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);
204 *length = (*length << 8) | (*p++);
211 return p - (unsigned char *) source;
215 * Write an ASN.1/BER identifier and length pair. Returns the
216 * number of bytes consumed. Assumes dest contains enough space.
217 * Will avoid writing anything if dest is NULL, but still return
218 * amount of space required.
220 static int ber_write_id_len(void *dest, int id, int length, int flags)
222 unsigned char *d = (unsigned char *)dest;
227 * Identifier is one byte.
230 if (d) *d++ = id | flags;
234 * Identifier is multiple bytes: the first byte is 11111
235 * plus the flags, and subsequent bytes encode the value of
236 * the identifier, 7 bits at a time, with the top bit of
237 * each byte 1 except the last one which is 0.
240 if (d) *d++ = 0x1F | flags;
241 for (n = 1; (id >> (7*n)) > 0; n++)
242 continue; /* count the bytes */
245 if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F);
251 * Length is one byte.
254 if (d) *d++ = length;
258 * Length is multiple bytes. The first is 0x80 plus the
259 * number of subsequent bytes, and the subsequent bytes
260 * encode the actual length.
262 for (n = 1; (length >> (8*n)) > 0; n++)
263 continue; /* count the bytes */
265 if (d) *d++ = 0x80 | n;
268 if (d) *d++ = (length >> (8*n)) & 0xFF;
275 static int put_uint32(void *target, unsigned val)
277 unsigned char *d = (unsigned char *)target;
283 static int put_string(void *target, const void *data, int len)
285 unsigned char *d = (unsigned char *)target;
288 memcpy(d+4, data, len);
292 static int put_string_z(void *target, const char *string)
294 return put_string(target, string, strlen(string));
297 static int put_mp(void *target, void *data, int len)
299 unsigned char *d = (unsigned char *)target;
300 unsigned char *i = (unsigned char *)data;
305 memcpy(d+5, data, len);
309 memcpy(d+4, data, len);
314 /* Simple structure to point to an mp-int within a blob. */
315 struct mpint_pos { void *start; int bytes; };
317 static int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret)
320 unsigned char *d = (unsigned char *) data;
324 bytes = toint(GET_32BIT(d));
325 if (bytes < 0 || len-4 < bytes)
335 return len; /* ensure further calls fail as well */
338 /* ----------------------------------------------------------------------
339 * Code to read and write OpenSSH private keys, in the old-style PEM
344 OP_DSA, OP_RSA, OP_ECDSA
345 } openssh_pem_keytype;
350 struct openssh_pem_key {
351 openssh_pem_keytype keytype;
353 openssh_pem_enc encryption;
355 unsigned char *keyblob;
356 int keyblob_len, keyblob_size;
359 static struct openssh_pem_key *load_openssh_pem_key(const Filename *filename,
360 const char **errmsg_p)
362 struct openssh_pem_key *ret;
368 int base64_chars = 0;
370 ret = snew(struct openssh_pem_key);
372 ret->keyblob_len = ret->keyblob_size = 0;
374 fp = f_open(filename, "r", FALSE);
376 errmsg = "unable to open key file";
380 if (!(line = fgetline(fp))) {
381 errmsg = "unexpected end of file";
385 if (0 != strncmp(line, "-----BEGIN ", 11) ||
386 0 != strcmp(line+strlen(line)-16, "PRIVATE KEY-----")) {
387 errmsg = "file does not begin with OpenSSH key header";
391 * Parse the BEGIN line. For old-format keys, this tells us the
392 * type of the key; for new-format keys, all it tells us is the
393 * format, and we'll find out the key type once we parse the
396 if (!strcmp(line, "-----BEGIN RSA PRIVATE KEY-----")) {
397 ret->keytype = OP_RSA;
398 } else if (!strcmp(line, "-----BEGIN DSA PRIVATE KEY-----")) {
399 ret->keytype = OP_DSA;
400 } else if (!strcmp(line, "-----BEGIN EC PRIVATE KEY-----")) {
401 ret->keytype = OP_ECDSA;
402 } else if (!strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
403 errmsg = "this is a new-style OpenSSH key";
406 errmsg = "unrecognised key type";
409 smemclr(line, strlen(line));
413 ret->encrypted = FALSE;
414 memset(ret->iv, 0, sizeof(ret->iv));
418 if (!(line = fgetline(fp))) {
419 errmsg = "unexpected end of file";
423 if (0 == strncmp(line, "-----END ", 9) &&
424 0 == strcmp(line+strlen(line)-16, "PRIVATE KEY-----")) {
429 if ((p = strchr(line, ':')) != NULL) {
431 errmsg = "header found in body of key data";
435 while (*p && isspace((unsigned char)*p)) p++;
436 if (!strcmp(line, "Proc-Type")) {
437 if (p[0] != '4' || p[1] != ',') {
438 errmsg = "Proc-Type is not 4 (only 4 is supported)";
442 if (!strcmp(p, "ENCRYPTED"))
443 ret->encrypted = TRUE;
444 } else if (!strcmp(line, "DEK-Info")) {
447 if (!strncmp(p, "DES-EDE3-CBC,", 13)) {
448 ret->encryption = OP_E_3DES;
450 } else if (!strncmp(p, "AES-128-CBC,", 12)) {
451 ret->encryption = OP_E_AES;
454 errmsg = "unsupported cipher";
457 p = strchr(p, ',') + 1;/* always non-NULL, by above checks */
458 for (i = 0; i < ivlen; i++) {
459 if (1 != sscanf(p, "%2x", &j)) {
460 errmsg = "expected more iv data in DEK-Info";
467 errmsg = "more iv data than expected in DEK-Info";
475 while (isbase64(*p)) {
476 base64_bit[base64_chars++] = *p;
477 if (base64_chars == 4) {
478 unsigned char out[3];
483 len = base64_decode_atom(base64_bit, out);
486 errmsg = "invalid base64 encoding";
490 if (ret->keyblob_len + len > ret->keyblob_size) {
491 ret->keyblob_size = ret->keyblob_len + len + 256;
492 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
496 memcpy(ret->keyblob + ret->keyblob_len, out, len);
497 ret->keyblob_len += len;
499 smemclr(out, sizeof(out));
505 smemclr(line, strlen(line));
513 if (ret->keyblob_len == 0 || !ret->keyblob) {
514 errmsg = "key body not present";
518 if (ret->encrypted && ret->keyblob_len % 8 != 0) {
519 errmsg = "encrypted key blob is not a multiple of "
524 smemclr(base64_bit, sizeof(base64_bit));
525 if (errmsg_p) *errmsg_p = NULL;
530 smemclr(line, strlen(line));
534 smemclr(base64_bit, sizeof(base64_bit));
537 smemclr(ret->keyblob, ret->keyblob_size);
540 smemclr(ret, sizeof(*ret));
543 if (errmsg_p) *errmsg_p = errmsg;
548 int openssh_pem_encrypted(const Filename *filename)
550 struct openssh_pem_key *key = load_openssh_pem_key(filename, NULL);
555 ret = key->encrypted;
556 smemclr(key->keyblob, key->keyblob_size);
558 smemclr(key, sizeof(*key));
563 struct ssh2_userkey *openssh_pem_read(const Filename *filename,
565 const char **errmsg_p)
567 struct openssh_pem_key *key = load_openssh_pem_key(filename, errmsg_p);
568 struct ssh2_userkey *retkey;
570 int ret, id, len, flags;
572 struct ssh2_userkey *retval = NULL;
575 int blobsize = 0, blobptr, privptr;
584 if (key->encrypted) {
586 * Derive encryption key from passphrase and iv/salt:
588 * - let block A equal MD5(passphrase || iv)
589 * - let block B equal MD5(A || passphrase || iv)
590 * - block C would be MD5(B || passphrase || iv) and so on
591 * - encryption key is the first N bytes of A || B
593 * (Note that only 8 bytes of the iv are used for key
594 * derivation, even when the key is encrypted with AES and
595 * hence there are 16 bytes available.)
