2 * Code for PuTTY to import and export private key files in other
3 * SSH clients' formats.
15 int openssh_pem_encrypted(const Filename *filename);
16 int openssh_new_encrypted(const Filename *filename);
17 struct ssh2_userkey *openssh_pem_read(const Filename *filename,
19 const char **errmsg_p);
20 struct ssh2_userkey *openssh_new_read(const Filename *filename,
22 const char **errmsg_p);
23 int openssh_auto_write(const Filename *filename, struct ssh2_userkey *key,
25 int openssh_pem_write(const Filename *filename, struct ssh2_userkey *key,
27 int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
30 int sshcom_encrypted(const Filename *filename, char **comment);
31 struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
32 const char **errmsg_p);
33 int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
37 * Given a key type, determine whether we know how to import it.
39 int import_possible(int type)
41 if (type == SSH_KEYTYPE_OPENSSH_PEM)
43 if (type == SSH_KEYTYPE_OPENSSH_NEW)
45 if (type == SSH_KEYTYPE_SSHCOM)
51 * Given a key type, determine what native key type
52 * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once
55 int import_target_type(int type)
58 * There are no known foreign SSH-1 key formats.
60 return SSH_KEYTYPE_SSH2;
64 * Determine whether a foreign key is encrypted.
66 int import_encrypted(const Filename *filename, int type, char **comment)
68 if (type == SSH_KEYTYPE_OPENSSH_PEM) {
69 /* OpenSSH PEM format doesn't contain a key comment at all */
70 *comment = dupstr(filename_to_str(filename));
71 return openssh_pem_encrypted(filename);
72 } else if (type == SSH_KEYTYPE_OPENSSH_NEW) {
73 /* OpenSSH new format does, but it's inside the encrypted
74 * section for some reason */
75 *comment = dupstr(filename_to_str(filename));
76 return openssh_new_encrypted(filename);
77 } else if (type == SSH_KEYTYPE_SSHCOM) {
78 return sshcom_encrypted(filename, comment);
84 * Import an SSH-1 key.
86 int import_ssh1(const Filename *filename, int type,
87 struct RSAKey *key, char *passphrase, const char **errmsg_p)
93 * Import an SSH-2 key.
95 struct ssh2_userkey *import_ssh2(const Filename *filename, int type,
96 char *passphrase, const char **errmsg_p)
98 if (type == SSH_KEYTYPE_OPENSSH_PEM)
99 return openssh_pem_read(filename, passphrase, errmsg_p);
100 else if (type == SSH_KEYTYPE_OPENSSH_NEW)
101 return openssh_new_read(filename, passphrase, errmsg_p);
102 if (type == SSH_KEYTYPE_SSHCOM)
103 return sshcom_read(filename, passphrase, errmsg_p);
108 * Export an SSH-1 key.
110 int export_ssh1(const Filename *filename, int type, struct RSAKey *key,
117 * Export an SSH-2 key.
119 int export_ssh2(const Filename *filename, int type,
120 struct ssh2_userkey *key, char *passphrase)
122 if (type == SSH_KEYTYPE_OPENSSH_AUTO)
123 return openssh_auto_write(filename, key, passphrase);
124 if (type == SSH_KEYTYPE_OPENSSH_NEW)
125 return openssh_new_write(filename, key, passphrase);
126 if (type == SSH_KEYTYPE_SSHCOM)
127 return sshcom_write(filename, key, passphrase);
132 * Strip trailing CRs and LFs at the end of a line of text.
134 void strip_crlf(char *str)
136 char *p = str + strlen(str);
138 while (p > str && (p[-1] == '\r' || p[-1] == '\n'))
142 /* ----------------------------------------------------------------------
143 * Helper routines. (The base64 ones are defined in sshpubk.c.)
146 #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \
147 ((c) >= 'a' && (c) <= 'z') || \
148 ((c) >= '0' && (c) <= '9') || \
149 (c) == '+' || (c) == '/' || (c) == '=' \
153 * Read an ASN.1/BER identifier and length pair.
155 * Flags are a combination of the #defines listed below.
157 * Returns -1 if unsuccessful; otherwise returns the number of
158 * bytes used out of the source data.
161 /* ASN.1 tag classes. */
162 #define ASN1_CLASS_UNIVERSAL (0 << 6)
163 #define ASN1_CLASS_APPLICATION (1 << 6)
164 #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6)
165 #define ASN1_CLASS_PRIVATE (3 << 6)
166 #define ASN1_CLASS_MASK (3 << 6)
168 /* Primitive versus constructed bit. */
169 #define ASN1_CONSTRUCTED (1 << 5)
171 static int ber_read_id_len(void *source, int sourcelen,
172 int *id, int *length, int *flags)
174 unsigned char *p = (unsigned char *) source;
179 *flags = (*p & 0xE0);
180 if ((*p & 0x1F) == 0x1F) {
186 *id = (*id << 7) | (*p & 0x7F);
205 len = (len << 8) | (*p++);
207 *length = toint(len);
213 return p - (unsigned char *) source;
217 * Write an ASN.1/BER identifier and length pair. Returns the
218 * number of bytes consumed. Assumes dest contains enough space.
219 * Will avoid writing anything if dest is NULL, but still return
220 * amount of space required.
222 static int ber_write_id_len(void *dest, int id, int length, int flags)
224 unsigned char *d = (unsigned char *)dest;
229 * Identifier is one byte.
232 if (d) *d++ = id | flags;
236 * Identifier is multiple bytes: the first byte is 11111
237 * plus the flags, and subsequent bytes encode the value of
238 * the identifier, 7 bits at a time, with the top bit of
239 * each byte 1 except the last one which is 0.
242 if (d) *d++ = 0x1F | flags;
243 for (n = 1; (id >> (7*n)) > 0; n++)
244 continue; /* count the bytes */
247 if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F);
253 * Length is one byte.
256 if (d) *d++ = length;
260 * Length is multiple bytes. The first is 0x80 plus the
261 * number of subsequent bytes, and the subsequent bytes
262 * encode the actual length.
