct openssh_key *load_openssh_key(const Filename *filename, | |
321 | const char **errmsg_p) | |
322 | { | |
323 | struct openssh_key *ret; | |
324 | FILE *fp; | |
325 | char *line = NULL; | |
326 | char *errmsg, *p; | |
327 | int headers_done; | |
328 | char base64_bit[4]; | |
329 | int base64_chars = 0; | |
330 | ||
331 | ret = snew(struct openssh_key); | |
332 | ret->keyblob = NULL; | |
333 | ret->keyblob_len = ret->keyblob_size = 0; | |
334 | ret->encrypted = 0; | |
335 | memset(ret->iv, 0, sizeof(ret->iv)); | |
336 | ||
337 | fp = f_open(*filename, "r", FALSE); | |
338 | if (!fp) { | |
339 | errmsg = "unable to open key file"; | |
340 | goto error; | |
341 | } | |
342 | ||
343 | if (!(line = fgetline(fp))) { | |
344 | errmsg = "unexpected end of file"; | |
345 | goto error; | |
346 | } | |
347 | strip_crlf(line); | |
348 | if (0 != strncmp(line, "-----BEGIN ", 11) || | |
349 | 0 != strcmp(line+strlen(line)-16, "PRIVATE KEY-----")) { | |
350 | errmsg = "file does not begin with OpenSSH key header"; | |
351 | goto error; | |
352 | } | |
353 | if (!strcmp(line, "-----BEGIN RSA PRIVATE KEY-----")) | |
354 | ret->type = OSSH_RSA; | |
355 | else if (!strcmp(line, "-----BEGIN DSA PRIVATE KEY-----")) | |
356 | ret->type = OSSH_DSA; | |
357 | else { | |
358 | errmsg = "unrecognised key type"; | |
359 | goto error; | |
360 | } | |
361 | memset(line, 0, strlen(line)); | |
362 | sfree(line); | |
363 | line = NULL; | |
364 | ||
365 | headers_done = 0; | |
366 | while (1) { | |
367 | if (!(line = fgetline(fp))) { | |
368 | errmsg = "unexpected end of file"; | |
369 | goto error; | |
370 | } | |
371 | strip_crlf(line); | |
372 | if (0 == strncmp(line, "-----END ", 9) && | |
373 | 0 == strcmp(line+strlen(line)-16, "PRIVATE KEY-----")) | |
374 | break; /* done */ | |
375 | if ((p = strchr(line, ':')) != NULL) { | |
376 | if (headers_done) { | |
377 | errmsg = "header found in body of key data"; | |
378 | goto error; | |
379 | } | |
380 | *p++ = '\0'; | |
381 | while (*p && isspace((unsigned char)*p)) p++; | |
382 | if (!strcmp(line, "Proc-Type")) { | |
383 | if (p[0] != '4' || p[1] != ',') { | |
384 | errmsg = "Proc-Type is not 4 (only 4 is supported)"; | |
385 | goto error; | |
386 | } | |
387 | p += 2; | |
388 | if (!strcmp(p, "ENCRYPTED")) | |
389 | ret->encrypted = 1; | |
390 | } else if (!strcmp(line, "DEK-Info")) { | |
391 | int i, j, ivlen; | |
392 | ||
393 | if (!strncmp(p, "DES-EDE3-CBC,", 13)) { | |
394 | ret->encryption = OSSH_ENC_3DES; | |
395 | ivlen = 8; | |
396 | } else if (!strncmp(p, "AES-128-CBC,", 12)) { | |
397 | ret->encryption = OSSH_ENC_AES; | |
398 | ivlen = 16; | |
399 | } else { | |
400 | errmsg = "unsupported cipher"; | |
401 | goto error; | |
402 | } | |
403 | p = strchr(p, ',') + 1;/* always non-NULL, by above checks */ | |
404 | for (i = 0; i < ivlen; i++) { | |
405 | if (1 != sscanf(p, "%2x", &j)) { | |
406 | errmsg = "expected more iv data in DEK-Info"; | |
407 | goto error; | |
408 | } | |
409 | ret->iv[i] = j; | |
410 | p += 2; | |
411 | } | |
412 | if (*p) { | |
413 | errmsg = "more iv data than expected in DEK-Info"; | |
414 | goto error; | |
415 | } | |
416 | } | |
417 | } else { | |
418 | headers_done = 1; | |
419 | ||
420 | p = line; | |
421 | while (isbase64(*p)) { | |
422 | base64_bit[base64_chars++] = *p; | |
423 | if (base64_chars == 4) { | |
424 | unsigned char out[3]; | |
425 | int len; | |
426 | ||
427 | base64_chars = 0; | |
428 | ||
429 | len = base64_decode_atom(base64_bit, out); | |
430 | ||
431 | if (len <= 0) { | |
432 | errmsg = "invalid base64 encoding"; | |
433 | goto error; | |
434 | } | |
435 | ||
436 | if (ret->keyblob_len + len > ret->keyblob_size) { | |
437 | ret->keyblob_size = ret->keyblob_len + len + 256; | |
438 | ret->keyblob = sresize(ret->keyblob, ret->keyblob_size, | |
439 | unsigned char); | |
440 | } | |
441 | ||
442 | memcpy(ret->keyblob + ret->keyblob_len, out, len); | |
443 | ret->keyblob_len += len; | |
444 | ||
445 | memset(out, 0, sizeof(out)); | |
446 | } | |
447 | ||
448 | p++; | |
449 | } | |
450 | } | |
451 | memset(line, 0, strlen(line)); | |
452 | sfree(line); | |
453 | line = NULL; | |
454 | } | |
455 | ||
456 | if (ret->keyblob_len == 0 || !ret->keyblob) { | |
457 | errmsg = "key body not present"; | |
458 | goto error; | |
459 | } | |
460 | ||
461 | if (ret->encrypted && ret->keyblob_len % 8 != 0) { | |
462 | errmsg = "encrypted key blob is not a multiple of cipher block size"; | |
463 | goto error; | |
464 | } | |
465 | ||
466 | memset(base64_bit, 0, sizeof(base64_bit)); | |
467 | if (errmsg_p) *errmsg_p = NULL; | |
468 | return ret; | |
469 | ||
470 | error: | |
471 | if (line) { | |
472 | memset(line, 0, strlen(line)); | |
473 | sfree(line); | |
474 | line = NULL; | |
475 | } | |
476 | memset(base64_bit, 0, sizeof(base64_bit)); | |
477 | if (ret) { | |
478 | if (ret->keyblob) { | |
479 | memset(ret->keyblob, 0, ret->keyblob_size); | |
480 | sfree(ret->keyblob); | |
481 | } | |
482 | memset(ret, 0, sizeof(*ret)); | |
483 | sfree(ret); | |
484 | } | |
485 | if (errmsg_p) *errmsg_p = errmsg; | |
486 | return NULL; | |
487 | } | |
488 | ||
489 | int openssh_encrypted(const Filename *filename) | |
490 | { | |
491 | struct openssh_key *key = load_openssh_key(filename, NULL); | |
492 | int ret; | |
493 | ||
494 | if (!key) | |
495 | return 0; | |
496 | ret = key->encrypted; | |
497 | memset(key->keyblob, 0, key->keyblob_size); | |
498 | sfree(key->keyblob); | |
499 | memset(key, 0, sizeof(*key)); | |
500 | sfree(key); | |
501 | return ret; | |
502 | } | |
503 | ||
504 | struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase, | |
505 | const char **errmsg_p) | |
506 | { | |
507 | struct openssh_key *key = load_openssh_key(filename, errmsg_p); | |
508 | struct ssh2_userkey *retkey; | |
509 | unsigned char *p; | |
510 | int ret, id, len, flags; | |
511 | int i, num_integers; | |
512 | struct ssh2_userkey *retval = NULL; | |
513 | char *errmsg; | |
514 | unsigned char *blob; | |
515 | int blobsize = 0, blobptr, privptr; | |
516 | char *modptr = NULL; | |
