3eca8453 |
1 | /* |
a52f067e |
2 | * Generic SSH public-key handling operations. In particular, |
3 | * reading of SSH public-key files, and also the generic `sign' |
4 | * operation for ssh2 (which checks the type of the key and |
5 | * dispatches to the appropriate key-type specific function). |
3eca8453 |
6 | */ |
7 | |
8 | #include <stdio.h> |
a52f067e |
9 | #include <stdlib.h> |
65a22376 |
10 | #include <assert.h> |
3eca8453 |
11 | |
3eca8453 |
12 | #include "ssh.h" |
13 | |
6e522441 |
14 | #define PUT_32BIT(cp, value) do { \ |
15 | (cp)[3] = (value); \ |
16 | (cp)[2] = (value) >> 8; \ |
17 | (cp)[1] = (value) >> 16; \ |
18 | (cp)[0] = (value) >> 24; } while (0) |
19 | |
3eca8453 |
20 | #define GET_32BIT(cp) \ |
21 | (((unsigned long)(unsigned char)(cp)[0] << 24) | \ |
22 | ((unsigned long)(unsigned char)(cp)[1] << 16) | \ |
23 | ((unsigned long)(unsigned char)(cp)[2] << 8) | \ |
24 | ((unsigned long)(unsigned char)(cp)[3])) |
25 | |
26 | #define rsa_signature "SSH PRIVATE KEY FILE FORMAT 1.1\n" |
27 | |
a52f067e |
28 | #define BASE64_TOINT(x) ( (x)-'A'<26 ? (x)-'A'+0 :\ |
29 | (x)-'a'<26 ? (x)-'a'+26 :\ |
30 | (x)-'0'<10 ? (x)-'0'+52 :\ |
31 | (x)=='+' ? 62 : \ |
32 | (x)=='/' ? 63 : 0 ) |
33 | |
65a22376 |
34 | static int loadrsakey_main(FILE *fp, struct RSAKey *key, |
a52f067e |
35 | char **commentptr, char *passphrase) { |
3eca8453 |
36 | unsigned char buf[16384]; |
37 | unsigned char keybuf[16]; |
38 | int len; |
39 | int i, j, ciphertype; |
40 | int ret = 0; |
41 | struct MD5Context md5c; |
a52f067e |
42 | char *comment; |
3eca8453 |
43 | |
a52f067e |
44 | /* Slurp the whole file (minus the header) into a buffer. */ |
3eca8453 |
45 | len = fread(buf, 1, sizeof(buf), fp); |
46 | fclose(fp); |
47 | if (len < 0 || len == sizeof(buf)) |
48 | goto end; /* file too big or not read */ |
49 | |
a52f067e |
50 | i = 0; |
3eca8453 |
51 | |
a52f067e |
52 | /* |
53 | * A zero byte. (The signature includes a terminating NUL.) |
54 | */ |
55 | if (len-i < 1 || buf[i] != 0) |
56 | goto end; |
57 | i++; |
3eca8453 |
58 | |
a52f067e |
59 | /* One byte giving encryption type, and one reserved uint32. */ |
3eca8453 |
60 | if (len-i < 1) |
61 | goto end; |
62 | ciphertype = buf[i]; |
63 | if (ciphertype != 0 && ciphertype != SSH_CIPHER_3DES) |
64 | goto end; |
65 | i++; |
66 | if (len-i < 4) |
67 | goto end; /* reserved field not present */ |
68 | if (buf[i] != 0 || buf[i+1] != 0 || buf[i+2] != 0 || buf[i+3] != 0) |
69 | goto end; /* reserved field nonzero, panic! */ |
70 | i += 4; |
71 | |
72 | /* Now the serious stuff. An ordinary SSH 1 public key. */ |
73 | i += makekey(buf+i, key, NULL, 1); |
74 | if (len-i < 0) |
75 | goto end; /* overran */ |
76 | |
77 | /* Next, the comment field. */ |
78 | j = GET_32BIT(buf+i); |
5c58ad2d |
79 | i += 4; |
80 | if (len-i < j) goto end; |
dcbde236 |
81 | comment = smalloc(j+1); |
a52f067e |
82 | if (comment) { |
83 | memcpy(comment, buf+i, j); |
84 | comment[j] = '\0'; |
5c58ad2d |
85 | } |
86 | i += j; |
a52f067e |
87 | if (commentptr) |
88 | *commentptr = comment; |
89 | if (key) |
90 | key->comment = comment; |
91 | if (!key) { |
92 | return ciphertype != 0; |
93 | } |
3eca8453 |
94 | |
95 | /* |
96 | * Decrypt remainder of buffer. |
97 | */ |
98 | if (ciphertype) { |
99 | MD5Init(&md5c); |
100 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
101 | MD5Final(keybuf, &md5c); |
102 | des3_decrypt_pubkey(keybuf, buf+i, (len-i+7)&~7); |
