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 | |
32874aea |
34 | static int loadrsakey_main(FILE * fp, struct RSAKey *key, |
35 | char **commentptr, char *passphrase) |
36 | { |
3eca8453 |
37 | unsigned char buf[16384]; |
38 | unsigned char keybuf[16]; |
39 | int len; |
40 | int i, j, ciphertype; |
41 | int ret = 0; |
42 | struct MD5Context md5c; |
a52f067e |
43 | char *comment; |
3eca8453 |
44 | |
a52f067e |
45 | /* Slurp the whole file (minus the header) into a buffer. */ |
3eca8453 |
46 | len = fread(buf, 1, sizeof(buf), fp); |
47 | fclose(fp); |
48 | if (len < 0 || len == sizeof(buf)) |
32874aea |
49 | goto end; /* file too big or not read */ |
3eca8453 |
50 | |
a52f067e |
51 | i = 0; |
3eca8453 |
52 | |
a52f067e |
53 | /* |
54 | * A zero byte. (The signature includes a terminating NUL.) |
55 | */ |
32874aea |
56 | if (len - i < 1 || buf[i] != 0) |
57 | goto end; |
a52f067e |
58 | i++; |
3eca8453 |
59 | |
a52f067e |
60 | /* One byte giving encryption type, and one reserved uint32. */ |
32874aea |
61 | if (len - i < 1) |
62 | goto end; |
3eca8453 |
63 | ciphertype = buf[i]; |
64 | if (ciphertype != 0 && ciphertype != SSH_CIPHER_3DES) |
32874aea |
65 | goto end; |
3eca8453 |
66 | i++; |
32874aea |
67 | if (len - i < 4) |
68 | goto end; /* reserved field not present */ |
69 | if (buf[i] != 0 || buf[i + 1] != 0 || buf[i + 2] != 0 |
70 | || buf[i + 3] != 0) goto end; /* reserved field nonzero, panic! */ |
3eca8453 |
71 | i += 4; |
72 | |
73 | /* Now the serious stuff. An ordinary SSH 1 public key. */ |
32874aea |
74 | i += makekey(buf + i, key, NULL, 1); |
75 | if (len - i < 0) |
76 | goto end; /* overran */ |
3eca8453 |
77 | |
78 | /* Next, the comment field. */ |
32874aea |
79 | j = GET_32BIT(buf + i); |
5c58ad2d |
80 | i += 4; |
32874aea |
81 | if (len - i < j) |
82 | goto end; |
83 | comment = smalloc(j + 1); |
a52f067e |
84 | if (comment) { |
32874aea |
85 | memcpy(comment, buf + i, j); |
86 | comment[j] = '\0'; |
5c58ad2d |
87 | } |
88 | i += j; |
a52f067e |
89 | if (commentptr) |
32874aea |
90 | *commentptr = comment; |
a52f067e |
91 | if (key) |
32874aea |
92 | key->comment = comment; |
a52f067e |
93 | if (!key) { |
32874aea |
94 | return ciphertype != 0; |
a52f067e |
95 | } |
3eca8453 |
96 | |
97 | /* |
98 | * Decrypt remainder of buffer. |
99 | */ |
100 | if (ciphertype) { |
32874aea |
101 | MD5Init(&md5c); |
102 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
103 | MD5Final(keybuf, &md5c); |
104 | des3_decrypt_pubkey(keybuf, buf + i, (len - i + 7) & ~7); |
105 | memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */ |
3eca8453 |
106 | } |
107 | |
108 | /* |
109 | * We are now in the secret part of the key. The first four |
110 | * bytes should be of the form a, b, a, b. |
111 | */ |
32874aea |
112 | if (len - i < 4) |
113 | goto end; |
114 | if (buf[i] != buf[i + 2] || buf[i + 1] != buf[i + 3]) { |
115 | ret = -1; |
116 | goto end; |
117 | } |
3eca8453 |
118 | i += 4; |
119 | |
120 | /* |
121 | * After that, we have one further bignum which is our |
6e522441 |
122 | * decryption exponent, and then the three auxiliary values |
123 | * (iqmp, q, p). |
3eca8453 |
124 | */ |
32874aea |
125 | i += makeprivate(buf + i, key); |
126 | if (len - i < 0) |
127 | goto end; |
128 | i += ssh1_read_bignum(buf + i, &key->iqmp); |
129 | if (len - i < 0) |
130 | goto end; |
131 | i += ssh1_read_bignum(buf + i, &key->q); |
132 | if (len - i < 0) |
133 | goto end; |
134 | i += ssh1_read_bignum(buf + i, &key->p); |
135 | if (len - i < 0) |
136 | goto end; |
3eca8453 |
137 | |
98f022f5 |
138 | if (!rsa_verify(key)) { |
139 | freersakey(key); |
140 | ret = 0; |
