2 * Code for PuTTY to import and export private key files in other
\r
3 * SSH clients' formats.
\r
15 int openssh_encrypted(const Filename *filename);
\r
16 struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase,
\r
17 const char **errmsg_p);
\r
18 int openssh_write(const Filename *filename, struct ssh2_userkey *key,
\r
21 int sshcom_encrypted(const Filename *filename, char **comment);
\r
22 struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
\r
23 const char **errmsg_p);
\r
24 int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
\r
28 * Given a key type, determine whether we know how to import it.
\r
30 int import_possible(int type)
\r
32 if (type == SSH_KEYTYPE_OPENSSH)
\r
34 if (type == SSH_KEYTYPE_SSHCOM)
\r
40 * Given a key type, determine what native key type
\r
41 * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once
\r
42 * we've imported it.
\r
44 int import_target_type(int type)
\r
47 * There are no known foreign SSH-1 key formats.
\r
49 return SSH_KEYTYPE_SSH2;
\r
53 * Determine whether a foreign key is encrypted.
\r
55 int import_encrypted(const Filename *filename, int type, char **comment)
\r
57 if (type == SSH_KEYTYPE_OPENSSH) {
\r
58 /* OpenSSH doesn't do key comments */
\r
59 *comment = dupstr(filename_to_str(filename));
\r
60 return openssh_encrypted(filename);
\r
62 if (type == SSH_KEYTYPE_SSHCOM) {
\r
63 return sshcom_encrypted(filename, comment);
\r
69 * Import an SSH-1 key.
\r
71 int import_ssh1(const Filename *filename, int type,
\r
72 struct RSAKey *key, char *passphrase, const char **errmsg_p)
\r
78 * Import an SSH-2 key.
\r
80 struct ssh2_userkey *import_ssh2(const Filename *filename, int type,
\r
81 char *passphrase, const char **errmsg_p)
\r
83 if (type == SSH_KEYTYPE_OPENSSH)
\r
84 return openssh_read(filename, passphrase, errmsg_p);
\r
85 if (type == SSH_KEYTYPE_SSHCOM)
\r
86 return sshcom_read(filename, passphrase, errmsg_p);
\r
91 * Export an SSH-1 key.
\r
93 int export_ssh1(const Filename *filename, int type, struct RSAKey *key,
\r
100 * Export an SSH-2 key.
\r
102 int export_ssh2(const Filename *filename, int type,
\r
103 struct ssh2_userkey *key, char *passphrase)
\r
105 if (type == SSH_KEYTYPE_OPENSSH)
\r
106 return openssh_write(filename, key, passphrase);
\r
107 if (type == SSH_KEYTYPE_SSHCOM)
\r
108 return sshcom_write(filename, key, passphrase);
\r
113 * Strip trailing CRs and LFs at the end of a line of text.
\r
115 void strip_crlf(char *str)
\r
117 char *p = str + strlen(str);
\r
119 while (p > str && (p[-1] == '\r' || p[-1] == '\n'))
\r
123 /* ----------------------------------------------------------------------
\r
124 * Helper routines. (The base64 ones are defined in sshpubk.c.)
\r
127 #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \
\r
128 ((c) >= 'a' && (c) <= 'z') || \
\r
129 ((c) >= '0' && (c) <= '9') || \
\r
130 (c) == '+' || (c) == '/' || (c) == '=' \
\r
134 * Read an ASN.1/BER identifier and length pair.
\r
136 * Flags are a combination of the #defines listed below.
\r
138 * Returns -1 if unsuccessful; otherwise returns the number of
\r
139 * bytes used out of the source data.
\r
142 /* ASN.1 tag classes. */
\r
143 #define ASN1_CLASS_UNIVERSAL (0 << 6)
\r
144 #define ASN1_CLASS_APPLICATION (1 << 6)
\r
145 #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6)
\r
146 #define ASN1_CLASS_PRIVATE (3 << 6)
\r
147 #define ASN1_CLASS_MASK (3 << 6)
\r
149 /* Primitive versus constructed bit. */
\r
150 #define ASN1_CONSTRUCTED (1 << 5)
\r
152 static int ber_read_id_len(void *source, int sourcelen,
\r
153 int *id, int *length, int *flags)
\r
155 unsigned char *p = (unsigned char *) source;
\r
157 if (sourcelen == 0)
\r
160 *flags = (*p & 0xE0);
\r
161 if ((*p & 0x1F) == 0x1F) {
\r
163 while (*p & 0x80) {
\r
165 if (sourcelen == 0)
\r
167 *id = (*id << 7) | (*p & 0x7F);
\r
175 if (sourcelen == 0)
\r
185 *length = (*length << 8) | (*p++);
\r
192 return p - (unsigned char *) source;
\r
196 * Write an ASN.1/BER identifier and length pair. Returns the
\r
197 * number of bytes consumed. Assumes dest contains enough space.
\r
198 * Will avoid writing anything if dest is NULL, but still return
\r
199 * amount of space required.
\r
201 static int ber_write_id_len(void *dest, int id, int length, int flags)
\r
203 unsigned char *d = (unsigned char *)dest;
\r
208 * Identifier is one byte.
\r
211 if (d) *d++ = id | flags;
\r
215 * Identifier is multiple bytes: the first byte is 11111
\r
216 * plus the flags, and subsequent bytes encode the value of
\r
217 * the identifier, 7 bits at a time, with the top bit of
\r
218 * each byte 1 except the last one which is 0.
\r
221 if (d) *d++ = 0x1F | flags;
\r
222 for (n = 1; (id >> (7*n)) > 0; n++)
\r
223 continue; /* count the bytes */
\r
226 if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F);
\r
230 if (length < 128) {
\r
232 * Length is one byte.
\r
235 if (d) *d++ = length;
\r
239 * Length is multiple bytes. The first is 0x80 plus the
\r
240 * number of subsequent bytes, and the subsequent bytes
\r
241 * encode the actual length.
