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: |
5c72ca61 |
305 | * |
65a22376 |
306 | * The file is text. Lines are terminated by CRLF, although CR-only |
307 | * and LF-only are tolerated on input. |
5c72ca61 |
308 | * |
65a22376 |
309 | * The first line says "PuTTY-User-Key-File-1: " plus the name of the |
5c72ca61 |
310 | * algorithm ("ssh-dss", "ssh-rsa" etc). |
311 | * |
65a22376 |
312 | * The next line says "Encryption: " plus an encryption type. |
313 | * Currently the only supported encryption types are "aes256-cbc" |
314 | * and "none". |
5c72ca61 |
315 | * |
65a22376 |
316 | * The next line says "Comment: " plus the comment string. |
5c72ca61 |
317 | * |
65a22376 |
318 | * Next there is a line saying "Public-Lines: " plus a number N. |
319 | * The following N lines contain a base64 encoding of the public |
320 | * part of the key. This is encoded as the standard SSH2 public key |
321 | * blob (with no initial length): so for RSA, for example, it will |
322 | * read |
5c72ca61 |
323 | * |
65a22376 |
324 | * string "ssh-rsa" |
325 | * mpint exponent |
326 | * mpint modulus |
5c72ca61 |
327 | * |
65a22376 |
328 | * Next, there is a line saying "Private-Lines: " plus a number N, |
329 | * and then N lines containing the (potentially encrypted) private |
330 | * part of the key. For the key type "ssh-rsa", this will be |
331 | * composed of |
5c72ca61 |
332 | * |
65a22376 |
333 | * mpint private_exponent |
334 | * mpint p (the larger of the two primes) |
335 | * mpint q (the smaller prime) |
336 | * mpint iqmp (the inverse of q modulo p) |
337 | * data padding (to reach a multiple of the cipher block size) |
5c72ca61 |
338 | * |
339 | * And for "ssh-dss", it will be composed of |
340 | * |
341 | * mpint x (the private key parameter) |
342 | * string hash (20-byte hash of mpints p || q || g) |
343 | * |
344 | * Finally, there is a line saying _either_ |
345 | * |
346 | * - "Private-Hash: " plus a hex representation of a SHA-1 hash of |
347 | * the plaintext version of the private part, including the |
348 | * final padding. |
349 | * |
350 | * or |
351 | * |
352 | * - "Private-MAC: " plus a hex representation of a HMAC-SHA-1 of |
353 | * the plaintext version of the private part, including the |
354 | * final padding. |
65a22376 |
355 | * |
5c72ca61 |
356 | * The key to the MAC is itself a SHA-1 hash of: |
65a22376 |
357 | * |
5c72ca61 |
358 | * data "putty-private-key-file-mac-key" |
359 | * data passphrase |
360 | * |
361 | * Encrypted keys should have a MAC, whereas unencrypted ones must |
362 | * have a hash. |
363 | * |
65a22376 |
364 | * If the key is encrypted, the encryption key is derived from the |
365 | * passphrase by means of a succession of SHA-1 hashes. Each hash |
366 | * is the hash of: |
5c72ca61 |
367 | * |
65a22376 |
368 | * uint32 sequence-number |
5c72ca61 |
369 | * data passphrase |
370 | * |
65a22376 |
371 | * where the sequence-number increases from zero. As many of these |
372 | * hashes are used as necessary. |
5c72ca61 |
373 | * |
98f022f5 |
374 | * NOTE! It is important that all _public_ data can be verified |
375 | * with reference to the _private_ data. There exist attacks based |
376 | * on modifying the public key but leaving the private section |
377 | * intact. |
5c72ca61 |
378 | * |
98f022f5 |
379 | * With RSA, this is easy: verify that n = p*q, and also verify |
