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(retkey->alg,
781 blob, 4+19+4+8+4+len,
786 errmsg = "unable to create key data structure";
790 } else if (key->keytype == OP_RSA || key->keytype == OP_DSA) {
793 * Space to create key blob in.
795 blobsize = 256+key->keyblob_len;
796 blob = snewn(blobsize, unsigned char);
798 if (key->keytype == OP_DSA)
799 memcpy(blob+4, "ssh-dss", 7);
800 else if (key->keytype == OP_RSA)
801 memcpy(blob+4, "ssh-rsa", 7);
805 for (i = 0; i < num_integers; i++) {
806 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
809 if (ret < 0 || id != 2 ||
810 key->keyblob+key->keyblob_len-p < len) {
811 errmsg = "ASN.1 decoding failure";
812 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
818 * The first integer should be zero always (I think
819 * this is some sort of version indication).
821 if (len != 1 || p[0] != 0) {
822 errmsg = "version number mismatch";
825 } else if (key->keytype == OP_RSA) {
827 * Integers 1 and 2 go into the public blob but in the
828 * opposite order; integers 3, 4, 5 and 8 go into the
829 * private blob. The other two (6 and 7) are ignored.
832 /* Save the details for after we deal with number 2. */
835 } else if (i != 6 && i != 7) {
836 PUT_32BIT(blob+blobptr, len);
837 memcpy(blob+blobptr+4, p, len);
840 PUT_32BIT(blob+blobptr, modlen);
841 memcpy(blob+blobptr+4, modptr, modlen);
846 } else if (key->keytype == OP_DSA) {
848 * Integers 1-4 go into the public blob; integer 5 goes
849 * into the private blob.
851 PUT_32BIT(blob+blobptr, len);
852 memcpy(blob+blobptr+4, p, len);
858 /* Skip past the number. */
863 * Now put together the actual key. Simplest way to do this is
864 * to assemble our own key blobs and feed them to the createkey
865 * functions; this is a bit faffy but it does mean we get all
866 * the sanity checks for free.
868 assert(privptr > 0); /* should have bombed by now if not */
869 retkey = snew(struct ssh2_userkey);
870 retkey->alg = (key->keytype == OP_RSA ? &ssh_rsa : &ssh_dss);
871 retkey->data = retkey->alg->createkey(retkey->alg, blob, privptr,
876 errmsg = "unable to create key data structure";
881 assert(0 && "Bad key type from load_openssh_pem_key");
885 * The old key format doesn't include a comment in the private
888 retkey->comment = dupstr("imported-openssh-key");
890 errmsg = NULL; /* no error */
895 smemclr(blob, blobsize);
898 smemclr(key->keyblob, key->keyblob_size);
900 smemclr(key, sizeof(*key));
902 if (errmsg_p) *errmsg_p = errmsg;
906 int openssh_pem_write(const Filename *filename, struct ssh2_userkey *key,
909 unsigned char *pubblob, *privblob, *spareblob;
910 int publen, privlen, sparelen = 0;
911 unsigned char *outblob;
913 struct mpint_pos numbers[9];
914 int nnumbers, pos, len, seqlen, i;
915 char *header, *footer;
922 * Fetch the key blobs.
924 pubblob = key->alg->public_blob(key->data, &publen);
925 privblob = key->alg->private_blob(key->data, &privlen);
926 spareblob = outblob = NULL;
932 * Encode the OpenSSH key blob, and also decide on the header
935 if (key->alg == &ssh_rsa || key->alg == &ssh_dss) {
937 * The RSA and DSS handlers share some code because the two
938 * key types have very similar ASN.1 representations, as a
939 * plain SEQUENCE of big integers. So we set up a list of
940 * bignums per key type and then construct the actual blob in
941 * common code after that.
943 if (key->alg == &ssh_rsa) {
945 struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
946 Bignum bd, bp, bq, bdmp1, bdmq1;
949 * These blobs were generated from inside PuTTY, so we needn't
950 * treat them as untrusted.
952 pos = 4 + GET_32BIT(pubblob);
953 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
954 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
956 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
957 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
958 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
959 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
961 assert(e.start && iqmp.start); /* can't go wrong */
963 /* We also need d mod (p-1) and d mod (q-1). */
964 bd = bignum_from_bytes(d.start, d.bytes);
965 bp = bignum_from_bytes(p.start, p.bytes);
966 bq = bignum_from_bytes(q.start, q.bytes);
969 bdmp1 = bigmod(bd, bp);
970 bdmq1 = bigmod(bd, bq);
975 dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
976 dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
977 sparelen = dmp1.bytes + dmq1.bytes;
978 spareblob = snewn(sparelen, unsigned char);
979 dmp1.start = spareblob;
980 dmq1.start = spareblob + dmp1.bytes;
981 for (i = 0; i < dmp1.bytes; i++)
982 spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
983 for (i = 0; i < dmq1.bytes; i++)
984 spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
988 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
999 header = "-----BEGIN RSA PRIVATE KEY-----\n";
1000 footer = "-----END RSA PRIVATE KEY-----\n";
1001 } else { /* ssh-dss */
1003 struct mpint_pos p, q, g, y, x;
1006 * These blobs were generated from inside PuTTY, so we needn't
1007 * treat them as untrusted.