264 for (n = 1; (length >> (8*n)) > 0; n++)
265 continue; /* count the bytes */
267 if (d) *d++ = 0x80 | n;
270 if (d) *d++ = (length >> (8*n)) & 0xFF;
277 static int put_uint32(void *target, unsigned val)
279 unsigned char *d = (unsigned char *)target;
285 static int put_string(void *target, const void *data, int len)
287 unsigned char *d = (unsigned char *)target;
290 memcpy(d+4, data, len);
294 static int put_string_z(void *target, const char *string)
296 return put_string(target, string, strlen(string));
299 static int put_mp(void *target, void *data, int len)
301 unsigned char *d = (unsigned char *)target;
302 unsigned char *i = (unsigned char *)data;
307 memcpy(d+5, data, len);
311 memcpy(d+4, data, len);
316 /* Simple structure to point to an mp-int within a blob. */
317 struct mpint_pos { void *start; int bytes; };
319 static int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret)
322 unsigned char *d = (unsigned char *) data;
326 bytes = toint(GET_32BIT(d));
327 if (bytes < 0 || len-4 < bytes)
337 return len; /* ensure further calls fail as well */
340 /* ----------------------------------------------------------------------
341 * Code to read and write OpenSSH private keys, in the old-style PEM
346 OP_DSA, OP_RSA, OP_ECDSA
347 } openssh_pem_keytype;
352 struct openssh_pem_key {
353 openssh_pem_keytype keytype;
355 openssh_pem_enc encryption;
357 unsigned char *keyblob;
358 int keyblob_len, keyblob_size;
361 static struct openssh_pem_key *load_openssh_pem_key(const Filename *filename,
362 const char **errmsg_p)
364 struct openssh_pem_key *ret;
371 int base64_chars = 0;
373 ret = snew(struct openssh_pem_key);
375 ret->keyblob_len = ret->keyblob_size = 0;
377 fp = f_open(filename, "r", FALSE);
379 errmsg = "unable to open key file";
383 if (!(line = fgetline(fp))) {
384 errmsg = "unexpected end of file";
388 if (!strstartswith(line, "-----BEGIN ") ||
389 !strendswith(line, "PRIVATE KEY-----")) {
390 errmsg = "file does not begin with OpenSSH key header";
394 * Parse the BEGIN line. For old-format keys, this tells us the
395 * type of the key; for new-format keys, all it tells us is the
396 * format, and we'll find out the key type once we parse the
399 if (!strcmp(line, "-----BEGIN RSA PRIVATE KEY-----")) {
400 ret->keytype = OP_RSA;
401 } else if (!strcmp(line, "-----BEGIN DSA PRIVATE KEY-----")) {
402 ret->keytype = OP_DSA;
403 } else if (!strcmp(line, "-----BEGIN EC PRIVATE KEY-----")) {
404 ret->keytype = OP_ECDSA;
405 } else if (!strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
406 errmsg = "this is a new-style OpenSSH key";
409 errmsg = "unrecognised key type";
412 smemclr(line, strlen(line));
416 ret->encrypted = FALSE;
417 memset(ret->iv, 0, sizeof(ret->iv));
421 if (!(line = fgetline(fp))) {
422 errmsg = "unexpected end of file";
426 if (strstartswith(line, "-----END ") &&
427 strendswith(line, "PRIVATE KEY-----")) {
432 if ((p = strchr(line, ':')) != NULL) {
434 errmsg = "header found in body of key data";
438 while (*p && isspace((unsigned char)*p)) p++;
439 if (!strcmp(line, "Proc-Type")) {
440 if (p[0] != '4' || p[1] != ',') {
441 errmsg = "Proc-Type is not 4 (only 4 is supported)";
445 if (!strcmp(p, "ENCRYPTED"))
446 ret->encrypted = TRUE;
447 } else if (!strcmp(line, "DEK-Info")) {
450 if (!strncmp(p, "DES-EDE3-CBC,", 13)) {
451 ret->encryption = OP_E_3DES;
453 } else if (!strncmp(p, "AES-128-CBC,", 12)) {
454 ret->encryption = OP_E_AES;
457 errmsg = "unsupported cipher";
460 p = strchr(p, ',') + 1;/* always non-NULL, by above checks */
461 for (i = 0; i < ivlen; i++) {
462 if (1 != sscanf(p, "%2x", &j)) {
463 errmsg = "expected more iv data in DEK-Info";
470 errmsg = "more iv data than expected in DEK-Info";
478 while (isbase64(*p)) {
479 base64_bit[base64_chars++] = *p;
480 if (base64_chars == 4) {
481 unsigned char out[3];
486 len = base64_decode_atom(base64_bit, out);
489 errmsg = "invalid base64 encoding";
493 if (ret->keyblob_len + len > ret->keyblob_size) {
494 ret->keyblob_size = ret->keyblob_len + len + 256;
495 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
499 memcpy(ret->keyblob + ret->keyblob_len, out, len);
500 ret->keyblob_len += len;
502 smemclr(out, sizeof(out));
508 smemclr(line, strlen(line));
516 if (ret->keyblob_len == 0 || !ret->keyblob) {
517 errmsg = "key body not present";
521 if (ret->encrypted && ret->keyblob_len % 8 != 0) {
522 errmsg = "encrypted key blob is not a multiple of "
527 smemclr(base64_bit, sizeof(base64_bit));
528 if (errmsg_p) *errmsg_p = NULL;
533 smemclr(line, strlen(line));
537 smemclr(base64_bit, sizeof(base64_bit));
540 smemclr(ret->keyblob, ret->keyblob_size);
543 smemclr(ret, sizeof(*ret));
546 if (errmsg_p) *errmsg_p = errmsg;
551 int openssh_pem_encrypted(const Filename *filename)
553 struct openssh_pem_key *key = load_openssh_pem_key(filename, NULL);
558 ret = key->encrypted;
559 smemclr(key->keyblob, key->keyblob_size);
561 smemclr(key, sizeof(*key));
566 struct ssh2_userkey *openssh_pem_read(const Filename *filename,
568 const char **errmsg_p)
570 struct openssh_pem_key *key = load_openssh_pem_key(filename, errmsg_p);
571 struct ssh2_userkey *retkey;
572 unsigned char *p, *q;
573 int ret, id, len, flags;
575 struct ssh2_userkey *retval = NULL;
578 int blobsize = 0, blobptr, privptr;
587 if (key->encrypted) {
589 * Derive encryption key from passphrase and iv/salt:
591 * - let block A equal MD5(passphrase || iv)
592 * - let block B equal MD5(A || passphrase || iv)
593 * - block C would be MD5(B || passphrase || iv) and so on
594 * - encryption key is the first N bytes of A || B
596 * (Note that only 8 bytes of the iv are used for key
597 * derivation, even when the key is encrypted with AES and
598 * hence there are 16 bytes available.)
600 struct MD5Context md5c;
601 unsigned char keybuf[32];
604 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
605 MD5Update(&md5c, (unsigned char *)key->iv, 8);
606 MD5Final(keybuf, &md5c);
609 MD5Update(&md5c, keybuf, 16);
610 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
611 MD5Update(&md5c, (unsigned char *)key->iv, 8);
612 MD5Final(keybuf+16, &md5c);
615 * Now decrypt the key blob.
617 if (key->encryption == OP_E_3DES)
618 des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv,
619 key->keyblob, key->keyblob_len);
622 assert(key->encryption == OP_E_AES);
623 ctx = aes_make_context();
624 aes128_key(ctx, keybuf);
625 aes_iv(ctx, (unsigned char *)key->iv);
626 aes_ssh2_decrypt_blk(ctx, key->keyblob, key->keyblob_len);
627 aes_free_context(ctx);
630 smemclr(&md5c, sizeof(md5c));
631 smemclr(keybuf, sizeof(keybuf));
635 * Now we have a decrypted key blob, which contains an ASN.1
636 * encoded private key. We must now untangle the ASN.1.
638 * We expect the whole key blob to be formatted as a SEQUENCE
639 * (0x30 followed by a length code indicating that the rest of
640 * the blob is part of the sequence). Within that SEQUENCE we
641 * expect to see a bunch of INTEGERs. What those integers mean
642 * depends on the key type:
644 * - For RSA, we expect the integers to be 0, n, e, d, p, q,
645 * dmp1, dmq1, iqmp in that order. (The last three are d mod
646 * (p-1), d mod (q-1), inverse of q mod p respectively.)