5c72ca61 |
380 | * that e*d == 1 modulo (p-1)(q-1). With DSA, we need to store |
381 | * extra data in the private section other than just x, namely a |
382 | * hash of p||q||g. (It's then easy to verify that y is equal to |
383 | * g^x mod p.) |
65a22376 |
384 | */ |
385 | |
32874aea |
386 | static int read_header(FILE * fp, char *header) |
387 | { |
65a22376 |
388 | int len = 39; |
389 | int c; |
390 | |
391 | while (len > 0) { |
392 | c = fgetc(fp); |
393 | if (c == '\n' || c == '\r' || c == EOF) |
394 | return 0; /* failure */ |
395 | if (c == ':') { |
396 | c = fgetc(fp); |
397 | if (c != ' ') |
398 | return 0; |
399 | *header = '\0'; |
400 | return 1; /* success! */ |
401 | } |
402 | if (len == 0) |
403 | return 0; /* failure */ |
404 | *header++ = c; |
405 | len--; |
406 | } |
407 | return 0; /* failure */ |
408 | } |
409 | |
32874aea |
410 | static char *read_body(FILE * fp) |
411 | { |
65a22376 |
412 | char *text; |
413 | int len; |
414 | int size; |
415 | int c; |
416 | |
417 | size = 128; |
418 | text = smalloc(size); |
419 | len = 0; |
420 | text[len] = '\0'; |
421 | |
422 | while (1) { |
423 | c = fgetc(fp); |
424 | if (c == '\r' || c == '\n') { |
425 | c = fgetc(fp); |
426 | if (c != '\r' && c != '\n' && c != EOF) |
427 | ungetc(c, fp); |
428 | return text; |
429 | } |
430 | if (c == EOF) { |
431 | sfree(text); |
432 | return NULL; |
433 | } |
434 | if (len + 1 > size) { |
435 | size += 128; |
436 | text = srealloc(text, size); |
437 | } |
438 | text[len++] = c; |
439 | text[len] = '\0'; |
440 | } |
441 | } |
442 | |
32874aea |
443 | int base64_decode_atom(char *atom, unsigned char *out) |
444 | { |
65a22376 |
445 | int vals[4]; |
446 | int i, v, len; |
447 | unsigned word; |
448 | char c; |
32874aea |
449 | |
65a22376 |
450 | for (i = 0; i < 4; i++) { |
451 | c = atom[i]; |
452 | if (c >= 'A' && c <= 'Z') |
453 | v = c - 'A'; |
454 | else if (c >= 'a' && c <= 'z') |
455 | v = c - 'a' + 26; |
456 | else if (c >= '0' && c <= '9') |
457 | v = c - '0' + 52; |
458 | else if (c == '+') |
459 | v = 62; |
460 | else if (c == '/') |
461 | v = 63; |
462 | else if (c == '=') |
463 | v = -1; |
464 | else |
465 | return 0; /* invalid atom */ |
466 | vals[i] = v; |
467 | } |
468 | |
469 | if (vals[0] == -1 || vals[1] == -1) |
470 | return 0; |
471 | if (vals[2] == -1 && vals[3] != -1) |
472 | return 0; |
473 | |
474 | if (vals[3] != -1) |
475 | len = 3; |
476 | else if (vals[2] != -1) |
477 | len = 2; |
478 | else |
479 | len = 1; |
480 | |
481 | word = ((vals[0] << 18) | |
32874aea |
482 | (vals[1] << 12) | ((vals[2] & 0x3F) << 6) | (vals[3] & 0x3F)); |
65a22376 |
483 | out[0] = (word >> 16) & 0xFF; |
484 | if (len > 1) |
485 | out[1] = (word >> 8) & 0xFF; |
486 | if (len > 2) |
487 | out[2] = word & 0xFF; |
488 | return len; |
489 | } |
490 | |
32874aea |
491 | static char *read_blob(FILE * fp, int nlines, int *bloblen) |
492 | { |
65a22376 |
493 | unsigned char *blob; |
494 | char *line; |
495 | int linelen, len; |
496 | int i, j, k; |
497 | |
498 | /* We expect at most 64 base64 characters, ie 48 real bytes, per line. */ |
499 | blob = smalloc(48 * nlines); |
500 | len = 0; |
501 | for (i = 0; i < nlines; i++) { |
502 | line = read_body(fp); |
503 | if (!line) { |
504 | sfree(blob); |
505 | return NULL; |
506 | } |
507 | linelen = strlen(line); |
508 | if (linelen % 4 != 0 || linelen > 64) { |