1009 pos = 4 + GET_32BIT(pubblob);
1010 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
1011 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
1012 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
1013 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
1015 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
1017 assert(y.start && x.start); /* can't go wrong */
1019 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
1027 header = "-----BEGIN DSA PRIVATE KEY-----\n";
1028 footer = "-----END DSA PRIVATE KEY-----\n";
1032 * Now count up the total size of the ASN.1 encoded integers,
1033 * so as to determine the length of the containing SEQUENCE.
1036 for (i = 0; i < nnumbers; i++) {
1037 len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
1038 len += numbers[i].bytes;
1041 /* Now add on the SEQUENCE header. */
1042 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1045 * Now we know how big outblob needs to be. Allocate it.
1047 outblob = snewn(len, unsigned char);
1050 * And write the data into it.
1053 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1054 for (i = 0; i < nnumbers; i++) {
1055 pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
1056 memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
1057 pos += numbers[i].bytes;
1059 } else if (key->alg == &ssh_ecdsa_nistp256 ||
1060 key->alg == &ssh_ecdsa_nistp384 ||
1061 key->alg == &ssh_ecdsa_nistp521) {
1067 * Structure of asn1:
1070 * OCTET STRING (private key)
1074 * BIT STRING (0x00 public key point)
1076 switch (((struct ec_key *)key->data)->publicKey.curve->fieldBits) {
1078 /* OID: 1.2.840.10045.3.1.7 (ansiX9p256r1) */
1080 oidlen = nistp256_oid_len;
1084 /* OID: 1.3.132.0.34 (secp384r1) */
1086 oidlen = nistp384_oid_len;
1090 /* OID: 1.3.132.0.35 (secp521r1) */
1092 oidlen = nistp521_oid_len;
1099 len = ber_write_id_len(NULL, 2, 1, 0);
1101 len += ber_write_id_len(NULL, 4, privlen - 4, 0);
1103 len += ber_write_id_len(NULL, 0, oidlen +
1104 ber_write_id_len(NULL, 6, oidlen, 0),
1105 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1106 len += ber_write_id_len(NULL, 6, oidlen, 0);
1108 len += ber_write_id_len(NULL, 1, 2 + pointlen +
1109 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1110 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1111 len += ber_write_id_len(NULL, 3, 2 + pointlen, 0);
1112 len += 2 + pointlen;
1115 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1117 outblob = snewn(len, unsigned char);
1121 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1122 pos += ber_write_id_len(outblob+pos, 2, 1, 0);
1124 pos += ber_write_id_len(outblob+pos, 4, privlen - 4, 0);
1125 memcpy(outblob+pos, privblob + 4, privlen - 4);
1127 pos += ber_write_id_len(outblob+pos, 0, oidlen +
1128 ber_write_id_len(NULL, 6, oidlen, 0),
1129 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1130 pos += ber_write_id_len(outblob+pos, 6, oidlen, 0);
1131 memcpy(outblob+pos, oid, oidlen);
1133 pos += ber_write_id_len(outblob+pos, 1, 2 + pointlen +
1134 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1135 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1136 pos += ber_write_id_len(outblob+pos, 3, 2 + pointlen, 0);
1138 memcpy(outblob+pos, pubblob+39, 1 + pointlen);
1139 pos += 1 + pointlen;
1141 header = "-----BEGIN EC PRIVATE KEY-----\n";
1142 footer = "-----END EC PRIVATE KEY-----\n";
1144 assert(0); /* zoinks! */
1145 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
1151 * For the moment, we still encrypt our OpenSSH keys using
1155 struct MD5Context md5c;
1156 unsigned char keybuf[32];
1159 * Round up to the cipher block size, ensuring we have at
1160 * least one byte of padding (see below).