648 * - For DSA, we expect them to be 0, p, q, g, y, x in that
651 * - In ECDSA the format is totally different: we see the
652 * SEQUENCE, but beneath is an INTEGER 1, OCTET STRING priv
653 * EXPLICIT [0] OID curve, EXPLICIT [1] BIT STRING pubPoint
658 /* Expect the SEQUENCE header. Take its absence as a failure to
659 * decrypt, if the key was encrypted. */
660 ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
662 if (ret < 0 || id != 16 || len < 0 ||
663 key->keyblob+key->keyblob_len-p < len) {
664 errmsg = "ASN.1 decoding failure";
665 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
669 /* Expect a load of INTEGERs. */
670 if (key->keytype == OP_RSA)
672 else if (key->keytype == OP_DSA)
675 num_integers = 0; /* placate compiler warnings */
678 if (key->keytype == OP_ECDSA) {
679 /* And now for something completely different */
682 const struct ssh_signkey *alg;
683 const struct ec_curve *curve;
684 int algnamelen, curvenamelen;
686 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
689 if (ret < 0 || id != 2 || len != 1 ||
690 key->keyblob+key->keyblob_len-p < len || p[0] != 1) {
691 errmsg = "ASN.1 decoding failure";
692 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
696 /* Read private key OCTET STRING */
697 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
700 if (ret < 0 || id != 4 || len < 0 ||
701 key->keyblob+key->keyblob_len-p < len) {
702 errmsg = "ASN.1 decoding failure";
703 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
710 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
713 if (ret < 0 || id != 0 || len < 0 ||
714 key->keyblob+key->keyblob_len-p < len) {
715 errmsg = "ASN.1 decoding failure";
716 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
719 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
722 if (ret < 0 || id != 6 || len < 0 ||
723 key->keyblob+key->keyblob_len-p < len) {
724 errmsg = "ASN.1 decoding failure";
725 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
728 alg = ec_alg_by_oid(len, p, &curve);
730 errmsg = "Unsupported ECDSA curve.";
735 /* Read BIT STRING point */
736 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
739 if (ret < 0 || id != 1 || len < 0 ||
740 key->keyblob+key->keyblob_len-p < len) {
741 errmsg = "ASN.1 decoding failure";
742 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
745 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
748 if (ret < 0 || id != 3 || len < 0 ||
749 key->keyblob+key->keyblob_len-p < len ||
750 len != ((((curve->fieldBits + 7) / 8) * 2) + 2)) {
751 errmsg = "ASN.1 decoding failure";
752 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
755 p += 1; len -= 1; /* Skip 0x00 before point */
757 /* Construct the key */
758 retkey = snew(struct ssh2_userkey);
760 errmsg = "out of memory";
764 blob = snewn((4+19 + 4+8 + 4+len) + (4+1+privlen), unsigned char);
767 errmsg = "out of memory";
773 algnamelen = strlen(alg->name);
774 PUT_32BIT(q, algnamelen); q += 4;
775 memcpy(q, alg->name, algnamelen); q += algnamelen;
777 curvenamelen = strlen(curve->name);
778 PUT_32BIT(q, curvenamelen); q += 4;
779 memcpy(q, curve->name, curvenamelen); q += curvenamelen;
781 PUT_32BIT(q, len); q += 4;
782 memcpy(q, p, len); q += len;
785 * To be acceptable to our createkey(), the private blob must
786 * contain a valid mpint, i.e. without the top bit set. But
787 * the input private string may have the top bit set, so we
788 * prefix a zero byte to ensure createkey() doesn't fail for
791 PUT_32BIT(q, privlen+1);
793 memcpy(q+5, priv, privlen);
795 retkey->data = retkey->alg->createkey(retkey->alg,
801 errmsg = "unable to create key data structure";
805 } else if (key->keytype == OP_RSA || key->keytype == OP_DSA) {
808 * Space to create key blob in.
810 blobsize = 256+key->keyblob_len;
811 blob = snewn(blobsize, unsigned char);
813 if (key->keytype == OP_DSA)
814 memcpy(blob+4, "ssh-dss", 7);
815 else if (key->keytype == OP_RSA)
816 memcpy(blob+4, "ssh-rsa", 7);
820 for (i = 0; i < num_integers; i++) {
821 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
824 if (ret < 0 || id != 2 || len < 0 ||
825 key->keyblob+key->keyblob_len-p < len) {
826 errmsg = "ASN.1 decoding failure";
827 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
833 * The first integer should be zero always (I think
834 * this is some sort of version indication).
836 if (len != 1 || p[0] != 0) {
837 errmsg = "version number mismatch";
840 } else if (key->keytype == OP_RSA) {
842 * Integers 1 and 2 go into the public blob but in the
843 * opposite order; integers 3, 4, 5 and 8 go into the
844 * private blob. The other two (6 and 7) are ignored.
847 /* Save the details for after we deal with number 2. */
850 } else if (i != 6 && i != 7) {
851 PUT_32BIT(blob+blobptr, len);
852 memcpy(blob+blobptr+4, p, len);
855 PUT_32BIT(blob+blobptr, modlen);
856 memcpy(blob+blobptr+4, modptr, modlen);
861 } else if (key->keytype == OP_DSA) {
863 * Integers 1-4 go into the public blob; integer 5 goes
864 * into the private blob.
866 PUT_32BIT(blob+blobptr, len);
867 memcpy(blob+blobptr+4, p, len);
873 /* Skip past the number. */
878 * Now put together the actual key. Simplest way to do this is
879 * to assemble our own key blobs and feed them to the createkey
880 * functions; this is a bit faffy but it does mean we get all
881 * the sanity checks for free.
883 assert(privptr > 0); /* should have bombed by now if not */
884 retkey = snew(struct ssh2_userkey);
885 retkey->alg = (key->keytype == OP_RSA ? &ssh_rsa : &ssh_dss);
886 retkey->data = retkey->alg->createkey(retkey->alg, blob, privptr,
891 errmsg = "unable to create key data structure";
896 assert(0 && "Bad key type from load_openssh_pem_key");
897 errmsg = "Bad key type from load_openssh_pem_key";
902 * The old key format doesn't include a comment in the private
905 retkey->comment = dupstr("imported-openssh-key");
907 errmsg = NULL; /* no error */
912 smemclr(blob, blobsize);
915 smemclr(key->keyblob, key->keyblob_size);
917 smemclr(key, sizeof(*key));
919 if (errmsg_p) *errmsg_p = errmsg;
923 int openssh_pem_write(const Filename *filename, struct ssh2_userkey *key,
926 unsigned char *pubblob, *privblob, *spareblob;
927 int publen, privlen, sparelen = 0;
928 unsigned char *outblob;
930 struct mpint_pos numbers[9];
931 int nnumbers, pos, len, seqlen, i;
932 const char *header, *footer;
939 * Fetch the key blobs.
941 pubblob = key->alg->public_blob(key->data, &publen);
942 privblob = key->alg->private_blob(key->data, &privlen);
943 spareblob = outblob = NULL;
949 * Encode the OpenSSH key blob, and also decide on the header
952 if (key->alg == &ssh_rsa || key->alg == &ssh_dss) {
954 * The RSA and DSS handlers share some code because the two
955 * key types have very similar ASN.1 representations, as a
956 * plain SEQUENCE of big integers. So we set up a list of
957 * bignums per key type and then construct the actual blob in
958 * common code after that.
960 if (key->alg == &ssh_rsa) {
962 struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
963 Bignum bd, bp, bq, bdmp1, bdmq1;
966 * These blobs were generated from inside PuTTY, so we needn't
967 * treat them as untrusted.
969 pos = 4 + GET_32BIT(pubblob);
970 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
971 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
973 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
974 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
975 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
976 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
978 assert(e.start && iqmp.start); /* can't go wrong */
980 /* We also need d mod (p-1) and d mod (q-1). */
981 bd = bignum_from_bytes(d.start, d.bytes);
982 bp = bignum_from_bytes(p.start, p.bytes);
983 bq = bignum_from_bytes(q.start, q.bytes);
986 bdmp1 = bigmod(bd, bp);
987 bdmq1 = bigmod(bd, bq);
992 dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
993 dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
994 sparelen = dmp1.bytes + dmq1.bytes;
995 spareblob = snewn(sparelen, unsigned char);
996 dmp1.start = spareblob;
997 dmq1.start = spareblob + dmp1.bytes;
998 for (i = 0; i < dmp1.bytes; i++)
999 spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
1000 for (i = 0; i < dmq1.bytes; i++)
1001 spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
1005 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
1016 header = "-----BEGIN RSA PRIVATE KEY-----\n";
1017 footer = "-----END RSA PRIVATE KEY-----\n";
1018 } else { /* ssh-dss */
1020 struct mpint_pos p, q, g, y, x;
1023 * These blobs were generated from inside PuTTY, so we needn't
1024 * treat them as untrusted.