5c58ad2d |
103 | memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */ |
3eca8453 |
104 | } |
105 | |
106 | /* |
107 | * We are now in the secret part of the key. The first four |
108 | * bytes should be of the form a, b, a, b. |
109 | */ |
110 | if (len-i < 4) goto end; |
111 | if (buf[i] != buf[i+2] || buf[i+1] != buf[i+3]) { ret = -1; goto end; } |
112 | i += 4; |
113 | |
114 | /* |
115 | * After that, we have one further bignum which is our |
6e522441 |
116 | * decryption exponent, and then the three auxiliary values |
117 | * (iqmp, q, p). |
3eca8453 |
118 | */ |
119 | i += makeprivate(buf+i, key); |
120 | if (len-i < 0) goto end; |
65a22376 |
121 | i += ssh1_read_bignum(buf+i, &key->iqmp); |
122 | if (len-i < 0) goto end; |
123 | i += ssh1_read_bignum(buf+i, &key->q); |
124 | if (len-i < 0) goto end; |
125 | i += ssh1_read_bignum(buf+i, &key->p); |
126 | if (len-i < 0) goto end; |
3eca8453 |
127 | |
128 | ret = 1; |
129 | end: |
130 | memset(buf, 0, sizeof(buf)); /* burn the evidence */ |
131 | return ret; |
132 | } |
133 | |
65a22376 |
134 | int loadrsakey(char *filename, struct RSAKey *key, char *passphrase) { |
3eca8453 |
135 | FILE *fp; |
a52f067e |
136 | unsigned char buf[64]; |
3eca8453 |
137 | |
138 | fp = fopen(filename, "rb"); |
139 | if (!fp) |
140 | return 0; /* doesn't even exist */ |
141 | |
a52f067e |
142 | /* |
143 | * Read the first line of the file and see if it's a v1 private |
144 | * key file. |
145 | */ |
146 | if (fgets(buf, sizeof(buf), fp) && |
147 | !strcmp(buf, rsa_signature)) { |
65a22376 |
148 | return loadrsakey_main(fp, key, NULL, passphrase); |
a52f067e |
149 | } |
150 | |
151 | /* |
152 | * Otherwise, we have nothing. Return empty-handed. |
153 | */ |
3eca8453 |
154 | fclose(fp); |
3eca8453 |
155 | return 0; |
156 | } |
a52f067e |
157 | |
158 | /* |
159 | * See whether an RSA key is encrypted. Return its comment field as |
160 | * well. |
161 | */ |
162 | int rsakey_encrypted(char *filename, char **comment) { |
163 | FILE *fp; |
164 | unsigned char buf[64]; |
165 | |
166 | fp = fopen(filename, "rb"); |
167 | if (!fp) |
168 | return 0; /* doesn't even exist */ |
169 | |
170 | /* |
171 | * Read the first line of the file and see if it's a v1 private |
172 | * key file. |
173 | */ |
174 | if (fgets(buf, sizeof(buf), fp) && |
175 | !strcmp(buf, rsa_signature)) { |
65a22376 |
176 | return loadrsakey_main(fp, NULL, comment, NULL); |
a52f067e |
177 | } |
404f728b |
178 | fclose(fp); |
a52f067e |
179 | return 0; /* wasn't the right kind of file */ |
180 | } |
6e522441 |
181 | |
182 | /* |
183 | * Save an RSA key file. Return nonzero on success. |
184 | */ |
65a22376 |
185 | int saversakey(char *filename, struct RSAKey *key, char *passphrase) { |
6e522441 |
186 | unsigned char buf[16384]; |
187 | unsigned char keybuf[16]; |
188 | struct MD5Context md5c; |
49bad831 |
189 | unsigned char *p, *estart; |
6e522441 |
190 | FILE *fp; |
191 | |
192 | /* |
193 | * Write the initial signature. |
194 | */ |
195 | p = buf; |
196 | memcpy(p, rsa_signature, sizeof(rsa_signature)); |
197 | p += sizeof(rsa_signature); |
198 | |
199 | /* |
200 | * One byte giving encryption type, and one reserved (zero) |
201 | * uint32. |
202 | */ |
203 | *p++ = (passphrase ? SSH_CIPHER_3DES : 0); |
204 | PUT_32BIT(p, 0); p += 4; |
205 | |
206 | /* |
207 | * An ordinary SSH 1 public key consists of: a uint32 |
208 | * containing the bit count, then two bignums containing the |