1162 outlen = (len+8) &~ 7;
1164 unsigned char *tmp = snewn(outlen, unsigned char);
1165 memcpy(tmp, outblob, len);
1166 smemclr(outblob, len);
1172 * Padding on OpenSSH keys is deterministic. The number of
1173 * padding bytes is always more than zero, and always at most
1174 * the cipher block length. The value of each padding byte is
1175 * equal to the number of padding bytes. So a plaintext that's
1176 * an exact multiple of the block size will be padded with 08
1177 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
1178 * plaintext one byte less than a multiple of the block size
1179 * will be padded with just 01.
1181 * This enables the OpenSSL key decryption function to strip
1182 * off the padding algorithmically and return the unpadded
1183 * plaintext to the next layer: it looks at the final byte, and
1184 * then expects to find that many bytes at the end of the data
1185 * with the same value. Those are all removed and the rest is
1189 while (pos < outlen) {
1190 outblob[pos++] = outlen - len;
1194 * Invent an iv. Then derive encryption key from passphrase
1197 * - let block A equal MD5(passphrase || iv)
1198 * - let block B equal MD5(A || passphrase || iv)
1199 * - block C would be MD5(B || passphrase || iv) and so on
1200 * - encryption key is the first N bytes of A || B
1202 for (i = 0; i < 8; i++) iv[i] = random_byte();
1205 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1206 MD5Update(&md5c, iv, 8);
1207 MD5Final(keybuf, &md5c);
1210 MD5Update(&md5c, keybuf, 16);
1211 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1212 MD5Update(&md5c, iv, 8);
1213 MD5Final(keybuf+16, &md5c);
1216 * Now encrypt the key blob.
1218 des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
1220 smemclr(&md5c, sizeof(md5c));
1221 smemclr(keybuf, sizeof(keybuf));
1224 * If no encryption, the blob has exactly its original
1231 * And save it. We'll use Unix line endings just in case it's
1232 * subsequently transferred in binary mode.
1234 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1239 fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
1240 for (i = 0; i < 8; i++)
1241 fprintf(fp, "%02X", iv[i]);
1242 fprintf(fp, "\n\n");
1244 base64_encode(fp, outblob, outlen, 64);
1251 smemclr(outblob, outlen);
1255 smemclr(spareblob, sparelen);
1259 smemclr(privblob, privlen);
1263 smemclr(pubblob, publen);
1269 /* ----------------------------------------------------------------------
1270 * Code to read and write OpenSSH private keys in the new-style format.
1274 ON_E_NONE, ON_E_AES256CBC
1275 } openssh_new_cipher;
1277 ON_K_NONE, ON_K_BCRYPT
1280 struct openssh_new_key {
1281 openssh_new_cipher cipher;
1282 openssh_new_kdf kdf;
1286 /* This points to a position within keyblob, not a
1287 * separately allocated thing */
1288 const unsigned char *salt;
1292 int nkeys, key_wanted;
1293 /* This too points to a position within keyblob */
1294 unsigned char *privatestr;
1297 unsigned char *keyblob;
1298 int keyblob_len, keyblob_size;
1301 static struct openssh_new_key *load_openssh_new_key(const Filename *filename,
1302 const char **errmsg_p)
1304 struct openssh_new_key *ret;
1309 int base64_chars = 0;
1310 const void *filedata;
1312 const void *string, *kdfopts, *bcryptsalt, *pubkey;
1313 int stringlen, kdfoptlen, bcryptsaltlen, pubkeylen;
1314 unsigned bcryptrounds, nkeys, key_index;
1316 ret = snew(struct openssh_new_key);
1317 ret->keyblob = NULL;
1318 ret->keyblob_len = ret->keyblob_size = 0;
1320 fp = f_open(filename, "r", FALSE);
1322 errmsg = "unable to open key file";
1326 if (!(line = fgetline(fp))) {
1327 errmsg = "unexpected end of file";
1331 if (0 != strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
1332 errmsg = "file does not begin with OpenSSH new-style key header";
1335 smemclr(line, strlen(line));
1340 if (!(line = fgetline(fp))) {
1341 errmsg = "unexpected end of file";
1345 if (0 == strcmp(line, "-----END OPENSSH PRIVATE KEY-----")) {
1352 while (isbase64(*p)) {
1353 base64_bit[base64_chars++] = *p;
1354 if (base64_chars == 4) {
1355 unsigned char out[3];
1360 len = base64_decode_atom(base64_bit, out);
1363 errmsg = "invalid base64 encoding";
1367 if (ret->keyblob_len + len > ret->keyblob_size) {
1368 ret->keyblob_size = ret->keyblob_len + len + 256;
