forked from yath/android_external_dropbear
-
Notifications
You must be signed in to change notification settings - Fork 32
/
keyimport.c
1693 lines (1502 loc) · 42.8 KB
/
keyimport.c
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/*
* Based on PuTTY's import.c for importing/exporting OpenSSH and SSH.com
* keyfiles.
*
* The horribleness of the code is probably mine (matt).
*
* Modifications copyright 2003 Matt Johnston
*
* PuTTY is copyright 1997-2003 Simon Tatham.
*
* Portions copyright Robert de Bath, Joris van Rantwijk, Delian
* Delchev, Andreas Schultz, Jeroen Massar, Wez Furlong, Nicolas Barry,
* Justin Bradford, and CORE SDI S.A.
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation files
* (the "Software"), to deal in the Software without restriction,
* including without limitation the rights to use, copy, modify, merge,
* publish, distribute, sublicense, and/or sell copies of the Software,
* and to permit persons to whom the Software is furnished to do so,
* subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE
* FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "keyimport.h"
#include "bignum.h"
#include "buffer.h"
#include "dbutil.h"
#define PUT_32BIT(cp, value) do { \
(cp)[3] = (unsigned char)(value); \
(cp)[2] = (unsigned char)((value) >> 8); \
(cp)[1] = (unsigned char)((value) >> 16); \
(cp)[0] = (unsigned char)((value) >> 24); } while (0)
#define GET_32BIT(cp) \
(((unsigned long)(unsigned char)(cp)[0] << 24) | \
((unsigned long)(unsigned char)(cp)[1] << 16) | \
((unsigned long)(unsigned char)(cp)[2] << 8) | \
((unsigned long)(unsigned char)(cp)[3]))
static int openssh_encrypted(const char *filename);
static sign_key *openssh_read(const char *filename, char *passphrase);
static int openssh_write(const char *filename, sign_key *key,
char *passphrase);
static int dropbear_write(const char*filename, sign_key * key);
static sign_key *dropbear_read(const char* filename);
#if 0
static int sshcom_encrypted(const char *filename, char **comment);
static struct ssh2_userkey *sshcom_read(const char *filename, char *passphrase);
static int sshcom_write(const char *filename, struct ssh2_userkey *key,
char *passphrase);
#endif
int import_encrypted(const char* filename, int filetype) {
if (filetype == KEYFILE_OPENSSH) {
return openssh_encrypted(filename);
#if 0
} else if (filetype == KEYFILE_SSHCOM) {
return sshcom_encrypted(filename, NULL);
#endif
}
return 0;
}
sign_key *import_read(const char *filename, char *passphrase, int filetype) {
if (filetype == KEYFILE_OPENSSH) {
return openssh_read(filename, passphrase);
} else if (filetype == KEYFILE_DROPBEAR) {
return dropbear_read(filename);
#if 0
} else if (filetype == KEYFILE_SSHCOM) {
return sshcom_read(filename, passphrase);
#endif
}
return NULL;
}
int import_write(const char *filename, sign_key *key, char *passphrase,
int filetype) {
if (filetype == KEYFILE_OPENSSH) {
return openssh_write(filename, key, passphrase);
} else if (filetype == KEYFILE_DROPBEAR) {
return dropbear_write(filename, key);
#if 0
} else if (filetype == KEYFILE_SSHCOM) {
return sshcom_write(filename, key, passphrase);
#endif
}
return 0;
}
static sign_key *dropbear_read(const char* filename) {
buffer * buf = NULL;
sign_key *ret = NULL;
int type;
buf = buf_new(MAX_PRIVKEY_SIZE);
if (buf_readfile(buf, filename) == DROPBEAR_FAILURE) {
goto error;
}
buf_setpos(buf, 0);
ret = new_sign_key();
type = DROPBEAR_SIGNKEY_ANY;
if (buf_get_priv_key(buf, ret, &type) == DROPBEAR_FAILURE){
goto error;
}
buf_free(buf);
return ret;
error:
if (buf) {
buf_free(buf);
}
if (ret) {
sign_key_free(ret);
}
return NULL;
}
/* returns 0 on fail, 1 on success */
static int dropbear_write(const char*filename, sign_key * key) {
int keytype = -1;
buffer * buf;
FILE*fp;
int len;
int ret;
#ifdef DROPBEAR_RSA
if (key->rsakey != NULL) {
keytype = DROPBEAR_SIGNKEY_RSA;
}
#endif
#ifdef DROPBEAR_DSS
if (key->dsskey != NULL) {
keytype = DROPBEAR_SIGNKEY_DSS;
}
#endif
buf = buf_new(MAX_PRIVKEY_SIZE);
buf_put_priv_key(buf, key, keytype);
fp = fopen(filename, "w");
if (!fp) {
ret = 0;
goto out;
}
buf_setpos(buf, 0);
do {
len = fwrite(buf_getptr(buf, buf->len - buf->pos),
1, buf->len - buf->pos, fp);
buf_incrpos(buf, len);
} while (len > 0 && buf->len != buf->pos);
fclose(fp);
if (buf->pos != buf->len) {
ret = 0;
} else {
ret = 1;
}
out:
buf_free(buf);
return ret;
}
/* ----------------------------------------------------------------------
* Helper routines. (The base64 ones are defined in sshpubk.c.)