209 | * modulus and exponent respectively. |
210 | */ |
211 | PUT_32BIT(p, ssh1_bignum_bitcount(key->modulus)); p += 4; |
212 | p += ssh1_write_bignum(p, key->modulus); |
213 | p += ssh1_write_bignum(p, key->exponent); |
214 | |
215 | /* |
216 | * A string containing the comment field. |
217 | */ |
218 | if (key->comment) { |
219 | PUT_32BIT(p, strlen(key->comment)); p += 4; |
220 | memcpy(p, key->comment, strlen(key->comment)); |
221 | p += strlen(key->comment); |
222 | } else { |
223 | PUT_32BIT(p, 0); p += 4; |
224 | } |
225 | |
226 | /* |
227 | * The encrypted portion starts here. |
228 | */ |
229 | estart = p; |
230 | |
231 | /* |
232 | * Two bytes, then the same two bytes repeated. |
233 | */ |
234 | *p++ = random_byte(); |
235 | *p++ = random_byte(); |
236 | p[0] = p[-2]; p[1] = p[-1]; p += 2; |
237 | |
238 | /* |
239 | * Four more bignums: the decryption exponent, then iqmp, then |
240 | * q, then p. |
241 | */ |
242 | p += ssh1_write_bignum(p, key->private_exponent); |
65a22376 |
243 | p += ssh1_write_bignum(p, key->iqmp); |
244 | p += ssh1_write_bignum(p, key->q); |
245 | p += ssh1_write_bignum(p, key->p); |
6e522441 |
246 | |
247 | /* |
248 | * Now write zeros until the encrypted portion is a multiple of |
249 | * 8 bytes. |
250 | */ |
251 | while ((p-estart) % 8) |
252 | *p++ = '\0'; |
253 | |
254 | /* |
255 | * Now encrypt the encrypted portion. |
256 | */ |
257 | if (passphrase) { |
258 | MD5Init(&md5c); |
259 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
260 | MD5Final(keybuf, &md5c); |
261 | des3_encrypt_pubkey(keybuf, estart, p-estart); |
262 | memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */ |
263 | } |
264 | |
265 | /* |
266 | * Done. Write the result to the file. |
267 | */ |
268 | fp = fopen(filename, "wb"); |
269 | if (fp) { |
270 | int ret = (fwrite(buf, 1, p-buf, fp) == (size_t)(p-buf)); |
271 | ret = ret && (fclose(fp) == 0); |
272 | return ret; |
273 | } else |
274 | return 0; |
275 | } |
65a22376 |
276 | |
277 | /* ---------------------------------------------------------------------- |
278 | * SSH2 private key load/store functions. |
279 | */ |
280 | |
281 | /* |
282 | * PuTTY's own format for SSH2 keys is as follows: |
283 | * |
284 | * The file is text. Lines are terminated by CRLF, although CR-only |
285 | * and LF-only are tolerated on input. |
286 | * |
287 | * The first line says "PuTTY-User-Key-File-1: " plus the name of the |
288 | * algorithm ("ssh-dss", "ssh-rsa" etc. Although, of course, this |
289 | * being PuTTY, "ssh-dss" is not supported.) |
290 | * |
291 | * The next line says "Encryption: " plus an encryption type. |
292 | * Currently the only supported encryption types are "aes256-cbc" |
293 | * and "none". |
294 | * |
295 | * The next line says "Comment: " plus the comment string. |
296 | * |
297 | * Next there is a line saying "Public-Lines: " plus a number N. |
298 | * The following N lines contain a base64 encoding of the public |
299 | * part of the key. This is encoded as the standard SSH2 public key |
300 | * blob (with no initial length): so for RSA, for example, it will |
301 | * read |
302 | * |
303 | * string "ssh-rsa" |
304 | * mpint exponent |
305 | * mpint modulus |
306 | * |
307 | * Next, there is a line saying "Private-Lines: " plus a number N, |
308 | * and then N lines containing the (potentially encrypted) private |
309 | * part of the key. For the key type "ssh-rsa", this will be |