\r
243 for (n = 1; (length >> (8*n)) > 0; n++)
\r
244 continue; /* count the bytes */
\r
246 if (d) *d++ = 0x80 | n;
\r
249 if (d) *d++ = (length >> (8*n)) & 0xFF;
\r
256 static int put_string(void *target, void *data, int len)
\r
258 unsigned char *d = (unsigned char *)target;
\r
261 memcpy(d+4, data, len);
\r
265 static int put_mp(void *target, void *data, int len)
\r
267 unsigned char *d = (unsigned char *)target;
\r
268 unsigned char *i = (unsigned char *)data;
\r
271 PUT_32BIT(d, len+1);
\r
273 memcpy(d+5, data, len);
\r
277 memcpy(d+4, data, len);
\r
282 /* Simple structure to point to an mp-int within a blob. */
\r
283 struct mpint_pos { void *start; int bytes; };
\r
285 static int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret)
\r
288 unsigned char *d = (unsigned char *) data;
\r
292 bytes = toint(GET_32BIT(d));
\r
293 if (bytes < 0 || len-4 < bytes)
\r
296 ret->start = d + 4;
\r
297 ret->bytes = bytes;
\r
303 return len; /* ensure further calls fail as well */
\r
306 /* ----------------------------------------------------------------------
\r
307 * Code to read and write OpenSSH private keys.
\r
310 enum { OSSH_DSA, OSSH_RSA };
\r
311 enum { OSSH_ENC_3DES, OSSH_ENC_AES };
\r
312 struct openssh_key {
\r
314 int encrypted, encryption;
\r
316 unsigned char *keyblob;
\r
317 int keyblob_len, keyblob_size;
\r
320 static struct openssh_key *load_openssh_key(const Filename *filename,
\r
321 const char **errmsg_p)
\r
323 struct openssh_key *ret;
\r
328 char base64_bit[4];
\r
329 int base64_chars = 0;
\r
331 ret = snew(struct openssh_key);
\r
332 ret->keyblob = NULL;
\r
333 ret->keyblob_len = ret->keyblob_size = 0;
\r
334 ret->encrypted = 0;
\r
335 memset(ret->iv, 0, sizeof(ret->iv));
\r
337 fp = f_open(filename, "r", FALSE);
\r
339 errmsg = "unable to open key file";
\r
343 if (!(line = fgetline(fp))) {
\r
344 errmsg = "unexpected end of file";
\r
348 if (0 != strncmp(line, "-----BEGIN ", 11) ||
\r
349 0 != strcmp(line+strlen(line)-16, "PRIVATE KEY-----")) {
\r
350 errmsg = "file does not begin with OpenSSH key header";
\r
353 if (!strcmp(line, "-----BEGIN RSA PRIVATE KEY-----"))
\r
354 ret->type = OSSH_RSA;
\r
355 else if (!strcmp(line, "-----BEGIN DSA PRIVATE KEY-----"))
\r
356 ret->type = OSSH_DSA;
\r
358 errmsg = "unrecognised key type";
\r
361 smemclr(line, strlen(line));
\r
367 if (!(line = fgetline(fp))) {
\r
368 errmsg = "unexpected end of file";
\r
372 if (0 == strncmp(line, "-----END ", 9) &&
\r
373 0 == strcmp(line+strlen(line)-16, "PRIVATE KEY-----")) {
\r
378 if ((p = strchr(line, ':')) != NULL) {
\r
379 if (headers_done) {
\r
380 errmsg = "header found in body of key data";
\r
384 while (*p && isspace((unsigned char)*p)) p++;
\r
385 if (!strcmp(line, "Proc-Type")) {
\r
386 if (p[0] != '4' || p[1] != ',') {
\r
387 errmsg = "Proc-Type is not 4 (only 4 is supported)";
\r
391 if (!strcmp(p, "ENCRYPTED"))
\r
392 ret->encrypted = 1;
\r
393 } else if (!strcmp(line, "DEK-Info")) {
\r
396 if (!strncmp(p, "DES-EDE3-CBC,", 13)) {
\r
397 ret->encryption = OSSH_ENC_3DES;
\r
399 } else if (!strncmp(p, "AES-128-CBC,", 12)) {
\r
400 ret->encryption = OSSH_ENC_AES;
\r
403 errmsg = "unsupported cipher";
\r
406 p = strchr(p, ',') + 1;/* always non-NULL, by above checks */
\r
407 for (i = 0; i < ivlen; i++) {
\r
408 if (1 != sscanf(p, "%2x", &j)) {
\r
409 errmsg = "expected more iv data in DEK-Info";
\r
416 errmsg = "more iv data than expected in DEK-Info";
\r
424 while (isbase64(*p)) {
\r
425 base64_bit[base64_chars++] = *p;
\r
426 if (base64_chars == 4) {
\r
427 unsigned char out[3];
\r
432 len = base64_decode_atom(base64_bit, out);
\r
435 errmsg = "invalid base64 encoding";
\r
439 if (ret->keyblob_len + len > ret->keyblob_size) {
\r
440 ret->keyblob_size = ret->keyblob_len + len + 256;
\r
441 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
\r
445 memcpy(ret->keyblob + ret->keyblob_len, out, len);
\r
446 ret->keyblob_len += len;
\r
448 smemclr(out, sizeof(out));
\r
454 smemclr(line, strlen(line));
\r
462 if (ret->keyblob_len == 0 || !ret->keyblob) {
\r
463 errmsg = "key body not present";
\r
467 if (ret->encrypted && ret->keyblob_len % 8 != 0) {
\r
468 errmsg = "encrypted key blob is not a multiple of cipher block size";
\r
472 smemclr(base64_bit, sizeof(base64_bit));
\r
473 if (errmsg_p) *errmsg_p = NULL;
\r
478 smemclr(line, strlen(line));
\r
482 smemclr(base64_bit, sizeof(base64_bit));
\r
484 if (ret->keyblob) {
\r
485 smemclr(ret->keyblob, ret->keyblob_size);