597 struct MD5Context md5c;
598 unsigned char keybuf[32];
601 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
602 MD5Update(&md5c, (unsigned char *)key->iv, 8);
603 MD5Final(keybuf, &md5c);
606 MD5Update(&md5c, keybuf, 16);
607 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
608 MD5Update(&md5c, (unsigned char *)key->iv, 8);
609 MD5Final(keybuf+16, &md5c);
612 * Now decrypt the key blob.
614 if (key->encryption == OP_E_3DES)
615 des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv,
616 key->keyblob, key->keyblob_len);
619 assert(key->encryption == OP_E_AES);
620 ctx = aes_make_context();
621 aes128_key(ctx, keybuf);
622 aes_iv(ctx, (unsigned char *)key->iv);
623 aes_ssh2_decrypt_blk(ctx, key->keyblob, key->keyblob_len);
624 aes_free_context(ctx);
627 smemclr(&md5c, sizeof(md5c));
628 smemclr(keybuf, sizeof(keybuf));
632 * Now we have a decrypted key blob, which contains an ASN.1
633 * encoded private key. We must now untangle the ASN.1.
635 * We expect the whole key blob to be formatted as a SEQUENCE
636 * (0x30 followed by a length code indicating that the rest of
637 * the blob is part of the sequence). Within that SEQUENCE we
638 * expect to see a bunch of INTEGERs. What those integers mean
639 * depends on the key type:
641 * - For RSA, we expect the integers to be 0, n, e, d, p, q,
642 * dmp1, dmq1, iqmp in that order. (The last three are d mod
643 * (p-1), d mod (q-1), inverse of q mod p respectively.)
645 * - For DSA, we expect them to be 0, p, q, g, y, x in that
648 * - In ECDSA the format is totally different: we see the
649 * SEQUENCE, but beneath is an INTEGER 1, OCTET STRING priv
650 * EXPLICIT [0] OID curve, EXPLICIT [1] BIT STRING pubPoint
655 /* Expect the SEQUENCE header. Take its absence as a failure to
656 * decrypt, if the key was encrypted. */
657 ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
659 if (ret < 0 || id != 16) {
660 errmsg = "ASN.1 decoding failure";
661 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
665 /* Expect a load of INTEGERs. */
666 if (key->keytype == OP_RSA)
668 else if (key->keytype == OP_DSA)
671 num_integers = 0; /* placate compiler warnings */
674 if (key->keytype == OP_ECDSA) {
675 /* And now for something completely different */
678 struct ec_curve *curve;
680 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
683 if (ret < 0 || id != 2 || key->keyblob+key->keyblob_len-p < len ||
684 len != 1 || p[0] != 1) {
685 errmsg = "ASN.1 decoding failure";
686 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
690 /* Read private key OCTET STRING */
691 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
694 if (ret < 0 || id != 4 || key->keyblob+key->keyblob_len-p < len) {
695 errmsg = "ASN.1 decoding failure";
696 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
703 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
706 if (ret < 0 || id != 0 || key->keyblob+key->keyblob_len-p < len) {
707 errmsg = "ASN.1 decoding failure";
708 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
711 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
714 if (ret < 0 || id != 6 || key->keyblob+key->keyblob_len-p < len) {
715 errmsg = "ASN.1 decoding failure";
716 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
719 if (len == 8 && !memcmp(p, nistp256_oid, nistp256_oid_len)) {
721 } else if (len == 5 && !memcmp(p, nistp384_oid,
724 } else if (len == 5 && !memcmp(p, nistp521_oid,
728 errmsg = "Unsupported ECDSA curve.";
733 /* Read BIT STRING point */
734 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
737 if (ret < 0 || id != 1 || key->keyblob+key->keyblob_len-p < len) {
738 errmsg = "ASN.1 decoding failure";
739 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
742 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
745 if (ret < 0 || id != 3 || key->keyblob+key->keyblob_len-p < len ||
746 len != ((((curve->fieldBits + 7) / 8) * 2) + 2)) {
747 errmsg = "ASN.1 decoding failure";
748 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
751 p += 1; len -= 1; /* Skip 0x00 before point */
753 /* Construct the key */
754 retkey = snew(struct ssh2_userkey);
756 errmsg = "out of memory";
759 if (curve->fieldBits == 256) {
760 retkey->alg = &ssh_ecdsa_nistp256;
761 } else if (curve->fieldBits == 384) {
762 retkey->alg = &ssh_ecdsa_nistp384;
764 retkey->alg = &ssh_ecdsa_nistp521;
766 blob = snewn((4+19 + 4+8 + 4+len) + (4+privlen), unsigned char);
769 errmsg = "out of memory";
773 sprintf((char*)blob+4, "ecdsa-sha2-nistp%d", curve->fieldBits);
774 PUT_32BIT(blob+4+19, 8);
775 sprintf((char*)blob+4+19+4, "nistp%d", curve->fieldBits);
776 PUT_32BIT(blob+4+19+4+8, len);
777 memcpy(blob+4+19+4+8+4, p, len);
778 PUT_32BIT(blob+4+19+4+8+4+len, privlen);
779 memcpy(blob+4+19+4+8+4+len+4, priv, privlen);
780 retkey->data = retkey->alg->createkey(blob, 4+19+4+8+4+len,
785 errmsg = "unable to create key data structure";
789 } else if (key->keytype == OP_RSA || key->keytype == OP_DSA) {
792 * Space to create key blob in.