1369 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
1373 memcpy(ret->keyblob + ret->keyblob_len, out, len);
1374 ret->keyblob_len += len;
1376 smemclr(out, sizeof(out));
1381 smemclr(line, strlen(line));
1389 if (ret->keyblob_len == 0 || !ret->keyblob) {
1390 errmsg = "key body not present";
1394 filedata = ret->keyblob;
1395 filelen = ret->keyblob_len;
1397 if (filelen < 15 || 0 != memcmp(filedata, "openssh-key-v1\0", 15)) {
1398 errmsg = "new-style OpenSSH magic number missing\n";
1401 filedata = (const char *)filedata + 15;
1404 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1405 errmsg = "encountered EOF before cipher name\n";
1408 if (match_ssh_id(stringlen, string, "none")) {
1409 ret->cipher = ON_E_NONE;
1410 } else if (match_ssh_id(stringlen, string, "aes256-cbc")) {
1411 ret->cipher = ON_E_AES256CBC;
1413 errmsg = "unrecognised cipher name\n";
1417 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1418 errmsg = "encountered EOF before kdf name\n";
1421 if (match_ssh_id(stringlen, string, "none")) {
1422 ret->kdf = ON_K_NONE;
1423 } else if (match_ssh_id(stringlen, string, "bcrypt")) {
1424 ret->kdf = ON_K_BCRYPT;
1426 errmsg = "unrecognised kdf name\n";
1430 if (!(kdfopts = get_ssh_string(&filelen, &filedata, &kdfoptlen))) {
1431 errmsg = "encountered EOF before kdf options\n";
1436 if (kdfoptlen != 0) {
1437 errmsg = "expected empty options string for 'none' kdf";
1442 if (!(bcryptsalt = get_ssh_string(&kdfoptlen, &kdfopts,
1444 errmsg = "bcrypt options string did not contain salt\n";
1447 if (!get_ssh_uint32(&kdfoptlen, &kdfopts, &bcryptrounds)) {
1448 errmsg = "bcrypt options string did not contain round count\n";
1451 ret->kdfopts.bcrypt.salt = bcryptsalt;
1452 ret->kdfopts.bcrypt.saltlen = bcryptsaltlen;
1453 ret->kdfopts.bcrypt.rounds = bcryptrounds;
1458 * At this point we expect a uint32 saying how many keys are
1459 * stored in this file. OpenSSH new-style key files can
1460 * contain more than one. Currently we don't have any user
1461 * interface to specify which one we're trying to extract, so
1462 * we just bomb out with an error if more than one is found in
1463 * the file. However, I've put in all the mechanism here to
1464 * extract the nth one for a given n, in case we later connect
1465 * up some UI to that mechanism. Just arrange that the
1466 * 'key_wanted' field is set to a value in the range [0,
1467 * nkeys) by some mechanism.
1469 if (!get_ssh_uint32(&filelen, &filedata, &nkeys)) {
1470 errmsg = "encountered EOF before key count\n";
1474 errmsg = "multiple keys in new-style OpenSSH key file "
1479 ret->key_wanted = 0;
1481 for (key_index = 0; key_index < nkeys; key_index++) {
1482 if (!(pubkey = get_ssh_string(&filelen, &filedata, &pubkeylen))) {
1483 errmsg = "encountered EOF before kdf options\n";
1489 * Now we expect a string containing the encrypted part of the
1492 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1493 errmsg = "encountered EOF before private key container\n";
1496 ret->privatestr = (unsigned char *)string;
1497 ret->privatelen = stringlen;
1500 * And now we're done, until asked to actually decrypt.
1503 smemclr(base64_bit, sizeof(base64_bit));
1504 if (errmsg_p) *errmsg_p = NULL;
1509 smemclr(line, strlen(line));
1513 smemclr(base64_bit, sizeof(base64_bit));
1516 smemclr(ret->keyblob, ret->keyblob_size);
1517 sfree(ret->keyblob);
1519 smemclr(ret, sizeof(*ret));
1522 if (errmsg_p) *errmsg_p = errmsg;
1527 int openssh_new_encrypted(const Filename *filename)
1529 struct openssh_new_key *key = load_openssh_new_key(filename, NULL);
1534 ret = (key->cipher != ON_E_NONE);
1535 smemclr(key->keyblob, key->keyblob_size);
1536 sfree(key->keyblob);
1537 smemclr(key, sizeof(*key));
1542 struct ssh2_userkey *openssh_new_read(const Filename *filename,
1544 const char **errmsg_p)
1546 struct openssh_new_key *key = load_openssh_new_key(filename, errmsg_p);
1547 struct ssh2_userkey *retkey;
1549 struct ssh2_userkey *retval = NULL;
1551 unsigned char *blob;
1553 unsigned checkint0, checkint1;
1554 const void *priv, *string;
1555 int privlen, stringlen, key_index;
1556 const struct ssh_signkey *alg;
1563 if (key->cipher != ON_E_NONE) {
1564 unsigned char keybuf[48];
1568 * Construct the decryption key, and decrypt the string.