\r
486 sfree(ret->keyblob);
\r
488 smemclr(ret, sizeof(*ret));
\r
491 if (errmsg_p) *errmsg_p = errmsg;
\r
492 if (fp) fclose(fp);
\r
496 int openssh_encrypted(const Filename *filename)
\r
498 struct openssh_key *key = load_openssh_key(filename, NULL);
\r
503 ret = key->encrypted;
\r
504 smemclr(key->keyblob, key->keyblob_size);
\r
505 sfree(key->keyblob);
\r
506 smemclr(key, sizeof(*key));
\r
511 struct ssh2_userkey *openssh_read(const Filename *filename, char *passphrase,
\r
512 const char **errmsg_p)
\r
514 struct openssh_key *key = load_openssh_key(filename, errmsg_p);
\r
515 struct ssh2_userkey *retkey;
\r
517 int ret, id, len, flags;
\r
518 int i, num_integers;
\r
519 struct ssh2_userkey *retval = NULL;
\r
521 unsigned char *blob;
\r
522 int blobsize = 0, blobptr, privptr;
\r
523 char *modptr = NULL;
\r
531 if (key->encrypted) {
\r
533 * Derive encryption key from passphrase and iv/salt:
\r
535 * - let block A equal MD5(passphrase || iv)
\r
536 * - let block B equal MD5(A || passphrase || iv)
\r
537 * - block C would be MD5(B || passphrase || iv) and so on
\r
538 * - encryption key is the first N bytes of A || B
\r
540 * (Note that only 8 bytes of the iv are used for key
\r
541 * derivation, even when the key is encrypted with AES and
\r
542 * hence there are 16 bytes available.)
\r
544 struct MD5Context md5c;
\r
545 unsigned char keybuf[32];
\r
548 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
\r
549 MD5Update(&md5c, (unsigned char *)key->iv, 8);
\r
550 MD5Final(keybuf, &md5c);
\r
553 MD5Update(&md5c, keybuf, 16);
\r
554 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
\r
555 MD5Update(&md5c, (unsigned char *)key->iv, 8);
\r
556 MD5Final(keybuf+16, &md5c);
\r
559 * Now decrypt the key blob.
\r
561 if (key->encryption == OSSH_ENC_3DES)
\r
562 des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv,
\r
563 key->keyblob, key->keyblob_len);
\r
566 assert(key->encryption == OSSH_ENC_AES);
\r
567 ctx = aes_make_context();
\r
568 aes128_key(ctx, keybuf);
\r
569 aes_iv(ctx, (unsigned char *)key->iv);
\r
570 aes_ssh2_decrypt_blk(ctx, key->keyblob, key->keyblob_len);
\r
571 aes_free_context(ctx);
\r
574 smemclr(&md5c, sizeof(md5c));
\r
575 smemclr(keybuf, sizeof(keybuf));
\r
579 * Now we have a decrypted key blob, which contains an ASN.1
\r
580 * encoded private key. We must now untangle the ASN.1.
\r
582 * We expect the whole key blob to be formatted as a SEQUENCE
\r
583 * (0x30 followed by a length code indicating that the rest of
\r
584 * the blob is part of the sequence). Within that SEQUENCE we
\r
585 * expect to see a bunch of INTEGERs. What those integers mean
\r
586 * depends on the key type:
\r
588 * - For RSA, we expect the integers to be 0, n, e, d, p, q,
\r
589 * dmp1, dmq1, iqmp in that order. (The last three are d mod
\r
590 * (p-1), d mod (q-1), inverse of q mod p respectively.)
\r
592 * - For DSA, we expect them to be 0, p, q, g, y, x in that
\r
598 /* Expect the SEQUENCE header. Take its absence as a failure to
\r
599 * decrypt, if the key was encrypted. */
\r
600 ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
\r
602 if (ret < 0 || id != 16) {
\r
603 errmsg = "ASN.1 decoding failure";
\r
604 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
\r
608 /* Expect a load of INTEGERs. */
\r
609 if (key->type == OSSH_RSA)
\r
611 else if (key->type == OSSH_DSA)
\r
614 num_integers = 0; /* placate compiler warnings */
\r
617 * Space to create key blob in.
\r
619 blobsize = 256+key->keyblob_len;
\r
620 blob = snewn(blobsize, unsigned char);
\r
621 PUT_32BIT(blob, 7);
\r
622 if (key->type == OSSH_DSA)
\r
623 memcpy(blob+4, "ssh-dss", 7);
\r
624 else if (key->type == OSSH_RSA)
\r
625 memcpy(blob+4, "ssh-rsa", 7);
\r
629 for (i = 0; i < num_integers; i++) {
\r
630 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
\r
631 &id, &len, &flags);
\r
633 if (ret < 0 || id != 2 ||
\r
634 key->keyblob+key->keyblob_len-p < len) {
\r
635 errmsg = "ASN.1 decoding failure";
\r
636 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
\r
642 * The first integer should be zero always (I think
\r
643 * this is some sort of version indication).
\r
645 if (len != 1 || p[0] != 0) {
\r
646 errmsg = "version number mismatch";
\r
649 } else if (key->type == OSSH_RSA) {
\r
651 * Integers 1 and 2 go into the public blob but in the
\r
652 * opposite order; integers 3, 4, 5 and 8 go into the
\r
653 * private blob. The other two (6 and 7) are ignored.