1026 pos = 4 + GET_32BIT(pubblob);
1027 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
1028 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
1029 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
1030 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
1032 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
1034 assert(y.start && x.start); /* can't go wrong */
1036 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
1044 header = "-----BEGIN DSA PRIVATE KEY-----\n";
1045 footer = "-----END DSA PRIVATE KEY-----\n";
1049 * Now count up the total size of the ASN.1 encoded integers,
1050 * so as to determine the length of the containing SEQUENCE.
1053 for (i = 0; i < nnumbers; i++) {
1054 len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
1055 len += numbers[i].bytes;
1058 /* Now add on the SEQUENCE header. */
1059 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1062 * Now we know how big outblob needs to be. Allocate it.
1064 outblob = snewn(len, unsigned char);
1067 * And write the data into it.
1070 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1071 for (i = 0; i < nnumbers; i++) {
1072 pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
1073 memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
1074 pos += numbers[i].bytes;
1076 } else if (key->alg == &ssh_ecdsa_nistp256 ||
1077 key->alg == &ssh_ecdsa_nistp384 ||
1078 key->alg == &ssh_ecdsa_nistp521) {
1079 const unsigned char *oid;
1084 * Structure of asn1:
1087 * OCTET STRING (private key)
1091 * BIT STRING (0x00 public key point)
1093 oid = ec_alg_oid(key->alg, &oidlen);
1094 pointlen = (((struct ec_key *)key->data)->publicKey.curve->fieldBits
1097 len = ber_write_id_len(NULL, 2, 1, 0);
1099 len += ber_write_id_len(NULL, 4, privlen - 4, 0);
1101 len += ber_write_id_len(NULL, 0, oidlen +
1102 ber_write_id_len(NULL, 6, oidlen, 0),
1103 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1104 len += ber_write_id_len(NULL, 6, oidlen, 0);
1106 len += ber_write_id_len(NULL, 1, 2 + pointlen +
1107 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1108 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1109 len += ber_write_id_len(NULL, 3, 2 + pointlen, 0);
1110 len += 2 + pointlen;
1113 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1115 outblob = snewn(len, unsigned char);
1119 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1120 pos += ber_write_id_len(outblob+pos, 2, 1, 0);
1122 pos += ber_write_id_len(outblob+pos, 4, privlen - 4, 0);
1123 memcpy(outblob+pos, privblob + 4, privlen - 4);
1125 pos += ber_write_id_len(outblob+pos, 0, oidlen +
1126 ber_write_id_len(NULL, 6, oidlen, 0),
1127 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1128 pos += ber_write_id_len(outblob+pos, 6, oidlen, 0);
1129 memcpy(outblob+pos, oid, oidlen);
1131 pos += ber_write_id_len(outblob+pos, 1, 2 + pointlen +
1132 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1133 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1134 pos += ber_write_id_len(outblob+pos, 3, 2 + pointlen, 0);
1136 memcpy(outblob+pos, pubblob+39, 1 + pointlen);
1137 pos += 1 + pointlen;
1139 header = "-----BEGIN EC PRIVATE KEY-----\n";
1140 footer = "-----END EC PRIVATE KEY-----\n";
1142 assert(0); /* zoinks! */
1143 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
1149 * For the moment, we still encrypt our OpenSSH keys using
1153 struct MD5Context md5c;
1154 unsigned char keybuf[32];
1157 * Round up to the cipher block size, ensuring we have at
1158 * least one byte of padding (see below).
1160 outlen = (len+8) &~ 7;
1162 unsigned char *tmp = snewn(outlen, unsigned char);
1163 memcpy(tmp, outblob, len);
1164 smemclr(outblob, len);
1170 * Padding on OpenSSH keys is deterministic. The number of
1171 * padding bytes is always more than zero, and always at most
1172 * the cipher block length. The value of each padding byte is
1173 * equal to the number of padding bytes. So a plaintext that's
1174 * an exact multiple of the block size will be padded with 08
1175 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
1176 * plaintext one byte less than a multiple of the block size
1177 * will be padded with just 01.
1179 * This enables the OpenSSL key decryption function to strip
1180 * off the padding algorithmically and return the unpadded
1181 * plaintext to the next layer: it looks at the final byte, and
1182 * then expects to find that many bytes at the end of the data
1183 * with the same value. Those are all removed and the rest is
1187 while (pos < outlen) {
1188 outblob[pos++] = outlen - len;
1192 * Invent an iv. Then derive encryption key from passphrase
1195 * - let block A equal MD5(passphrase || iv)
1196 * - let block B equal MD5(A || passphrase || iv)
1197 * - block C would be MD5(B || passphrase || iv) and so on
1198 * - encryption key is the first N bytes of A || B
1200 for (i = 0; i < 8; i++) iv[i] = random_byte();
1203 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1204 MD5Update(&md5c, iv, 8);
1205 MD5Final(keybuf, &md5c);
1208 MD5Update(&md5c, keybuf, 16);
1209 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1210 MD5Update(&md5c, iv, 8);
1211 MD5Final(keybuf+16, &md5c);
1214 * Now encrypt the key blob.
1216 des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
1218 smemclr(&md5c, sizeof(md5c));
1219 smemclr(keybuf, sizeof(keybuf));
1222 * If no encryption, the blob has exactly its original
1229 * And save it. We'll use Unix line endings just in case it's
1230 * subsequently transferred in binary mode.
1232 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1237 fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
1238 for (i = 0; i < 8; i++)
1239 fprintf(fp, "%02X", iv[i]);
1240 fprintf(fp, "\n\n");
1242 base64_encode(fp, outblob, outlen, 64);
1249 smemclr(outblob, outlen);
1253 smemclr(spareblob, sparelen);
1257 smemclr(privblob, privlen);
1261 smemclr(pubblob, publen);
1267 /* ----------------------------------------------------------------------
1268 * Code to read and write OpenSSH private keys in the new-style format.