509 | sfree(blob); |
510 | sfree(line); |
511 | return NULL; |
512 | } |
513 | for (j = 0; j < linelen; j += 4) { |
32874aea |
514 | k = base64_decode_atom(line + j, blob + len); |
65a22376 |
515 | if (!k) { |
516 | sfree(line); |
517 | sfree(blob); |
518 | return NULL; |
519 | } |
520 | len += k; |
521 | } |
522 | sfree(line); |
523 | } |
524 | *bloblen = len; |
525 | return blob; |
526 | } |
527 | |
528 | /* |
529 | * Magic error return value for when the passphrase is wrong. |
530 | */ |
531 | struct ssh2_userkey ssh2_wrong_passphrase = { |
532 | NULL, NULL, NULL |
533 | }; |
534 | |
32874aea |
535 | struct ssh2_userkey *ssh2_load_userkey(char *filename, char *passphrase) |
536 | { |
65a22376 |
537 | FILE *fp; |
5c72ca61 |
538 | char header[40], *b, *comment, *mac; |
65a22376 |
539 | const struct ssh_signkey *alg; |
540 | struct ssh2_userkey *ret; |
541 | int cipher, cipherblk; |
542 | unsigned char *public_blob, *private_blob; |
543 | int public_blob_len, private_blob_len; |
5c72ca61 |
544 | int i, is_mac; |
545 | int passlen = passphrase ? strlen(passphrase) : 0; |
65a22376 |
546 | |
547 | ret = NULL; /* return NULL for most errors */ |
5c72ca61 |
548 | comment = mac = NULL; |
65a22376 |
549 | public_blob = private_blob = NULL; |
550 | |
551 | fp = fopen(filename, "rb"); |
552 | if (!fp) |
553 | goto error; |
554 | |
555 | /* Read the first header line which contains the key type. */ |
32874aea |
556 | if (!read_header(fp, header) |
557 | || 0 != strcmp(header, "PuTTY-User-Key-File-1")) |
65a22376 |
558 | goto error; |
559 | if ((b = read_body(fp)) == NULL) |
560 | goto error; |
5c72ca61 |
561 | /* Select key algorithm structure. */ |
65a22376 |
562 | if (!strcmp(b, "ssh-rsa")) |
563 | alg = &ssh_rsa; |
5c72ca61 |
564 | else if (!strcmp(b, "ssh-dss")) |
565 | alg = &ssh_dss; |
65a22376 |
566 | else { |
567 | sfree(b); |
568 | goto error; |
569 | } |
570 | sfree(b); |
32874aea |
571 | |
65a22376 |
572 | /* Read the Encryption header line. */ |
32874aea |
573 | if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) |
65a22376 |
574 | goto error; |
575 | if ((b = read_body(fp)) == NULL) |
576 | goto error; |
577 | if (!strcmp(b, "aes256-cbc")) { |
32874aea |
578 | cipher = 1; |
579 | cipherblk = 16; |
65a22376 |
580 | } else if (!strcmp(b, "none")) { |
32874aea |
581 | cipher = 0; |
582 | cipherblk = 1; |
65a22376 |
583 | } else { |
584 | sfree(b); |
585 | goto error; |
586 | } |
587 | sfree(b); |
588 | |
589 | /* Read the Comment header line. */ |
32874aea |
590 | if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) |
65a22376 |
591 | goto error; |
592 | if ((comment = read_body(fp)) == NULL) |
593 | goto error; |
594 | |
595 | /* Read the Public-Lines header line and the public blob. */ |
32874aea |
596 | if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines")) |
65a22376 |
597 | goto error; |
598 | if ((b = read_body(fp)) == NULL) |
599 | goto error; |
600 | i = atoi(b); |
601 | sfree(b); |
602 | if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL) |
603 | goto error; |
604 | |
605 | /* Read the Private-Lines header line and the Private blob. */ |
32874aea |
606 | if (!read_header(fp, header) || 0 != strcmp(header, "Private-Lines")) |
65a22376 |
607 | goto error; |
608 | if ((b = read_body(fp)) == NULL) |
609 | goto error; |
610 | i = atoi(b); |