517 | int modlen = 0; | |
518 | ||
519 | blob = NULL; | |
520 | ||
521 | if (!key) | |
522 | return NULL; | |
523 | ||
524 | if (key->encrypted) { | |
525 | /* | |
526 | * Derive encryption key from passphrase and iv/salt: | |
527 | * | |
528 | * - let block A equal MD5(passphrase || iv) | |
529 | * - let block B equal MD5(A || passphrase || iv) | |
530 | * - block C would be MD5(B || passphrase || iv) and so on | |
531 | * - encryption key is the first N bytes of A || B | |
532 | * | |
533 | * (Note that only 8 bytes of the iv are used for key | |
534 | * derivation, even when the key is encrypted with AES and | |
535 | * hence there are 16 bytes available.) | |
536 | */ | |
537 | struct MD5Context md5c; | |
538 | unsigned char keybuf[32]; | |
539 | ||
540 | MD5Init(&md5c); | |
541 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); | |
542 | MD5Update(&md5c, (unsigned char *)key->iv, 8); | |
543 | MD5Final(keybuf, &md5c); | |
544 | ||
545 | MD5Init(&md5c); | |
546 | MD5Update(&md5c, keybuf, 16); | |
547 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); | |
548 | MD5Update(&md5c, (unsigned char *)key->iv, 8); | |
549 | MD5Final(keybuf+16, &md5c); | |
550 | ||
551 | /* | |
552 | * Now decrypt the key blob. | |
553 | */ | |
554 | if (key->encryption == OSSH_ENC_3DES) | |
555 | des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv, | |
556 | key->keyblob, key->keyblob_len); | |
557 | else { | |
558 | void *ctx; | |
559 | assert(key->encryption == OSSH_ENC_AES); | |
560 | ctx = aes_make_context(); | |
561 | aes128_key(ctx, keybuf); | |
562 | aes_iv(ctx, (unsigned char *)key->iv); | |
563 | aes_ssh2_decrypt_blk(ctx, key->keyblob, key->keyblob_len); | |
564 | aes_free_context(ctx); | |
565 | } | |
566 | ||
567 | memset(&md5c, 0, sizeof(md5c)); | |
568 | memset(keybuf, 0, sizeof(keybuf)); | |
569 | } | |
570 | ||
571 | /* | |
572 | * Now we have a decrypted key blob, which contains an ASN.1 | |
573 | * encoded private key. We must now untangle the ASN.1. | |
574 | * | |
575 | * We expect the whole key blob to be formatted as a SEQUENCE | |
576 | * (0x30 followed by a length code indicating that the rest of | |
577 | * the blob is part of the sequence). Within that SEQUENCE we | |
578 | * expect to see a bunch of INTEGERs. What those integers mean | |
579 | * depends on the key type: | |
580 | * | |
581 | * - For RSA, we expect the integers to be 0, n, e, d, p, q, | |
582 | * dmp1, dmq1, iqmp in that order. (The last three are d mod | |
583 | * (p-1), d mod (q-1), inverse of q mod p respectively.) | |
584 | * | |
585 | * - For DSA, we expect them to be 0, p, q, g, y, x in that | |
586 | * order. | |
587 | */ | |
588 | ||
589 | p = key->keyblob; | |
590 | ||
591 | /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */ | |
592 | ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags); | |
593 | p += ret; | |
594 | if (ret < 0 || id != 16) { | |
595 | errmsg = "ASN.1 decoding failure"; | |
596 | retval = SSH2_WRONG_PASSPHRASE; | |
597 | goto error; | |
598 | } | |
599 | ||
600 | /* Expect a load of INTEGERs. */ | |
601 | if (key->type == OSSH_RSA) | |
602 | num_integers = 9; | |
603 | else if (key->type == OSSH_DSA) | |
604 | num_integers = 6; | |
605 | else | |
606 | num_integers = 0; /* placate compiler warnings */ | |
607 | ||
608 | /* | |
609 | * Space to create key blob in. | |
610 | */ | |
611 | blobsize = 256+key->keyblob_len; | |
612 | blob = snewn(blobsize, unsigned char); | |
613 | PUT_32BIT(blob, 7); | |
614 | if (key->type == OSSH_DSA) | |
615 | memcpy(blob+4, "ssh-dss", 7); | |
616 | else if (key->type == OSSH_RSA) | |
617 | memcpy(blob+4, "ssh-rsa", 7); | |
618 | blobptr = 4+7; | |
619 | privptr = -1; | |
620 | ||
621 | for (i = 0; i < num_integers; i++) { | |
622 | ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p, | |
623 | &id, &len, &flags); | |
624 | p += ret; | |
625 | if (ret < 0 || id != 2 || | |
626 | key->keyblob+key->keyblob_len-p < len) { | |
627 | errmsg = "ASN.1 decoding failure"; | |
628 | retval = SSH2_WRONG_PASSPHRASE; | |
629 | goto error; | |
630 | } | |
631 | ||
632 | if (i == 0) { | |
633 | /* | |
634 | * The first integer should be zero always (I think | |
635 | * this is some sort of version indication). | |
636 | */ | |
637 | if (len != 1 || p[0] != 0) { | |
638 | errmsg = "version number mismatch"; | |
639 | goto error; | |
640 | } | |
641 | } else if (key->type == OSSH_RSA) { | |
642 | /* | |
643 | * Integers 1 and 2 go into the public blob but in the | |
644 | * opposite order; integers 3, 4, 5 and 8 go into the | |
645 | * private blob. The other two (6 and 7) are ignored. | |
646 | */ | |
647 | if (i == 1) { | |
648 | /* Save the details for after we deal with number 2. */ | |
649 | modptr = (char *)p; | |
650 | modlen = len; | |
651 | } else if (i != 6 && i != 7) { | |
652 | PUT_32BIT(blob+blobptr, len); | |
653 | memcpy(blob+blobptr+4, p, len); | |
654 | blobptr += 4+len; | |
655 | if (i == 2) { | |
656 | PUT_32BIT(blob+blobptr, modlen); | |
657 | memcpy(blob+blobptr+4, modptr, modlen); | |
658 | blobptr += 4+modlen; | |
659 | privptr = blobptr; | |
660 | } | |
661 | } | |
662 | } else if (key->type == OSSH_DSA) { | |
663 | /* | |
664 | * Integers 1-4 go into the public blob; integer 5 goes | |
665 | * into the private blob. | |
666 | */ | |
667 | PUT_32BIT(blob+blobptr, len); | |
668 | memcpy(blob+blobptr+4, p, len); | |
669 | blobptr += 4+len; | |
670 | if (i == 4) | |
671 | privptr = blobptr; | |
672 | } | |
673 | ||
674 | /* Skip past the number. */ | |
675 | p += len; | |
676 | } | |
677 | ||
678 | /* | |
679 | * Now put together the actual key. Simplest way to do this is | |
680 | * to assemble our own key blobs and feed them to the createkey | |
681 | * functions; this is a bit faffy but it does mean we get all | |
682 | * the sanity checks for free. | |
683 | */ | |
684 | assert(privptr > 0); /* should have bombed by now if not */ | |
685 | retkey = snew(struct ssh2_userkey); | |
686 | retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss); | |