\r
656 /* Save the details for after we deal with number 2. */
\r
657 modptr = (char *)p;
\r
659 } else if (i != 6 && i != 7) {
\r
660 PUT_32BIT(blob+blobptr, len);
\r
661 memcpy(blob+blobptr+4, p, len);
\r
664 PUT_32BIT(blob+blobptr, modlen);
\r
665 memcpy(blob+blobptr+4, modptr, modlen);
\r
666 blobptr += 4+modlen;
\r
670 } else if (key->type == OSSH_DSA) {
\r
672 * Integers 1-4 go into the public blob; integer 5 goes
\r
673 * into the private blob.
\r
675 PUT_32BIT(blob+blobptr, len);
\r
676 memcpy(blob+blobptr+4, p, len);
\r
682 /* Skip past the number. */
\r
687 * Now put together the actual key. Simplest way to do this is
\r
688 * to assemble our own key blobs and feed them to the createkey
\r
689 * functions; this is a bit faffy but it does mean we get all
\r
690 * the sanity checks for free.
\r
692 assert(privptr > 0); /* should have bombed by now if not */
\r
693 retkey = snew(struct ssh2_userkey);
\r
694 retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss);
\r
695 retkey->data = retkey->alg->createkey(blob, privptr,
\r
696 blob+privptr, blobptr-privptr);
\r
697 if (!retkey->data) {
\r
699 errmsg = "unable to create key data structure";
\r
703 retkey->comment = dupstr("imported-openssh-key");
\r
704 errmsg = NULL; /* no error */
\r
709 smemclr(blob, blobsize);
\r
712 smemclr(key->keyblob, key->keyblob_size);
\r
713 sfree(key->keyblob);
\r
714 smemclr(key, sizeof(*key));
\r
716 if (errmsg_p) *errmsg_p = errmsg;
\r
720 int openssh_write(const Filename *filename, struct ssh2_userkey *key,
\r
723 unsigned char *pubblob, *privblob, *spareblob;
\r
724 int publen, privlen, sparelen = 0;
\r
725 unsigned char *outblob;
\r
727 struct mpint_pos numbers[9];
\r
728 int nnumbers, pos, len, seqlen, i;
\r
729 char *header, *footer;
\r
731 unsigned char iv[8];
\r
736 * Fetch the key blobs.
\r
738 pubblob = key->alg->public_blob(key->data, &publen);
\r
739 privblob = key->alg->private_blob(key->data, &privlen);
\r
740 spareblob = outblob = NULL;
\r
743 * Find the sequence of integers to be encoded into the OpenSSH
\r
744 * key blob, and also decide on the header line.
\r
746 if (key->alg == &ssh_rsa) {
\r
748 struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
\r
749 Bignum bd, bp, bq, bdmp1, bdmq1;
\r
752 * These blobs were generated from inside PuTTY, so we needn't
\r
753 * treat them as untrusted.
\r
755 pos = 4 + GET_32BIT(pubblob);
\r
756 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
\r
757 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
\r
759 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
\r
760 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
\r
761 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
\r
762 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
\r
764 assert(e.start && iqmp.start); /* can't go wrong */
\r
766 /* We also need d mod (p-1) and d mod (q-1). */
\r
767 bd = bignum_from_bytes(d.start, d.bytes);
\r
768 bp = bignum_from_bytes(p.start, p.bytes);
\r
769 bq = bignum_from_bytes(q.start, q.bytes);
\r
772 bdmp1 = bigmod(bd, bp);
\r
773 bdmq1 = bigmod(bd, bq);
\r
778 dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
\r
779 dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
\r
780 sparelen = dmp1.bytes + dmq1.bytes;
\r
781 spareblob = snewn(sparelen, unsigned char);
\r
782 dmp1.start = spareblob;
\r
783 dmq1.start = spareblob + dmp1.bytes;
\r
784 for (i = 0; i < dmp1.bytes; i++)
\r
785 spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
\r
786 for (i = 0; i < dmq1.bytes; i++)
\r
787 spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
\r
791 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
\r
802 header = "-----BEGIN RSA PRIVATE KEY-----\n";
\r
803 footer = "-----END RSA PRIVATE KEY-----\n";
\r
804 } else if (key->alg == &ssh_dss) {
\r
806 struct mpint_pos p, q, g, y, x;
\r
809 * These blobs were generated from inside PuTTY, so we needn't
\r
810 * treat them as untrusted.
\r
812 pos = 4 + GET_32BIT(pubblob);
\r
813 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
\r
814 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
\r
815 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
\r
816 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
\r
818 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
\r
820 assert(y.start && x.start); /* can't go wrong */
\r
822 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
\r
830 header = "-----BEGIN DSA PRIVATE KEY-----\n";
\r
831 footer = "-----END DSA PRIVATE KEY-----\n";
\r
833 assert(0); /* zoinks! */
\r
834 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
\r
838 * Now count up the total size of the ASN.1 encoded integers,
\r
839 * so as to determine the length of the containing SEQUENCE.
\r
842 for (i = 0; i < nnumbers; i++) {
\r
843 len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
\r
844 len += numbers[i].bytes;
\r
847 /* Now add on the SEQUENCE header. */
\r
848 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
\r
849 /* Round up to the cipher block size, ensuring we have at least one
\r
850 * byte of padding (see below). */
\r
853 outlen = (outlen+8) &~ 7;
\r
856 * Now we know how big outblob needs to be. Allocate it.
\r
858 outblob = snewn(outlen, unsigned char);
\r
861 * And write the data into it.
\r
864 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
\r
865 for (i = 0; i < nnumbers; i++) {
\r
866 pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
\r
867 memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
\r
868 pos += numbers[i].bytes;
\r
872 * Padding on OpenSSH keys is deterministic. The number of
\r
873 * padding bytes is always more than zero, and always at most
\r
874 * the cipher block length. The value of each padding byte is
\r
875 * equal to the number of padding bytes. So a plaintext that's
\r
876 * an exact multiple of the block size will be padded with 08
\r
877 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
\r
878 * plaintext one byte less than a multiple of the block size
\r
879 * will be padded with just 01.