310 | * composed of |
311 | * |
312 | * mpint private_exponent |
313 | * mpint p (the larger of the two primes) |
314 | * mpint q (the smaller prime) |
315 | * mpint iqmp (the inverse of q modulo p) |
316 | * data padding (to reach a multiple of the cipher block size) |
317 | * |
318 | * Finally, there is a line saying "Private-Hash: " plus a hex |
319 | * representation of a SHA-1 hash of the plaintext version of the |
320 | * private part, including the final padding. |
321 | * |
322 | * If the key is encrypted, the encryption key is derived from the |
323 | * passphrase by means of a succession of SHA-1 hashes. Each hash |
324 | * is the hash of: |
325 | * |
326 | * uint32 sequence-number |
327 | * string passphrase |
328 | * |
329 | * where the sequence-number increases from zero. As many of these |
330 | * hashes are used as necessary. |
331 | */ |
332 | |
333 | static int read_header(FILE *fp, char *header) { |
334 | int len = 39; |
335 | int c; |
336 | |
337 | while (len > 0) { |
338 | c = fgetc(fp); |
339 | if (c == '\n' || c == '\r' || c == EOF) |
340 | return 0; /* failure */ |
341 | if (c == ':') { |
342 | c = fgetc(fp); |
343 | if (c != ' ') |
344 | return 0; |
345 | *header = '\0'; |
346 | return 1; /* success! */ |
347 | } |
348 | if (len == 0) |
349 | return 0; /* failure */ |
350 | *header++ = c; |
351 | len--; |
352 | } |
353 | return 0; /* failure */ |
354 | } |
355 | |
356 | static char *read_body(FILE *fp) { |
357 | char *text; |
358 | int len; |
359 | int size; |
360 | int c; |
361 | |
362 | size = 128; |
363 | text = smalloc(size); |
364 | len = 0; |
365 | text[len] = '\0'; |
366 | |
367 | while (1) { |
368 | c = fgetc(fp); |
369 | if (c == '\r' || c == '\n') { |
370 | c = fgetc(fp); |
371 | if (c != '\r' && c != '\n' && c != EOF) |
372 | ungetc(c, fp); |
373 | return text; |
374 | } |
375 | if (c == EOF) { |
376 | sfree(text); |
377 | return NULL; |
378 | } |
379 | if (len + 1 > size) { |
380 | size += 128; |
381 | text = srealloc(text, size); |
382 | } |
383 | text[len++] = c; |
384 | text[len] = '\0'; |
385 | } |
386 | } |
387 | |
388 | int base64_decode_atom(char *atom, unsigned char *out) { |
389 | int vals[4]; |
390 | int i, v, len; |
391 | unsigned word; |
392 | char c; |
393 | |
394 | for (i = 0; i < 4; i++) { |
395 | c = atom[i]; |
396 | if (c >= 'A' && c <= 'Z') |
397 | v = c - 'A'; |
398 | else if (c >= 'a' && c <= 'z') |
399 | v = c - 'a' + 26; |
400 | else if (c >= '0' && c <= '9') |
401 | v = c - '0' + 52; |
402 | else if (c == '+') |
403 | v = 62; |
404 | else if (c == '/') |
405 | v = 63; |
406 | else if (c == '=') |
407 | v = -1; |
408 | else |
409 | return 0; /* invalid atom */ |
410 | vals[i] = v; |
411 | } |
412 | |
413 | if (vals[0] == -1 || vals[1] == -1) |
414 | return 0; |
415 | if (vals[2] == -1 && vals[3] != -1) |
416 | return 0; |
417 | |
418 | if (vals[3] != -1) |
419 | len = 3; |
420 | else if (vals[2] != -1) |
421 | len = 2; |
422 | else |
423 | len = 1; |
424 | |
425 | word = ((vals[0] << 18) | |
426 | (vals[1] << 12) | |
427 | ((vals[2] & 0x3F) << 6) | |
428 | (vals[3] & 0x3F)); |
429 | out[0] = (word >> 16) & 0xFF; |
430 | if (len > 1) |
431 | out[1] = (word >> 8) & 0xFF; |
432 | if (len > 2) |
433 | out[2] = word & 0xFF; |
434 | return len; |
435 | } |
436 | |
437 | static char *read_blob(FILE *fp, int nlines, int *bloblen) { |
438 | unsigned char *blob; |
439 | char *line; |
440 | int linelen, len; |