794 blobsize = 256+key->keyblob_len;
795 blob = snewn(blobsize, unsigned char);
797 if (key->keytype == OP_DSA)
798 memcpy(blob+4, "ssh-dss", 7);
799 else if (key->keytype == OP_RSA)
800 memcpy(blob+4, "ssh-rsa", 7);
804 for (i = 0; i < num_integers; i++) {
805 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
808 if (ret < 0 || id != 2 ||
809 key->keyblob+key->keyblob_len-p < len) {
810 errmsg = "ASN.1 decoding failure";
811 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
817 * The first integer should be zero always (I think
818 * this is some sort of version indication).
820 if (len != 1 || p[0] != 0) {
821 errmsg = "version number mismatch";
824 } else if (key->keytype == OP_RSA) {
826 * Integers 1 and 2 go into the public blob but in the
827 * opposite order; integers 3, 4, 5 and 8 go into the
828 * private blob. The other two (6 and 7) are ignored.
831 /* Save the details for after we deal with number 2. */
834 } else if (i != 6 && i != 7) {
835 PUT_32BIT(blob+blobptr, len);
836 memcpy(blob+blobptr+4, p, len);
839 PUT_32BIT(blob+blobptr, modlen);
840 memcpy(blob+blobptr+4, modptr, modlen);
845 } else if (key->keytype == OP_DSA) {
847 * Integers 1-4 go into the public blob; integer 5 goes
848 * into the private blob.
850 PUT_32BIT(blob+blobptr, len);
851 memcpy(blob+blobptr+4, p, len);
857 /* Skip past the number. */
862 * Now put together the actual key. Simplest way to do this is
863 * to assemble our own key blobs and feed them to the createkey
864 * functions; this is a bit faffy but it does mean we get all
865 * the sanity checks for free.
867 assert(privptr > 0); /* should have bombed by now if not */
868 retkey = snew(struct ssh2_userkey);
869 retkey->alg = (key->keytype == OP_RSA ? &ssh_rsa : &ssh_dss);
870 retkey->data = retkey->alg->createkey(blob, privptr,
875 errmsg = "unable to create key data structure";
880 assert(0 && "Bad key type from load_openssh_pem_key");
884 * The old key format doesn't include a comment in the private
887 retkey->comment = dupstr("imported-openssh-key");
889 errmsg = NULL; /* no error */
894 smemclr(blob, blobsize);
897 smemclr(key->keyblob, key->keyblob_size);
899 smemclr(key, sizeof(*key));
901 if (errmsg_p) *errmsg_p = errmsg;
905 int openssh_pem_write(const Filename *filename, struct ssh2_userkey *key,
908 unsigned char *pubblob, *privblob, *spareblob;
909 int publen, privlen, sparelen = 0;
910 unsigned char *outblob;
912 struct mpint_pos numbers[9];
913 int nnumbers, pos, len, seqlen, i;
914 char *header, *footer;
921 * Fetch the key blobs.
923 pubblob = key->alg->public_blob(key->data, &publen);
924 privblob = key->alg->private_blob(key->data, &privlen);
925 spareblob = outblob = NULL;
931 * Encode the OpenSSH key blob, and also decide on the header
934 if (key->alg == &ssh_rsa || key->alg == &ssh_dss) {
936 * The RSA and DSS handlers share some code because the two
937 * key types have very similar ASN.1 representations, as a
938 * plain SEQUENCE of big integers. So we set up a list of
939 * bignums per key type and then construct the actual blob in
940 * common code after that.
942 if (key->alg == &ssh_rsa) {
944 struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
945 Bignum bd, bp, bq, bdmp1, bdmq1;
948 * These blobs were generated from inside PuTTY, so we needn't
949 * treat them as untrusted.
951 pos = 4 + GET_32BIT(pubblob);
952 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
953 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
955 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
956 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
957 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
958 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
960 assert(e.start && iqmp.start); /* can't go wrong */
962 /* We also need d mod (p-1) and d mod (q-1). */
963 bd = bignum_from_bytes(d.start, d.bytes);
964 bp = bignum_from_bytes(p.start, p.bytes);
965 bq = bignum_from_bytes(q.start, q.bytes);
968 bdmp1 = bigmod(bd, bp);
969 bdmq1 = bigmod(bd, bq);
974 dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
975 dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
976 sparelen = dmp1.bytes + dmq1.bytes;
977 spareblob = snewn(sparelen, unsigned char);
978 dmp1.start = spareblob;
979 dmq1.start = spareblob + dmp1.bytes;
980 for (i = 0; i < dmp1.bytes; i++)
981 spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
982 for (i = 0; i < dmq1.bytes; i++)
983 spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
987 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
998 header = "-----BEGIN RSA PRIVATE KEY-----\n";
999 footer = "-----END RSA PRIVATE KEY-----\n";
1000 } else { /* ssh-dss */
1002 struct mpint_pos p, q, g, y, x;
1005 * These blobs were generated from inside PuTTY, so we needn't
1006 * treat them as untrusted.
1008 pos = 4 + GET_32BIT(pubblob);
1009 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
1010 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
1011 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
1012 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
1014 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
1016 assert(y.start && x.start); /* can't go wrong */
1018 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
1026 header = "-----BEGIN DSA PRIVATE KEY-----\n";
1027 footer = "-----END DSA PRIVATE KEY-----\n";
1031 * Now count up the total size of the ASN.1 encoded integers,
1032 * so as to determine the length of the containing SEQUENCE.
1035 for (i = 0; i < nnumbers; i++) {
1036 len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
1037 len += numbers[i].bytes;
1040 /* Now add on the SEQUENCE header. */
1041 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1044 * Now we know how big outblob needs to be. Allocate it.
1046 outblob = snewn(len, unsigned char);
1049 * And write the data into it.