687 | retkey->data = retkey->alg->createkey(blob, privptr, | |
688 | blob+privptr, blobptr-privptr); | |
689 | if (!retkey->data) { | |
690 | sfree(retkey); | |
691 | errmsg = "unable to create key data structure"; | |
692 | goto error; | |
693 | } | |
694 | ||
695 | retkey->comment = dupstr("imported-openssh-key"); | |
696 | errmsg = NULL; /* no error */ | |
697 | retval = retkey; | |
698 | ||
699 | error: | |
700 | if (blob) { | |
701 | memset(blob, 0, blobsize); | |
702 | sfree(blob); | |
703 | } | |
704 | memset(key->keyblob, 0, key->keyblob_size); | |
705 | sfree(key->keyblob); | |
706 | memset(key, 0, sizeof(*key)); | |
707 | sfree(key); | |
708 | if (errmsg_p) *errmsg_p = errmsg; | |
709 | return retval; | |
710 | } | |
711 | ||
712 | int openssh_write(const Filename *filename, struct ssh2_userkey *key, | |
713 | char *passphrase) | |
714 | { | |
715 | unsigned char *pubblob, *privblob, *spareblob; | |
716 | int publen, privlen, sparelen = 0; | |
717 | unsigned char *outblob; | |
718 | int outlen; | |
719 | struct mpint_pos numbers[9]; | |
720 | int nnumbers, pos, len, seqlen, i; | |
721 | char *header, *footer; | |
722 | char zero[1]; | |
723 | unsigned char iv[8]; | |
724 | int ret = 0; | |
725 | FILE *fp; | |
726 | ||
727 | /* | |
728 | * Fetch the key blobs. | |
729 | */ | |
730 | pubblob = key->alg->public_blob(key->data, &publen); | |
731 | privblob = key->alg->private_blob(key->data, &privlen); | |
732 | spareblob = outblob = NULL; | |
733 | ||
734 | /* | |
735 | * Find the sequence of integers to be encoded into the OpenSSH | |
736 | * key blob, and also decide on the header line. | |
737 | */ | |
738 | if (key->alg == &ssh_rsa) { | |
739 | int pos; | |
740 | struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1; | |
741 | Bignum bd, bp, bq, bdmp1, bdmq1; | |
742 | ||
743 | pos = 4 + GET_32BIT(pubblob); | |
744 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); | |
745 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); | |
746 | pos = 0; | |
747 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); | |
748 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); | |
749 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); | |
750 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); | |
751 | ||
752 | assert(e.start && iqmp.start); /* can't go wrong */ | |
753 | ||
754 | /* We also need d mod (p-1) and d mod (q-1). */ | |
755 | bd = bignum_from_bytes(d.start, d.bytes); | |
756 | bp = bignum_from_bytes(p.start, p.bytes); | |
757 | bq = bignum_from_bytes(q.start, q.bytes); | |
758 | decbn(bp); | |
759 | decbn(bq); | |
760 | bdmp1 = bigmod(bd, bp); | |
761 | bdmq1 = bigmod(bd, bq); | |
762 | freebn(bd); | |
763 | freebn(bp); | |
764 | freebn(bq); | |
765 | ||
766 | dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8; | |
767 | dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8; | |
768 | sparelen = dmp1.bytes + dmq1.bytes; | |
769 | spareblob = snewn(sparelen, unsigned char); | |
770 | dmp1.start = spareblob; | |
771 | dmq1.start = spareblob + dmp1.bytes; | |
772 | for (i = 0; i < dmp1.bytes; i++) | |
773 | spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i); | |
774 | for (i = 0; i < dmq1.bytes; i++) | |
775 | spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i); | |
776 | freebn(bdmp1); | |
777 | freebn(bdmq1); | |
778 | ||
779 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; | |
780 | numbers[1] = n; | |
781 | numbers[2] = e; | |
782 | numbers[3] = d; | |
783 | numbers[4] = p; | |
784 | numbers[5] = q; | |
785 | numbers[6] = dmp1; | |
786 | numbers[7] = dmq1; | |
787 | numbers[8] = iqmp; | |
788 | ||
789 | nnumbers = 9; | |
790 | header = "-----BEGIN RSA PRIVATE KEY-----\n"; | |
791 | footer = "-----END RSA PRIVATE KEY-----\n"; | |
792 | } else if (key->alg == &ssh_dss) { | |
793 | int pos; | |
794 | struct mpint_pos p, q, g, y, x; | |
795 | ||
796 | pos = 4 + GET_32BIT(pubblob); | |
797 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); | |
798 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); | |
799 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); | |
800 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); | |
801 | pos = 0; | |
802 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); | |
803 | ||
804 | assert(y.start && x.start); /* can't go wrong */ | |
805 | ||
806 | numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0'; | |
807 | numbers[1] = p; | |
808 | numbers[2] = q; | |
809 | numbers[3] = g; | |
810 | numbers[4] = y; | |
811 | numbers[5] = x; | |
812 | ||
813 | nnumbers = 6; | |
814 | header = "-----BEGIN DSA PRIVATE KEY-----\n"; | |
815 | footer = "-----END DSA PRIVATE KEY-----\n"; | |
816 | } else { | |
817 | assert(0); /* zoinks! */ | |
818 | exit(1); /* XXX: GCC doesn't understand assert() on some systems. */ | |
819 | } | |
820 | ||
821 | /* | |
822 | * Now count up the total size of the ASN.1 encoded integers, | |
823 | * so as to determine the length of the containing SEQUENCE. | |
824 | */ | |
825 | len = 0; | |
826 | for (i = 0; i < nnumbers; i++) { | |
827 | len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0); | |
828 | len += numbers[i].bytes; | |
829 | } | |
830 | seqlen = len; | |
831 | /* Now add on the SEQUENCE header. */ | |
832 | len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED); | |
833 | /* Round up to the cipher block size, ensuring we have at least one | |
834 | * byte of padding (see below). */ | |
835 | outlen = len; | |
836 | if (passphrase) | |
837 | outlen = (outlen+8) &~ 7; | |
838 | ||
839 | /* | |
840 | * Now we know how big outblob needs to be. Allocate it. | |
841 | */ | |
842 | outblob = snewn(outlen, unsigned char); | |
843 | ||
844 | /* | |
845 | * And write the data into it. | |
846 | */ | |
847 | pos = 0; | |
848 | pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED); | |
849 | for (i = 0; i < nnumbers; i++) { | |
850 | pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0); | |
851 | memcpy(outblob+pos, numbers[i].start, numbers[i].bytes); | |