441 | int i, j, k; |
442 | |
443 | /* We expect at most 64 base64 characters, ie 48 real bytes, per line. */ |
444 | blob = smalloc(48 * nlines); |
445 | len = 0; |
446 | for (i = 0; i < nlines; i++) { |
447 | line = read_body(fp); |
448 | if (!line) { |
449 | sfree(blob); |
450 | return NULL; |
451 | } |
452 | linelen = strlen(line); |
453 | if (linelen % 4 != 0 || linelen > 64) { |
454 | sfree(blob); |
455 | sfree(line); |
456 | return NULL; |
457 | } |
458 | for (j = 0; j < linelen; j += 4) { |
459 | k = base64_decode_atom(line+j, blob+len); |
460 | if (!k) { |
461 | sfree(line); |
462 | sfree(blob); |
463 | return NULL; |
464 | } |
465 | len += k; |
466 | } |
467 | sfree(line); |
468 | } |
469 | *bloblen = len; |
470 | return blob; |
471 | } |
472 | |
473 | /* |
474 | * Magic error return value for when the passphrase is wrong. |
475 | */ |
476 | struct ssh2_userkey ssh2_wrong_passphrase = { |
477 | NULL, NULL, NULL |
478 | }; |
479 | |
480 | struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) { |
481 | FILE *fp; |
482 | char header[40], *b, *comment, *hash; |
483 | const struct ssh_signkey *alg; |
484 | struct ssh2_userkey *ret; |
485 | int cipher, cipherblk; |
486 | unsigned char *public_blob, *private_blob; |
487 | int public_blob_len, private_blob_len; |
488 | int i; |
489 | |
490 | ret = NULL; /* return NULL for most errors */ |
491 | comment = hash = NULL; |
492 | public_blob = private_blob = NULL; |
493 | |
494 | fp = fopen(filename, "rb"); |
495 | if (!fp) |
496 | goto error; |
497 | |
498 | /* Read the first header line which contains the key type. */ |
499 | if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1")) |
500 | goto error; |
501 | if ((b = read_body(fp)) == NULL) |
502 | goto error; |
503 | /* Select key algorithm structure. Currently only ssh-rsa. */ |
504 | if (!strcmp(b, "ssh-rsa")) |
505 | alg = &ssh_rsa; |
506 | else { |
507 | sfree(b); |
508 | goto error; |
509 | } |
510 | sfree(b); |
511 | |
512 | /* Read the Encryption header line. */ |
513 | if (!read_header(fp, header) || 0!=strcmp(header, "Encryption")) |
514 | goto error; |
515 | if ((b = read_body(fp)) == NULL) |
516 | goto error; |
517 | if (!strcmp(b, "aes256-cbc")) { |
518 | cipher = 1; cipherblk = 16; |
519 | } else if (!strcmp(b, "none")) { |
520 | cipher = 0; cipherblk = 1; |
521 | } else { |
522 | sfree(b); |
523 | goto error; |
524 | } |
525 | sfree(b); |
526 | |
527 | /* Read the Comment header line. */ |
528 | if (!read_header(fp, header) || 0!=strcmp(header, "Comment")) |
529 | goto error; |
530 | if ((comment = read_body(fp)) == NULL) |
531 | goto error; |
532 | |
533 | /* Read the Public-Lines header line and the public blob. */ |
534 | if (!read_header(fp, header) || 0!=strcmp(header, "Public-Lines")) |
535 | goto error; |
536 | if ((b = read_body(fp)) == NULL) |
537 | goto error; |
538 | i = atoi(b); |
539 | sfree(b); |
540 | if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL) |
541 | goto error; |
542 | |
543 | /* Read the Private-Lines header line and the Private blob. */ |
544 | if (!read_header(fp, header) || 0!=strcmp(header, "Private-Lines")) |
545 | goto error; |
546 | if ((b = read_body(fp)) == NULL) |
547 | goto error; |
548 | i = atoi(b); |
549 | sfree(b); |
550 | if ((private_blob = read_blob(fp, i, &private_blob_len)) == NULL) |
551 | goto error; |
552 | |
553 | /* Read the Private-Hash header line. */ |