1052 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1053 for (i = 0; i < nnumbers; i++) {
1054 pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
1055 memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
1056 pos += numbers[i].bytes;
1058 } else if (key->alg == &ssh_ecdsa_nistp256 ||
1059 key->alg == &ssh_ecdsa_nistp384 ||
1060 key->alg == &ssh_ecdsa_nistp521) {
1066 * Structure of asn1:
1069 * OCTET STRING (private key)
1073 * BIT STRING (0x00 public key point)
1075 switch (((struct ec_key *)key->data)->publicKey.curve->fieldBits) {
1077 /* OID: 1.2.840.10045.3.1.7 (ansiX9p256r1) */
1079 oidlen = nistp256_oid_len;
1083 /* OID: 1.3.132.0.34 (secp384r1) */
1085 oidlen = nistp384_oid_len;
1089 /* OID: 1.3.132.0.35 (secp521r1) */
1091 oidlen = nistp521_oid_len;
1098 len = ber_write_id_len(NULL, 2, 1, 0);
1100 len += ber_write_id_len(NULL, 4, privlen - 4, 0);
1102 len += ber_write_id_len(NULL, 0, oidlen +
1103 ber_write_id_len(NULL, 6, oidlen, 0),
1104 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1105 len += ber_write_id_len(NULL, 6, oidlen, 0);
1107 len += ber_write_id_len(NULL, 1, 2 + pointlen +
1108 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1109 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1110 len += ber_write_id_len(NULL, 3, 2 + pointlen, 0);
1111 len += 2 + pointlen;
1114 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1116 outblob = snewn(len, unsigned char);
1120 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1121 pos += ber_write_id_len(outblob+pos, 2, 1, 0);
1123 pos += ber_write_id_len(outblob+pos, 4, privlen - 4, 0);
1124 memcpy(outblob+pos, privblob + 4, privlen - 4);
1126 pos += ber_write_id_len(outblob+pos, 0, oidlen +
1127 ber_write_id_len(NULL, 6, oidlen, 0),
1128 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1129 pos += ber_write_id_len(outblob+pos, 6, oidlen, 0);
1130 memcpy(outblob+pos, oid, oidlen);
1132 pos += ber_write_id_len(outblob+pos, 1, 2 + pointlen +
1133 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1134 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1135 pos += ber_write_id_len(outblob+pos, 3, 2 + pointlen, 0);
1137 memcpy(outblob+pos, pubblob+39, 1 + pointlen);
1138 pos += 1 + pointlen;
1140 header = "-----BEGIN EC PRIVATE KEY-----\n";
1141 footer = "-----END EC PRIVATE KEY-----\n";
1143 assert(0); /* zoinks! */
1144 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
1150 * For the moment, we still encrypt our OpenSSH keys using
1154 struct MD5Context md5c;
1155 unsigned char keybuf[32];
1158 * Round up to the cipher block size, ensuring we have at
1159 * least one byte of padding (see below).
1161 outlen = (len+8) &~ 7;
1163 unsigned char *tmp = snewn(outlen, unsigned char);
1164 memcpy(tmp, outblob, len);
1165 smemclr(outblob, len);
1171 * Padding on OpenSSH keys is deterministic. The number of
1172 * padding bytes is always more than zero, and always at most
1173 * the cipher block length. The value of each padding byte is
1174 * equal to the number of padding bytes. So a plaintext that's
1175 * an exact multiple of the block size will be padded with 08
1176 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
1177 * plaintext one byte less than a multiple of the block size
1178 * will be padded with just 01.
1180 * This enables the OpenSSL key decryption function to strip
1181 * off the padding algorithmically and return the unpadded
1182 * plaintext to the next layer: it looks at the final byte, and
1183 * then expects to find that many bytes at the end of the data
1184 * with the same value. Those are all removed and the rest is
1188 while (pos < outlen) {
1189 outblob[pos++] = outlen - len;
1193 * Invent an iv. Then derive encryption key from passphrase
1196 * - let block A equal MD5(passphrase || iv)
1197 * - let block B equal MD5(A || passphrase || iv)
1198 * - block C would be MD5(B || passphrase || iv) and so on
1199 * - encryption key is the first N bytes of A || B
1201 for (i = 0; i < 8; i++) iv[i] = random_byte();
1204 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1205 MD5Update(&md5c, iv, 8);
1206 MD5Final(keybuf, &md5c);
1209 MD5Update(&md5c, keybuf, 16);
1210 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1211 MD5Update(&md5c, iv, 8);
1212 MD5Final(keybuf+16, &md5c);
1215 * Now encrypt the key blob.
1217 des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
1219 smemclr(&md5c, sizeof(md5c));
1220 smemclr(keybuf, sizeof(keybuf));
1223 * If no encryption, the blob has exactly its original
1230 * And save it. We'll use Unix line endings just in case it's
1231 * subsequently transferred in binary mode.
1233 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1238 fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
1239 for (i = 0; i < 8; i++)
1240 fprintf(fp, "%02X", iv[i]);
1241 fprintf(fp, "\n\n");
1243 base64_encode(fp, outblob, outlen, 64);
1250 smemclr(outblob, outlen);
1254 smemclr(spareblob, sparelen);
1258 smemclr(privblob, privlen);
1262 smemclr(pubblob, publen);
1268 /* ----------------------------------------------------------------------
1269 * Code to read and write OpenSSH private keys in the new-style format.
1273 ON_E_NONE, ON_E_AES256CBC
1274 } openssh_new_cipher;
1276 ON_K_NONE, ON_K_BCRYPT
1279 struct openssh_new_key {
1280 openssh_new_cipher cipher;
1281 openssh_new_kdf kdf;
1285 /* This points to a position within keyblob, not a
1286 * separately allocated thing */
1287 const unsigned char *salt;
1291 int nkeys, key_wanted;
1292 /* This too points to a position within keyblob */
1293 unsigned char *privatestr;
1296 unsigned char *keyblob;
1297 int keyblob_len, keyblob_size;
1300 static struct openssh_new_key *load_openssh_new_key(const Filename *filename,
1301 const char **errmsg_p)
1303 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;
1548 struct ssh2_userkey *retval = NULL;
1550 unsigned char *blob;
1552 unsigned checkint0, checkint1;
1553 const void *priv, *string;
1554 int privlen, stringlen, key_index;
1555 const struct ssh_signkey *alg;
1562 if (key->cipher != ON_E_NONE) {
1563 unsigned char keybuf[48];
1567 * Construct the decryption key, and decrypt the string.