141 | } else |
142 | ret = 1; |
143 | |
32874aea |
144 | end: |
3eca8453 |
145 | memset(buf, 0, sizeof(buf)); /* burn the evidence */ |
146 | return ret; |
147 | } |
148 | |
32874aea |
149 | int loadrsakey(char *filename, struct RSAKey *key, char *passphrase) |
150 | { |
3eca8453 |
151 | FILE *fp; |
a52f067e |
152 | unsigned char buf[64]; |
3eca8453 |
153 | |
154 | fp = fopen(filename, "rb"); |
155 | if (!fp) |
32874aea |
156 | return 0; /* doesn't even exist */ |
3eca8453 |
157 | |
a52f067e |
158 | /* |
159 | * Read the first line of the file and see if it's a v1 private |
160 | * key file. |
161 | */ |
32874aea |
162 | if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) { |
163 | return loadrsakey_main(fp, key, NULL, passphrase); |
a52f067e |
164 | } |
165 | |
166 | /* |
167 | * Otherwise, we have nothing. Return empty-handed. |
168 | */ |
3eca8453 |
169 | fclose(fp); |
3eca8453 |
170 | return 0; |
171 | } |
a52f067e |
172 | |
173 | /* |
174 | * See whether an RSA key is encrypted. Return its comment field as |
175 | * well. |
176 | */ |
32874aea |
177 | int rsakey_encrypted(char *filename, char **comment) |
178 | { |
a52f067e |
179 | FILE *fp; |
180 | unsigned char buf[64]; |
181 | |
182 | fp = fopen(filename, "rb"); |
183 | if (!fp) |
32874aea |
184 | return 0; /* doesn't even exist */ |
a52f067e |
185 | |
186 | /* |
187 | * Read the first line of the file and see if it's a v1 private |
188 | * key file. |
189 | */ |
32874aea |
190 | if (fgets(buf, sizeof(buf), fp) && !strcmp(buf, rsa_signature)) { |
191 | return loadrsakey_main(fp, NULL, comment, NULL); |
a52f067e |
192 | } |
404f728b |
193 | fclose(fp); |
32874aea |
194 | return 0; /* wasn't the right kind of file */ |
a52f067e |
195 | } |
6e522441 |
196 | |
197 | /* |
198 | * Save an RSA key file. Return nonzero on success. |
199 | */ |
32874aea |
200 | int saversakey(char *filename, struct RSAKey *key, char *passphrase) |
201 | { |
6e522441 |
202 | unsigned char buf[16384]; |
203 | unsigned char keybuf[16]; |
204 | struct MD5Context md5c; |
49bad831 |
205 | unsigned char *p, *estart; |
6e522441 |
206 | FILE *fp; |
207 | |
208 | /* |
209 | * Write the initial signature. |
210 | */ |
211 | p = buf; |
212 | memcpy(p, rsa_signature, sizeof(rsa_signature)); |
213 | p += sizeof(rsa_signature); |
214 | |
215 | /* |
216 | * One byte giving encryption type, and one reserved (zero) |
217 | * uint32. |
218 | */ |
219 | *p++ = (passphrase ? SSH_CIPHER_3DES : 0); |
32874aea |
220 | PUT_32BIT(p, 0); |
221 | p += 4; |
6e522441 |
222 | |
223 | /* |
224 | * An ordinary SSH 1 public key consists of: a uint32 |
225 | * containing the bit count, then two bignums containing the |
226 | * modulus and exponent respectively. |
227 | */ |
32874aea |
228 | PUT_32BIT(p, bignum_bitcount(key->modulus)); |
229 | p += 4; |
6e522441 |
230 | p += ssh1_write_bignum(p, key->modulus); |
231 | p += ssh1_write_bignum(p, key->exponent); |
232 | |
233 | /* |
234 | * A string containing the comment field. |
235 | */ |
236 | if (key->comment) { |
32874aea |
237 | PUT_32BIT(p, strlen(key->comment)); |
238 | p += 4; |
239 | memcpy(p, key->comment, strlen(key->comment)); |
240 | p += strlen(key->comment); |
6e522441 |
241 | } else { |
32874aea |
242 | PUT_32BIT(p, 0); |
243 | p += 4; |
6e522441 |
244 | } |
245 | |
246 | /* |
247 | * The encrypted portion starts here. |
248 | */ |
249 | estart = p; |
250 | |
251 | /* |
252 | * Two bytes, then the same two bytes repeated. |
253 | */ |
254 | *p++ = random_byte(); |
255 | *p++ = random_byte(); |
32874aea |
256 | p[0] = p[-2]; |
257 | p[1] = p[-1]; |
258 | p += 2; |
6e522441 |
259 | |