554 | if (!read_header(fp, header) || 0!=strcmp(header, "Private-Hash")) |
555 | goto error; |
556 | if ((hash = read_body(fp)) == NULL) |
557 | goto error; |
558 | |
559 | fclose(fp); |
560 | fp = NULL; |
561 | |
562 | /* |
563 | * Decrypt the private blob. |
564 | */ |
565 | if (cipher) { |
566 | unsigned char key[40]; |
567 | SHA_State s; |
568 | int passlen; |
569 | |
570 | if (!passphrase) |
571 | goto error; |
572 | if (private_blob_len % cipherblk) |
573 | goto error; |
574 | |
575 | passlen = strlen(passphrase); |
576 | |
577 | SHA_Init(&s); |
578 | SHA_Bytes(&s, "\0\0\0\0", 4); |
579 | SHA_Bytes(&s, passphrase, passlen); |
580 | SHA_Final(&s, key+0); |
581 | SHA_Init(&s); |
582 | SHA_Bytes(&s, "\0\0\0\1", 4); |
583 | SHA_Bytes(&s, passphrase, passlen); |
584 | SHA_Final(&s, key+20); |
585 | aes256_decrypt_pubkey(key, private_blob, private_blob_len); |
586 | } |
587 | |
588 | /* |
589 | * Verify the private hash. |
590 | */ |
591 | { |
592 | char realhash[41]; |
593 | unsigned char binary[20]; |
65a22376 |
594 | |
595 | SHA_Simple(private_blob, private_blob_len, binary); |
596 | for (i = 0; i < 20; i++) |
597 | sprintf(realhash+2*i, "%02x", binary[i]); |
598 | |
599 | if (strcmp(hash, realhash)) { |
600 | /* An incorrect hash is an unconditional Error if the key is |
601 | * unencrypted. Otherwise, it means Wrong Passphrase. */ |
602 | ret = cipher ? SSH2_WRONG_PASSPHRASE : NULL; |
603 | goto error; |
604 | } |
605 | } |
606 | sfree(hash); |
607 | |
608 | /* |
609 | * Create and return the key. |
610 | */ |
611 | ret = smalloc(sizeof(struct ssh2_userkey)); |
612 | ret->alg = alg; |
613 | ret->comment = comment; |
614 | ret->data = alg->createkey(public_blob, public_blob_len, |
615 | private_blob, private_blob_len); |
616 | sfree(public_blob); |
617 | sfree(private_blob); |
618 | return ret; |
619 | |
620 | /* |
621 | * Error processing. |
622 | */ |
623 | error: |
624 | if (fp) fclose(fp); |
625 | if (comment) sfree(comment); |
626 | if (hash) sfree(hash); |
627 | if (public_blob) sfree(public_blob); |
628 | if (private_blob) sfree(private_blob); |
629 | return ret; |
630 | } |
631 | |
632 | char *ssh2_userkey_loadpub(char *filename, char **algorithm, int *pub_blob_len) { |
633 | FILE *fp; |
634 | char header[40], *b; |
635 | const struct ssh_signkey *alg; |
65a22376 |
636 | unsigned char *public_blob; |
637 | int public_blob_len; |
638 | int i; |
639 | |
640 | public_blob = NULL; |
641 | |
642 | fp = fopen(filename, "rb"); |
643 | if (!fp) |
644 | goto error; |
645 | |
646 | /* Read the first header line which contains the key type. */ |
647 | if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1")) |
648 | goto error; |
649 | if ((b = read_body(fp)) == NULL) |
650 | goto error; |
651 | /* Select key algorithm structure. Currently only ssh-rsa. */ |
652 | if (!strcmp(b, "ssh-rsa")) |
653 | alg = &ssh_rsa; |
654 | else { |
655 | sfree(b); |
656 | goto error; |
657 | } |
658 | sfree(b); |
659 | |
660 | /* Read the Encryption header line. */ |
661 | if (!read_header(fp, header) || 0!=strcmp(header, "Encryption")) |
662 | goto error; |
663 | if ((b = read_body(fp)) == NULL) |
664 | goto error; |
665 | sfree(b); /* we don't care */ |
666 | |
667 | /* Read the Comment header line. */ |
668 | if (!read_header(fp, header) || 0!=strcmp(header, "Comment")) |
669 | goto error; |
670 | if ((b = read_body(fp)) == NULL) |
671 | goto error; |
672 | sfree(b); /* we don't care */ |
673 | |