611 | sfree(b); |
612 | if ((private_blob = read_blob(fp, i, &private_blob_len)) == NULL) |
613 | goto error; |
614 | |
5c72ca61 |
615 | /* Read the Private-MAC or Private-Hash header line. */ |
616 | if (!read_header(fp, header)) |
65a22376 |
617 | goto error; |
5c72ca61 |
618 | if (0 == strcmp(header, "Private-MAC")) { |
619 | if ((mac = read_body(fp)) == NULL) |
620 | goto error; |
621 | is_mac = 1; |
622 | } else if (0 == strcmp(header, "Private-Hash")) { |
623 | if ((mac = read_body(fp)) == NULL) |
624 | goto error; |
625 | is_mac = 0; |
626 | } else |
65a22376 |
627 | goto error; |
628 | |
629 | fclose(fp); |
630 | fp = NULL; |
631 | |
632 | /* |
633 | * Decrypt the private blob. |
634 | */ |
635 | if (cipher) { |
636 | unsigned char key[40]; |
637 | SHA_State s; |
65a22376 |
638 | |
639 | if (!passphrase) |
640 | goto error; |
641 | if (private_blob_len % cipherblk) |
642 | goto error; |
643 | |
65a22376 |
644 | SHA_Init(&s); |
645 | SHA_Bytes(&s, "\0\0\0\0", 4); |
646 | SHA_Bytes(&s, passphrase, passlen); |
32874aea |
647 | SHA_Final(&s, key + 0); |
65a22376 |
648 | SHA_Init(&s); |
649 | SHA_Bytes(&s, "\0\0\0\1", 4); |
650 | SHA_Bytes(&s, passphrase, passlen); |
32874aea |
651 | SHA_Final(&s, key + 20); |
65a22376 |
652 | aes256_decrypt_pubkey(key, private_blob, private_blob_len); |
653 | } |
654 | |
655 | /* |
656 | * Verify the private hash. |
657 | */ |
658 | { |
5c72ca61 |
659 | char realmac[41]; |
65a22376 |
660 | unsigned char binary[20]; |
65a22376 |
661 | |
5c72ca61 |
662 | if (is_mac) { |
663 | SHA_State s; |
664 | unsigned char mackey[20]; |
665 | char header[] = "putty-private-key-file-mac-key"; |
666 | |
667 | if (!passphrase) /* can't have MAC in unencrypted key */ |
668 | goto error; |
669 | |
670 | SHA_Init(&s); |
671 | SHA_Bytes(&s, header, sizeof(header)-1); |
672 | SHA_Bytes(&s, passphrase, passlen); |
673 | SHA_Final(&s, mackey); |
674 | |
675 | hmac_sha1_simple(mackey, 20, private_blob, private_blob_len, |
676 | binary); |
677 | |
678 | memset(mackey, 0, sizeof(mackey)); |
679 | memset(&s, 0, sizeof(s)); |
680 | } else { |
681 | SHA_Simple(private_blob, private_blob_len, binary); |
682 | } |
65a22376 |
683 | for (i = 0; i < 20; i++) |
5c72ca61 |
684 | sprintf(realmac + 2 * i, "%02x", binary[i]); |
65a22376 |
685 | |
5c72ca61 |
686 | if (strcmp(mac, realmac)) { |
687 | /* An incorrect MAC is an unconditional Error if the key is |
65a22376 |
688 | * unencrypted. Otherwise, it means Wrong Passphrase. */ |
689 | ret = cipher ? SSH2_WRONG_PASSPHRASE : NULL; |
690 | goto error; |
691 | } |
692 | } |
5c72ca61 |
693 | sfree(mac); |
65a22376 |
694 | |
695 | /* |
696 | * Create and return the key. |
697 | */ |
698 | ret = smalloc(sizeof(struct ssh2_userkey)); |
699 | ret->alg = alg; |
700 | ret->comment = comment; |
701 | ret->data = alg->createkey(public_blob, public_blob_len, |
702 | private_blob, private_blob_len); |
98f022f5 |
703 | if (!ret->data) { |
704 | sfree(ret->comment); |
705 | sfree(ret); |
706 | ret = NULL; |
707 | } |
65a22376 |
708 | sfree(public_blob); |
709 | sfree(private_blob); |
710 | return ret; |
711 | |
712 | /* |
713 | * Error processing. |
714 | */ |
32874aea |
715 | error: |
716 | if (fp) |
717 | fclose(fp); |
718 | if (comment) |
719 | sfree(comment); |
5c72ca61 |
720 | if (mac) |
721 | sfree(mac); |
32874aea |
722 | if (public_blob) |
723 | sfree(public_blob); |