1272 ON_E_NONE, ON_E_AES256CBC
1273 } openssh_new_cipher;
1275 ON_K_NONE, ON_K_BCRYPT
1278 struct openssh_new_key {
1279 openssh_new_cipher cipher;
1280 openssh_new_kdf kdf;
1284 /* This points to a position within keyblob, not a
1285 * separately allocated thing */
1286 const unsigned char *salt;
1290 int nkeys, key_wanted;
1291 /* This too points to a position within keyblob */
1292 unsigned char *privatestr;
1295 unsigned char *keyblob;
1296 int keyblob_len, keyblob_size;
1299 static struct openssh_new_key *load_openssh_new_key(const Filename *filename,
1300 const char **errmsg_p)
1302 struct openssh_new_key *ret;
1308 int base64_chars = 0;
1309 const void *filedata;
1311 const void *string, *kdfopts, *bcryptsalt, *pubkey;
1312 int stringlen, kdfoptlen, bcryptsaltlen, pubkeylen;
1313 unsigned bcryptrounds, nkeys, key_index;
1315 ret = snew(struct openssh_new_key);
1316 ret->keyblob = NULL;
1317 ret->keyblob_len = ret->keyblob_size = 0;
1319 fp = f_open(filename, "r", FALSE);
1321 errmsg = "unable to open key file";
1325 if (!(line = fgetline(fp))) {
1326 errmsg = "unexpected end of file";
1330 if (0 != strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
1331 errmsg = "file does not begin with OpenSSH new-style key header";
1334 smemclr(line, strlen(line));
1339 if (!(line = fgetline(fp))) {
1340 errmsg = "unexpected end of file";
1344 if (0 == strcmp(line, "-----END OPENSSH PRIVATE KEY-----")) {
1351 while (isbase64(*p)) {
1352 base64_bit[base64_chars++] = *p;
1353 if (base64_chars == 4) {
1354 unsigned char out[3];
1359 len = base64_decode_atom(base64_bit, out);
1362 errmsg = "invalid base64 encoding";
1366 if (ret->keyblob_len + len > ret->keyblob_size) {
1367 ret->keyblob_size = ret->keyblob_len + len + 256;
1368 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
1372 memcpy(ret->keyblob + ret->keyblob_len, out, len);
1373 ret->keyblob_len += len;
1375 smemclr(out, sizeof(out));
1380 smemclr(line, strlen(line));
1388 if (ret->keyblob_len == 0 || !ret->keyblob) {
1389 errmsg = "key body not present";
1393 filedata = ret->keyblob;
1394 filelen = ret->keyblob_len;
1396 if (filelen < 15 || 0 != memcmp(filedata, "openssh-key-v1\0", 15)) {
1397 errmsg = "new-style OpenSSH magic number missing\n";
1400 filedata = (const char *)filedata + 15;
1403 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1404 errmsg = "encountered EOF before cipher name\n";
1407 if (match_ssh_id(stringlen, string, "none")) {
1408 ret->cipher = ON_E_NONE;
1409 } else if (match_ssh_id(stringlen, string, "aes256-cbc")) {
1410 ret->cipher = ON_E_AES256CBC;
1412 errmsg = "unrecognised cipher name\n";
1416 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1417 errmsg = "encountered EOF before kdf name\n";
1420 if (match_ssh_id(stringlen, string, "none")) {
1421 ret->kdf = ON_K_NONE;
1422 } else if (match_ssh_id(stringlen, string, "bcrypt")) {
1423 ret->kdf = ON_K_BCRYPT;
1425 errmsg = "unrecognised kdf name\n";
1429 if (!(kdfopts = get_ssh_string(&filelen, &filedata, &kdfoptlen))) {
1430 errmsg = "encountered EOF before kdf options\n";
1435 if (kdfoptlen != 0) {
1436 errmsg = "expected empty options string for 'none' kdf";
1441 if (!(bcryptsalt = get_ssh_string(&kdfoptlen, &kdfopts,
1443 errmsg = "bcrypt options string did not contain salt\n";
1446 if (!get_ssh_uint32(&kdfoptlen, &kdfopts, &bcryptrounds)) {
1447 errmsg = "bcrypt options string did not contain round count\n";
1450 ret->kdfopts.bcrypt.salt = bcryptsalt;
1451 ret->kdfopts.bcrypt.saltlen = bcryptsaltlen;
1452 ret->kdfopts.bcrypt.rounds = bcryptrounds;
1457 * At this point we expect a uint32 saying how many keys are
1458 * stored in this file. OpenSSH new-style key files can
1459 * contain more than one. Currently we don't have any user
1460 * interface to specify which one we're trying to extract, so
1461 * we just bomb out with an error if more than one is found in
1462 * the file. However, I've put in all the mechanism here to
1463 * extract the nth one for a given n, in case we later connect
1464 * up some UI to that mechanism. Just arrange that the
1465 * 'key_wanted' field is set to a value in the range [0,
1466 * nkeys) by some mechanism.
1468 if (!get_ssh_uint32(&filelen, &filedata, &nkeys)) {
1469 errmsg = "encountered EOF before key count\n";
1473 errmsg = "multiple keys in new-style OpenSSH key file "
1478 ret->key_wanted = 0;
1480 for (key_index = 0; key_index < nkeys; key_index++) {
1481 if (!(pubkey = get_ssh_string(&filelen, &filedata, &pubkeylen))) {
1482 errmsg = "encountered EOF before kdf options\n";
1488 * Now we expect a string containing the encrypted part of the
1491 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1492 errmsg = "encountered EOF before private key container\n";
1495 ret->privatestr = (unsigned char *)string;
1496 ret->privatelen = stringlen;
1499 * And now we're done, until asked to actually decrypt.
1502 smemclr(base64_bit, sizeof(base64_bit));
1503 if (errmsg_p) *errmsg_p = NULL;
1508 smemclr(line, strlen(line));
1512 smemclr(base64_bit, sizeof(base64_bit));
1515 smemclr(ret->keyblob, ret->keyblob_size);
1516 sfree(ret->keyblob);
1518 smemclr(ret, sizeof(*ret));
1521 if (errmsg_p) *errmsg_p = errmsg;
1526 int openssh_new_encrypted(const Filename *filename)
1528 struct openssh_new_key *key = load_openssh_new_key(filename, NULL);
1533 ret = (key->cipher != ON_E_NONE);
1534 smemclr(key->keyblob, key->keyblob_size);
1535 sfree(key->keyblob);
1536 smemclr(key, sizeof(*key));
1541 struct ssh2_userkey *openssh_new_read(const Filename *filename,
1543 const char **errmsg_p)
1545 struct openssh_new_key *key = load_openssh_new_key(filename, errmsg_p);
1546 struct ssh2_userkey *retkey = NULL;
1548 struct ssh2_userkey *retval = NULL;
1550 unsigned checkint0, checkint1;
1551 const void *priv, *string;
1552 int privlen, stringlen, key_index;
1553 const struct ssh_signkey *alg = NULL;
1558 if (key->cipher != ON_E_NONE) {
1559 unsigned char keybuf[48];
1563 * Construct the decryption key, and decrypt the string.
1565 switch (key->cipher) {
1569 case ON_E_AES256CBC:
1570 keysize = 48; /* 32 byte key + 16 byte IV */
1573 assert(0 && "Bad cipher enumeration value");
1575 assert(keysize <= sizeof(keybuf));
1578 memset(keybuf, 0, keysize);
1581 openssh_bcrypt(passphrase,
1582 key->kdfopts.bcrypt.salt,
1583 key->kdfopts.bcrypt.saltlen,
1584 key->kdfopts.bcrypt.rounds,
1588 assert(0 && "Bad kdf enumeration value");
1590 switch (key->cipher) {
1593 case ON_E_AES256CBC:
1594 if (key->privatelen % 16 != 0) {
1595 errmsg = "private key container length is not a"
1596 " multiple of AES block size\n";
1600 void *ctx = aes_make_context();
1601 aes256_key(ctx, keybuf);
1602 aes_iv(ctx, keybuf + 32);
1603 aes_ssh2_decrypt_blk(ctx, key->privatestr,
1605 aes_free_context(ctx);
1609 assert(0 && "Bad cipher enumeration value");
1614 * Now parse the entire encrypted section, and extract the key
1615 * identified by key_wanted.
1617 priv = key->privatestr;
1618 privlen = key->privatelen;
1620 if (!get_ssh_uint32(&privlen, &priv, &checkint0) ||
1621 !get_ssh_uint32(&privlen, &priv, &checkint1) ||
1622 checkint0 != checkint1) {
1623 errmsg = "decryption check failed";
1628 for (key_index = 0; key_index < key->nkeys; key_index++) {
1629 const unsigned char *thiskey;
1633 * Read the key type, which will tell us how to scan over
1634 * the key to get to the next one.
1636 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1637 errmsg = "expected key type in private string";
1642 * Preliminary key type identification, and decide how
1643 * many pieces of key we expect to see. Currently
1644 * (conveniently) all key types can be seen as some number
1645 * of strings, so we just need to know how many of them to
1646 * skip over. (The numbers below exclude the key comment.)
1649 /* find_pubkey_alg needs a zero-terminated copy of the
1651 char *name_zt = dupprintf("%.*s", stringlen, (char *)string);
1652 alg = find_pubkey_alg(name_zt);
1657 errmsg = "private key type not recognised\n";
1664 * Skip over the pieces of key.
1666 for (i = 0; i < alg->openssh_private_npieces; i++) {
1667 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1668 errmsg = "ran out of data in mid-private-key";
1673 thiskeylen = (int)((const unsigned char *)priv -
1674 (const unsigned char *)thiskey);
1675 if (key_index == key->key_wanted) {
1676 retkey = snew(struct ssh2_userkey);
1677 retkey->comment = NULL;
1679 retkey->data = alg->openssh_createkey(alg, &thiskey, &thiskeylen);
1680 if (!retkey->data) {
1681 errmsg = "unable to create key data structure";
1687 * Read the key comment.