852 | pos += numbers[i].bytes; | |
853 | } | |
854 | ||
855 | /* | |
856 | * Padding on OpenSSH keys is deterministic. The number of | |
857 | * padding bytes is always more than zero, and always at most | |
858 | * the cipher block length. The value of each padding byte is | |
859 | * equal to the number of padding bytes. So a plaintext that's | |
860 | * an exact multiple of the block size will be padded with 08 | |
861 | * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a | |
862 | * plaintext one byte less than a multiple of the block size | |
863 | * will be padded with just 01. | |
864 | * | |
865 | * This enables the OpenSSL key decryption function to strip | |
866 | * off the padding algorithmically and return the unpadded | |
867 | * plaintext to the next layer: it looks at the final byte, and | |
868 | * then expects to find that many bytes at the end of the data | |
869 | * with the same value. Those are all removed and the rest is | |
870 | * returned. | |
871 | */ | |
872 | assert(pos == len); | |
873 | while (pos < outlen) { | |
874 | outblob[pos++] = outlen - len; | |
875 | } | |
876 | ||
877 | /* | |
878 | * Encrypt the key. | |
879 | * | |
880 | * For the moment, we still encrypt our OpenSSH keys using | |
881 | * old-style 3DES. | |
882 | */ | |
883 | if (passphrase) { | |
884 | /* | |
885 | * Invent an iv. Then derive encryption key from passphrase | |
886 | * and iv/salt: | |
887 | * | |
888 | * - let block A equal MD5(passphrase || iv) | |
889 | * - let block B equal MD5(A || passphrase || iv) | |
890 | * - block C would be MD5(B || passphrase || iv) and so on | |
891 | * - encryption key is the first N bytes of A || B | |
892 | */ | |
893 | struct MD5Context md5c; | |
894 | unsigned char keybuf[32]; | |
895 | ||
896 | for (i = 0; i < 8; i++) iv[i] = random_byte(); | |
897 | ||
898 | MD5Init(&md5c); | |
899 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); | |
900 | MD5Update(&md5c, iv, 8); | |
901 | MD5Final(keybuf, &md5c); | |
902 | ||
903 | MD5Init(&md5c); | |
904 | MD5Update(&md5c, keybuf, 16); | |
905 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); | |
906 | MD5Update(&md5c, iv, 8); | |
907 | MD5Final(keybuf+16, &md5c); | |
908 | ||
909 | /* | |
910 | * Now encrypt the key blob. | |
911 | */ | |
912 | des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen); | |
913 | ||
914 | memset(&md5c, 0, sizeof(md5c)); | |
915 | memset(keybuf, 0, sizeof(keybuf)); | |
916 | } | |
917 | ||
918 | /* | |
919 | * And save it. We'll use Unix line endings just in case it's | |
920 | * subsequently transferred in binary mode. | |
921 | */ | |
922 | fp = f_open(*filename, "wb", TRUE); /* ensure Unix line endings */ | |
923 | if (!fp) | |
924 | goto error; | |
925 | fputs(header, fp); | |
926 | if (passphrase) { | |
927 | fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,"); | |
928 | for (i = 0; i < 8; i++) | |
929 | fprintf(fp, "%02X", iv[i]); | |
930 | fprintf(fp, "\n\n"); | |
931 | } | |
932 | base64_encode(fp, outblob, outlen, 64); | |
933 | fputs(footer, fp); | |
934 | fclose(fp); | |
935 | ret = 1; | |
936 | ||
937 | error: | |
938 | if (outblob) { | |
939 | memset(outblob, 0, outlen); | |
940 | sfree(outblob); | |
941 | } | |
942 | if (spareblob) { | |
943 | memset(spareblob, 0, sparelen); | |
944 | sfree(spareblob); | |
945 | } | |
946 | if (privblob) { | |
947 | memset(privblob, 0, privlen); | |
948 | sfree(privblob); | |
949 | } | |
950 | if (pubblob) { | |
951 | memset(pubblob, 0, publen); | |
952 | sfree(pubblob); | |
953 | } | |
954 | return ret; | |
955 | } | |
956 | ||
957 | /* ---------------------------------------------------------------------- | |
958 | * Code to read ssh.com private keys. | |
959 | */ | |
960 | ||
961 | /* | |
962 | * The format of the base64 blob is largely SSH-2-packet-formatted, | |
963 | * except that mpints are a bit different: they're more like the | |
964 | * old SSH-1 mpint. You have a 32-bit bit count N, followed by | |
965 | * (N+7)/8 bytes of data. | |
966 | * | |
967 | * So. The blob contains: | |
968 | * | |
969 | * - uint32 0x3f6ff9eb (magic number) | |
970 | * - uint32 size (total blob size) | |
971 | * - string key-type (see below) | |
972 | * - string cipher-type (tells you if key is encrypted) | |
973 | * - string encrypted-blob | |
974 | * | |
975 | * (The first size field includes the size field itself and the | |
976 | * magic number before it. All other size fields are ordinary SSH-2 | |
977 | * strings, so the size field indicates how much data is to | |
978 | * _follow_.) | |
979 | * | |
980 | * The encrypted blob, once decrypted, contains a single string | |
981 | * which in turn contains the payload. (This allows padding to be | |
982 | * added after that string while still making it clear where the | |
983 | * real payload ends. Also it probably makes for a reasonable | |
984 | * decryption check.) | |
985 | * | |
986 | * The payload blob, for an RSA key, contains: | |
987 | * - mpint e | |
988 | * - mpint d | |
989 | * - mpint n (yes, the public and private stuff is intermixed) | |
990 | * - mpint u (presumably inverse of p mod q) | |
991 | * - mpint p (p is the smaller prime) | |
992 | * - mpint q (q is the larger) | |
993 | * | |
994 | * For a DSA key, the payload blob contains: | |
995 | * - uint32 0 | |
996 | * - mpint p | |
997 | * - mpint g | |
998 | * - mpint q | |
999 | * - mpint y | |
1000 | * - mpint x | |
1001 | * | |
1002 | * Alternatively, if the parameters are `predefined', that | |
1003 | * (0,p,g,q) sequence can be replaced by a uint32 1 and a string | |
1004 | * containing some predefined parameter specification. *shudder*, | |
1005 | * but I doubt we'll encounter this in real life. | |
1006 | * | |
1007 | * The key type strings are ghastly. The RSA key I looked at had a | |
1008 | * type string of | |
1009 | * | |
1010 | * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}' | |
1011 | * | |
1012 | * and the DSA key wasn't much better: | |
1013 | * | |
1014 | * `dl-modp{sign{dsa-nist-sha1},dh{plain}}' | |