1570 switch (key->cipher) {
1574 case ON_E_AES256CBC:
1575 keysize = 48; /* 32 byte key + 16 byte IV */
1578 assert(0 && "Bad cipher enumeration value");
1580 assert(keysize <= sizeof(keybuf));
1583 memset(keybuf, 0, keysize);
1586 openssh_bcrypt(passphrase,
1587 key->kdfopts.bcrypt.salt,
1588 key->kdfopts.bcrypt.saltlen,
1589 key->kdfopts.bcrypt.rounds,
1593 assert(0 && "Bad kdf enumeration value");
1595 switch (key->cipher) {
1598 case ON_E_AES256CBC:
1599 if (key->privatelen % 16 != 0) {
1600 errmsg = "private key container length is not a"
1601 " multiple of AES block size\n";
1605 void *ctx = aes_make_context();
1606 aes256_key(ctx, keybuf);
1607 aes_iv(ctx, keybuf + 32);
1608 aes_ssh2_decrypt_blk(ctx, key->privatestr,
1610 aes_free_context(ctx);
1614 assert(0 && "Bad cipher enumeration value");
1619 * Now parse the entire encrypted section, and extract the key
1620 * identified by key_wanted.
1622 priv = key->privatestr;
1623 privlen = key->privatelen;
1625 if (!get_ssh_uint32(&privlen, &priv, &checkint0) ||
1626 !get_ssh_uint32(&privlen, &priv, &checkint1) ||
1627 checkint0 != checkint1) {
1628 errmsg = "decryption check failed";
1633 for (key_index = 0; key_index < key->nkeys; key_index++) {
1634 const unsigned char *thiskey;
1638 * Read the key type, which will tell us how to scan over
1639 * the key to get to the next one.
1641 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1642 errmsg = "expected key type in private string";
1647 * Preliminary key type identification, and decide how
1648 * many pieces of key we expect to see. Currently
1649 * (conveniently) all key types can be seen as some number
1650 * of strings, so we just need to know how many of them to
1651 * skip over. (The numbers below exclude the key comment.)
1654 /* find_pubkey_alg needs a zero-terminated copy of the
1656 char *name_zt = dupprintf("%.*s", stringlen, (char *)string);
1657 alg = find_pubkey_alg(name_zt);
1662 errmsg = "private key type not recognised\n";
1669 * Skip over the pieces of key.
1671 for (i = 0; i < alg->openssh_private_npieces; i++) {
1672 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1673 errmsg = "ran out of data in mid-private-key";
1678 thiskeylen = (int)((const unsigned char *)priv -
1679 (const unsigned char *)thiskey);
1680 if (key_index == key->key_wanted) {
1681 retkey = snew(struct ssh2_userkey);
1683 retkey->data = alg->openssh_createkey(alg, &thiskey, &thiskeylen);
1684 if (!retkey->data) {
1686 errmsg = "unable to create key data structure";
1692 * Read the key comment.
1694 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1695 errmsg = "ran out of data at key comment";
1698 if (key_index == key->key_wanted) {
1700 retkey->comment = dupprintf("%.*s", stringlen,
1701 (const char *)string);
1706 errmsg = "key index out of range";
1711 * Now we expect nothing left but padding.