1689 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1690 errmsg = "ran out of data at key comment";
1693 if (key_index == key->key_wanted) {
1695 retkey->comment = dupprintf("%.*s", stringlen,
1696 (const char *)string);
1701 errmsg = "key index out of range";
1706 * Now we expect nothing left but padding.
1708 for (i = 0; i < privlen; i++) {
1709 if (((const unsigned char *)priv)[i] != (unsigned char)(i+1)) {
1710 errmsg = "padding at end of private string did not match";
1715 errmsg = NULL; /* no error */
1717 retkey = NULL; /* prevent the free */
1721 sfree(retkey->comment);
1724 alg->freekey(retkey->data);
1728 smemclr(key->keyblob, key->keyblob_size);
1729 sfree(key->keyblob);
1730 smemclr(key, sizeof(*key));
1732 if (errmsg_p) *errmsg_p = errmsg;
1736 int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
1739 unsigned char *pubblob, *privblob, *outblob, *p;
1740 unsigned char *private_section_start, *private_section_length_field;
1741 int publen, privlen, commentlen, maxsize, padvalue, i;
1744 unsigned char bcrypt_salt[16];
1745 const int bcrypt_rounds = 16;
1749 * Fetch the key blobs and find out the lengths of things.
1751 pubblob = key->alg->public_blob(key->data, &publen);
1752 i = key->alg->openssh_fmtkey(key->data, NULL, 0);
1753 privblob = snewn(i, unsigned char);
1754 privlen = key->alg->openssh_fmtkey(key->data, privblob, i);
1755 assert(privlen == i);
1756 commentlen = strlen(key->comment);
1759 * Allocate enough space for the full binary key format. No need
1760 * to be absolutely precise here.
1762 maxsize = (16 + /* magic number */
1763 32 + /* cipher name string */
1764 32 + /* kdf name string */
1765 64 + /* kdf options string */
1767 4+publen + /* public key string */
1768 4 + /* string header for private section */
1769 8 + /* checkint x 2 */
1770 4+strlen(key->alg->name) + /* key type string */
1771 privlen + /* private blob */
1772 4+commentlen + /* comment string */
1773 16); /* padding at end of private section */
1774 outblob = snewn(maxsize, unsigned char);
1777 * Construct the cleartext version of the blob.
1782 memcpy(p, "openssh-key-v1\0", 15);
1785 /* Cipher and kdf names, and kdf options. */
1787 memset(bcrypt_salt, 0, sizeof(bcrypt_salt)); /* prevent warnings */
1788 p += put_string_z(p, "none");
1789 p += put_string_z(p, "none");
1790 p += put_string_z(p, "");
1793 for (i = 0; i < (int)sizeof(bcrypt_salt); i++)
1794 bcrypt_salt[i] = random_byte();
1795 p += put_string_z(p, "aes256-cbc");
1796 p += put_string_z(p, "bcrypt");
1799 p += put_string(p, bcrypt_salt, sizeof(bcrypt_salt));
1800 p += put_uint32(p, bcrypt_rounds);
1801 PUT_32BIT_MSB_FIRST(q, (unsigned)(p - (q+4)));
1804 /* Number of keys. */
1805 p += put_uint32(p, 1);
1808 p += put_string(p, pubblob, publen);
1810 /* Begin private section. */
1811 private_section_length_field = p;
1813 private_section_start = p;
1817 for (i = 0; i < 4; i++)
1818 checkint = (checkint << 8) + random_byte();
1819 p += put_uint32(p, checkint);
1820 p += put_uint32(p, checkint);
1822 /* Private key. The main private blob goes inline, with no string
1824 p += put_string_z(p, key->alg->name);
1825 memcpy(p, privblob, privlen);
1829 p += put_string_z(p, key->comment);
1831 /* Pad out the encrypted section. */
1835 } while ((p - private_section_start) & 15);
1837 assert(p - outblob < maxsize);
1839 /* Go back and fill in the length field for the private section. */
1840 PUT_32BIT_MSB_FIRST(private_section_length_field,
1841 p - private_section_start);
1845 * Encrypt the private section. We need 48 bytes of key
1846 * material: 32 bytes AES key + 16 bytes iv.
1848 unsigned char keybuf[48];
1851 openssh_bcrypt(passphrase,
1852 bcrypt_salt, sizeof(bcrypt_salt), bcrypt_rounds,
1853 keybuf, sizeof(keybuf));
1855 ctx = aes_make_context();
1856 aes256_key(ctx, keybuf);
1857 aes_iv(ctx, keybuf + 32);
1858 aes_ssh2_encrypt_blk(ctx, private_section_start,
1859 p - private_section_start);
1860 aes_free_context(ctx);
1862 smemclr(keybuf, sizeof(keybuf));
1866 * And save it. We'll use Unix line endings just in case it's
1867 * subsequently transferred in binary mode.
1869 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1872 fputs("-----BEGIN OPENSSH PRIVATE KEY-----\n", fp);
1873 base64_encode(fp, outblob, p - outblob, 64);
1874 fputs("-----END OPENSSH PRIVATE KEY-----\n", fp);
1880 smemclr(outblob, maxsize);
1884 smemclr(privblob, privlen);
1888 smemclr(pubblob, publen);
1894 /* ----------------------------------------------------------------------
1895 * The switch function openssh_auto_write(), which chooses one of the
1896 * concrete OpenSSH output formats based on the key type.
1898 int openssh_auto_write(const Filename *filename, struct ssh2_userkey *key,
1902 * The old OpenSSH format supports a fixed list of key types. We
1903 * assume that anything not in that fixed list is newer, and hence
1904 * will use the new format.
1906 if (key->alg == &ssh_dss ||
1907 key->alg == &ssh_rsa ||
1908 key->alg == &ssh_ecdsa_nistp256 ||
1909 key->alg == &ssh_ecdsa_nistp384 ||
1910 key->alg == &ssh_ecdsa_nistp521)
1911 return openssh_pem_write(filename, key, passphrase);
1913 return openssh_new_write(filename, key, passphrase);
1916 /* ----------------------------------------------------------------------
1917 * Code to read ssh.com private keys.
1921 * The format of the base64 blob is largely SSH-2-packet-formatted,
1922 * except that mpints are a bit different: they're more like the
1923 * old SSH-1 mpint. You have a 32-bit bit count N, followed by
1924 * (N+7)/8 bytes of data.
1926 * So. The blob contains:
1928 * - uint32 0x3f6ff9eb (magic number)
1929 * - uint32 size (total blob size)
1930 * - string key-type (see below)
1931 * - string cipher-type (tells you if key is encrypted)
1932 * - string encrypted-blob
1934 * (The first size field includes the size field itself and the
1935 * magic number before it. All other size fields are ordinary SSH-2
1936 * strings, so the size field indicates how much data is to
1939 * The encrypted blob, once decrypted, contains a single string
1940 * which in turn contains the payload. (This allows padding to be
1941 * added after that string while still making it clear where the
1942 * real payload ends. Also it probably makes for a reasonable
1943 * decryption check.)
1945 * The payload blob, for an RSA key, contains:
1948 * - mpint n (yes, the public and private stuff is intermixed)
1949 * - mpint u (presumably inverse of p mod q)
1950 * - mpint p (p is the smaller prime)
1951 * - mpint q (q is the larger)
1953 * For a DSA key, the payload blob contains:
1961 * Alternatively, if the parameters are `predefined', that
1962 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
1963 * containing some predefined parameter specification. *shudder*,
1964 * but I doubt we'll encounter this in real life.
1966 * The key type strings are ghastly. The RSA key I looked at had a
1969 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
1971 * and the DSA key wasn't much better:
1973 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
1975 * It isn't clear that these will always be the same. I think it
1976 * might be wise just to look at the `if-modn{sign{rsa' and
1977 * `dl-modp{sign{dsa' prefixes.