724 | if (private_blob) |
725 | sfree(private_blob); |
65a22376 |
726 | return ret; |
727 | } |
728 | |
32874aea |
729 | char *ssh2_userkey_loadpub(char *filename, char **algorithm, |
730 | int *pub_blob_len) |
731 | { |
65a22376 |
732 | FILE *fp; |
733 | char header[40], *b; |
734 | const struct ssh_signkey *alg; |
65a22376 |
735 | unsigned char *public_blob; |
736 | int public_blob_len; |
737 | int i; |
738 | |
739 | public_blob = NULL; |
740 | |
741 | fp = fopen(filename, "rb"); |
742 | if (!fp) |
743 | goto error; |
744 | |
745 | /* Read the first header line which contains the key type. */ |
32874aea |
746 | if (!read_header(fp, header) |
747 | || 0 != strcmp(header, "PuTTY-User-Key-File-1")) |
65a22376 |
748 | goto error; |
749 | if ((b = read_body(fp)) == NULL) |
750 | goto error; |
751 | /* Select key algorithm structure. Currently only ssh-rsa. */ |
752 | if (!strcmp(b, "ssh-rsa")) |
753 | alg = &ssh_rsa; |
5c72ca61 |
754 | else if (!strcmp(b, "ssh-dss")) |
755 | alg = &ssh_dss; |
65a22376 |
756 | else { |
757 | sfree(b); |
758 | goto error; |
759 | } |
760 | sfree(b); |
32874aea |
761 | |
65a22376 |
762 | /* Read the Encryption header line. */ |
32874aea |
763 | if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) |
65a22376 |
764 | goto error; |
765 | if ((b = read_body(fp)) == NULL) |
766 | goto error; |
767 | sfree(b); /* we don't care */ |
768 | |
769 | /* Read the Comment header line. */ |
32874aea |
770 | if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) |
65a22376 |
771 | goto error; |
772 | if ((b = read_body(fp)) == NULL) |
773 | goto error; |
774 | sfree(b); /* we don't care */ |
775 | |
776 | /* Read the Public-Lines header line and the public blob. */ |
32874aea |
777 | if (!read_header(fp, header) || 0 != strcmp(header, "Public-Lines")) |
65a22376 |
778 | goto error; |
779 | if ((b = read_body(fp)) == NULL) |
780 | goto error; |
781 | i = atoi(b); |
782 | sfree(b); |
783 | if ((public_blob = read_blob(fp, i, &public_blob_len)) == NULL) |
784 | goto error; |
785 | |
786 | fclose(fp); |
787 | *pub_blob_len = public_blob_len; |
788 | *algorithm = alg->name; |
789 | return public_blob; |
790 | |
791 | /* |
792 | * Error processing. |
793 | */ |
32874aea |
794 | error: |
795 | if (fp) |
796 | fclose(fp); |
797 | if (public_blob) |
798 | sfree(public_blob); |
65a22376 |
799 | return NULL; |
800 | } |
801 | |
32874aea |
802 | int ssh2_userkey_encrypted(char *filename, char **commentptr) |
803 | { |
65a22376 |
804 | FILE *fp; |
805 | char header[40], *b, *comment; |
806 | int ret; |
807 | |
32874aea |
808 | if (commentptr) |
809 | *commentptr = NULL; |
65a22376 |
810 | |
811 | fp = fopen(filename, "rb"); |
812 | if (!fp) |
813 | return 0; |
32874aea |
814 | if (!read_header(fp, header) |
815 | || 0 != strcmp(header, "PuTTY-User-Key-File-1")) { |
816 | fclose(fp); |
817 | return 0; |
65a22376 |
818 | } |
819 | if ((b = read_body(fp)) == NULL) { |
32874aea |
820 | fclose(fp); |
821 | return 0; |
65a22376 |
822 | } |
823 | sfree(b); /* we don't care about key type here */ |
824 | /* Read the Encryption header line. */ |
32874aea |
825 | if (!read_header(fp, header) || 0 != strcmp(header, "Encryption")) { |
826 | fclose(fp); |
827 | return 0; |
65a22376 |
828 | } |
829 | if ((b = read_body(fp)) == NULL) { |
32874aea |
830 | fclose(fp); |
831 | return 0; |
65a22376 |