1569 switch (key->cipher) {
1573 case ON_E_AES256CBC:
1574 keysize = 48; /* 32 byte key + 16 byte IV */
1577 assert(0 && "Bad cipher enumeration value");
1579 assert(keysize <= sizeof(keybuf));
1582 memset(keybuf, 0, keysize);
1585 openssh_bcrypt(passphrase,
1586 key->kdfopts.bcrypt.salt,
1587 key->kdfopts.bcrypt.saltlen,
1588 key->kdfopts.bcrypt.rounds,
1592 assert(0 && "Bad kdf enumeration value");
1594 switch (key->cipher) {
1597 case ON_E_AES256CBC:
1598 if (key->privatelen % 16 != 0) {
1599 errmsg = "private key container length is not a"
1600 " multiple of AES block size\n";
1604 void *ctx = aes_make_context();
1605 aes256_key(ctx, keybuf);
1606 aes_iv(ctx, keybuf + 32);
1607 aes_ssh2_decrypt_blk(ctx, key->privatestr,
1609 aes_free_context(ctx);
1613 assert(0 && "Bad cipher enumeration value");
1618 * Now parse the entire encrypted section, and extract the key
1619 * identified by key_wanted.
1621 priv = key->privatestr;
1622 privlen = key->privatelen;
1624 if (!get_ssh_uint32(&privlen, &priv, &checkint0) ||
1625 !get_ssh_uint32(&privlen, &priv, &checkint1) ||
1626 checkint0 != checkint1) {
1627 errmsg = "decryption check failed";
1632 for (key_index = 0; key_index < key->nkeys; key_index++) {
1633 const unsigned char *thiskey;
1637 * Read the key type, which will tell us how to scan over
1638 * the key to get to the next one.
1640 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1641 errmsg = "expected key type in private string";
1646 * Preliminary key type identification, and decide how
1647 * many pieces of key we expect to see. Currently
1648 * (conveniently) all key types can be seen as some number
1649 * of strings, so we just need to know how many of them to
1650 * skip over. (The numbers below exclude the key comment.)
1653 /* find_pubkey_alg needs a zero-terminated copy of the
1655 char *name_zt = dupprintf("%.*s", stringlen, (char *)string);
1656 alg = find_pubkey_alg(name_zt);
1661 errmsg = "private key type not recognised\n";
1668 * Skip over the pieces of key.
1670 for (i = 0; i < alg->openssh_private_npieces; i++) {
1671 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1672 errmsg = "ran out of data in mid-private-key";
1677 thiskeylen = (int)((const unsigned char *)priv -
1678 (const unsigned char *)thiskey);
1679 if (key_index == key->key_wanted) {
1680 retkey = snew(struct ssh2_userkey);
1682 retkey->data = alg->openssh_createkey(&thiskey, &thiskeylen);
1683 if (!retkey->data) {
1685 errmsg = "unable to create key data structure";
1691 * Read the key comment.
1693 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1694 errmsg = "ran out of data at key comment";
1697 if (key_index == key->key_wanted) {
1699 retkey->comment = dupprintf("%.*s", stringlen,
1700 (const char *)string);
1705 errmsg = "key index out of range";
1710 * Now we expect nothing left but padding.
1712 for (i = 0; i < privlen; i++) {
1713 if (((const unsigned char *)priv)[i] != (unsigned char)(i+1)) {
1714 errmsg = "padding at end of private string did not match";
1719 errmsg = NULL; /* no error */
1724 smemclr(blob, blobsize);
1727 smemclr(key->keyblob, key->keyblob_size);
1728 sfree(key->keyblob);
1729 smemclr(key, sizeof(*key));
1731 if (errmsg_p) *errmsg_p = errmsg;
1735 int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
1738 unsigned char *pubblob, *privblob, *outblob, *p;
1739 unsigned char *private_section_start, *private_section_length_field;
1740 int publen, privlen, commentlen, maxsize, padvalue, i;
1743 unsigned char bcrypt_salt[16];
1744 const int bcrypt_rounds = 16;
1748 * Fetch the key blobs and find out the lengths of things.
1750 pubblob = key->alg->public_blob(key->data, &publen);
1751 i = key->alg->openssh_fmtkey(key->data, NULL, 0);
1752 privblob = snewn(i, unsigned char);
1753 privlen = key->alg->openssh_fmtkey(key->data, privblob, i);
1754 assert(privlen == i);
1755 commentlen = strlen(key->comment);
1758 * Allocate enough space for the full binary key format. No need
1759 * to be absolutely precise here.
1761 maxsize = (16 + /* magic number */
1762 32 + /* cipher name string */
1763 32 + /* kdf name string */
1764 64 + /* kdf options string */
1766 4+publen + /* public key string */
1767 4 + /* string header for private section */
1768 8 + /* checkint x 2 */
1769 4+strlen(key->alg->name) + /* key type string */
1770 privlen + /* private blob */
1771 4+commentlen + /* comment string */
1772 16); /* padding at end of private section */
1773 outblob = snewn(maxsize, unsigned char);
1776 * Construct the cleartext version of the blob.
1781 memcpy(p, "openssh-key-v1\0", 15);
1784 /* Cipher and kdf names, and kdf options. */
1786 memset(bcrypt_salt, 0, sizeof(bcrypt_salt)); /* prevent warnings */
1787 p += put_string_z(p, "none");
1788 p += put_string_z(p, "none");
1789 p += put_string_z(p, "");
1792 for (i = 0; i < (int)sizeof(bcrypt_salt); i++)
1793 bcrypt_salt[i] = random_byte();
1794 p += put_string_z(p, "aes256-cbc");
1795 p += put_string_z(p, "bcrypt");
1798 p += put_string(p, bcrypt_salt, sizeof(bcrypt_salt));
1799 p += put_uint32(p, bcrypt_rounds);
1800 PUT_32BIT_MSB_FIRST(q, (unsigned)(p - (q+4)));
1803 /* Number of keys. */
1804 p += put_uint32(p, 1);
1807 p += put_string(p, pubblob, publen);
1809 /* Begin private section. */
1810 private_section_length_field = p;
1812 private_section_start = p;
1816 for (i = 0; i < 4; i++)
1817 checkint = (checkint << 8) + random_byte();
1818 p += put_uint32(p, checkint);
1819 p += put_uint32(p, checkint);
1821 /* Private key. The main private blob goes inline, with no string
1823 p += put_string_z(p, key->alg->name);
1824 memcpy(p, privblob, privlen);
1828 p += put_string_z(p, key->comment);
1830 /* Pad out the encrypted section. */
1834 } while ((p - private_section_start) & 15);
1836 assert(p - outblob < maxsize);
1838 /* Go back and fill in the length field for the private section. */
1839 PUT_32BIT_MSB_FIRST(private_section_length_field,
1840 p - private_section_start);
1844 * Encrypt the private section. We need 48 bytes of key
1845 * material: 32 bytes AES key + 16 bytes iv.