260 | /* |
261 | * Four more bignums: the decryption exponent, then iqmp, then |
262 | * q, then p. |
263 | */ |
264 | p += ssh1_write_bignum(p, key->private_exponent); |
65a22376 |
265 | p += ssh1_write_bignum(p, key->iqmp); |
266 | p += ssh1_write_bignum(p, key->q); |
267 | p += ssh1_write_bignum(p, key->p); |
6e522441 |
268 | |
269 | /* |
270 | * Now write zeros until the encrypted portion is a multiple of |
271 | * 8 bytes. |
272 | */ |
32874aea |
273 | while ((p - estart) % 8) |
274 | *p++ = '\0'; |
6e522441 |
275 | |
276 | /* |
277 | * Now encrypt the encrypted portion. |
278 | */ |
279 | if (passphrase) { |
32874aea |
280 | MD5Init(&md5c); |
281 | MD5Update(&md5c, passphrase, strlen(passphrase)); |
282 | MD5Final(keybuf, &md5c); |
283 | des3_encrypt_pubkey(keybuf, estart, p - estart); |
284 | memset(keybuf, 0, sizeof(keybuf)); /* burn the evidence */ |
6e522441 |
285 | } |
286 | |
287 | /* |
288 | * Done. Write the result to the file. |
289 | */ |
290 | fp = fopen(filename, "wb"); |
291 | if (fp) { |
32874aea |
292 | int ret = (fwrite(buf, 1, p - buf, fp) == (size_t) (p - buf)); |
293 | ret = ret && (fclose(fp) == 0); |
294 | return ret; |
6e522441 |
295 | } else |
32874aea |
296 | return 0; |
6e522441 |
297 | } |
65a22376 |
298 | |
299 | /* ---------------------------------------------------------------------- |
300 | * SSH2 private key load/store functions. |
301 | */ |
302 | |
303 | /* |
304 | * PuTTY's own format for SSH2 keys is as follows: |
305 | * |
306 | * The file is text. Lines are terminated by CRLF, although CR-only |
307 | * and LF-only are tolerated on input. |
308 | * |
309 | * The first line says "PuTTY-User-Key-File-1: " plus the name of the |
310 | * algorithm ("ssh-dss", "ssh-rsa" etc. Although, of course, this |
311 | * being PuTTY, "ssh-dss" is not supported.) |
312 | * |
313 | * The next line says "Encryption: " plus an encryption type. |
314 | * Currently the only supported encryption types are "aes256-cbc" |
315 | * and "none". |
316 | * |
317 | * The next line says "Comment: " plus the comment string. |
318 | * |
319 | * Next there is a line saying "Public-Lines: " plus a number N. |
320 | * The following N lines contain a base64 encoding of the public |
321 | * part of the key. This is encoded as the standard SSH2 public key |
322 | * blob (with no initial length): so for RSA, for example, it will |
323 | * read |
324 | * |
325 | * string "ssh-rsa" |
326 | * mpint exponent |
327 | * mpint modulus |
328 | * |
329 | * Next, there is a line saying "Private-Lines: " plus a number N, |
330 | * and then N lines containing the (potentially encrypted) private |
331 | * part of the key. For the key type "ssh-rsa", this will be |
332 | * composed of |
333 | * |
334 | * mpint private_exponent |
335 | * mpint p (the larger of the two primes) |
336 | * mpint q (the smaller prime) |
337 | * mpint iqmp (the inverse of q modulo p) |
338 | * data padding (to reach a multiple of the cipher block size) |
339 | * |
340 | * Finally, there is a line saying "Private-Hash: " plus a hex |
341 | * representation of a SHA-1 hash of the plaintext version of the |
342 | * private part, including the final padding. |
343 | * |
344 | * If the key is encrypted, the encryption key is derived from the |
345 | * passphrase by means of a succession of SHA-1 hashes. Each hash |
346 | * is the hash of: |
347 | * |
348 | * uint32 sequence-number |
349 | * string passphrase |
350 | * |
351 | * where the sequence-number increases from zero. As many of these |
352 | * hashes are used as necessary. |
98f022f5 |
353 | * |
354 | * NOTE! It is important that all _public_ data can be verified |