1979 * Finally, the encryption. The cipher-type string appears to be
1980 * either `none' or `3des-cbc'. Looks as if this is SSH-2-style
1981 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
1982 * from the passphrase by means of yet another hashing faff:
1984 * - first 16 bytes are MD5(passphrase)
1985 * - next 16 bytes are MD5(passphrase || first 16 bytes)
1986 * - if there were more, they'd be MD5(passphrase || first 32),
1990 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
1993 char comment[256]; /* allowing any length is overkill */
1994 unsigned char *keyblob;
1995 int keyblob_len, keyblob_size;
1998 static struct sshcom_key *load_sshcom_key(const Filename *filename,
1999 const char **errmsg_p)
2001 struct sshcom_key *ret;
2009 int base64_chars = 0;
2011 ret = snew(struct sshcom_key);
2012 ret->comment[0] = '\0';
2013 ret->keyblob = NULL;
2014 ret->keyblob_len = ret->keyblob_size = 0;
2016 fp = f_open(filename, "r", FALSE);
2018 errmsg = "unable to open key file";
2021 if (!(line = fgetline(fp))) {
2022 errmsg = "unexpected end of file";
2026 if (0 != strcmp(line, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
2027 errmsg = "file does not begin with ssh.com key header";
2030 smemclr(line, strlen(line));
2036 if (!(line = fgetline(fp))) {
2037 errmsg = "unexpected end of file";
2041 if (!strcmp(line, "---- END SSH2 ENCRYPTED PRIVATE KEY ----")) {
2046 if ((p = strchr(line, ':')) != NULL) {
2048 errmsg = "header found in body of key data";
2052 while (*p && isspace((unsigned char)*p)) p++;
2053 hdrstart = p - line;
2056 * Header lines can end in a trailing backslash for
2059 len = hdrstart + strlen(line+hdrstart);
2061 while (line[len-1] == '\\') {
2065 line2 = fgetline(fp);
2067 errmsg = "unexpected end of file";
2072 line2len = strlen(line2);
2073 line = sresize(line, len + line2len + 1, char);
2074 strcpy(line + len - 1, line2);
2075 len += line2len - 1;
2078 smemclr(line2, strlen(line2));
2082 p = line + hdrstart;
2084 if (!strcmp(line, "Comment")) {
2085 /* Strip quotes in comment if present. */
2086 if (p[0] == '"' && p[strlen(p)-1] == '"') {
2088 p[strlen(p)-1] = '\0';
2090 strncpy(ret->comment, p, sizeof(ret->comment));
2091 ret->comment[sizeof(ret->comment)-1] = '\0';
2097 while (isbase64(*p)) {
2098 base64_bit[base64_chars++] = *p;
2099 if (base64_chars == 4) {
2100 unsigned char out[3];
2104 len = base64_decode_atom(base64_bit, out);
2107 errmsg = "invalid base64 encoding";
2111 if (ret->keyblob_len + len > ret->keyblob_size) {
2112 ret->keyblob_size = ret->keyblob_len + len + 256;
2113 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
2117 memcpy(ret->keyblob + ret->keyblob_len, out, len);
2118 ret->keyblob_len += len;
2124 smemclr(line, strlen(line));
2129 if (ret->keyblob_len == 0 || !ret->keyblob) {
2130 errmsg = "key body not present";
2135 if (errmsg_p) *errmsg_p = NULL;
2143 smemclr(line, strlen(line));
2149 smemclr(ret->keyblob, ret->keyblob_size);
2150 sfree(ret->keyblob);
2152 smemclr(ret, sizeof(*ret));
2155 if (errmsg_p) *errmsg_p = errmsg;
2159 int sshcom_encrypted(const Filename *filename, char **comment)
2161 struct sshcom_key *key = load_sshcom_key(filename, NULL);
2162 int pos, len, answer;
2171 * Check magic number.
2173 if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) {
2174 goto done; /* key is invalid */
2178 * Find the cipher-type string.
2181 if (key->keyblob_len < pos+4)
2182 goto done; /* key is far too short */
2183 len = toint(GET_32BIT(key->keyblob + pos));
2184 if (len < 0 || len > key->keyblob_len - pos - 4)
2185 goto done; /* key is far too short */
2186 pos += 4 + len; /* skip key type */
2187 len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
2188 if (len < 0 || len > key->keyblob_len - pos - 4)
2189 goto done; /* cipher type string is incomplete */
2190 if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
2195 *comment = dupstr(key->comment);
2196 smemclr(key->keyblob, key->keyblob_size);
2197 sfree(key->keyblob);
2198 smemclr(key, sizeof(*key));
2201 *comment = dupstr("");
2206 static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
2208 unsigned bits, bytes;
2209 unsigned char *d = (unsigned char *) data;
2213 bits = GET_32BIT(d);
2215 bytes = (bits + 7) / 8;
2226 return len; /* ensure further calls fail as well */
2229 static int sshcom_put_mpint(void *target, void *data, int len)
2231 unsigned char *d = (unsigned char *)target;
2232 unsigned char *i = (unsigned char *)data;
2233 int bits = len * 8 - 1;
2236 if (*i & (1 << (bits & 7)))
2242 PUT_32BIT(d, bits+1);
2243 memcpy(d+4, i, len);
2247 struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
2248 const char **errmsg_p)
2250 struct sshcom_key *key = load_sshcom_key(filename, errmsg_p);
2253 const char prefix_rsa[] = "if-modn{sign{rsa";
2254 const char prefix_dsa[] = "dl-modp{sign{dsa";
2255 enum { RSA, DSA } type;
2259 struct ssh2_userkey *ret = NULL, *retkey;
2260 const struct ssh_signkey *alg;
2261 unsigned char *blob = NULL;
2262 int blobsize = 0, publen, privlen;
2268 * Check magic number.
2270 if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) {
2271 errmsg = "key does not begin with magic number";
2276 * Determine the key type.
2279 if (key->keyblob_len < pos+4 ||
2280 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2281 len > key->keyblob_len - pos - 4) {
2282 errmsg = "key blob does not contain a key type string";
2285 if (len > sizeof(prefix_rsa) - 1 &&
2286 !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) {
2288 } else if (len > sizeof(prefix_dsa) - 1 &&
2289 !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) {
2292 errmsg = "key is of unknown type";
2298 * Determine the cipher type.
2300 if (key->keyblob_len < pos+4 ||
2301 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2302 len > key->keyblob_len - pos - 4) {
2303 errmsg = "key blob does not contain a cipher type string";
2306 if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4))
2308 else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8))
2311 errmsg = "key encryption is of unknown type";
2317 * Get hold of the encrypted part of the key.
2319 if (key->keyblob_len < pos+4 ||
2320 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2321 len > key->keyblob_len - pos - 4) {
2322 errmsg = "key blob does not contain actual key data";
2325 ciphertext = (char *)key->keyblob + pos + 4;
2327 if (cipherlen == 0) {
2328 errmsg = "length of key data is zero";
2333 * Decrypt it if necessary.
2337 * Derive encryption key from passphrase and iv/salt:
2339 * - let block A equal MD5(passphrase)
2340 * - let block B equal MD5(passphrase || A)
2341 * - block C would be MD5(passphrase || A || B) and so on
2342 * - encryption key is the first N bytes of A || B
2344 struct MD5Context md5c;
2345 unsigned char keybuf[32], iv[8];
2347 if (cipherlen % 8 != 0) {
2348 errmsg = "encrypted part of key is not a multiple of cipher block"
2354 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2355 MD5Final(keybuf, &md5c);
2358 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2359 MD5Update(&md5c, keybuf, 16);
2360 MD5Final(keybuf+16, &md5c);
2363 * Now decrypt the key blob.