1847 unsigned char keybuf[48];
1850 openssh_bcrypt(passphrase,
1851 bcrypt_salt, sizeof(bcrypt_salt), bcrypt_rounds,
1852 keybuf, sizeof(keybuf));
1854 ctx = aes_make_context();
1855 aes256_key(ctx, keybuf);
1856 aes_iv(ctx, keybuf + 32);
1857 aes_ssh2_encrypt_blk(ctx, private_section_start,
1858 p - private_section_start);
1859 aes_free_context(ctx);
1861 smemclr(keybuf, sizeof(keybuf));
1865 * And save it. We'll use Unix line endings just in case it's
1866 * subsequently transferred in binary mode.
1868 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1871 fputs("-----BEGIN OPENSSH PRIVATE KEY-----\n", fp);
1872 base64_encode(fp, outblob, p - outblob, 64);
1873 fputs("-----END OPENSSH PRIVATE KEY-----\n", fp);
1879 smemclr(outblob, maxsize);
1883 smemclr(privblob, privlen);
1887 smemclr(pubblob, publen);
1893 /* ----------------------------------------------------------------------
1894 * The switch function openssh_auto_write(), which chooses one of the
1895 * concrete OpenSSH output formats based on the key type.
1897 int openssh_auto_write(const Filename *filename, struct ssh2_userkey *key,
1901 * The old OpenSSH format supports a fixed list of key types. We
1902 * assume that anything not in that fixed list is newer, and hence
1903 * will use the new format.
1905 if (key->alg == &ssh_dss ||
1906 key->alg == &ssh_rsa ||
1907 key->alg == &ssh_ecdsa_nistp256 ||
1908 key->alg == &ssh_ecdsa_nistp384 ||
1909 key->alg == &ssh_ecdsa_nistp521)
1910 return openssh_pem_write(filename, key, passphrase);
1912 return openssh_new_write(filename, key, passphrase);
1915 /* ----------------------------------------------------------------------
1916 * Code to read ssh.com private keys.
1920 * The format of the base64 blob is largely SSH-2-packet-formatted,
1921 * except that mpints are a bit different: they're more like the
1922 * old SSH-1 mpint. You have a 32-bit bit count N, followed by
1923 * (N+7)/8 bytes of data.
1925 * So. The blob contains:
1927 * - uint32 0x3f6ff9eb (magic number)
1928 * - uint32 size (total blob size)
1929 * - string key-type (see below)
1930 * - string cipher-type (tells you if key is encrypted)
1931 * - string encrypted-blob
1933 * (The first size field includes the size field itself and the
1934 * magic number before it. All other size fields are ordinary SSH-2
1935 * strings, so the size field indicates how much data is to
1938 * The encrypted blob, once decrypted, contains a single string
1939 * which in turn contains the payload. (This allows padding to be
1940 * added after that string while still making it clear where the
1941 * real payload ends. Also it probably makes for a reasonable
1942 * decryption check.)
1944 * The payload blob, for an RSA key, contains:
1947 * - mpint n (yes, the public and private stuff is intermixed)
1948 * - mpint u (presumably inverse of p mod q)
1949 * - mpint p (p is the smaller prime)
1950 * - mpint q (q is the larger)
1952 * For a DSA key, the payload blob contains:
1960 * Alternatively, if the parameters are `predefined', that
1961 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
1962 * containing some predefined parameter specification. *shudder*,
1963 * but I doubt we'll encounter this in real life.
1965 * The key type strings are ghastly. The RSA key I looked at had a
1968 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
1970 * and the DSA key wasn't much better:
1972 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
1974 * It isn't clear that these will always be the same. I think it
1975 * might be wise just to look at the `if-modn{sign{rsa' and
1976 * `dl-modp{sign{dsa' prefixes.
1978 * Finally, the encryption. The cipher-type string appears to be
1979 * either `none' or `3des-cbc'. Looks as if this is SSH-2-style
1980 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
1981 * from the passphrase by means of yet another hashing faff:
1983 * - first 16 bytes are MD5(passphrase)
1984 * - next 16 bytes are MD5(passphrase || first 16 bytes)
1985 * - if there were more, they'd be MD5(passphrase || first 32),
1989 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
1992 char comment[256]; /* allowing any length is overkill */
1993 unsigned char *keyblob;
1994 int keyblob_len, keyblob_size;
1997 static struct sshcom_key *load_sshcom_key(const Filename *filename,
1998 const char **errmsg_p)
2000 struct sshcom_key *ret;
2007 int base64_chars = 0;
2009 ret = snew(struct sshcom_key);
2010 ret->comment[0] = '\0';
2011 ret->keyblob = NULL;
2012 ret->keyblob_len = ret->keyblob_size = 0;
2014 fp = f_open(filename, "r", FALSE);
2016 errmsg = "unable to open key file";
2019 if (!(line = fgetline(fp))) {
2020 errmsg = "unexpected end of file";
2024 if (0 != strcmp(line, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
2025 errmsg = "file does not begin with ssh.com key header";
2028 smemclr(line, strlen(line));
2034 if (!(line = fgetline(fp))) {
2035 errmsg = "unexpected end of file";
2039 if (!strcmp(line, "---- END SSH2 ENCRYPTED PRIVATE KEY ----")) {
2044 if ((p = strchr(line, ':')) != NULL) {
2046 errmsg = "header found in body of key data";
2050 while (*p && isspace((unsigned char)*p)) p++;
2051 hdrstart = p - line;
2054 * Header lines can end in a trailing backslash for
2057 len = hdrstart + strlen(line+hdrstart);
2059 while (line[len-1] == '\\') {
2063 line2 = fgetline(fp);
2065 errmsg = "unexpected end of file";
2070 line2len = strlen(line2);
2071 line = sresize(line, len + line2len + 1, char);
2072 strcpy(line + len - 1, line2);
2073 len += line2len - 1;
2076 smemclr(line2, strlen(line2));
2080 p = line + hdrstart;
2082 if (!strcmp(line, "Comment")) {
2083 /* Strip quotes in comment if present. */
2084 if (p[0] == '"' && p[strlen(p)-1] == '"') {
2086 p[strlen(p)-1] = '\0';
2088 strncpy(ret->comment, p, sizeof(ret->comment));
2089 ret->comment[sizeof(ret->comment)-1] = '\0';
2095 while (isbase64(*p)) {
2096 base64_bit[base64_chars++] = *p;
2097 if (base64_chars == 4) {
2098 unsigned char out[3];
2102 len = base64_decode_atom(base64_bit, out);
2105 errmsg = "invalid base64 encoding";
2109 if (ret->keyblob_len + len > ret->keyblob_size) {
2110 ret->keyblob_size = ret->keyblob_len + len + 256;
2111 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
2115 memcpy(ret->keyblob + ret->keyblob_len, out, len);
2116 ret->keyblob_len += len;
2122 smemclr(line, strlen(line));
2127 if (ret->keyblob_len == 0 || !ret->keyblob) {
2128 errmsg = "key body not present";
2133 if (errmsg_p) *errmsg_p = NULL;
2141 smemclr(line, strlen(line));
2147 smemclr(ret->keyblob, ret->keyblob_size);
2148 sfree(ret->keyblob);
2150 smemclr(ret, sizeof(*ret));
2153 if (errmsg_p) *errmsg_p = errmsg;
2157 int sshcom_encrypted(const Filename *filename, char **comment)
2159 struct sshcom_key *key = load_sshcom_key(filename, NULL);
2160 int pos, len, answer;
2169 * Check magic number.