355 | * with reference to the _private_ data. There exist attacks based |
356 | * on modifying the public key but leaving the private section |
357 | * intact. |
358 | * |
359 | * With RSA, this is easy: verify that n = p*q, and also verify |
360 | * that e*d == 1 modulo (p-1)(q-1). With DSA (if we were ever to |
361 | * support it), we would need to store extra data in the private |
362 | * section other than just x. |
65a22376 |
363 | */ |
364 | |
32874aea |
365 | static int read_header(FILE * fp, char *header) |
366 | { |
65a22376 |
367 | int len = 39; |
368 | int c; |
369 | |
370 | while (len > 0) { |
371 | c = fgetc(fp); |
372 | if (c == '\n' || c == '\r' || c == EOF) |
373 | return 0; /* failure */ |
374 | if (c == ':') { |
375 | c = fgetc(fp); |
376 | if (c != ' ') |
377 | return 0; |
378 | *header = '\0'; |
379 | return 1; /* success! */ |
380 | } |
381 | if (len == 0) |
382 | return 0; /* failure */ |
383 | *header++ = c; |
384 | len--; |
385 | } |
386 | return 0; /* failure */ |
387 | } |
388 | |
32874aea |
389 | static char *read_body(FILE * fp) |
390 | { |
65a22376 |
391 | char *text; |
392 | int len; |
393 | int size; |
394 | int c; |
395 | |
396 | size = 128; |
397 | text = smalloc(size); |
398 | len = 0; |
399 | text[len] = '\0'; |
400 | |
401 | while (1) { |
402 | c = fgetc(fp); |
403 | if (c == '\r' || c == '\n') { |
404 | c = fgetc(fp); |
405 | if (c != '\r' && c != '\n' && c != EOF) |
406 | ungetc(c, fp); |
407 | return text; |
408 | } |
409 | if (c == EOF) { |
410 | sfree(text); |
411 | return NULL; |
412 | } |
413 | if (len + 1 > size) { |
414 | size += 128; |
415 | text = srealloc(text, size); |
416 | } |
417 | text[len++] = c; |
418 | text[len] = '\0'; |
419 | } |
420 | } |
421 | |
32874aea |
422 | int base64_decode_atom(char *atom, unsigned char *out) |
423 | { |
65a22376 |
424 | int vals[4]; |
425 | int i, v, len; |
426 | unsigned word; |
427 | char c; |
32874aea |
428 | |
65a22376 |
429 | for (i = 0; i < 4; i++) { |
430 | c = atom[i]; |
431 | if (c >= 'A' && c <= 'Z') |
432 | v = c - 'A'; |
433 | else if (c >= 'a' && c <= 'z') |
434 | v = c - 'a' + 26; |
435 | else if (c >= '0' && c <= '9') |
436 | v = c - '0' + 52; |
437 | else if (c == '+') |
438 | v = 62; |
439 | else if (c == '/') |
440 | v = 63; |
441 | else if (c == '=') |
442 | v = -1; |
443 | else |
444 | return 0; /* invalid atom */ |
445 | vals[i] = v; |
446 | } |
447 | |
448 | if (vals[0] == -1 || vals[1] == -1) |
449 | return 0; |
450 | if (vals[2] == -1 && vals[3] != -1) |
451 | return 0; |
452 | |
453 | if (vals[3] != -1) |
454 | len = 3; |
455 | else if (vals[2] != -1) |
456 | len = 2; |
457 | else |
458 | len = 1; |
459 | |
460 | word = ((vals[0] << 18) | |
32874aea |
461 | (vals[1] << 12) | ((vals[2] & 0x3F) << 6) | (vals[3] & 0x3F)); |
65a22376 |
462 | out[0] = (word >> 16) & 0xFF; |
463 | if (len > 1) |
464 | out[1] = (word >> 8) & 0xFF; |
465 | if (len > 2) |
466 | out[2] = word & 0xFF; |
467 | return len; |
468 | } |
469 | |
32874aea |
470 | static char *read_blob(FILE * fp, int nlines, int *bloblen) |
471 | { |
65a22376 |
472 | unsigned char *blob; |
473 | char *line; |
474 | int linelen, len; |
475 | int i, j, k; |
476 | |
477 | /* We expect at most 64 base64 characters, ie 48 real bytes, per line. */ |
478 | blob = smalloc(48 * nlines); |
479 | len = 0; |
480 | for (i = 0; i < nlines; i++) { |
481 | line = read_body(fp); |
482 | if (!line) { |
483 | sfree(blob); |
484 | return NULL; |
485 | } |
486 | linelen = strlen(line); |
487 | if (linelen % 4 != 0 || linelen > 64) { |
488 | sfree(blob); |
489 | sfree(line); |
490 | return NULL; |
491 | } |