1713 for (i = 0; i < privlen; i++) {
1714 if (((const unsigned char *)priv)[i] != (unsigned char)(i+1)) {
1715 errmsg = "padding at end of private string did not match";
1720 errmsg = NULL; /* no error */
1725 smemclr(blob, blobsize);
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;
2008 int base64_chars = 0;
2010 ret = snew(struct sshcom_key);
2011 ret->comment[0] = '\0';
2012 ret->keyblob = NULL;
2013 ret->keyblob_len = ret->keyblob_size = 0;
2015 fp = f_open(filename, "r", FALSE);
2017 errmsg = "unable to open key file";
2020 if (!(line = fgetline(fp))) {
2021 errmsg = "unexpected end of file";
2025 if (0 != strcmp(line, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
2026 errmsg = "file does not begin with ssh.com key header";
2029 smemclr(line, strlen(line));
2035 if (!(line = fgetline(fp))) {
2036 errmsg = "unexpected end of file";
2040 if (!strcmp(line, "---- END SSH2 ENCRYPTED PRIVATE KEY ----")) {
2045 if ((p = strchr(line, ':')) != NULL) {
2047 errmsg = "header found in body of key data";
2051 while (*p && isspace((unsigned char)*p)) p++;
2052 hdrstart = p - line;
2055 * Header lines can end in a trailing backslash for
2058 len = hdrstart + strlen(line+hdrstart);
2060 while (line[len-1] == '\\') {
2064 line2 = fgetline(fp);
2066 errmsg = "unexpected end of file";
2071 line2len = strlen(line2);
2072 line = sresize(line, len + line2len + 1, char);
2073 strcpy(line + len - 1, line2);
2074 len += line2len - 1;
2077 smemclr(line2, strlen(line2));
2081 p = line + hdrstart;
2083 if (!strcmp(line, "Comment")) {
2084 /* Strip quotes in comment if present. */
2085 if (p[0] == '"' && p[strlen(p)-1] == '"') {
2087 p[strlen(p)-1] = '\0';
2089 strncpy(ret->comment, p, sizeof(ret->comment));
2090 ret->comment[sizeof(ret->comment)-1] = '\0';
2096 while (isbase64(*p)) {
2097 base64_bit[base64_chars++] = *p;
2098 if (base64_chars == 4) {
2099 unsigned char out[3];
2103 len = base64_decode_atom(base64_bit, out);
2106 errmsg = "invalid base64 encoding";
2110 if (ret->keyblob_len + len > ret->keyblob_size) {
2111 ret->keyblob_size = ret->keyblob_len + len + 256;
2112 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
2116 memcpy(ret->keyblob + ret->keyblob_len, out, len);
2117 ret->keyblob_len += len;
2123 smemclr(line, strlen(line));
2128 if (ret->keyblob_len == 0 || !ret->keyblob) {
2129 errmsg = "key body not present";
2134 if (errmsg_p) *errmsg_p = NULL;
2142 smemclr(line, strlen(line));
2148 smemclr(ret->keyblob, ret->keyblob_size);
2149 sfree(ret->keyblob);
2151 smemclr(ret, sizeof(*ret));
2154 if (errmsg_p) *errmsg_p = errmsg;
2158 int sshcom_encrypted(const Filename *filename, char **comment)
2160 struct sshcom_key *key = load_sshcom_key(filename, NULL);
2161 int pos, len, answer;
2170 * Check magic number.
2172 if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) {
2173 goto done; /* key is invalid */
2177 * Find the cipher-type string.
2180 if (key->keyblob_len < pos+4)
2181 goto done; /* key is far too short */
2182 len = toint(GET_32BIT(key->keyblob + pos));
2183 if (len < 0 || len > key->keyblob_len - pos - 4)
2184 goto done; /* key is far too short */
2185 pos += 4 + len; /* skip key type */
2186 len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
2187 if (len < 0 || len > key->keyblob_len - pos - 4)
2188 goto done; /* cipher type string is incomplete */
2189 if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
2194 *comment = dupstr(key->comment);
2195 smemclr(key->keyblob, key->keyblob_size);
2196 sfree(key->keyblob);
2197 smemclr(key, sizeof(*key));
2200 *comment = dupstr("");
2205 static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
2207 unsigned bits, bytes;
2208 unsigned char *d = (unsigned char *) data;
2212 bits = GET_32BIT(d);
2214 bytes = (bits + 7) / 8;
2225 return len; /* ensure further calls fail as well */
2228 static int sshcom_put_mpint(void *target, void *data, int len)
2230 unsigned char *d = (unsigned char *)target;
2231 unsigned char *i = (unsigned char *)data;
2232 int bits = len * 8 - 1;
2235 if (*i & (1 << (bits & 7)))
2241 PUT_32BIT(d, bits+1);
2242 memcpy(d+4, i, len);
2246 struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
2247 const char **errmsg_p)
2249 struct sshcom_key *key = load_sshcom_key(filename, errmsg_p);
2252 const char prefix_rsa[] = "if-modn{sign{rsa";
2253 const char prefix_dsa[] = "dl-modp{sign{dsa";
2254 enum { RSA, DSA } type;
2258 struct ssh2_userkey *ret = NULL, *retkey;
2259 const struct ssh_signkey *alg;
2260 unsigned char *blob = NULL;
2261 int blobsize = 0, publen, privlen;
2267 * Check magic number.
2269 if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) {
2270 errmsg = "key does not begin with magic number";
2275 * Determine the key type.
2278 if (key->keyblob_len < pos+4 ||
2279 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2280 len > key->keyblob_len - pos - 4) {
2281 errmsg = "key blob does not contain a key type string";
2284 if (len > sizeof(prefix_rsa) - 1 &&
2285 !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) {
2287 } else if (len > sizeof(prefix_dsa) - 1 &&
2288 !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) {
2291 errmsg = "key is of unknown type";
2297 * Determine the cipher type.