2171 if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) {
2172 goto done; /* key is invalid */
2176 * Find the cipher-type string.
2179 if (key->keyblob_len < pos+4)
2180 goto done; /* key is far too short */
2181 len = toint(GET_32BIT(key->keyblob + pos));
2182 if (len < 0 || len > key->keyblob_len - pos - 4)
2183 goto done; /* key is far too short */
2184 pos += 4 + len; /* skip key type */
2185 len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
2186 if (len < 0 || len > key->keyblob_len - pos - 4)
2187 goto done; /* cipher type string is incomplete */
2188 if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
2193 *comment = dupstr(key->comment);
2194 smemclr(key->keyblob, key->keyblob_size);
2195 sfree(key->keyblob);
2196 smemclr(key, sizeof(*key));
2199 *comment = dupstr("");
2204 static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
2206 unsigned bits, bytes;
2207 unsigned char *d = (unsigned char *) data;
2211 bits = GET_32BIT(d);
2213 bytes = (bits + 7) / 8;
2224 return len; /* ensure further calls fail as well */
2227 static int sshcom_put_mpint(void *target, void *data, int len)
2229 unsigned char *d = (unsigned char *)target;
2230 unsigned char *i = (unsigned char *)data;
2231 int bits = len * 8 - 1;
2234 if (*i & (1 << (bits & 7)))
2240 PUT_32BIT(d, bits+1);
2241 memcpy(d+4, i, len);
2245 struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
2246 const char **errmsg_p)
2248 struct sshcom_key *key = load_sshcom_key(filename, errmsg_p);
2251 const char prefix_rsa[] = "if-modn{sign{rsa";
2252 const char prefix_dsa[] = "dl-modp{sign{dsa";
2253 enum { RSA, DSA } type;
2257 struct ssh2_userkey *ret = NULL, *retkey;
2258 const struct ssh_signkey *alg;
2259 unsigned char *blob = NULL;
2260 int blobsize = 0, publen, privlen;
2266 * Check magic number.
2268 if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) {
2269 errmsg = "key does not begin with magic number";
2274 * Determine the key type.
2277 if (key->keyblob_len < pos+4 ||
2278 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2279 len > key->keyblob_len - pos - 4) {
2280 errmsg = "key blob does not contain a key type string";
2283 if (len > sizeof(prefix_rsa) - 1 &&
2284 !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) {
2286 } else if (len > sizeof(prefix_dsa) - 1 &&
2287 !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) {
2290 errmsg = "key is of unknown type";
2296 * Determine the cipher type.
2298 if (key->keyblob_len < pos+4 ||
2299 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2300 len > key->keyblob_len - pos - 4) {
2301 errmsg = "key blob does not contain a cipher type string";
2304 if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4))
2306 else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8))
2309 errmsg = "key encryption is of unknown type";
2315 * Get hold of the encrypted part of the key.
2317 if (key->keyblob_len < pos+4 ||
2318 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2319 len > key->keyblob_len - pos - 4) {
2320 errmsg = "key blob does not contain actual key data";
2323 ciphertext = (char *)key->keyblob + pos + 4;
2325 if (cipherlen == 0) {
2326 errmsg = "length of key data is zero";
2331 * Decrypt it if necessary.
2335 * Derive encryption key from passphrase and iv/salt:
2337 * - let block A equal MD5(passphrase)
2338 * - let block B equal MD5(passphrase || A)
2339 * - block C would be MD5(passphrase || A || B) and so on
2340 * - encryption key is the first N bytes of A || B
2342 struct MD5Context md5c;
2343 unsigned char keybuf[32], iv[8];
2345 if (cipherlen % 8 != 0) {
2346 errmsg = "encrypted part of key is not a multiple of cipher block"
2352 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2353 MD5Final(keybuf, &md5c);
2356 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2357 MD5Update(&md5c, keybuf, 16);
2358 MD5Final(keybuf+16, &md5c);
2361 * Now decrypt the key blob.
2363 memset(iv, 0, sizeof(iv));
2364 des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2367 smemclr(&md5c, sizeof(md5c));
2368 smemclr(keybuf, sizeof(keybuf));
2371 * Hereafter we return WRONG_PASSPHRASE for any parsing
2372 * error. (But only if we've just tried to decrypt it!
2373 * Returning WRONG_PASSPHRASE for an unencrypted key is
2377 ret = SSH2_WRONG_PASSPHRASE;
2381 * Strip away the containing string to get to the real meat.
2383 len = toint(GET_32BIT(ciphertext));
2384 if (len < 0 || len > cipherlen-4) {
2385 errmsg = "containing string was ill-formed";
2392 * Now we break down into RSA versus DSA. In either case we'll
2393 * construct public and private blobs in our own format, and
2394 * end up feeding them to alg->createkey().