832 | } |
833 | |
834 | /* Read the Comment header line. */ |
32874aea |
835 | if (!read_header(fp, header) || 0 != strcmp(header, "Comment")) { |
836 | fclose(fp); |
837 | sfree(b); |
838 | return 1; |
65a22376 |
839 | } |
840 | if ((comment = read_body(fp)) == NULL) { |
32874aea |
841 | fclose(fp); |
842 | sfree(b); |
843 | return 1; |
65a22376 |
844 | } |
845 | |
32874aea |
846 | if (commentptr) |
847 | *commentptr = comment; |
65a22376 |
848 | |
849 | fclose(fp); |
850 | if (!strcmp(b, "aes256-cbc")) |
851 | ret = 1; |
852 | else |
853 | ret = 0; |
854 | sfree(b); |
855 | return ret; |
856 | } |
857 | |
32874aea |
858 | int base64_lines(int datalen) |
859 | { |
65a22376 |
860 | /* When encoding, we use 64 chars/line, which equals 48 real chars. */ |
32874aea |
861 | return (datalen + 47) / 48; |
65a22376 |
862 | } |
863 | |
32874aea |
864 | void base64_encode_atom(unsigned char *data, int n, char *out) |
865 | { |
65a22376 |
866 | static const char base64_chars[] = |
867 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
868 | |
869 | unsigned word; |
870 | |
871 | word = data[0] << 16; |
872 | if (n > 1) |
873 | word |= data[1] << 8; |
874 | if (n > 2) |
875 | word |= data[2]; |
876 | out[0] = base64_chars[(word >> 18) & 0x3F]; |
877 | out[1] = base64_chars[(word >> 12) & 0x3F]; |
878 | if (n > 1) |
879 | out[2] = base64_chars[(word >> 6) & 0x3F]; |
880 | else |
881 | out[2] = '='; |
882 | if (n > 2) |
883 | out[3] = base64_chars[word & 0x3F]; |
884 | else |
885 | out[3] = '='; |
886 | } |
887 | |
32874aea |
888 | void base64_encode(FILE * fp, unsigned char *data, int datalen) |
889 | { |
65a22376 |
890 | int linelen = 0; |
891 | char out[4]; |
892 | int n; |
893 | |
894 | while (datalen > 0) { |
895 | if (linelen >= 64) { |
896 | linelen = 0; |
897 | fputc('\n', fp); |
898 | } |
899 | n = (datalen < 3 ? datalen : 3); |
900 | base64_encode_atom(data, n, out); |
901 | data += n; |
902 | datalen -= n; |
903 | fwrite(out, 1, 4, fp); |
904 | linelen += 4; |
905 | } |
906 | fputc('\n', fp); |
907 | } |
908 | |
32874aea |
909 | int ssh2_save_userkey(char *filename, struct ssh2_userkey *key, |
910 | char *passphrase) |
911 | { |
65a22376 |
912 | FILE *fp; |
913 | unsigned char *pub_blob, *priv_blob, *priv_blob_encrypted; |
914 | int pub_blob_len, priv_blob_len, priv_encrypted_len; |
915 | int passlen; |
916 | int cipherblk; |
5c72ca61 |
917 | int i, is_mac; |
65a22376 |
918 | char *cipherstr; |
5c72ca61 |
919 | unsigned char priv_mac[20]; |
65a22376 |
920 | |
921 | /* |
922 | * Fetch the key component blobs. |
923 | */ |
924 | pub_blob = key->alg->public_blob(key->data, &pub_blob_len); |
925 | priv_blob = key->alg->private_blob(key->data, &priv_blob_len); |
926 | if (!pub_blob || !priv_blob) { |
927 | sfree(pub_blob); |
928 | sfree(priv_blob); |
929 | return 0; |
930 | } |
931 | |
932 | /* |
933 | * Determine encryption details, and encrypt the private blob. |
934 | */ |
935 | if (passphrase) { |
936 | cipherstr = "aes256-cbc"; |
937 | cipherblk = 16; |
938 | } else { |
939 | cipherstr = "none"; |
940 | cipherblk = 1; |
941 | } |
942 | priv_encrypted_len = priv_blob_len + cipherblk - 1; |
943 | priv_encrypted_len -= priv_encrypted_len % cipherblk; |
944 | priv_blob_encrypted = smalloc(priv_encrypted_len); |
945 | memset(priv_blob_encrypted, 0, priv_encrypted_len); |