*/
#define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \
((c) >= 'a' && (c) <= 'z') || \
((c) >= '0' && (c) <= '9') || \
(c) == '+' || (c) == '/' || (c) == '=' \
)
/* cpl has to be less than 100 */
static void base64_encode_fp(FILE * fp, unsigned char *data,
int datalen, int cpl)
{
char out[100];
int n;
unsigned long outlen;
int rawcpl;
rawcpl = cpl * 3 / 4;
dropbear_assert((unsigned int)cpl < sizeof(out));
while (datalen > 0) {
n = (datalen < rawcpl ? datalen : rawcpl);
outlen = sizeof(out);
base64_encode(data, n, out, &outlen);
data += n;
datalen -= n;
fwrite(out, 1, outlen, fp);
fputc('\n', fp);
}
}
/*
* Read an ASN.1/BER identifier and length pair.
*
* Flags are a combination of the #defines listed below.
*
* Returns -1 if unsuccessful; otherwise returns the number of
* bytes used out of the source data.
*/
/* ASN.1 tag classes. */
#define ASN1_CLASS_UNIVERSAL (0 << 6)
#define ASN1_CLASS_APPLICATION (1 << 6)
#define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6)
#define ASN1_CLASS_PRIVATE (3 << 6)
#define ASN1_CLASS_MASK (3 << 6)
/* Primitive versus constructed bit. */
#define ASN1_CONSTRUCTED (1 << 5)
static int ber_read_id_len(void *source, int sourcelen,
int *id, int *length, int *flags)
{
unsigned char *p = (unsigned char *) source;
if (sourcelen == 0)
return -1;
*flags = (*p & 0xE0);
if ((*p & 0x1F) == 0x1F) {
*id = 0;
while (*p & 0x80) {
*id = (*id << 7) | (*p & 0x7F);
p++, sourcelen--;
if (sourcelen == 0)
return -1;
}
*id = (*id << 7) | (*p & 0x7F);
p++, sourcelen--;
} else {
*id = *p & 0x1F;
p++, sourcelen--;
}
if (sourcelen == 0)
return -1;
if (*p & 0x80) {
int n = *p & 0x7F;
p++, sourcelen--;
if (sourcelen < n)
return -1;
*length = 0;
while (n--)
*length = (*length << 8) | (*p++);
sourcelen -= n;
} else {
*length = *p;
p++, sourcelen--;
}
return p - (unsigned char *) source;
}
/*
* Write an ASN.1/BER identifier and length pair. Returns the
* number of bytes consumed. Assumes dest contains enough space.
* Will avoid writing anything if dest is NULL, but still return
* amount of space required.
*/
static int ber_write_id_len(void *dest, int id, int length, int flags)
{
unsigned char *d = (unsigned char *)dest;
int len = 0;
if (id <= 30) {
/*
* Identifier is one byte.