\r
881 * This enables the OpenSSL key decryption function to strip
\r
882 * off the padding algorithmically and return the unpadded
\r
883 * plaintext to the next layer: it looks at the final byte, and
\r
884 * then expects to find that many bytes at the end of the data
\r
885 * with the same value. Those are all removed and the rest is
\r
888 assert(pos == len);
\r
889 while (pos < outlen) {
\r
890 outblob[pos++] = outlen - len;
\r
896 * For the moment, we still encrypt our OpenSSH keys using
\r
901 * Invent an iv. Then derive encryption key from passphrase
\r
904 * - let block A equal MD5(passphrase || iv)
\r
905 * - let block B equal MD5(A || passphrase || iv)
\r
906 * - block C would be MD5(B || passphrase || iv) and so on
\r
907 * - encryption key is the first N bytes of A || B
\r
909 struct MD5Context md5c;
\r
910 unsigned char keybuf[32];
\r
912 for (i = 0; i < 8; i++) iv[i] = random_byte();
\r
915 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
\r
916 MD5Update(&md5c, iv, 8);
\r
917 MD5Final(keybuf, &md5c);
\r
920 MD5Update(&md5c, keybuf, 16);
\r
921 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
\r
922 MD5Update(&md5c, iv, 8);
\r
923 MD5Final(keybuf+16, &md5c);
\r
926 * Now encrypt the key blob.
\r
928 des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
\r
930 smemclr(&md5c, sizeof(md5c));
\r
931 smemclr(keybuf, sizeof(keybuf));
\r
935 * And save it. We'll use Unix line endings just in case it's
\r
936 * subsequently transferred in binary mode.
\r
938 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
\r
943 fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
\r
944 for (i = 0; i < 8; i++)
\r
945 fprintf(fp, "%02X", iv[i]);
\r
946 fprintf(fp, "\n\n");
\r
948 base64_encode(fp, outblob, outlen, 64);
\r
955 smemclr(outblob, outlen);
\r
959 smemclr(spareblob, sparelen);
\r
963 smemclr(privblob, privlen);
\r
967 smemclr(pubblob, publen);
\r
973 /* ----------------------------------------------------------------------
\r
974 * Code to read ssh.com private keys.
\r
978 * The format of the base64 blob is largely SSH-2-packet-formatted,
\r
979 * except that mpints are a bit different: they're more like the
\r
980 * old SSH-1 mpint. You have a 32-bit bit count N, followed by
\r
981 * (N+7)/8 bytes of data.
\r
983 * So. The blob contains:
\r
985 * - uint32 0x3f6ff9eb (magic number)
\r
986 * - uint32 size (total blob size)
\r
987 * - string key-type (see below)
\r
988 * - string cipher-type (tells you if key is encrypted)
\r
989 * - string encrypted-blob
\r
991 * (The first size field includes the size field itself and the
\r
992 * magic number before it. All other size fields are ordinary SSH-2
\r
993 * strings, so the size field indicates how much data is to
\r
996 * The encrypted blob, once decrypted, contains a single string
\r
997 * which in turn contains the payload. (This allows padding to be
\r
998 * added after that string while still making it clear where the
\r
999 * real payload ends. Also it probably makes for a reasonable
\r
1000 * decryption check.)
\r
1002 * The payload blob, for an RSA key, contains:
\r
1005 * - mpint n (yes, the public and private stuff is intermixed)
\r
1006 * - mpint u (presumably inverse of p mod q)
\r
1007 * - mpint p (p is the smaller prime)
\r
1008 * - mpint q (q is the larger)
\r
1010 * For a DSA key, the payload blob contains:
\r
1018 * Alternatively, if the parameters are `predefined', that
\r
1019 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
\r
1020 * containing some predefined parameter specification. *shudder*,
\r
1021 * but I doubt we'll encounter this in real life.
\r
1023 * The key type strings are ghastly. The RSA key I looked at had a
\r
1026 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
\r
1028 * and the DSA key wasn't much better:
\r
1030 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
\r
1032 * It isn't clear that these will always be the same. I think it
\r
1033 * might be wise just to look at the `if-modn{sign{rsa' and
\r
1034 * `dl-modp{sign{dsa' prefixes.