1015 | * | |
1016 | * It isn't clear that these will always be the same. I think it | |
1017 | * might be wise just to look at the `if-modn{sign{rsa' and | |
1018 | * `dl-modp{sign{dsa' prefixes. | |
1019 | * | |
1020 | * Finally, the encryption. The cipher-type string appears to be | |
1021 | * either `none' or `3des-cbc'. Looks as if this is SSH-2-style | |
1022 | * 3des-cbc (i.e. outer cbc rather than inner). The key is created | |
1023 | * from the passphrase by means of yet another hashing faff: | |
1024 | * | |
1025 | * - first 16 bytes are MD5(passphrase) | |
1026 | * - next 16 bytes are MD5(passphrase || first 16 bytes) | |
1027 | * - if there were more, they'd be MD5(passphrase || first 32), | |
1028 | * and so on. | |
1029 | */ | |
1030 | ||
1031 | #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb | |
1032 | ||
1033 | struct sshcom_key { | |
1034 | char comment[256]; /* allowing any length is overkill */ | |
1035 | unsigned char *keyblob; | |
1036 | int keyblob_len, keyblob_size; | |
1037 | }; | |
1038 | ||
1039 | static struct sshcom_key *load_sshcom_key(const Filename *filename, | |
1040 | const char **errmsg_p) | |
1041 | { | |
1042 | struct sshcom_key *ret; | |
1043 | FILE *fp; | |
1044 | char *line = NULL; | |
1045 | int hdrstart, len; | |
1046 | char *errmsg, *p; | |
1047 | int headers_done; | |
1048 | char base64_bit[4]; | |
1049 | int base64_chars = 0; | |
1050 | ||
1051 | ret = snew(struct sshcom_key); | |
1052 | ret->comment[0] = '\0'; | |
1053 | ret->keyblob = NULL; | |
1054 | ret->keyblob_len = ret->keyblob_size = 0; | |
1055 | ||
1056 | fp = f_open(*filename, "r", FALSE); | |
1057 | if (!fp) { | |
1058 | errmsg = "unable to open key file"; | |
1059 | goto error; | |
1060 | } | |
1061 | if (!(line = fgetline(fp))) { | |
1062 | errmsg = "unexpected end of file"; | |
1063 | goto error; | |
1064 | } | |
1065 | strip_crlf(line); | |
1066 | if (0 != strcmp(line, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) { | |
1067 | errmsg = "file does not begin with ssh.com key header"; | |
1068 | goto error; | |
1069 | } | |
1070 | memset(line, 0, strlen(line)); | |
1071 | sfree(line); | |
1072 | line = NULL; | |
1073 | ||
1074 | headers_done = 0; | |
1075 | while (1) { | |
1076 | if (!(line = fgetline(fp))) { | |
1077 | errmsg = "unexpected end of file"; | |
1078 | goto error; | |
1079 | } | |
1080 | strip_crlf(line); | |
1081 | if (!strcmp(line, "---- END SSH2 ENCRYPTED PRIVATE KEY ----")) | |
1082 | break; /* done */ | |
1083 | if ((p = strchr(line, ':')) != NULL) { | |
1084 | if (headers_done) { | |
1085 | errmsg = "header found in body of key data"; | |
1086 | goto error; | |
1087 | } | |
1088 | *p++ = '\0'; | |
1089 | while (*p && isspace((unsigned char)*p)) p++; | |
1090 | hdrstart = p - line; | |
1091 | ||
1092 | /* | |
1093 | * Header lines can end in a trailing backslash for | |
1094 | * continuation. | |
1095 | */ | |
1096 | len = hdrstart + strlen(line+hdrstart); | |
1097 | assert(!line[len]); | |
1098 | while (line[len-1] == '\\') { | |
1099 | char *line2; | |
1100 | int line2len; | |
1101 | ||
1102 | line2 = fgetline(fp); | |
1103 | if (!line2) { | |
1104 | errmsg = "unexpected end of file"; | |
1105 | goto error; | |
1106 | } | |
1107 | strip_crlf(line2); | |
1108 | ||
1109 | line2len = strlen(line2); | |
1110 | line = sresize(line, len + line2len + 1, char); | |
1111 | strcpy(line + len - 1, line2); | |
1112 | len += line2len - 1; | |
1113 | assert(!line[len]); | |
1114 | ||
1115 | memset(line2, 0, strlen(line2)); | |
1116 | sfree(line2); | |
1117 | line2 = NULL; | |
1118 | } | |
1119 | p = line + hdrstart; | |
1120 | strip_crlf(p); | |
1121 | if (!strcmp(line, "Comment")) { | |
1122 | /* Strip quotes in comment if present. */ | |
1123 | if (p[0] == '"' && p[strlen(p)-1] == '"') { | |
1124 | p++; | |
1125 | p[strlen(p)-1] = '\0'; | |
1126 | } | |
1127 | strncpy(ret->comment, p, sizeof(ret->comment)); | |
1128 | ret->comment[sizeof(ret->comment)-1] = '\0'; | |
1129 | } | |
1130 | } else { | |
1131 | headers_done = 1; | |
1132 | ||
1133 | p = line; | |
1134 | while (isbase64(*p)) { | |
1135 | base64_bit[base64_chars++] = *p; | |
1136 | if (base64_chars == 4) { | |
1137 | unsigned char out[3]; | |
1138 | ||
1139 | base64_chars = 0; | |
1140 | ||
1141 | len = base64_decode_atom(base64_bit, out); | |
1142 | ||
1143 | if (len <= 0) { | |
1144 | errmsg = "invalid base64 encoding"; | |
1145 | goto error; | |
1146 | } | |
1147 | ||
1148 | if (ret->keyblob_len + len > ret->keyblob_size) { | |
1149 | ret->keyblob_size = ret->keyblob_len + len + 256; | |
1150 | ret->keyblob = sresize(ret->keyblob, ret->keyblob_size, | |
1151 | unsigned char); | |
1152 | } | |
1153 | ||
1154 | memcpy(ret->keyblob + ret->keyblob_len, out, len); | |
1155 | ret->keyblob_len += len; | |
1156 | } | |
1157 | ||
1158 | p++; | |
1159 | } | |
1160 | } | |
1161 | memset(line, 0, strlen(line)); | |
1162 | sfree(line); | |
1163 | line = NULL; | |
1164 | } | |
1165 | ||
1166 | if (ret->keyblob_len == 0 || !ret->keyblob) { | |
1167 | errmsg = "key body not present"; | |
1168 | goto error; | |
1169 | } | |
1170 | ||
1171 | if (errmsg_p) *errmsg_p = NULL; | |
1172 | return ret; | |
1173 | ||
1174 | error: | |
1175 | if (line) { | |
1176 | memset(line, 0, strlen(line)); | |
1177 | sfree(line); | |
1178 | line = NULL; | |
1179 | } | |
1180 | if (ret) { | |
1181 | if (ret->keyblob) { | |
1182 | memset(ret->keyblob, 0, ret->keyblob_size); | |
1183 | sfree(ret->keyblob); | |
1184 | } | |
1185 | memset(ret, 0, sizeof(*ret)); | |
1186 | sfree(ret); | |
1187 | } | |
1188 | if (errmsg_p) *errmsg_p = errmsg; | |
1189 | return NULL; | |
1190 | } | |
1191 | ||
1192 | int sshcom_encrypted(const Filename *filename, char **comment) | |
1193 | { | |
1194 | struct sshcom_key *key = load_sshcom_key(filename, NULL); | |
1195 | int pos, len, answer; | |
1196 | ||
1197 | *comment = NULL; | |
1198 | if (!key) | |
1199 | return 0; | |
1200 | ||
1201 | /* | |
1202 | * Check magic number. | |
1203 | */ | |