*/
len++;
if (d) *d++ = id | flags;
} else {
int n;
/*
* Identifier is multiple bytes: the first byte is 11111
* plus the flags, and subsequent bytes encode the value of
* the identifier, 7 bits at a time, with the top bit of
* each byte 1 except the last one which is 0.
*/
len++;
if (d) *d++ = 0x1F | flags;
for (n = 1; (id >> (7*n)) > 0; n++)
continue; /* count the bytes */
while (n--) {
len++;
if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F);
}
}
if (length < 128) {
/*
* Length is one byte.
*/
len++;
if (d) *d++ = length;
} else {
int n;
/*
* Length is multiple bytes. The first is 0x80 plus the
* number of subsequent bytes, and the subsequent bytes
* encode the actual length.
*/
for (n = 1; (length >> (8*n)) > 0; n++)
continue; /* count the bytes */
len++;
if (d) *d++ = 0x80 | n;
while (n--) {
len++;
if (d) *d++ = (length >> (8*n)) & 0xFF;
}
}
return len;
}
/* Simple structure to point to an mp-int within a blob. */
struct mpint_pos { void *start; int bytes; };
/* ----------------------------------------------------------------------
* Code to read and write OpenSSH private keys.
*/
enum { OSSH_DSA, OSSH_RSA };
struct openssh_key {
int type;
int encrypted;
char iv[32];
unsigned char *keyblob;
unsigned int keyblob_len, keyblob_size;
};
static struct openssh_key *load_openssh_key(const char *filename)
{
struct openssh_key *ret;
FILE *fp = NULL;
char buffer[256];
char *errmsg = NULL, *p = NULL;
int headers_done;
unsigned long len, outlen;
ret = (struct openssh_key*)m_malloc(sizeof(struct openssh_key));
ret->keyblob = NULL;
ret->keyblob_len = ret->keyblob_size = 0;
ret->encrypted = 0;
memset(ret->iv, 0, sizeof(ret->iv));
if (strlen(filename) == 1 && filename[0] == '-') {
fp = stdin;
} else {
fp = fopen(filename, "r");
}
if (!fp) {
errmsg = "Unable to open key file";
goto error;
}
if (!fgets(buffer, sizeof(buffer), fp) ||
0 != strncmp(buffer, "-----BEGIN ", 11) ||
0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) {
errmsg = "File does not begin with OpenSSH key header";
goto error;
}
if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n"))
ret->type = OSSH_RSA;
else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n"))
ret->type = OSSH_DSA;
else {
errmsg = "Unrecognised key type";
goto error;
}
headers_done = 0;
while (1) {
if (!fgets(buffer, sizeof(buffer), fp)) {
errmsg = "Unexpected end of file";
goto error;
}
if (0 == strncmp(buffer, "-----END ", 9) &&
0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n"))
break; /* done */
if ((p = strchr(buffer, ':')) != NULL) {
if (headers_done) {
errmsg = "Header found in body of key data";
goto error;
}
*p++ = '\0';
while (*p && isspace((unsigned char)*p)) p++;
if (!strcmp(buffer, "Proc-Type")) {
if (p[0] != '4' || p[1] != ',') {
errmsg = "Proc-Type is not 4 (only 4 is supported)";
goto error;
}
p += 2;
if (!strcmp(p, "ENCRYPTED\n"))
ret->encrypted = 1;
} else if (!strcmp(buffer, "DEK-Info")) {
int i, j;
if (strncmp(p, "DES-EDE3-CBC,", 13)) {
errmsg = "Ciphers other than DES-EDE3-CBC not supported";
goto error;
}
p += 13;
for (i = 0; i < 8; i++) {
if (1 != sscanf(p, "%2x", &j))
break;
ret->iv[i] = j;
p += 2;
}
if (i < 8) {
errmsg = "Expected 16-digit iv in DEK-Info";
goto error;
}
}
} else {
headers_done = 1;
len = strlen(buffer);
outlen = len*4/3;
if (ret->keyblob_len + outlen > ret->keyblob_size) {
ret->keyblob_size = ret->keyblob_len + outlen + 256;
ret->keyblob = (unsigned char*)m_realloc(ret->keyblob,