492 | for (j = 0; j < linelen; j += 4) { |
32874aea |
493 | k = base64_decode_atom(line + j, blob + len); |
65a22376 |
494 | if (!k) { |
495 | sfree(line); |
496 | sfree(blob); |
497 | return NULL; |
498 | } |
499 | len += k; |
500 | } |
501 | sfree(line); |
502 | } |
503 | *bloblen = len; |
504 | return blob; |
505 | } |
506 | |
507 | /* |
508 | * Magic error return value for when the passphrase is wrong. |
509 | */ |
510 | struct ssh2_userkey ssh2_wrong_passphrase = { |
511 | NULL, NULL, NULL |
512 | }; |
513 | |
32874aea |
514 | struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) |
515 | { |
65a22376 |
516 | FILE *fp; |
517 | char header[40], *b, *comment, *hash; |
518 | const struct ssh_signkey *alg; |
519 | struct ssh2_userkey *ret; |
520 | int cipher, cipherblk; |
521 | unsigned char *public_blob, *private_blob; |
522 | int public_blob_len, private_blob_len; |
523 | int i; |
524 | |
525 | ret = NULL; /* return NULL for most errors */ |
526 | comment = hash = NULL; |
527 | public_blob = private_blob = NULL; |
528 | |
529 | fp = fopen(filename, "rb"); |
530 | if (!fp) |
531 | goto error; |
532 | |
533 | /* Read the first header line which contains the key type. */ |
32874aea |
534 | if (!read_header(fp, header) |
535 | || 0 != strcmp(header, "PuTTY-User-Key-File-1")) |
65a22376 |
536 | goto error; |
537 | if ((b = read_body(fp)) == NULL) |
538 | goto error; |
539 | /* Select key algorithm structure. Currently only ssh-rsa. */ |
540 | if (!strcmp(b, "ssh-rsa")) |
541 | alg = &ssh_rsa; |
542 | else { |
543 | sfree(b); |
544 | goto error; |
545 | } |
546 | sfree(b); |
32874aea |
547 | |
65a22376 |
548 | /* Read the Encryption header line. */ |
32874aea |
549 | if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) |
65a22376 |
550 | goto error; |
551 | if ((b = read_body(fp)) == NULL) |
552 | goto error; |
553 | if (!strcmp(b, "aes256-cbc")) { |
32874aea |
554 | cipher = 1; |
555 | cipherblk = 16; |
65a22376 |
556 | } else if (!strcmp(b, "none")) { |
32874aea |
557 | cipher = 0; |
558 | cipherblk = 1; |
65a22376 |
559 | } else { |
560 | sfree(b); |
561 | goto error; |
562 | } |
563 | sfree(b); |
564 | |
565 | /* Read the Comment header line. */ |
32874aea |
566 | if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) |
65a22376 |
567 | goto error; |
568 | if ((comment = read_body(fp)) == NULL) |
569 | goto error; |
570 | |
571 | /* Read the Public-Lines header line and the public blob. */ |
32874aea |
572 | if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines")) |
65a22376 |
573 | goto error; |
574 | if ((b = read_body(fp)) == NULL) |
575 | goto error; |
576 | i = atoi(b); |
577 | sfree(b); |
578 | if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL) |
579 | goto error; |
580 | |
581 | /* Read the Private-Lines header line and the Private blob. */ |
32874aea |
582 | if (!read_header(fp, header) || 0 != strcmp(header, "Private-Lines")) |
65a22376 |
583 | goto error; |
584 | if ((b = read_body(fp)) == NULL) |
585 | goto error; |
586 | i = atoi(b); |
587 | sfree(b); |
588 | if ((private_blob = read_blob(fp, i, &private_blob_len)) == NULL) |
589 | goto error; |
590 | |
591 | /* Read the Private-Hash header line. */ |
32874aea |
592 | if (!read_header(fp, header) || 0 != strcmp(header, "Private-Hash")) |
65a22376 |
593 | goto error; |
594 | if ((hash = read_body(fp)) == NULL) |
595 | goto error; |
596 | |
597 | fclose(fp); |
598 | fp = NULL; |
599 | |
600 | /* |
601 | * Decrypt the private blob. |
602 | */ |
603 | if (cipher) { |
604 | unsigned char key[40]; |
605 | SHA_State s; |
606 | int passlen; |
607 | |
608 | if (!passphrase) |