1204 | if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) | |
1205 | return 0; /* key is invalid */ | |
1206 | ||
1207 | /* | |
1208 | * Find the cipher-type string. | |
1209 | */ | |
1210 | answer = 0; | |
1211 | pos = 8; | |
1212 | if (key->keyblob_len < pos+4) | |
1213 | goto done; /* key is far too short */ | |
1214 | pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */ | |
1215 | if (key->keyblob_len < pos+4) | |
1216 | goto done; /* key is far too short */ | |
1217 | len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */ | |
1218 | if (key->keyblob_len < pos+4+len) | |
1219 | goto done; /* cipher type string is incomplete */ | |
1220 | if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4)) | |
1221 | answer = 1; | |
1222 | ||
1223 | done: | |
1224 | *comment = dupstr(key->comment); | |
1225 | memset(key->keyblob, 0, key->keyblob_size); | |
1226 | sfree(key->keyblob); | |
1227 | memset(key, 0, sizeof(*key)); | |
1228 | sfree(key); | |
1229 | return answer; | |
1230 | } | |
1231 | ||
1232 | static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret) | |
1233 | { | |
1234 | int bits; | |
1235 | int bytes; | |
1236 | unsigned char *d = (unsigned char *) data; | |
1237 | ||
1238 | if (len < 4) | |
1239 | goto error; | |
1240 | bits = GET_32BIT(d); | |
1241 | ||
1242 | bytes = (bits + 7) / 8; | |
1243 | if (len < 4+bytes) | |
1244 | goto error; | |
1245 | ||
1246 | ret->start = d + 4; | |
1247 | ret->bytes = bytes; | |
1248 | return bytes+4; | |
1249 | ||
1250 | error: | |
1251 | ret->start = NULL; | |
1252 | ret->bytes = -1; | |
1253 | return len; /* ensure further calls fail as well */ | |
1254 | } | |
1255 | ||
1256 | static int sshcom_put_mpint(void *target, void *data, int len) | |
1257 | { | |
1258 | unsigned char *d = (unsigned char *)target; | |
1259 | unsigned char *i = (unsigned char *)data; | |
1260 | int bits = len * 8 - 1; | |
1261 | ||
1262 | while (bits > 0) { | |
1263 | if (*i & (1 << (bits & 7))) | |
1264 | break; | |
1265 | if (!(bits-- & 7)) | |
1266 | i++, len--; | |
1267 | } | |
1268 | ||
1269 | PUT_32BIT(d, bits+1); | |
1270 | memcpy(d+4, i, len); | |
1271 | return len+4; | |
1272 | } | |
1273 | ||
1274 | struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase, | |
1275 | const char **errmsg_p) | |
1276 | { | |
1277 | struct sshcom_key *key = load_sshcom_key(filename, errmsg_p); | |
1278 | char *errmsg; | |
1279 | int pos, len; | |
1280 | const char prefix_rsa[] = "if-modn{sign{rsa"; | |
1281 | const char prefix_dsa[] = "dl-modp{sign{dsa"; | |
1282 | enum { RSA, DSA } type; | |
1283 | int encrypted; | |
1284 | char *ciphertext; | |
1285 | int cipherlen; | |
1286 | struct ssh2_userkey *ret = NULL, *retkey; | |
1287 | const struct ssh_signkey *alg; | |
1288 | unsigned char *blob = NULL; | |
1289 | int blobsize = 0, publen, privlen; | |
1290 | ||
1291 | if (!key) | |
1292 | return NULL; | |
1293 | ||
1294 | /* | |
1295 | * Check magic number. | |
1296 | */ | |
1297 | if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) { | |
1298 | errmsg = "key does not begin with magic number"; | |
1299 | goto error; | |
1300 | } | |
1301 | ||
1302 | /* | |
1303 | * Determine the key type. | |
1304 | */ | |
1305 | pos = 8; | |
1306 | if (key->keyblob_len < pos+4 || | |
1307 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { | |
1308 | errmsg = "key blob does not contain a key type string"; | |
1309 | goto error; | |
1310 | } | |
1311 | if (len > sizeof(prefix_rsa) - 1 && | |
1312 | !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) { | |
1313 | type = RSA; | |
1314 | } else if (len > sizeof(prefix_dsa) - 1 && | |
1315 | !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) { | |
1316 | type = DSA; | |
1317 | } else { | |
1318 | errmsg = "key is of unknown type"; | |
1319 | goto error; | |
1320 | } | |
1321 | pos += 4+len; | |
1322 | ||
1323 | /* | |
1324 | * Determine the cipher type. | |
1325 | */ | |
1326 | if (key->keyblob_len < pos+4 || | |
1327 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { | |
1328 | errmsg = "key blob does not contain a cipher type string"; | |
1329 | goto error; | |
1330 | } | |
1331 | if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4)) | |
1332 | encrypted = 0; | |
1333 | else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8)) | |
1334 | encrypted = 1; | |
1335 | else { | |
1336 | errmsg = "key encryption is of unknown type"; | |
1337 | goto error; | |
1338 | } | |
1339 | pos += 4+len; | |
1340 | ||
1341 | /* | |
1342 | * Get hold of the encrypted part of the key. | |
1343 | */ | |
1344 | if (key->keyblob_len < pos+4 || | |
1345 | (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) { | |
1346 | errmsg = "key blob does not contain actual key data"; | |
1347 | goto error; | |
1348 | } | |
1349 | ciphertext = (char *)key->keyblob + pos + 4; | |
1350 | cipherlen = len; | |
1351 | if (cipherlen == 0) { | |
1352 | errmsg = "length of key data is zero"; | |
1353 | goto error; | |
1354 | } | |
1355 | ||
1356 | /* | |
1357 | * Decrypt it if necessary. | |
1358 | */ | |
1359 | if (encrypted) { | |
1360 | /* | |
1361 | * Derive encryption key from passphrase and iv/salt: | |
1362 | * | |
1363 | * - let block A equal MD5(passphrase) | |
1364 | * - let block B equal MD5(passphrase || A) | |
1365 | * - block C would be MD5(passphrase || A || B) and so on | |
1366 | * - encryption key is the first N bytes of A || B | |
1367 | */ | |
1368 | struct MD5Context md5c; | |
1369 | unsigned char keybuf[32], iv[8]; | |
1370 | ||
1371 | if (cipherlen % 8 != 0) { | |
1372 | errmsg = "encrypted part of key is not a multiple of cipher block" | |
1373 | " size"; | |
1374 | goto error; | |
1375 | } | |
1376 | ||
1377 | MD5Init(&md5c); | |
1378 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); | |
1379 | MD5Final(keybuf, &md5c); | |
1380 | ||
1381 | MD5Init(&md5c); | |
1382 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); | |
1383 | MD5Update(&md5c, keybuf, 16); | |
1384 | MD5Final(keybuf+16, &md5c); | |
1385 | ||
1386 | /* | |
1387 | * Now decrypt the key blob. | |