ret->keyblob_size);
}
outlen = ret->keyblob_size - ret->keyblob_len;
if (base64_decode(buffer, len,
ret->keyblob + ret->keyblob_len, &outlen) != CRYPT_OK){
errmsg = "Error decoding base64";
goto error;
}
ret->keyblob_len += outlen;
}
}
if (ret->keyblob_len == 0 || !ret->keyblob) {
errmsg = "Key body not present";
goto error;
}
if (ret->encrypted && ret->keyblob_len % 8 != 0) {
errmsg = "Encrypted key blob is not a multiple of cipher block size";
goto error;
}
memset(buffer, 0, sizeof(buffer));
return ret;
error:
memset(buffer, 0, sizeof(buffer));
if (ret) {
if (ret->keyblob) {
memset(ret->keyblob, 0, ret->keyblob_size);
m_free(ret->keyblob);
}
memset(&ret, 0, sizeof(ret));
m_free(ret);
}
if (fp) {
fclose(fp);
}
if (errmsg) {
fprintf(stderr, "Error: %s\n", errmsg);
}
return NULL;
}
static int openssh_encrypted(const char *filename)
{
struct openssh_key *key = load_openssh_key(filename);
int ret;
if (!key)
return 0;
ret = key->encrypted;
memset(key->keyblob, 0, key->keyblob_size);
m_free(key->keyblob);
memset(&key, 0, sizeof(key));
m_free(key);
return ret;
}
static sign_key *openssh_read(const char *filename, char *passphrase)
{
struct openssh_key *key;
unsigned char *p;
int ret, id, len, flags;
int i, num_integers = 0;
sign_key *retval = NULL;
char *errmsg;
char *modptr = NULL;
int modlen = -9999;
int type;
sign_key *retkey;
buffer * blobbuf = NULL;
key = load_openssh_key(filename);
if (!key)
return NULL;
if (key->encrypted) {
errmsg = "encrypted keys not supported currently";
goto error;
#if 0
/* matt TODO */
/*
* Derive encryption key from passphrase and iv/salt:
*
* - let block A equal MD5(passphrase || iv)
* - let block B equal MD5(A || passphrase || iv)
* - block C would be MD5(B || passphrase || iv) and so on
* - encryption key is the first N bytes of A || B
*/
struct MD5Context md5c;
unsigned char keybuf[32];
MD5Init(&md5c);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Update(&md5c, (unsigned char *)key->iv, 8);
MD5Final(keybuf, &md5c);
MD5Init(&md5c);
MD5Update(&md5c, keybuf, 16);
MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
MD5Update(&md5c, (unsigned char *)key->iv, 8);
MD5Final(keybuf+16, &md5c);
/*
* Now decrypt the key blob.
*/
des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv,
key->keyblob, key->keyblob_len);
memset(&md5c, 0, sizeof(md5c));
memset(keybuf, 0, sizeof(keybuf));
#endif
}
/*
* Now we have a decrypted key blob, which contains an ASN.1
* encoded private key. We must now untangle the ASN.1.
*
* We expect the whole key blob to be formatted as a SEQUENCE
* (0x30 followed by a length code indicating that the rest of
* the blob is part of the sequence). Within that SEQUENCE we
* expect to see a bunch of INTEGERs. What those integers mean
* depends on the key type:
*
* - For RSA, we expect the integers to be 0, n, e, d, p, q,
* dmp1, dmq1, iqmp in that order. (The last three are d mod
* (p-1), d mod (q-1), inverse of q mod p respectively.)
*
* - For DSA, we expect them to be 0, p, q, g, y, x in that
* order.
*/
p = key->keyblob;
/* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */
ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
p += ret;
if (ret < 0 || id != 16) {
errmsg = "ASN.1 decoding failure - wrong password?";
goto error;
}
/* Expect a load of INTEGERs. */
if (key->type == OSSH_RSA)
num_integers = 9;
else if (key->type == OSSH_DSA)
num_integers = 6;
/*
* Space to create key blob in.