609 | goto error; |
610 | if (private_blob_len % cipherblk) |
611 | goto error; |
612 | |
613 | passlen = strlen(passphrase); |
614 | |
615 | SHA_Init(&s); |
616 | SHA_Bytes(&s, "\0\0\0\0", 4); |
617 | SHA_Bytes(&s, passphrase, passlen); |
32874aea |
618 | SHA_Final(&s, key + 0); |
65a22376 |
619 | SHA_Init(&s); |
620 | SHA_Bytes(&s, "\0\0\0\1", 4); |
621 | SHA_Bytes(&s, passphrase, passlen); |
32874aea |
622 | SHA_Final(&s, key + 20); |
65a22376 |
623 | aes256_decrypt_pubkey(key, private_blob, private_blob_len); |
624 | } |
625 | |
626 | /* |
627 | * Verify the private hash. |
628 | */ |
629 | { |
630 | char realhash[41]; |
631 | unsigned char binary[20]; |
65a22376 |
632 | |
633 | SHA_Simple(private_blob, private_blob_len, binary); |
634 | for (i = 0; i < 20; i++) |
32874aea |
635 | sprintf(realhash + 2 * i, "%02x", binary[i]); |
65a22376 |
636 | |
637 | if (strcmp(hash, realhash)) { |
638 | /* An incorrect hash is an unconditional Error if the key is |
639 | * unencrypted. Otherwise, it means Wrong Passphrase. */ |
640 | ret = cipher ? SSH2_WRONG_PASSPHRASE : NULL; |
641 | goto error; |
642 | } |
643 | } |
644 | sfree(hash); |
645 | |
646 | /* |
647 | * Create and return the key. |
648 | */ |
649 | ret = smalloc(sizeof(struct ssh2_userkey)); |
650 | ret->alg = alg; |
651 | ret->comment = comment; |
652 | ret->data = alg->createkey(public_blob, public_blob_len, |
653 | private_blob, private_blob_len); |
98f022f5 |
654 | if (!ret->data) { |
655 | sfree(ret->comment); |
656 | sfree(ret); |
657 | ret = NULL; |
658 | } |
65a22376 |
659 | sfree(public_blob); |
660 | sfree(private_blob); |
661 | return ret; |
662 | |
663 | /* |
664 | * Error processing. |
665 | */ |
32874aea |
666 | error: |
667 | if (fp) |
668 | fclose(fp); |
669 | if (comment) |
670 | sfree(comment); |
671 | if (hash) |
672 | sfree(hash); |
673 | if (public_blob) |
674 | sfree(public_blob); |
675 | if (private_blob) |
676 | sfree(private_blob); |
65a22376 |
677 | return ret; |
678 | } |
679 | |
32874aea |
680 | char *ssh2_userkey_loadpub(char *filename, char **algorithm, |
681 | int *pub_blob_len) |
682 | { |
65a22376 |
683 | FILE *fp; |
684 | char header[40], *b; |
685 | const struct ssh_signkey *alg; |
65a22376 |
686 | unsigned char *public_blob; |
687 | int public_blob_len; |
688 | int i; |
689 | |
690 | public_blob = NULL; |
691 | |
692 | fp = fopen(filename, "rb"); |
693 | if (!fp) |
694 | goto error; |
695 | |
696 | /* Read the first header line which contains the key type. */ |
32874aea |
697 | if (!read_header(fp, header) |
698 | || 0 != strcmp(header, "PuTTY-User-Key-File-1")) |
65a22376 |
699 | goto error; |
700 | if ((b = read_body(fp)) == NULL) |
701 | goto error; |
702 | /* Select key algorithm structure. Currently only ssh-rsa. */ |
703 | if (!strcmp(b, "ssh-rsa")) |
704 | alg = &ssh_rsa; |
705 | else { |
706 | sfree(b); |
707 | goto error; |
708 | } |
709 | sfree(b); |
32874aea |
710 | |
65a22376 |
711 | /* Read the Encryption header line. */ |
32874aea |
712 | if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) |
65a22376 |
713 | goto error; |
714 | if ((b = read_body(fp)) == NULL) |
715 | goto error; |
716 | sfree(b); /* we don't care */ |
717 | |
718 | /* Read the Comment header line. */ |
32874aea |
719 | if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) |
65a22376 |
720 | goto error; |
721 | if ((b = read_body(fp)) == NULL) |
722 | goto error; |
723 | sfree(b); /* we don't care */ |
724 | |
725 | /* Read the Public-Lines header line and the public blob. */ |
32874aea |
726 | if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines")) |
65a22376 |
727 | goto error; |