2365 memset(iv, 0, sizeof(iv));
2366 des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2369 smemclr(&md5c, sizeof(md5c));
2370 smemclr(keybuf, sizeof(keybuf));
2373 * Hereafter we return WRONG_PASSPHRASE for any parsing
2374 * error. (But only if we've just tried to decrypt it!
2375 * Returning WRONG_PASSPHRASE for an unencrypted key is
2379 ret = SSH2_WRONG_PASSPHRASE;
2383 * Strip away the containing string to get to the real meat.
2385 len = toint(GET_32BIT(ciphertext));
2386 if (len < 0 || len > cipherlen-4) {
2387 errmsg = "containing string was ill-formed";
2394 * Now we break down into RSA versus DSA. In either case we'll
2395 * construct public and private blobs in our own format, and
2396 * end up feeding them to alg->createkey().
2398 blobsize = cipherlen + 256;
2399 blob = snewn(blobsize, unsigned char);
2402 struct mpint_pos n, e, d, u, p, q;
2404 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e);
2405 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d);
2406 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n);
2407 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u);
2408 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2409 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2411 errmsg = "key data did not contain six integers";
2417 pos += put_string(blob+pos, "ssh-rsa", 7);
2418 pos += put_mp(blob+pos, e.start, e.bytes);
2419 pos += put_mp(blob+pos, n.start, n.bytes);
2421 pos += put_string(blob+pos, d.start, d.bytes);
2422 pos += put_mp(blob+pos, q.start, q.bytes);
2423 pos += put_mp(blob+pos, p.start, p.bytes);
2424 pos += put_mp(blob+pos, u.start, u.bytes);
2425 privlen = pos - publen;
2427 struct mpint_pos p, q, g, x, y;
2430 assert(type == DSA); /* the only other option from the if above */
2432 if (GET_32BIT(ciphertext) != 0) {
2433 errmsg = "predefined DSA parameters not supported";
2436 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2437 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g);
2438 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2439 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y);
2440 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x);
2442 errmsg = "key data did not contain five integers";
2448 pos += put_string(blob+pos, "ssh-dss", 7);
2449 pos += put_mp(blob+pos, p.start, p.bytes);
2450 pos += put_mp(blob+pos, q.start, q.bytes);
2451 pos += put_mp(blob+pos, g.start, g.bytes);
2452 pos += put_mp(blob+pos, y.start, y.bytes);
2454 pos += put_mp(blob+pos, x.start, x.bytes);
2455 privlen = pos - publen;
2458 assert(privlen > 0); /* should have bombed by now if not */
2460 retkey = snew(struct ssh2_userkey);
2462 retkey->data = alg->createkey(alg, blob, publen, blob+publen, privlen);
2463 if (!retkey->data) {
2465 errmsg = "unable to create key data structure";
2468 retkey->comment = dupstr(key->comment);
2470 errmsg = NULL; /* no error */
2475 smemclr(blob, blobsize);
2478 smemclr(key->keyblob, key->keyblob_size);
2479 sfree(key->keyblob);
2480 smemclr(key, sizeof(*key));
2482 if (errmsg_p) *errmsg_p = errmsg;
2486 int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
2489 unsigned char *pubblob, *privblob;
2490 int publen, privlen;
2491 unsigned char *outblob;
2493 struct mpint_pos numbers[6];
2494 int nnumbers, initial_zero, pos, lenpos, i;
2502 * Fetch the key blobs.
2504 pubblob = key->alg->public_blob(key->data, &publen);
2505 privblob = key->alg->private_blob(key->data, &privlen);
2509 * Find the sequence of integers to be encoded into the OpenSSH
2510 * key blob, and also decide on the header line.
2512 if (key->alg == &ssh_rsa) {
2514 struct mpint_pos n, e, d, p, q, iqmp;
2517 * These blobs were generated from inside PuTTY, so we needn't
2518 * treat them as untrusted.
2520 pos = 4 + GET_32BIT(pubblob);
2521 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
2522 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
2524 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
2525 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
2526 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
2527 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
2529 assert(e.start && iqmp.start); /* can't go wrong */
2540 type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
2541 } else if (key->alg == &ssh_dss) {
2543 struct mpint_pos p, q, g, y, x;
2546 * These blobs were generated from inside PuTTY, so we needn't
2547 * treat them as untrusted.
2549 pos = 4 + GET_32BIT(pubblob);
2550 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
2551 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
2552 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
2553 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
2555 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
2557 assert(y.start && x.start); /* can't go wrong */
2567 type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
2569 assert(0); /* zoinks! */
2570 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
2574 * Total size of key blob will be somewhere under 512 plus
2575 * combined length of integers. We'll calculate the more
2576 * precise size as we construct the blob.
2579 for (i = 0; i < nnumbers; i++)
2580 outlen += 4 + numbers[i].bytes;
2581 outblob = snewn(outlen, unsigned char);
2584 * Create the unencrypted key blob.
2587 PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
2588 pos += 4; /* length field, fill in later */
2589 pos += put_string(outblob+pos, type, strlen(type));
2591 const char *ciphertype = passphrase ? "3des-cbc" : "none";
2592 pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
2594 lenpos = pos; /* remember this position */
2595 pos += 4; /* encrypted-blob size */
2596 pos += 4; /* encrypted-payload size */
2598 PUT_32BIT(outblob+pos, 0);
2601 for (i = 0; i < nnumbers; i++)
2602 pos += sshcom_put_mpint(outblob+pos,
2603 numbers[i].start, numbers[i].bytes);
2604 /* Now wrap up the encrypted payload. */
2605 PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8));
2606 /* Pad encrypted blob to a multiple of cipher block size. */
2608 int padding = -(pos - (lenpos+4)) & 7;
2610 outblob[pos++] = random_byte();
2612 ciphertext = (char *)outblob+lenpos+4;
2613 cipherlen = pos - (lenpos+4);
2614 assert(!passphrase || cipherlen % 8 == 0);
2615 /* Wrap up the encrypted blob string. */
2616 PUT_32BIT(outblob+lenpos, cipherlen);
2617 /* And finally fill in the total length field. */
2618 PUT_32BIT(outblob+4, pos);
2620 assert(pos < outlen);
2627 * Derive encryption key from passphrase and iv/salt:
2629 * - let block A equal MD5(passphrase)
2630 * - let block B equal MD5(passphrase || A)
2631 * - block C would be MD5(passphrase || A || B) and so on
2632 * - encryption key is the first N bytes of A || B
2634 struct MD5Context md5c;
2635 unsigned char keybuf[32], iv[8];
2638 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2639 MD5Final(keybuf, &md5c);
2642 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2643 MD5Update(&md5c, keybuf, 16);
2644 MD5Final(keybuf+16, &md5c);
2647 * Now decrypt the key blob.
2649 memset(iv, 0, sizeof(iv));
2650 des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2653 smemclr(&md5c, sizeof(md5c));
2654 smemclr(keybuf, sizeof(keybuf));
2658 * And save it. We'll use Unix line endings just in case it's
2659 * subsequently transferred in binary mode.
2661 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
2664 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2665 fprintf(fp, "Comment: \"");
2667 * Comment header is broken with backslash-newline if it goes
2668 * over 70 chars. Although it's surrounded by quotes, it
2669 * _doesn't_ escape backslashes or quotes within the string.
2670 * Don't ask me, I didn't design it.
2673 int slen = 60; /* starts at 60 due to "Comment: " */
2674 char *c = key->comment;
2675 while ((int)strlen(c) > slen) {
2676 fprintf(fp, "%.*s\\\n", slen, c);
2678 slen = 70; /* allow 70 chars on subsequent lines */
2680 fprintf(fp, "%s\"\n", c);
2682 base64_encode(fp, outblob, pos, 70);
2683 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2689 smemclr(outblob, outlen);
2693 smemclr(privblob, privlen);
2697 smemclr(pubblob, publen);