946 | memcpy(priv_blob_encrypted, priv_blob, priv_blob_len); |
947 | /* Create padding based on the SHA hash of the unpadded blob. This prevents |
948 | * too easy a known-plaintext attack on the last block. */ |
5c72ca61 |
949 | SHA_Simple(priv_blob, priv_blob_len, priv_mac); |
65a22376 |
950 | assert(priv_encrypted_len - priv_blob_len < 20); |
5c72ca61 |
951 | memcpy(priv_blob_encrypted + priv_blob_len, priv_mac, |
65a22376 |
952 | priv_encrypted_len - priv_blob_len); |
953 | |
5c72ca61 |
954 | /* Now create the private MAC. */ |
955 | if (passphrase) { |
956 | SHA_State s; |
957 | unsigned char mackey[20]; |
958 | char header[] = "putty-private-key-file-mac-key"; |
959 | |
960 | passlen = strlen(passphrase); |
961 | |
962 | SHA_Init(&s); |
963 | SHA_Bytes(&s, header, sizeof(header)-1); |
964 | SHA_Bytes(&s, passphrase, passlen); |
965 | SHA_Final(&s, mackey); |
966 | |
967 | hmac_sha1_simple(mackey, 20, |
968 | priv_blob_encrypted, priv_encrypted_len, |
969 | priv_mac); |
970 | is_mac = 1; |
971 | |
972 | memset(mackey, 0, sizeof(mackey)); |
973 | memset(&s, 0, sizeof(s)); |
974 | } else { |
975 | SHA_Simple(priv_blob_encrypted, priv_encrypted_len, priv_mac); |
976 | is_mac = 0; |
977 | } |
65a22376 |
978 | |
979 | if (passphrase) { |
980 | char key[40]; |
981 | SHA_State s; |
982 | |
983 | passlen = strlen(passphrase); |
984 | |
985 | SHA_Init(&s); |
986 | SHA_Bytes(&s, "\0\0\0\0", 4); |
987 | SHA_Bytes(&s, passphrase, passlen); |
32874aea |
988 | SHA_Final(&s, key + 0); |
65a22376 |
989 | SHA_Init(&s); |
990 | SHA_Bytes(&s, "\0\0\0\1", 4); |
991 | SHA_Bytes(&s, passphrase, passlen); |
32874aea |
992 | SHA_Final(&s, key + 20); |
993 | aes256_encrypt_pubkey(key, priv_blob_encrypted, |
994 | priv_encrypted_len); |
5c72ca61 |
995 | |
996 | memset(key, 0, sizeof(key)); |
997 | memset(&s, 0, sizeof(s)); |
65a22376 |
998 | } |
999 | |
1000 | fp = fopen(filename, "w"); |
1001 | if (!fp) |
1002 | return 0; |
1003 | fprintf(fp, "PuTTY-User-Key-File-1: %s\n", key->alg->name); |
1004 | fprintf(fp, "Encryption: %s\n", cipherstr); |
1005 | fprintf(fp, "Comment: %s\n", key->comment); |
1006 | fprintf(fp, "Public-Lines: %d\n", base64_lines(pub_blob_len)); |
1007 | base64_encode(fp, pub_blob, pub_blob_len); |
1008 | fprintf(fp, "Private-Lines: %d\n", base64_lines(priv_encrypted_len)); |
1009 | base64_encode(fp, priv_blob_encrypted, priv_encrypted_len); |
5c72ca61 |
1010 | if (is_mac) |
1011 | fprintf(fp, "Private-MAC: "); |
1012 | else |
1013 | fprintf(fp, "Private-Hash: "); |
65a22376 |
1014 | for (i = 0; i < 20; i++) |
5c72ca61 |
1015 | fprintf(fp, "%02x", priv_mac[i]); |
65a22376 |
1016 | fprintf(fp, "\n"); |
1017 | fclose(fp); |
1018 | return 1; |
1019 | } |
1020 | |
1021 | /* ---------------------------------------------------------------------- |
1022 | * A function to determine which version of SSH to try on a private |
1023 | * key file. Returns 0 on failure, 1 or 2 on success. |
1024 | */ |
32874aea |
1025 | int keyfile_version(char *filename) |
1026 | { |
65a22376 |
1027 | FILE *fp; |
1028 | int i; |
1029 | |
1030 | fp = fopen(filename, "r"); |
1031 | if (!fp) |
1032 | return 0; |
1033 | i = fgetc(fp); |
1034 | fclose(fp); |
1035 | if (i == 'S') |
1036 | return 1; /* "SSH PRIVATE KEY FORMAT" etc */ |
1037 | if (i == 'P') /* "PuTTY-User-Key-File" etc */ |
1038 | return 2; |
1039 | return 0; /* unrecognised or EOF */ |
1040 | } |