728 | if ((b = read_body(fp)) == NULL) |
729 | goto error; |
730 | i = atoi(b); |
731 | sfree(b); |
732 | if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL) |
733 | goto error; |
734 | |
735 | fclose(fp); |
736 | *pub_blob_len = public_blob_len; |
737 | *algorithm = alg->name; |
738 | return public_blob; |
739 | |
740 | /* |
741 | * Error processing. |
742 | */ |
32874aea |
743 | error: |
744 | if (fp) |
745 | fclose(fp); |
746 | if (public_blob) |
747 | sfree(public_blob); |
65a22376 |
748 | return NULL; |
749 | } |
750 | |
32874aea |
751 | int ssh2_userkey_encrypted(char *filename, char **commentptr) |
752 | { |
65a22376 |
753 | FILE *fp; |
754 | char header[40], *b, *comment; |
755 | int ret; |
756 | |
32874aea |
757 | if (commentptr) |
758 | *commentptr = NULL; |
65a22376 |
759 | |
760 | fp = fopen(filename, "rb"); |
761 | if (!fp) |
762 | return 0; |
32874aea |
763 | if (!read_header(fp, header) |
764 | || 0 != strcmp(header, "PuTTY-User-Key-File-1")) { |
765 | fclose(fp); |
766 | return 0; |
65a22376 |
767 | } |
768 | if ((b = read_body(fp)) == NULL) { |
32874aea |
769 | fclose(fp); |
770 | return 0; |
65a22376 |
771 | } |
772 | sfree(b); /* we don't care about key type here */ |
773 | /* Read the Encryption header line. */ |
32874aea |
774 | if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) { |
775 | fclose(fp); |
776 | return 0; |
65a22376 |
777 | } |
778 | if ((b = read_body(fp)) == NULL) { |
32874aea |
779 | fclose(fp); |
780 | return 0; |
65a22376 |
781 | } |
782 | |
783 | /* Read the Comment header line. */ |
32874aea |
784 | if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) { |
785 | fclose(fp); |
786 | sfree(b); |
787 | return 1; |
65a22376 |
788 | } |
789 | if ((comment = read_body(fp)) == NULL) { |
32874aea |
790 | fclose(fp); |
791 | sfree(b); |
792 | return 1; |
65a22376 |
793 | } |
794 | |
32874aea |
795 | if (commentptr) |
796 | *commentptr = comment; |
65a22376 |
797 | |
798 | fclose(fp); |
799 | if (!strcmp(b, "aes256-cbc")) |
800 | ret = 1; |
801 | else |
802 | ret = 0; |
803 | sfree(b); |
804 | return ret; |
805 | } |
806 | |
32874aea |
807 | int base64_lines(int datalen) |
808 | { |
65a22376 |
809 | /* When encoding, we use 64 chars/line, which equals 48 real chars. */ |
32874aea |
810 | return (datalen + 47) / 48; |
65a22376 |
811 | } |
812 | |
32874aea |
813 | void base64_encode_atom(unsigned char *data, int n, char *out) |
814 | { |
65a22376 |
815 | static const char base64_chars[] = |
816 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
817 | |
818 | unsigned word; |
819 | |
820 | word = data[0] << 16; |
821 | if (n > 1) |
822 | word |= data[1] << 8; |
823 | if (n > 2) |
824 | word |= data[2]; |
825 | out[0] = base64_chars[(word >> 18) & 0x3F]; |
826 | out[1] = base64_chars[(word >> 12) & 0x3F]; |
827 | if (n > 1) |
828 | out[2] = base64_chars[(word >> 6) & 0x3F]; |
829 | else |
830 | out[2] = '='; |
831 | if (n > 2) |
832 | out[3] = base64_chars[word & 0x3F]; |
833 | else |
834 | out[3] = '='; |
835 | } |
836 | |
32874aea |
837 | void base64_encode(FILE * fp, unsigned char *data, int datalen) |
838 | { |
65a22376 |
839 | int linelen = 0; |
840 | char out[4]; |
841 | int n; |
842 | |
843 | while (datalen > 0) { |
844 | if (linelen >= 64) { |
845 | linelen = 0; |
846 | fputc('\n', fp); |
847 | } |
848 | n = (datalen < 3 ? datalen : 3); |
849 | base64_encode_atom(data, n, out); |
850 | data += n; |
851 | datalen -= n; |
852 | fwrite(out, 1, 4, fp); |
853 | linelen += 4; |
854 | } |
855 | fputc('\n', fp); |
856 | } |
857 | |
32874aea |
858 | int ssh2_save_userkey(char *filename, struct ssh2_userkey *key, |