2299 if (key->keyblob_len < pos+4 ||
2300 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2301 len > key->keyblob_len - pos - 4) {
2302 errmsg = "key blob does not contain a cipher type string";
2305 if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4))
2307 else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8))
2310 errmsg = "key encryption is of unknown type";
2316 * Get hold of the encrypted part of the key.
2318 if (key->keyblob_len < pos+4 ||
2319 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2320 len > key->keyblob_len - pos - 4) {
2321 errmsg = "key blob does not contain actual key data";
2324 ciphertext = (char *)key->keyblob + pos + 4;
2326 if (cipherlen == 0) {
2327 errmsg = "length of key data is zero";
2332 * Decrypt it if necessary.
2336 * Derive encryption key from passphrase and iv/salt:
2338 * - let block A equal MD5(passphrase)
2339 * - let block B equal MD5(passphrase || A)
2340 * - block C would be MD5(passphrase || A || B) and so on
2341 * - encryption key is the first N bytes of A || B
2343 struct MD5Context md5c;
2344 unsigned char keybuf[32], iv[8];
2346 if (cipherlen % 8 != 0) {
2347 errmsg = "encrypted part of key is not a multiple of cipher block"
2353 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2354 MD5Final(keybuf, &md5c);
2357 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2358 MD5Update(&md5c, keybuf, 16);
2359 MD5Final(keybuf+16, &md5c);
2362 * Now decrypt the key blob.
2364 memset(iv, 0, sizeof(iv));
2365 des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2368 smemclr(&md5c, sizeof(md5c));
2369 smemclr(keybuf, sizeof(keybuf));
2372 * Hereafter we return WRONG_PASSPHRASE for any parsing
2373 * error. (But only if we've just tried to decrypt it!
2374 * Returning WRONG_PASSPHRASE for an unencrypted key is
2378 ret = SSH2_WRONG_PASSPHRASE;
2382 * Strip away the containing string to get to the real meat.
2384 len = toint(GET_32BIT(ciphertext));
2385 if (len < 0 || len > cipherlen-4) {
2386 errmsg = "containing string was ill-formed";
2393 * Now we break down into RSA versus DSA. In either case we'll
2394 * construct public and private blobs in our own format, and
2395 * end up feeding them to alg->createkey().
2397 blobsize = cipherlen + 256;
2398 blob = snewn(blobsize, unsigned char);
2401 struct mpint_pos n, e, d, u, p, q;
2403 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e);
2404 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d);
2405 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n);
2406 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u);
2407 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2408 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2410 errmsg = "key data did not contain six integers";
2416 pos += put_string(blob+pos, "ssh-rsa", 7);
2417 pos += put_mp(blob+pos, e.start, e.bytes);
2418 pos += put_mp(blob+pos, n.start, n.bytes);
2420 pos += put_string(blob+pos, d.start, d.bytes);
2421 pos += put_mp(blob+pos, q.start, q.bytes);
2422 pos += put_mp(blob+pos, p.start, p.bytes);
2423 pos += put_mp(blob+pos, u.start, u.bytes);
2424 privlen = pos - publen;
2426 struct mpint_pos p, q, g, x, y;
2429 assert(type == DSA); /* the only other option from the if above */
2431 if (GET_32BIT(ciphertext) != 0) {
2432 errmsg = "predefined DSA parameters not supported";
2435 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2436 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g);
2437 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2438 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y);
2439 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x);
2441 errmsg = "key data did not contain five integers";
2447 pos += put_string(blob+pos, "ssh-dss", 7);
2448 pos += put_mp(blob+pos, p.start, p.bytes);
2449 pos += put_mp(blob+pos, q.start, q.bytes);
2450 pos += put_mp(blob+pos, g.start, g.bytes);
2451 pos += put_mp(blob+pos, y.start, y.bytes);
2453 pos += put_mp(blob+pos, x.start, x.bytes);
2454 privlen = pos - publen;
2457 assert(privlen > 0); /* should have bombed by now if not */
2459 retkey = snew(struct ssh2_userkey);
2461 retkey->data = alg->createkey(alg, blob, publen, blob+publen, privlen);
2462 if (!retkey->data) {
2464 errmsg = "unable to create key data structure";
2467 retkey->comment = dupstr(key->comment);
2469 errmsg = NULL; /* no error */
2474 smemclr(blob, blobsize);
2477 smemclr(key->keyblob, key->keyblob_size);
2478 sfree(key->keyblob);
2479 smemclr(key, sizeof(*key));
2481 if (errmsg_p) *errmsg_p = errmsg;
2485 int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
2488 unsigned char *pubblob, *privblob;
2489 int publen, privlen;
2490 unsigned char *outblob;
2492 struct mpint_pos numbers[6];
2493 int nnumbers, initial_zero, pos, lenpos, i;
2501 * Fetch the key blobs.