1388 | */ | |
1389 | memset(iv, 0, sizeof(iv)); | |
1390 | des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, | |
1391 | cipherlen); | |
1392 | ||
1393 | memset(&md5c, 0, sizeof(md5c)); | |
1394 | memset(keybuf, 0, sizeof(keybuf)); | |
1395 | ||
1396 | /* | |
1397 | * Hereafter we return WRONG_PASSPHRASE for any parsing | |
1398 | * error. (But only if we've just tried to decrypt it! | |
1399 | * Returning WRONG_PASSPHRASE for an unencrypted key is | |
1400 | * automatic doom.) | |
1401 | */ | |
1402 | if (encrypted) | |
1403 | ret = SSH2_WRONG_PASSPHRASE; | |
1404 | } | |
1405 | ||
1406 | /* | |
1407 | * Strip away the containing string to get to the real meat. | |
1408 | */ | |
1409 | len = GET_32BIT(ciphertext); | |
1410 | if (len < 0 || len > cipherlen-4) { | |
1411 | errmsg = "containing string was ill-formed"; | |
1412 | goto error; | |
1413 | } | |
1414 | ciphertext += 4; | |
1415 | cipherlen = len; | |
1416 | ||
1417 | /* | |
1418 | * Now we break down into RSA versus DSA. In either case we'll | |
1419 | * construct public and private blobs in our own format, and | |
1420 | * end up feeding them to alg->createkey(). | |
1421 | */ | |
1422 | blobsize = cipherlen + 256; | |
1423 | blob = snewn(blobsize, unsigned char); | |
1424 | privlen = 0; | |
1425 | if (type == RSA) { | |
1426 | struct mpint_pos n, e, d, u, p, q; | |
1427 | int pos = 0; | |
1428 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e); | |
1429 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d); | |
1430 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n); | |
1431 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u); | |
1432 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); | |
1433 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); | |
1434 | if (!q.start) { | |
1435 | errmsg = "key data did not contain six integers"; | |
1436 | goto error; | |
1437 | } | |
1438 | ||
1439 | alg = &ssh_rsa; | |
1440 | pos = 0; | |
1441 | pos += put_string(blob+pos, "ssh-rsa", 7); | |
1442 | pos += put_mp(blob+pos, e.start, e.bytes); | |
1443 | pos += put_mp(blob+pos, n.start, n.bytes); | |
1444 | publen = pos; | |
1445 | pos += put_string(blob+pos, d.start, d.bytes); | |
1446 | pos += put_mp(blob+pos, q.start, q.bytes); | |
1447 | pos += put_mp(blob+pos, p.start, p.bytes); | |
1448 | pos += put_mp(blob+pos, u.start, u.bytes); | |
1449 | privlen = pos - publen; | |
1450 | } else if (type == DSA) { | |
1451 | struct mpint_pos p, q, g, x, y; | |
1452 | int pos = 4; | |
1453 | if (GET_32BIT(ciphertext) != 0) { | |
1454 | errmsg = "predefined DSA parameters not supported"; | |
1455 | goto error; | |
1456 | } | |
1457 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p); | |
1458 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g); | |
1459 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q); | |
1460 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y); | |
1461 | pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x); | |
1462 | if (!x.start) { | |
1463 | errmsg = "key data did not contain five integers"; | |
1464 | goto error; | |
1465 | } | |
1466 | ||
1467 | alg = &ssh_dss; | |
1468 | pos = 0; | |
1469 | pos += put_string(blob+pos, "ssh-dss", 7); | |
1470 | pos += put_mp(blob+pos, p.start, p.bytes); | |
1471 | pos += put_mp(blob+pos, q.start, q.bytes); | |
1472 | pos += put_mp(blob+pos, g.start, g.bytes); | |
1473 | pos += put_mp(blob+pos, y.start, y.bytes); | |
1474 | publen = pos; | |
1475 | pos += put_mp(blob+pos, x.start, x.bytes); | |
1476 | privlen = pos - publen; | |
1477 | } else | |
1478 | return NULL; | |
1479 | ||
1480 | assert(privlen > 0); /* should have bombed by now if not */ | |
1481 | ||
1482 | retkey = snew(struct ssh2_userkey); | |
1483 | retkey->alg = alg; | |
1484 | retkey->data = alg->createkey(blob, publen, blob+publen, privlen); | |
1485 | if (!retkey->data) { | |
1486 | sfree(retkey); | |
1487 | errmsg = "unable to create key data structure"; | |
1488 | goto error; | |
1489 | } | |
1490 | retkey->comment = dupstr(key->comment); | |
1491 | ||
1492 | errmsg = NULL; /* no error */ | |
1493 | ret = retkey; | |
1494 | ||
1495 | error: | |
1496 | if (blob) { | |
1497 | memset(blob, 0, blobsize); | |
1498 | sfree(blob); | |
1499 | } | |
1500 | memset(key->keyblob, 0, key->keyblob_size); | |
1501 | sfree(key->keyblob); | |
1502 | memset(key, 0, sizeof(*key)); | |
1503 | sfree(key); | |
1504 | if (errmsg_p) *errmsg_p = errmsg; | |
1505 | return ret; | |
1506 | } | |
1507 | ||
1508 | int sshcom_write(const Filename *filename, struct ssh2_userkey *key, | |
1509 | char *passphrase) | |
1510 | { | |
1511 | unsigned char *pubblob, *privblob; | |
1512 | int publen, privlen; | |
1513 | unsigned char *outblob; | |
1514 | int outlen; | |
1515 | struct mpint_pos numbers[6]; | |
1516 | int nnumbers, initial_zero, pos, lenpos, i; | |
1517 | char *type; | |
1518 | char *ciphertext; | |
1519 | int cipherlen; | |
1520 | int ret = 0; | |
1521 | FILE *fp; | |
1522 | ||
1523 | /* | |
1524 | * Fetch the key blobs. | |
1525 | */ | |
1526 | pubblob = key->alg->public_blob(key->data, &publen); | |
1527 | privblob = key->alg->private_blob(key->data, &privlen); | |
1528 | outblob = NULL; | |
1529 | ||
1530 | /* | |
1531 | * Find the sequence of integers to be encoded into the OpenSSH | |
1532 | * key blob, and also decide on the header line. | |
1533 | */ | |
1534 | if (key->alg == &ssh_rsa) { | |
1535 | int pos; | |
1536 | struct mpint_pos n, e, d, p, q, iqmp; | |
1537 | ||
1538 | pos = 4 + GET_32BIT(pubblob); | |
1539 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e); | |
1540 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n); | |
1541 | pos = 0; | |
1542 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d); | |
1543 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p); | |
1544 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q); | |
1545 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp); | |
1546 | ||
1547 | assert(e.start && iqmp.start); /* can't go wrong */ | |
1548 | ||