859 | char *passphrase) |
860 | { |
65a22376 |
861 | FILE *fp; |
862 | unsigned char *pub_blob, *priv_blob, *priv_blob_encrypted; |
863 | int pub_blob_len, priv_blob_len, priv_encrypted_len; |
864 | int passlen; |
865 | int cipherblk; |
866 | int i; |
867 | char *cipherstr; |
868 | unsigned char priv_hash[20]; |
869 | |
870 | /* |
871 | * Fetch the key component blobs. |
872 | */ |
873 | pub_blob = key->alg->public_blob(key->data, &pub_blob_len); |
874 | priv_blob = key->alg->private_blob(key->data, &priv_blob_len); |
875 | if (!pub_blob || !priv_blob) { |
876 | sfree(pub_blob); |
877 | sfree(priv_blob); |
878 | return 0; |
879 | } |
880 | |
881 | /* |
882 | * Determine encryption details, and encrypt the private blob. |
883 | */ |
884 | if (passphrase) { |
885 | cipherstr = "aes256-cbc"; |
886 | cipherblk = 16; |
887 | } else { |
888 | cipherstr = "none"; |
889 | cipherblk = 1; |
890 | } |
891 | priv_encrypted_len = priv_blob_len + cipherblk - 1; |
892 | priv_encrypted_len -= priv_encrypted_len % cipherblk; |
893 | priv_blob_encrypted = smalloc(priv_encrypted_len); |
894 | memset(priv_blob_encrypted, 0, priv_encrypted_len); |
895 | memcpy(priv_blob_encrypted, priv_blob, priv_blob_len); |
896 | /* Create padding based on the SHA hash of the unpadded blob. This prevents |
897 | * too easy a known-plaintext attack on the last block. */ |
898 | SHA_Simple(priv_blob, priv_blob_len, priv_hash); |
899 | assert(priv_encrypted_len - priv_blob_len < 20); |
900 | memcpy(priv_blob_encrypted + priv_blob_len, priv_hash, |
901 | priv_encrypted_len - priv_blob_len); |
902 | |
903 | /* Now create the _real_ private hash. */ |
904 | SHA_Simple(priv_blob_encrypted, priv_encrypted_len, priv_hash); |
905 | |
906 | if (passphrase) { |
907 | char key[40]; |
908 | SHA_State s; |
909 | |
910 | passlen = strlen(passphrase); |
911 | |
912 | SHA_Init(&s); |
913 | SHA_Bytes(&s, "\0\0\0\0", 4); |
914 | SHA_Bytes(&s, passphrase, passlen); |
32874aea |
915 | SHA_Final(&s, key + 0); |
65a22376 |
916 | SHA_Init(&s); |
917 | SHA_Bytes(&s, "\0\0\0\1", 4); |
918 | SHA_Bytes(&s, passphrase, passlen); |
32874aea |
919 | SHA_Final(&s, key + 20); |
920 | aes256_encrypt_pubkey(key, priv_blob_encrypted, |
921 | priv_encrypted_len); |
65a22376 |
922 | } |
923 | |
924 | fp = fopen(filename, "w"); |
925 | if (!fp) |
926 | return 0; |
927 | fprintf(fp, "PuTTY-User-Key-File-1: %s\n", key->alg->name); |
928 | fprintf(fp, "Encryption: %s\n", cipherstr); |
929 | fprintf(fp, "Comment: %s\n", key->comment); |
930 | fprintf(fp, "Public-Lines: %d\n", base64_lines(pub_blob_len)); |
931 | base64_encode(fp, pub_blob, pub_blob_len); |
932 | fprintf(fp, "Private-Lines: %d\n", base64_lines(priv_encrypted_len)); |
933 | base64_encode(fp, priv_blob_encrypted, priv_encrypted_len); |
934 | fprintf(fp, "Private-Hash: "); |
935 | for (i = 0; i < 20; i++) |
936 | fprintf(fp, "%02x", priv_hash[i]); |
937 | fprintf(fp, "\n"); |
938 | fclose(fp); |
939 | return 1; |
940 | } |
941 | |
942 | /* ---------------------------------------------------------------------- |
943 | * A function to determine which version of SSH to try on a private |
944 | * key file. Returns 0 on failure, 1 or 2 on success. |
945 | */ |
32874aea |
946 | int keyfile_version(char *filename) |
947 | { |
65a22376 |
948 | FILE *fp; |
949 | int i; |
950 | |
951 | fp = fopen(filename, "r"); |
952 | if (!fp) |
953 | return 0; |
954 | i = fgetc(fp); |
955 | fclose(fp); |
956 | if (i == 'S') |
957 | return 1; /* "SSH PRIVATE KEY FORMAT" etc */ |
958 | if (i == 'P') /* "PuTTY-User-Key-File" etc */ |
959 | return 2; |
960 | return 0; /* unrecognised or EOF */ |
961 | } |