*/
blobbuf = buf_new(3000);
if (key->type == OSSH_DSA) {
buf_putstring(blobbuf, "ssh-dss", 7);
} else if (key->type == OSSH_RSA) {
buf_putstring(blobbuf, "ssh-rsa", 7);
}
for (i = 0; i < num_integers; i++) {
ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
&id, &len, &flags);
p += ret;
if (ret < 0 || id != 2 ||
key->keyblob+key->keyblob_len-p < len) {
errmsg = "ASN.1 decoding failure";
goto error;
}
if (i == 0) {
/*
* The first integer should be zero always (I think
* this is some sort of version indication).
*/
if (len != 1 || p[0] != 0) {
errmsg = "Version number mismatch";
goto error;
}
} else if (key->type == OSSH_RSA) {
/*
* OpenSSH key order is n, e, d, p, q, dmp1, dmq1, iqmp
* but we want e, n, d, p, q
*/
if (i == 1) {
/* Save the details for after we deal with number 2. */
modptr = (char *)p;
modlen = len;
} else if (i >= 2 && i <= 5) {
buf_putstring(blobbuf, p, len);
if (i == 2) {
buf_putstring(blobbuf, modptr, modlen);
}
}
} else if (key->type == OSSH_DSA) {
/*
* OpenSSH key order is p, q, g, y, x,
* we want the same.
*/
buf_putstring(blobbuf, p, len);
}
/* Skip past the number. */
p += len;
}
/*
* Now put together the actual key. Simplest way to do this is
* to assemble our own key blobs and feed them to the createkey
* functions; this is a bit faffy but it does mean we get all
* the sanity checks for free.
*/
retkey = new_sign_key();
buf_setpos(blobbuf, 0);
type = DROPBEAR_SIGNKEY_ANY;
if (buf_get_priv_key(blobbuf, retkey, &type)
!= DROPBEAR_SUCCESS) {
errmsg = "unable to create key structure";
sign_key_free(retkey);
retkey = NULL;
goto error;
}
errmsg = NULL; /* no error */
retval = retkey;
error:
if (blobbuf) {
buf_burn(blobbuf);
buf_free(blobbuf);
}
m_burn(key->keyblob, key->keyblob_size);
m_free(key->keyblob);
m_burn(key, sizeof(key));
m_free(key);
if (errmsg) {
fprintf(stderr, "Error: %s\n", errmsg);
}
return retval;
}
static int openssh_write(const char *filename, sign_key *key,
char *passphrase)
{
buffer * keyblob = NULL;
buffer * extrablob = NULL; /* used for calculated values to write */
unsigned char *outblob = NULL;
int outlen = -9999;
struct mpint_pos numbers[9];
int nnumbers = -1, pos, len, seqlen, i;
char *header = NULL, *footer = NULL;
char zero[1];
unsigned char iv[8];
int ret = 0;
FILE *fp;
int keytype = -1;
#ifdef DROPBEAR_RSA
mp_int dmp1, dmq1, iqmp, tmpval; /* for rsa */
if (key->rsakey != NULL) {
keytype = DROPBEAR_SIGNKEY_RSA;
}
#endif
#ifdef DROPBEAR_DSS
if (key->dsskey != NULL) {
keytype = DROPBEAR_SIGNKEY_DSS;
}
#endif
dropbear_assert(keytype != -1);
/*
* Fetch the key blobs.
*/
keyblob = buf_new(3000);
buf_put_priv_key(keyblob, key, keytype);
buf_setpos(keyblob, 0);
/* skip the "ssh-rsa" or "ssh-dss" header */
buf_incrpos(keyblob, buf_getint(keyblob));
/*
* Find the sequence of integers to be encoded into the OpenSSH
* key blob, and also decide on the header line.