2396 blobsize = cipherlen + 256;
2397 blob = snewn(blobsize, unsigned char);
2400 struct mpint_pos n, e, d, u, p, q;
2402 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e);
2403 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d);
2404 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n);
2405 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u);
2406 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2407 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2409 errmsg = "key data did not contain six integers";
2415 pos += put_string(blob+pos, "ssh-rsa", 7);
2416 pos += put_mp(blob+pos, e.start, e.bytes);
2417 pos += put_mp(blob+pos, n.start, n.bytes);
2419 pos += put_string(blob+pos, d.start, d.bytes);
2420 pos += put_mp(blob+pos, q.start, q.bytes);
2421 pos += put_mp(blob+pos, p.start, p.bytes);
2422 pos += put_mp(blob+pos, u.start, u.bytes);
2423 privlen = pos - publen;
2425 struct mpint_pos p, q, g, x, y;
2428 assert(type == DSA); /* the only other option from the if above */
2430 if (GET_32BIT(ciphertext) != 0) {
2431 errmsg = "predefined DSA parameters not supported";
2434 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2435 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g);
2436 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2437 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y);
2438 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x);
2440 errmsg = "key data did not contain five integers";
2446 pos += put_string(blob+pos, "ssh-dss", 7);
2447 pos += put_mp(blob+pos, p.start, p.bytes);
2448 pos += put_mp(blob+pos, q.start, q.bytes);
2449 pos += put_mp(blob+pos, g.start, g.bytes);
2450 pos += put_mp(blob+pos, y.start, y.bytes);
2452 pos += put_mp(blob+pos, x.start, x.bytes);
2453 privlen = pos - publen;
2456 assert(privlen > 0); /* should have bombed by now if not */
2458 retkey = snew(struct ssh2_userkey);
2460 retkey->data = alg->createkey(blob, publen, blob+publen, privlen);
2461 if (!retkey->data) {
2463 errmsg = "unable to create key data structure";
2466 retkey->comment = dupstr(key->comment);
2468 errmsg = NULL; /* no error */
2473 smemclr(blob, blobsize);
2476 smemclr(key->keyblob, key->keyblob_size);
2477 sfree(key->keyblob);
2478 smemclr(key, sizeof(*key));
2480 if (errmsg_p) *errmsg_p = errmsg;
2484 int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
2487 unsigned char *pubblob, *privblob;
2488 int publen, privlen;
2489 unsigned char *outblob;
2491 struct mpint_pos numbers[6];
2492 int nnumbers, initial_zero, pos, lenpos, i;
2500 * Fetch the key blobs.
2502 pubblob = key->alg->public_blob(key->data, &publen);
2503 privblob = key->alg->private_blob(key->data, &privlen);
2507 * Find the sequence of integers to be encoded into the OpenSSH
2508 * key blob, and also decide on the header line.
2510 if (key->alg == &ssh_rsa) {
2512 struct mpint_pos n, e, d, p, q, iqmp;
2515 * These blobs were generated from inside PuTTY, so we needn't
2516 * treat them as untrusted.
2518 pos = 4 + GET_32BIT(pubblob);
2519 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
2520 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
2522 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
2523 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
2524 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
2525 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
2527 assert(e.start && iqmp.start); /* can't go wrong */
2538 type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
2539 } else if (key->alg == &ssh_dss) {
2541 struct mpint_pos p, q, g, y, x;
2544 * These blobs were generated from inside PuTTY, so we needn't
2545 * treat them as untrusted.
2547 pos = 4 + GET_32BIT(pubblob);
2548 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
2549 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
2550 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
2551 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
2553 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
2555 assert(y.start && x.start); /* can't go wrong */
2565 type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
2567 assert(0); /* zoinks! */
2568 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
2572 * Total size of key blob will be somewhere under 512 plus
2573 * combined length of integers. We'll calculate the more
2574 * precise size as we construct the blob.
2577 for (i = 0; i < nnumbers; i++)
2578 outlen += 4 + numbers[i].bytes;
2579 outblob = snewn(outlen, unsigned char);
2582 * Create the unencrypted key blob.
2585 PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
2586 pos += 4; /* length field, fill in later */
2587 pos += put_string(outblob+pos, type, strlen(type));
2589 char *ciphertype = passphrase ? "3des-cbc" : "none";
2590 pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
2592 lenpos = pos; /* remember this position */
2593 pos += 4; /* encrypted-blob size */
2594 pos += 4; /* encrypted-payload size */
2596 PUT_32BIT(outblob+pos, 0);
2599 for (i = 0; i < nnumbers; i++)
2600 pos += sshcom_put_mpint(outblob+pos,
2601 numbers[i].start, numbers[i].bytes);
2602 /* Now wrap up the encrypted payload. */
2603 PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8));
2604 /* Pad encrypted blob to a multiple of cipher block size. */
2606 int padding = -(pos - (lenpos+4)) & 7;
2608 outblob[pos++] = random_byte();
2610 ciphertext = (char *)outblob+lenpos+4;
2611 cipherlen = pos - (lenpos+4);
2612 assert(!passphrase || cipherlen % 8 == 0);
2613 /* Wrap up the encrypted blob string. */
2614 PUT_32BIT(outblob+lenpos, cipherlen);
2615 /* And finally fill in the total length field. */
2616 PUT_32BIT(outblob+4, pos);
2618 assert(pos < outlen);
2625 * Derive encryption key from passphrase and iv/salt:
2627 * - let block A equal MD5(passphrase)
2628 * - let block B equal MD5(passphrase || A)
2629 * - block C would be MD5(passphrase || A || B) and so on
2630 * - encryption key is the first N bytes of A || B
2632 struct MD5Context md5c;
2633 unsigned char keybuf[32], iv[8];
2636 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2637 MD5Final(keybuf, &md5c);
2640 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2641 MD5Update(&md5c, keybuf, 16);
2642 MD5Final(keybuf+16, &md5c);
2645 * Now decrypt the key blob.
2647 memset(iv, 0, sizeof(iv));
2648 des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2651 smemclr(&md5c, sizeof(md5c));
2652 smemclr(keybuf, sizeof(keybuf));
2656 * And save it. We'll use Unix line endings just in case it's
2657 * subsequently transferred in binary mode.
2659 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
2662 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2663 fprintf(fp, "Comment: \"");
2665 * Comment header is broken with backslash-newline if it goes
2666 * over 70 chars. Although it's surrounded by quotes, it
2667 * _doesn't_ escape backslashes or quotes within the string.
2668 * Don't ask me, I didn't design it.
2671 int slen = 60; /* starts at 60 due to "Comment: " */
2672 char *c = key->comment;
2673 while ((int)strlen(c) > slen) {
2674 fprintf(fp, "%.*s\\\n", slen, c);
2676 slen = 70; /* allow 70 chars on subsequent lines */
2678 fprintf(fp, "%s\"\n", c);
2680 base64_encode(fp, outblob, pos, 70);
2681 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2687 smemclr(outblob, outlen);
2691 smemclr(privblob, privlen);
2695 smemclr(pubblob, publen);