\r
1036 * Finally, the encryption. The cipher-type string appears to be
\r
1037 * either `none' or `3des-cbc'. Looks as if this is SSH-2-style
\r
1038 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
\r
1039 * from the passphrase by means of yet another hashing faff:
\r
1041 * - first 16 bytes are MD5(passphrase)
\r
1042 * - next 16 bytes are MD5(passphrase || first 16 bytes)
\r
1043 * - if there were more, they'd be MD5(passphrase || first 32),
\r
1047 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
\r
1049 struct sshcom_key {
\r
1050 char comment[256]; /* allowing any length is overkill */
\r
1051 unsigned char *keyblob;
\r
1052 int keyblob_len, keyblob_size;
\r
1055 static struct sshcom_key *load_sshcom_key(const Filename *filename,
\r
1056 const char **errmsg_p)
\r
1058 struct sshcom_key *ret;
\r
1060 char *line = NULL;
\r
1061 int hdrstart, len;
\r
1064 char base64_bit[4];
\r
1065 int base64_chars = 0;
\r
1067 ret = snew(struct sshcom_key);
\r
1068 ret->comment[0] = '\0';
\r
1069 ret->keyblob = NULL;
\r
1070 ret->keyblob_len = ret->keyblob_size = 0;
\r
1072 fp = f_open(filename, "r", FALSE);
\r
1074 errmsg = "unable to open key file";
\r
1077 if (!(line = fgetline(fp))) {
\r
1078 errmsg = "unexpected end of file";
\r
1082 if (0 != strcmp(line, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
\r
1083 errmsg = "file does not begin with ssh.com key header";
\r
1086 smemclr(line, strlen(line));
\r
1092 if (!(line = fgetline(fp))) {
\r
1093 errmsg = "unexpected end of file";
\r
1097 if (!strcmp(line, "---- END SSH2 ENCRYPTED PRIVATE KEY ----")) {
\r
1102 if ((p = strchr(line, ':')) != NULL) {
\r
1103 if (headers_done) {
\r
1104 errmsg = "header found in body of key data";
\r
1108 while (*p && isspace((unsigned char)*p)) p++;
\r
1109 hdrstart = p - line;
\r
1112 * Header lines can end in a trailing backslash for
\r
1115 len = hdrstart + strlen(line+hdrstart);
\r
1116 assert(!line[len]);
\r
1117 while (line[len-1] == '\\') {
\r
1121 line2 = fgetline(fp);
\r
1123 errmsg = "unexpected end of file";
\r
1126 strip_crlf(line2);
\r
1128 line2len = strlen(line2);
\r
1129 line = sresize(line, len + line2len + 1, char);
\r
1130 strcpy(line + len - 1, line2);
\r
1131 len += line2len - 1;
\r
1132 assert(!line[len]);
\r
1134 smemclr(line2, strlen(line2));
\r
1138 p = line + hdrstart;
\r
1140 if (!strcmp(line, "Comment")) {
\r
1141 /* Strip quotes in comment if present. */
\r
1142 if (p[0] == '"' && p[strlen(p)-1] == '"') {
\r
1144 p[strlen(p)-1] = '\0';
\r
1146 strncpy(ret->comment, p, sizeof(ret->comment));
\r
1147 ret->comment[sizeof(ret->comment)-1] = '\0';
\r
1153 while (isbase64(*p)) {
\r
1154 base64_bit[base64_chars++] = *p;
\r
1155 if (base64_chars == 4) {
\r
1156 unsigned char out[3];
\r
1160 len = base64_decode_atom(base64_bit, out);
\r
1163 errmsg = "invalid base64 encoding";
\r
1167 if (ret->keyblob_len + len > ret->keyblob_size) {
\r
1168 ret->keyblob_size = ret->keyblob_len + len + 256;
\r
1169 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
\r
1173 memcpy(ret->keyblob + ret->keyblob_len, out, len);
\r
1174 ret->keyblob_len += len;
\r
1180 smemclr(line, strlen(line));
\r
1185 if (ret->keyblob_len == 0 || !ret->keyblob) {
\r
1186 errmsg = "key body not present";
\r
1191 if (errmsg_p) *errmsg_p = NULL;
\r
1199 smemclr(line, strlen(line));
\r
1204 if (ret->keyblob) {
\r
1205 smemclr(ret->keyblob, ret->keyblob_size);
\r
1206 sfree(ret->keyblob);
\r
1208 smemclr(ret, sizeof(*ret));
\r
1211 if (errmsg_p) *errmsg_p = errmsg;
\r
1215 int sshcom_encrypted(const Filename *filename, char **comment)
\r
1217 struct sshcom_key *key = load_sshcom_key(filename, NULL);
\r
1218 int pos, len, answer;
\r
1227 * Check magic number.
\r
1229 if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) {
\r
1230 goto done; /* key is invalid */
\r
1234 * Find the cipher-type string.
\r
1237 if (key->keyblob_len < pos+4)
\r
1238 goto done; /* key is far too short */
\r
1239 len = toint(GET_32BIT(key->keyblob + pos));
\r
1240 if (len < 0 || len > key->keyblob_len - pos - 4)
\r
1241 goto done; /* key is far too short */
\r
1242 pos += 4 + len; /* skip key type */
\r
1243 len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
\r
1244 if (len < 0 || len > key->keyblob_len - pos - 4)
\r
1245 goto done; /* cipher type string is incomplete */
\r
1246 if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
\r
1251 *comment = dupstr(key->comment);
\r
1252 smemclr(key->keyblob, key->keyblob_size);
\r
1253 sfree(key->keyblob);
\r
1254 smemclr(key, sizeof(*key));
\r
1257 *comment = dupstr("");
\r
1262 static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
\r
1264 unsigned bits, bytes;
\r
1265 unsigned char *d = (unsigned char *) data;
\r
1269 bits = GET_32BIT(d);
\r
1271 bytes = (bits + 7) / 8;
\r
1272 if (len < 4+bytes)
\r
1275 ret->start = d + 4;
\r
1276 ret->bytes = bytes;
\r
1280 ret->start = NULL;
\r
1282 return len; /* ensure further calls fail as well */
\r
1285 static int sshcom_put_mpint(void *target, void *data, int len)
\r
1287 unsigned char *d = (unsigned char *)target;
\r
1288 unsigned char *i = (unsigned char *)data;
\r
1289 int bits = len * 8 - 1;
\r
1291 while (bits > 0) {
\r
1292 if (*i & (1 << (bits & 7)))
\r
1294 if (!(bits-- & 7))
\r
1298 PUT_32BIT(d, bits+1);
\r
1299 memcpy(d+4, i, len);
\r
1303 struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
\r
1304 const char **errmsg_p)
\r
1306 struct sshcom_key *key = load_sshcom_key(filename, errmsg_p);
\r
1309 const char prefix_rsa[] = "if-modn{sign{rsa";
\r
1310 const char prefix_dsa[] = "dl-modp{sign{dsa";
\r
1311 enum { RSA, DSA } type;
\r
1315 struct ssh2_userkey *ret = NULL, *retkey;
\r
1316 const struct ssh_signkey *alg;
\r
1317 unsigned char *blob = NULL;
\r
1318 int blobsize = 0, publen, privlen;
\r
1324 * Check magic number.
\r
1326 if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) {
\r
1327 errmsg = "key does not begin with magic number";
\r
1332 * Determine the key type.