1549 | numbers[0] = e; | |
1550 | numbers[1] = d; | |
1551 | numbers[2] = n; | |
1552 | numbers[3] = iqmp; | |
1553 | numbers[4] = q; | |
1554 | numbers[5] = p; | |
1555 | ||
1556 | nnumbers = 6; | |
1557 | initial_zero = 0; | |
1558 | type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}"; | |
1559 | } else if (key->alg == &ssh_dss) { | |
1560 | int pos; | |
1561 | struct mpint_pos p, q, g, y, x; | |
1562 | ||
1563 | pos = 4 + GET_32BIT(pubblob); | |
1564 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p); | |
1565 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q); | |
1566 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g); | |
1567 | pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y); | |
1568 | pos = 0; | |
1569 | pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x); | |
1570 | ||
1571 | assert(y.start && x.start); /* can't go wrong */ | |
1572 | ||
1573 | numbers[0] = p; | |
1574 | numbers[1] = g; | |
1575 | numbers[2] = q; | |
1576 | numbers[3] = y; | |
1577 | numbers[4] = x; | |
1578 | ||
1579 | nnumbers = 5; | |
1580 | initial_zero = 1; | |
1581 | type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}"; | |
1582 | } else { | |
1583 | assert(0); /* zoinks! */ | |
1584 | exit(1); /* XXX: GCC doesn't understand assert() on some systems. */ | |
1585 | } | |
1586 | ||
1587 | /* | |
1588 | * Total size of key blob will be somewhere under 512 plus | |
1589 | * combined length of integers. We'll calculate the more | |
1590 | * precise size as we construct the blob. | |
1591 | */ | |
1592 | outlen = 512; | |
1593 | for (i = 0; i < nnumbers; i++) | |
1594 | outlen += 4 + numbers[i].bytes; | |
1595 | outblob = snewn(outlen, unsigned char); | |
1596 | ||
1597 | /* | |
1598 | * Create the unencrypted key blob. | |
1599 | */ | |
1600 | pos = 0; | |
1601 | PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4; | |
1602 | pos += 4; /* length field, fill in later */ | |
1603 | pos += put_string(outblob+pos, type, strlen(type)); | |
1604 | { | |
1605 | char *ciphertype = passphrase ? "3des-cbc" : "none"; | |
1606 | pos += put_string(outblob+pos, ciphertype, strlen(ciphertype)); | |
1607 | } | |
1608 | lenpos = pos; /* remember this position */ | |
1609 | pos += 4; /* encrypted-blob size */ | |
1610 | pos += 4; /* encrypted-payload size */ | |
1611 | if (initial_zero) { | |
1612 | PUT_32BIT(outblob+pos, 0); | |
1613 | pos += 4; | |
1614 | } | |
1615 | for (i = 0; i < nnumbers; i++) | |
1616 | pos += sshcom_put_mpint(outblob+pos, | |
1617 | numbers[i].start, numbers[i].bytes); | |
1618 | /* Now wrap up the encrypted payload. */ | |
1619 | PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8)); | |
1620 | /* Pad encrypted blob to a multiple of cipher block size. */ | |
1621 | if (passphrase) { | |
1622 | int padding = -(pos - (lenpos+4)) & 7; | |
1623 | while (padding--) | |
1624 | outblob[pos++] = random_byte(); | |
1625 | } | |
1626 | ciphertext = (char *)outblob+lenpos+4; | |
1627 | cipherlen = pos - (lenpos+4); | |
1628 | assert(!passphrase || cipherlen % 8 == 0); | |
1629 | /* Wrap up the encrypted blob string. */ | |
1630 | PUT_32BIT(outblob+lenpos, cipherlen); | |
1631 | /* And finally fill in the total length field. */ | |
1632 | PUT_32BIT(outblob+4, pos); | |
1633 | ||
1634 | assert(pos < outlen); | |
1635 | ||
1636 | /* | |
1637 | * Encrypt the key. | |
1638 | */ | |
1639 | if (passphrase) { | |
1640 | /* | |
1641 | * Derive encryption key from passphrase and iv/salt: | |
1642 | * | |
1643 | * - let block A equal MD5(passphrase) | |
1644 | * - let block B equal MD5(passphrase || A) | |
1645 | * - block C would be MD5(passphrase || A || B) and so on | |
1646 | * - encryption key is the first N bytes of A || B | |
1647 | */ | |
1648 | struct MD5Context md5c; | |
1649 | unsigned char keybuf[32], iv[8]; | |
1650 | ||
1651 | MD5Init(&md5c); | |
1652 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); | |
1653 | MD5Final(keybuf, &md5c); | |
1654 | ||
1655 | MD5Init(&md5c); | |
1656 | MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase)); | |
1657 | MD5Update(&md5c, keybuf, 16); | |
1658 | MD5Final(keybuf+16, &md5c); | |
1659 | ||
1660 | /* | |
1661 | * Now decrypt the key blob. | |
1662 | */ | |
1663 | memset(iv, 0, sizeof(iv)); | |
1664 | des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext, | |
1665 | cipherlen); | |
1666 | ||
1667 | memset(&md5c, 0, sizeof(md5c)); | |
1668 | memset(keybuf, 0, sizeof(keybuf)); | |
1669 | } | |
1670 | ||
1671 | /* | |
1672 | * And save it. We'll use Unix line endings just in case it's | |
1673 | * subsequently transferred in binary mode. | |
1674 | */ | |
1675 | fp = f_open(*filename, "wb", TRUE); /* ensure Unix line endings */ | |
1676 | if (!fp) | |
1677 | goto error; | |
1678 | fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); | |
1679 | fprintf(fp, "Comment: \""); | |
1680 | /* | |
1681 | * Comment header is broken with backslash-newline if it goes | |
1682 | * over 70 chars. Although it's surrounded by quotes, it | |
1683 | * _doesn't_ escape backslashes or quotes within the string. | |
1684 | * Don't ask me, I didn't design it. | |
1685 | */ | |
1686 | { | |
1687 | int slen = 60; /* starts at 60 due to "Comment: " */ | |
1688 | char *c = key->comment; | |
1689 | while ((int)strlen(c) > slen) { | |
1690 | fprintf(fp, "%.*s\\\n", slen, c); | |
1691 | c += slen; | |
1692 | slen = 70; /* allow 70 chars on subsequent lines */ | |
1693 | } | |
1694 | fprintf(fp, "%s\"\n", c); | |
1695 | } | |
1696 | base64_encode(fp, outblob, pos, 70); | |
1697 | fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp); | |
1698 | fclose(fp); | |
1699 | ret = 1; | |
1700 | ||
1701 | error: | |
1702 | if (outblob) { | |
1703 | memset(outblob, 0, outlen); | |
1704 | sfree(outblob); | |
1705 | } | |
1706 | if (privblob) { | |
1707 | memset(privblob, 0, privlen); | |
1708 | sfree(privblob); | |
1709 | } | |
1710 | if (pubblob) { | |
1711 | memset(pubblob, 0, publen); | |
1712 | sfree(pubblob); | |
1713 | } | |
1714 | return ret; | |
1715 | } |