674 | /* Read the Public-Lines header line and the public blob. */ |
675 | if (!read_header(fp, header) || 0!=strcmp(header, "Public-Lines")) |
676 | goto error; |
677 | if ((b = read_body(fp)) == NULL) |
678 | goto error; |
679 | i = atoi(b); |
680 | sfree(b); |
681 | if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL) |
682 | goto error; |
683 | |
684 | fclose(fp); |
685 | *pub_blob_len = public_blob_len; |
686 | *algorithm = alg->name; |
687 | return public_blob; |
688 | |
689 | /* |
690 | * Error processing. |
691 | */ |
692 | error: |
693 | if (fp) fclose(fp); |
694 | if (public_blob) sfree(public_blob); |
695 | return NULL; |
696 | } |
697 | |
698 | int ssh2_userkey_encrypted(char *filename, char **commentptr) { |
699 | FILE *fp; |
700 | char header[40], *b, *comment; |
701 | int ret; |
702 | |
703 | if (commentptr) *commentptr = NULL; |
704 | |
705 | fp = fopen(filename, "rb"); |
706 | if (!fp) |
707 | return 0; |
708 | if (!read_header(fp, header) || 0!=strcmp(header, "PuTTY-User-Key-File-1")) { |
709 | fclose(fp); return 0; |
710 | } |
711 | if ((b = read_body(fp)) == NULL) { |
712 | fclose(fp); return 0; |
713 | } |
714 | sfree(b); /* we don't care about key type here */ |
715 | /* Read the Encryption header line. */ |
716 | if (!read_header(fp, header) || 0!=strcmp(header, "Encryption")) { |
717 | fclose(fp); return 0; |
718 | } |
719 | if ((b = read_body(fp)) == NULL) { |
720 | fclose(fp); return 0; |
721 | } |
722 | |
723 | /* Read the Comment header line. */ |
724 | if (!read_header(fp, header) || 0!=strcmp(header, "Comment")) { |
725 | fclose(fp); sfree(b); return 1; |
726 | } |
727 | if ((comment = read_body(fp)) == NULL) { |
728 | fclose(fp); sfree(b); return 1; |
729 | } |
730 | |
731 | if (commentptr) *commentptr = comment; |
732 | |
733 | fclose(fp); |
734 | if (!strcmp(b, "aes256-cbc")) |
735 | ret = 1; |
736 | else |
737 | ret = 0; |
738 | sfree(b); |
739 | return ret; |
740 | } |
741 | |
742 | int base64_lines(int datalen) { |
743 | /* When encoding, we use 64 chars/line, which equals 48 real chars. */ |
744 | return (datalen+47) / 48; |
745 | } |
746 | |
747 | void base64_encode_atom(unsigned char *data, int n, char *out) { |
748 | static const char base64_chars[] = |
749 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
750 | |
751 | unsigned word; |
752 | |
753 | word = data[0] << 16; |
754 | if (n > 1) |
755 | word |= data[1] << 8; |
756 | if (n > 2) |
757 | word |= data[2]; |
758 | out[0] = base64_chars[(word >> 18) & 0x3F]; |
759 | out[1] = base64_chars[(word >> 12) & 0x3F]; |
760 | if (n > 1) |
761 | out[2] = base64_chars[(word >> 6) & 0x3F]; |
762 | else |
763 | out[2] = '='; |
764 | if (n > 2) |
765 | out[3] = base64_chars[word & 0x3F]; |
766 | else |
767 | out[3] = '='; |
768 | } |
769 | |
770 | void base64_encode(FILE *fp, unsigned char *data, int datalen) { |
771 | int linelen = 0; |
772 | char out[4]; |
773 | int n; |
774 | |
775 | while (datalen > 0) { |
776 | if (linelen >= 64) { |
777 | linelen = 0; |
778 | fputc('\n', fp); |
779 | } |
780 | n = (datalen < 3 ? datalen : 3); |
781 | base64_encode_atom(data, n, out); |
782 | data += n; |
783 | datalen -= n; |
784 | fwrite(out, 1, 4, fp); |
785 | linelen += 4; |
786 | } |
787 | fputc('\n', fp); |
788 | } |
789 | |
790 | int ssh2_save_userkey(char *filename, struct ssh2_userkey *key, char *passphrase) { |
791 | FILE *fp; |
792 | unsigned char *pub_blob, *priv_blob, *priv_blob_encrypted; |