\r
1335 if (key->keyblob_len < pos+4 ||
\r
1336 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
\r
1337 len > key->keyblob_len - pos - 4) {
\r
1338 errmsg = "key blob does not contain a key type string";
\r
1341 if (len > sizeof(prefix_rsa) - 1 &&
\r
1342 !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) {
\r
1344 } else if (len > sizeof(prefix_dsa) - 1 &&
\r
1345 !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) {
\r
1348 errmsg = "key is of unknown type";
\r
1354 * Determine the cipher type.
\r
1356 if (key->keyblob_len < pos+4 ||
\r
1357 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
\r
1358 len > key->keyblob_len - pos - 4) {
\r
1359 errmsg = "key blob does not contain a cipher type string";
\r
1362 if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4))
\r
1364 else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8))
\r
1367 errmsg = "key encryption is of unknown type";
\r
1373 * Get hold of the encrypted part of the key.
\r
1375 if (key->keyblob_len < pos+4 ||
\r
1376 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
\r
1377 len > key->keyblob_len - pos - 4) {
\r
1378 errmsg = "key blob does not contain actual key data";
\r
1381 ciphertext = (char *)key->keyblob + pos + 4;
\r
1383 if (cipherlen == 0) {
\r
1384 errmsg = "length of key data is zero";
\r
1389 * Decrypt it if necessary.
\r
1393 * Derive encryption key from passphrase and iv/salt:
\r
1395 * - let block A equal MD5(passphrase)
\r
1396 * - let block B equal MD5(passphrase || A)
\r
1397 * - block C would be MD5(passphrase || A || B) and so on
\r
1398 * - encryption key is the first N bytes of A || B
\r
1400 struct MD5Context md5c;
\r
1401 unsigned char keybuf[32], iv[8];
\r
1403 if (cipherlen % 8 != 0) {
\r
1404 errmsg = "encrypted part of key is not a multiple of cipher block"
\r
1410 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
\r
1411 MD5Final(keybuf, &md5c);
\r
1414 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
\r
1415 MD5Update(&md5c, keybuf, 16);
\r
1416 MD5Final(keybuf+16, &md5c);
\r
1419 * Now decrypt the key blob.
\r
1421 memset(iv, 0, sizeof(iv));
\r
1422 des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
\r
1425 smemclr(&md5c, sizeof(md5c));
\r
1426 smemclr(keybuf, sizeof(keybuf));
\r
1429 * Hereafter we return WRONG_PASSPHRASE for any parsing
\r
1430 * error. (But only if we've just tried to decrypt it!
\r
1431 * Returning WRONG_PASSPHRASE for an unencrypted key is
\r
1432 * automatic doom.)
\r
1435 ret = SSH2_WRONG_PASSPHRASE;
\r
1439 * Strip away the containing string to get to the real meat.
\r
1441 len = toint(GET_32BIT(ciphertext));
\r
1442 if (len < 0 || len > cipherlen-4) {
\r
1443 errmsg = "containing string was ill-formed";
\r
1450 * Now we break down into RSA versus DSA. In either case we'll
\r
1451 * construct public and private blobs in our own format, and
\r
1452 * end up feeding them to alg->createkey().
\r
1454 blobsize = cipherlen + 256;
\r
1455 blob = snewn(blobsize, unsigned char);
\r
1457 if (type == RSA) {
\r
1458 struct mpint_pos n, e, d, u, p, q;
\r
1460 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e);
\r
1461 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d);
\r
1462 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n);
\r
1463 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u);
\r
1464 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
\r
1465 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
\r
1467 errmsg = "key data did not contain six integers";
\r
1473 pos += put_string(blob+pos, "ssh-rsa", 7);
\r
1474 pos += put_mp(blob+pos, e.start, e.bytes);
\r
1475 pos += put_mp(blob+pos, n.start, n.bytes);
\r
1477 pos += put_string(blob+pos, d.start, d.bytes);
\r
1478 pos += put_mp(blob+pos, q.start, q.bytes);
\r
1479 pos += put_mp(blob+pos, p.start, p.bytes);
\r
1480 pos += put_mp(blob+pos, u.start, u.bytes);
\r
1481 privlen = pos - publen;
\r
1483 struct mpint_pos p, q, g, x, y;
\r
1486 assert(type == DSA); /* the only other option from the if above */
\r
1488 if (GET_32BIT(ciphertext) != 0) {
\r
1489 errmsg = "predefined DSA parameters not supported";
\r
1492 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
\r
1493 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g);
\r
1494 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
\r
1495 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y);
\r
1496 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x);
\r
1498 errmsg = "key data did not contain five integers";
\r
1504 pos += put_string(blob+pos, "ssh-dss", 7);
\r
1505 pos += put_mp(blob+pos, p.start, p.bytes);
\r
1506 pos += put_mp(blob+pos, q.start, q.bytes);
\r
1507 pos += put_mp(blob+pos, g.start, g.bytes);
\r
1508 pos += put_mp(blob+pos, y.start, y.bytes);
\r
1510 pos += put_mp(blob+pos, x.start, x.bytes);
\r
1511 privlen = pos - publen;
\r
1514 assert(privlen > 0); /* should have bombed by now if not */
\r
1516 retkey = snew(struct ssh2_userkey);
\r
1517 retkey->alg = alg;
\r
1518 retkey->data = alg->createkey(blob, publen, blob+publen, privlen);
\r
1519 if (!retkey->data) {
\r
1521 errmsg = "unable to create key data structure";
\r
1524 retkey->comment = dupstr(key->comment);
\r
1526 errmsg = NULL; /* no error */
\r
1531 smemclr(blob, blobsize);
\r
1534 smemclr(key->keyblob, key->keyblob_size);
\r
1535 sfree(key->keyblob);
\r
1536 smemclr(key, sizeof(*key));
\r
1538 if (errmsg_p) *errmsg_p = errmsg;
\r
1542 int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
\r
1545 unsigned char *pubblob, *privblob;
\r
1546 int publen, privlen;
\r
1547 unsigned char *outblob;
\r
1549 struct mpint_pos numbers[6];
\r
1550 int nnumbers, initial_zero, pos, lenpos, i;
\r
1558 * Fetch the key blobs.