*/
numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
#ifdef DROPBEAR_RSA
if (keytype == DROPBEAR_SIGNKEY_RSA) {
if (key->rsakey->p == NULL || key->rsakey->q == NULL) {
fprintf(stderr, "Pre-0.33 Dropbear keys cannot be converted to OpenSSH keys.\n");
goto error;
}
/* e */
numbers[2].bytes = buf_getint(keyblob);
numbers[2].start = buf_getptr(keyblob, numbers[2].bytes);
buf_incrpos(keyblob, numbers[2].bytes);
/* n */
numbers[1].bytes = buf_getint(keyblob);
numbers[1].start = buf_getptr(keyblob, numbers[1].bytes);
buf_incrpos(keyblob, numbers[1].bytes);
/* d */
numbers[3].bytes = buf_getint(keyblob);
numbers[3].start = buf_getptr(keyblob, numbers[3].bytes);
buf_incrpos(keyblob, numbers[3].bytes);
/* p */
numbers[4].bytes = buf_getint(keyblob);
numbers[4].start = buf_getptr(keyblob, numbers[4].bytes);
buf_incrpos(keyblob, numbers[4].bytes);
/* q */
numbers[5].bytes = buf_getint(keyblob);
numbers[5].start = buf_getptr(keyblob, numbers[5].bytes);
buf_incrpos(keyblob, numbers[5].bytes);
/* now calculate some extra parameters: */
m_mp_init(&tmpval);
m_mp_init(&dmp1);
m_mp_init(&dmq1);
m_mp_init(&iqmp);
/* dmp1 = d mod (p-1) */
if (mp_sub_d(key->rsakey->p, 1, &tmpval) != MP_OKAY) {
fprintf(stderr, "Bignum error for p-1\n");
goto error;
}
if (mp_mod(key->rsakey->d, &tmpval, &dmp1) != MP_OKAY) {
fprintf(stderr, "Bignum error for dmp1\n");
goto error;
}
/* dmq1 = d mod (q-1) */
if (mp_sub_d(key->rsakey->q, 1, &tmpval) != MP_OKAY) {
fprintf(stderr, "Bignum error for q-1\n");
goto error;
}
if (mp_mod(key->rsakey->d, &tmpval, &dmq1) != MP_OKAY) {
fprintf(stderr, "Bignum error for dmq1\n");
goto error;
}
/* iqmp = (q^-1) mod p */
if (mp_invmod(key->rsakey->q, key->rsakey->p, &iqmp) != MP_OKAY) {
fprintf(stderr, "Bignum error for iqmp\n");
goto error;
}
extrablob = buf_new(2000);
buf_putmpint(extrablob, &dmp1);
buf_putmpint(extrablob, &dmq1);
buf_putmpint(extrablob, &iqmp);
buf_setpos(extrablob, 0);
mp_clear(&dmp1);
mp_clear(&dmq1);
mp_clear(&iqmp);
mp_clear(&tmpval);
/* dmp1 */
numbers[6].bytes = buf_getint(extrablob);
numbers[6].start = buf_getptr(extrablob, numbers[6].bytes);
buf_incrpos(extrablob, numbers[6].bytes);
/* dmq1 */
numbers[7].bytes = buf_getint(extrablob);
numbers[7].start = buf_getptr(extrablob, numbers[7].bytes);
buf_incrpos(extrablob, numbers[7].bytes);
/* iqmp */
numbers[8].bytes = buf_getint(extrablob);
numbers[8].start = buf_getptr(extrablob, numbers[8].bytes);
buf_incrpos(extrablob, numbers[8].bytes);
nnumbers = 9;
header = "-----BEGIN RSA PRIVATE KEY-----\n";
footer = "-----END RSA PRIVATE KEY-----\n";
}
#endif /* DROPBEAR_RSA */
#ifdef DROPBEAR_DSS
if (keytype == DROPBEAR_SIGNKEY_DSS) {
/* p */
numbers[1].bytes = buf_getint(keyblob);
numbers[1].start = buf_getptr(keyblob, numbers[1].bytes);
buf_incrpos(keyblob, numbers[1].bytes);
/* q */
numbers[2].bytes = buf_getint(keyblob);
numbers[2].start = buf_getptr(keyblob, numbers[2].bytes);
buf_incrpos(keyblob, numbers[2].bytes);
/* g */
numbers[3].bytes = buf_getint(keyblob);
numbers[3].start = buf_getptr(keyblob, numbers[3].bytes);
buf_incrpos(keyblob, numbers[3].bytes);
/* y */
numbers[4].bytes = buf_getint(keyblob);
numbers[4].start = buf_getptr(keyblob, numbers[4].bytes);
buf_incrpos(keyblob, numbers[4].bytes);
/* x */
numbers[5].bytes = buf_getint(keyblob);
numbers[5].start = buf_getptr(keyblob, numbers[5].bytes);
buf_incrpos(keyblob, numbers[5].bytes);
nnumbers = 6;
header = "-----BEGIN DSA PRIVATE KEY-----\n";
footer = "-----END DSA PRIVATE KEY-----\n";
}
#endif /* DROPBEAR_DSS */
/*
* Now count up the total size of the ASN.1 encoded integers,
* so as to determine the length of the containing SEQUENCE.