793 | int pub_blob_len, priv_blob_len, priv_encrypted_len; |
794 | int passlen; |
795 | int cipherblk; |
796 | int i; |
797 | char *cipherstr; |
798 | unsigned char priv_hash[20]; |
799 | |
800 | /* |
801 | * Fetch the key component blobs. |
802 | */ |
803 | pub_blob = key->alg->public_blob(key->data, &pub_blob_len); |
804 | priv_blob = key->alg->private_blob(key->data, &priv_blob_len); |
805 | if (!pub_blob || !priv_blob) { |
806 | sfree(pub_blob); |
807 | sfree(priv_blob); |
808 | return 0; |
809 | } |
810 | |
811 | /* |
812 | * Determine encryption details, and encrypt the private blob. |
813 | */ |
814 | if (passphrase) { |
815 | cipherstr = "aes256-cbc"; |
816 | cipherblk = 16; |
817 | } else { |
818 | cipherstr = "none"; |
819 | cipherblk = 1; |
820 | } |
821 | priv_encrypted_len = priv_blob_len + cipherblk - 1; |
822 | priv_encrypted_len -= priv_encrypted_len % cipherblk; |
823 | priv_blob_encrypted = smalloc(priv_encrypted_len); |
824 | memset(priv_blob_encrypted, 0, priv_encrypted_len); |
825 | memcpy(priv_blob_encrypted, priv_blob, priv_blob_len); |
826 | /* Create padding based on the SHA hash of the unpadded blob. This prevents |
827 | * too easy a known-plaintext attack on the last block. */ |
828 | SHA_Simple(priv_blob, priv_blob_len, priv_hash); |
829 | assert(priv_encrypted_len - priv_blob_len < 20); |
830 | memcpy(priv_blob_encrypted + priv_blob_len, priv_hash, |
831 | priv_encrypted_len - priv_blob_len); |
832 | |
833 | /* Now create the _real_ private hash. */ |
834 | SHA_Simple(priv_blob_encrypted, priv_encrypted_len, priv_hash); |
835 | |
836 | if (passphrase) { |
837 | char key[40]; |
838 | SHA_State s; |
839 | |
840 | passlen = strlen(passphrase); |
841 | |
842 | SHA_Init(&s); |
843 | SHA_Bytes(&s, "\0\0\0\0", 4); |
844 | SHA_Bytes(&s, passphrase, passlen); |
845 | SHA_Final(&s, key+0); |
846 | SHA_Init(&s); |
847 | SHA_Bytes(&s, "\0\0\0\1", 4); |
848 | SHA_Bytes(&s, passphrase, passlen); |
849 | SHA_Final(&s, key+20); |
850 | aes256_encrypt_pubkey(key, priv_blob_encrypted, priv_encrypted_len); |
851 | } |
852 | |
853 | fp = fopen(filename, "w"); |
854 | if (!fp) |
855 | return 0; |
856 | fprintf(fp, "PuTTY-User-Key-File-1: %s\n", key->alg->name); |
857 | fprintf(fp, "Encryption: %s\n", cipherstr); |
858 | fprintf(fp, "Comment: %s\n", key->comment); |
859 | fprintf(fp, "Public-Lines: %d\n", base64_lines(pub_blob_len)); |
860 | base64_encode(fp, pub_blob, pub_blob_len); |
861 | fprintf(fp, "Private-Lines: %d\n", base64_lines(priv_encrypted_len)); |
862 | base64_encode(fp, priv_blob_encrypted, priv_encrypted_len); |
863 | fprintf(fp, "Private-Hash: "); |
864 | for (i = 0; i < 20; i++) |
865 | fprintf(fp, "%02x", priv_hash[i]); |
866 | fprintf(fp, "\n"); |
867 | fclose(fp); |
868 | return 1; |
869 | } |
870 | |
871 | /* ---------------------------------------------------------------------- |
872 | * A function to determine which version of SSH to try on a private |
873 | * key file. Returns 0 on failure, 1 or 2 on success. |
874 | */ |
875 | int keyfile_version(char *filename) { |
876 | FILE *fp; |
877 | int i; |
878 | |
879 | fp = fopen(filename, "r"); |
880 | if (!fp) |
881 | return 0; |
882 | i = fgetc(fp); |
883 | fclose(fp); |
884 | if (i == 'S') |
885 | return 1; /* "SSH PRIVATE KEY FORMAT" etc */ |
886 | if (i == 'P') /* "PuTTY-User-Key-File" etc */ |
887 | return 2; |
888 | return 0; /* unrecognised or EOF */ |
889 | } |