\r
1560 pubblob = key->alg->public_blob(key->data, &publen);
\r
1561 privblob = key->alg->private_blob(key->data, &privlen);
\r
1565 * Find the sequence of integers to be encoded into the OpenSSH
\r
1566 * key blob, and also decide on the header line.
\r
1568 if (key->alg == &ssh_rsa) {
\r
1570 struct mpint_pos n, e, d, p, q, iqmp;
\r
1573 * These blobs were generated from inside PuTTY, so we needn't
\r
1574 * treat them as untrusted.
\r
1576 pos = 4 + GET_32BIT(pubblob);
\r
1577 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
\r
1578 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
\r
1580 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
\r
1581 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
\r
1582 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
\r
1583 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
\r
1585 assert(e.start && iqmp.start); /* can't go wrong */
\r
1590 numbers[3] = iqmp;
\r
1596 type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
\r
1597 } else if (key->alg == &ssh_dss) {
\r
1599 struct mpint_pos p, q, g, y, x;
\r
1602 * These blobs were generated from inside PuTTY, so we needn't
\r
1603 * treat them as untrusted.
\r
1605 pos = 4 + GET_32BIT(pubblob);
\r
1606 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
\r
1607 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
\r
1608 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
\r
1609 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
\r
1611 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
\r
1613 assert(y.start && x.start); /* can't go wrong */
\r
1623 type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
\r
1625 assert(0); /* zoinks! */
\r
1626 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
\r
1630 * Total size of key blob will be somewhere under 512 plus
\r
1631 * combined length of integers. We'll calculate the more
\r
1632 * precise size as we construct the blob.
\r
1635 for (i = 0; i < nnumbers; i++)
\r
1636 outlen += 4 + numbers[i].bytes;
\r
1637 outblob = snewn(outlen, unsigned char);
\r
1640 * Create the unencrypted key blob.
\r
1643 PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
\r
1644 pos += 4; /* length field, fill in later */
\r
1645 pos += put_string(outblob+pos, type, strlen(type));
\r
1647 char *ciphertype = passphrase ? "3des-cbc" : "none";
\r
1648 pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
\r
1650 lenpos = pos; /* remember this position */
\r
1651 pos += 4; /* encrypted-blob size */
\r
1652 pos += 4; /* encrypted-payload size */
\r
1653 if (initial_zero) {
\r
1654 PUT_32BIT(outblob+pos, 0);
\r
1657 for (i = 0; i < nnumbers; i++)
\r
1658 pos += sshcom_put_mpint(outblob+pos,
\r
1659 numbers[i].start, numbers[i].bytes);
\r
1660 /* Now wrap up the encrypted payload. */
\r
1661 PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8));
\r
1662 /* Pad encrypted blob to a multiple of cipher block size. */
\r
1664 int padding = -(pos - (lenpos+4)) & 7;
\r
1666 outblob[pos++] = random_byte();
\r
1668 ciphertext = (char *)outblob+lenpos+4;
\r
1669 cipherlen = pos - (lenpos+4);
\r
1670 assert(!passphrase || cipherlen % 8 == 0);
\r
1671 /* Wrap up the encrypted blob string. */
\r
1672 PUT_32BIT(outblob+lenpos, cipherlen);
\r
1673 /* And finally fill in the total length field. */
\r
1674 PUT_32BIT(outblob+4, pos);
\r
1676 assert(pos < outlen);
\r
1679 * Encrypt the key.
\r
1683 * Derive encryption key from passphrase and iv/salt:
\r
1685 * - let block A equal MD5(passphrase)
\r
1686 * - let block B equal MD5(passphrase || A)
\r
1687 * - block C would be MD5(passphrase || A || B) and so on
\r
1688 * - encryption key is the first N bytes of A || B
\r
1690 struct MD5Context md5c;
\r
1691 unsigned char keybuf[32], iv[8];
\r
1694 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
\r
1695 MD5Final(keybuf, &md5c);
\r
1698 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
\r
1699 MD5Update(&md5c, keybuf, 16);
\r
1700 MD5Final(keybuf+16, &md5c);
\r
1703 * Now decrypt the key blob.
\r
1705 memset(iv, 0, sizeof(iv));
\r
1706 des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
\r
1709 smemclr(&md5c, sizeof(md5c));
\r
1710 smemclr(keybuf, sizeof(keybuf));
\r
1714 * And save it. We'll use Unix line endings just in case it's
\r
1715 * subsequently transferred in binary mode.
\r
1717 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
\r
1720 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
\r
1721 fprintf(fp, "Comment: \"");
\r
1723 * Comment header is broken with backslash-newline if it goes
\r
1724 * over 70 chars. Although it's surrounded by quotes, it
\r
1725 * _doesn't_ escape backslashes or quotes within the string.
\r
1726 * Don't ask me, I didn't design it.
\r
1729 int slen = 60; /* starts at 60 due to "Comment: " */
\r
1730 char *c = key->comment;
\r
1731 while ((int)strlen(c) > slen) {
\r
1732 fprintf(fp, "%.*s\\\n", slen, c);
\r
1734 slen = 70; /* allow 70 chars on subsequent lines */
\r
1736 fprintf(fp, "%s\"\n", c);
\r
1738 base64_encode(fp, outblob, pos, 70);
\r
1739 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
\r
1745 smemclr(outblob, outlen);
\r
1749 smemclr(privblob, privlen);
\r
1753 smemclr(pubblob, publen);
\r