*/
len = 0;
for (i = 0; i < nnumbers; i++) {
len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
len += numbers[i].bytes;
}
seqlen = len;
/* Now add on the SEQUENCE header. */
len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
/* Round up to the cipher block size, ensuring we have at least one
* byte of padding (see below). */
outlen = len;
if (passphrase)
outlen = (outlen+8) &~ 7;
/*
* Now we know how big outblob needs to be. Allocate it.
*/
outblob = (unsigned char*)m_malloc(outlen);
/*
* And write the data into it.
*/
pos = 0;
pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
for (i = 0; i < nnumbers; i++) {
pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
pos += numbers[i].bytes;
}
/*
* Padding on OpenSSH keys is deterministic. The number of
* padding bytes is always more than zero, and always at most
* the cipher block length. The value of each padding byte is
* equal to the number of padding bytes. So a plaintext that's
* an exact multiple of the block size will be padded with 08
* 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
* plaintext one byte less than a multiple of the block size
* will be padded with just 01.
*
* This enables the OpenSSL key decryption function to strip
* off the padding algorithmically and return the unpadded
* plaintext to the next layer: it looks at the final byte, and
* then expects to find that many bytes at the end of the data
* with the same value. Those are all removed and the rest is
* returned.
*/
dropbear_assert(pos == len);
while (pos < outlen) {
outblob[pos++] = outlen - len;
}
/*
* Encrypt the key.
*/
if (passphrase) {
fprintf(stderr, "Encrypted keys aren't supported currently\n");
goto error;
}
/*
* And save it. We'll use Unix line endings just in case it's
* subsequently transferred in binary mode.
*/
if (strlen(filename) == 1 && filename[0] == '-') {
fp = stdout;
} else {
fp = fopen(filename, "wb"); /* ensure Unix line endings */
}
if (!fp) {
fprintf(stderr, "Failed opening output file\n");
goto error;
}
fputs(header, fp);
base64_encode_fp(fp, outblob, outlen, 64);
fputs(footer, fp);
fclose(fp);
ret = 1;
error:
if (outblob) {
memset(outblob, 0, outlen);
m_free(outblob);
}
if (keyblob) {
buf_burn(keyblob);
buf_free(keyblob);
}
if (extrablob) {
buf_burn(extrablob);
buf_free(extrablob);
}
return ret;
}
#if 0
/* XXX TODO ssh.com stuff isn't going yet */
/* ----------------------------------------------------------------------
* Code to read ssh.com private keys.
*/
/*
* The format of the base64 blob is largely ssh2-packet-formatted,
* except that mpints are a bit different: they're more like the
* old ssh1 mpint. You have a 32-bit bit count N, followed by
* (N+7)/8 bytes of data.
*
* So. The blob contains:
*
* - uint32 0x3f6ff9eb (magic number)
* - uint32 size (total blob size)
* - string key-type (see below)
* - string cipher-type (tells you if key is encrypted)
* - string encrypted-blob
*
* (The first size field includes the size field itself and the
* magic number before it. All other size fields are ordinary ssh2
* strings, so the size field indicates how much data is to
* _follow_.)
*
* The encrypted blob, once decrypted, contains a single string
* which in turn contains the payload. (This allows padding to be
* added after that string while still making it clear where the
* real payload ends. Also it probably makes for a reasonable
* decryption check.)
*