2503 pubblob = key->alg->public_blob(key->data, &publen);
2504 privblob = key->alg->private_blob(key->data, &privlen);
2508 * Find the sequence of integers to be encoded into the OpenSSH
2509 * key blob, and also decide on the header line.
2511 if (key->alg == &ssh_rsa) {
2513 struct mpint_pos n, e, d, p, q, iqmp;
2516 * These blobs were generated from inside PuTTY, so we needn't
2517 * treat them as untrusted.
2519 pos = 4 + GET_32BIT(pubblob);
2520 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
2521 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
2523 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
2524 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
2525 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
2526 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
2528 assert(e.start && iqmp.start); /* can't go wrong */
2539 type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
2540 } else if (key->alg == &ssh_dss) {
2542 struct mpint_pos p, q, g, y, x;
2545 * These blobs were generated from inside PuTTY, so we needn't
2546 * treat them as untrusted.
2548 pos = 4 + GET_32BIT(pubblob);
2549 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
2550 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
2551 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
2552 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
2554 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
2556 assert(y.start && x.start); /* can't go wrong */
2566 type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
2568 assert(0); /* zoinks! */
2569 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
2573 * Total size of key blob will be somewhere under 512 plus
2574 * combined length of integers. We'll calculate the more
2575 * precise size as we construct the blob.
2578 for (i = 0; i < nnumbers; i++)
2579 outlen += 4 + numbers[i].bytes;
2580 outblob = snewn(outlen, unsigned char);
2583 * Create the unencrypted key blob.
2586 PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
2587 pos += 4; /* length field, fill in later */
2588 pos += put_string(outblob+pos, type, strlen(type));
2590 char *ciphertype = passphrase ? "3des-cbc" : "none";
2591 pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
2593 lenpos = pos; /* remember this position */
2594 pos += 4; /* encrypted-blob size */
2595 pos += 4; /* encrypted-payload size */
2597 PUT_32BIT(outblob+pos, 0);
2600 for (i = 0; i < nnumbers; i++)
2601 pos += sshcom_put_mpint(outblob+pos,
2602 numbers[i].start, numbers[i].bytes);
2603 /* Now wrap up the encrypted payload. */
2604 PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8));
2605 /* Pad encrypted blob to a multiple of cipher block size. */
2607 int padding = -(pos - (lenpos+4)) & 7;
2609 outblob[pos++] = random_byte();
2611 ciphertext = (char *)outblob+lenpos+4;
2612 cipherlen = pos - (lenpos+4);
2613 assert(!passphrase || cipherlen % 8 == 0);
2614 /* Wrap up the encrypted blob string. */
2615 PUT_32BIT(outblob+lenpos, cipherlen);
2616 /* And finally fill in the total length field. */
2617 PUT_32BIT(outblob+4, pos);
2619 assert(pos < outlen);
2626 * Derive encryption key from passphrase and iv/salt:
2628 * - let block A equal MD5(passphrase)
2629 * - let block B equal MD5(passphrase || A)
2630 * - block C would be MD5(passphrase || A || B) and so on
2631 * - encryption key is the first N bytes of A || B
2633 struct MD5Context md5c;
2634 unsigned char keybuf[32], iv[8];
2637 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2638 MD5Final(keybuf, &md5c);
2641 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2642 MD5Update(&md5c, keybuf, 16);
2643 MD5Final(keybuf+16, &md5c);
2646 * Now decrypt the key blob.
2648 memset(iv, 0, sizeof(iv));
2649 des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2652 smemclr(&md5c, sizeof(md5c));
2653 smemclr(keybuf, sizeof(keybuf));
2657 * And save it. We'll use Unix line endings just in case it's
2658 * subsequently transferred in binary mode.
2660 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
2663 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2664 fprintf(fp, "Comment: \"");
2666 * Comment header is broken with backslash-newline if it goes
2667 * over 70 chars. Although it's surrounded by quotes, it
2668 * _doesn't_ escape backslashes or quotes within the string.
2669 * Don't ask me, I didn't design it.
2672 int slen = 60; /* starts at 60 due to "Comment: " */
2673 char *c = key->comment;
2674 while ((int)strlen(c) > slen) {
2675 fprintf(fp, "%.*s\\\n", slen, c);
2677 slen = 70; /* allow 70 chars on subsequent lines */
2679 fprintf(fp, "%s\"\n", c);
2681 base64_encode(fp, outblob, pos, 70);
2682 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2688 smemclr(outblob, outlen);
2692 smemclr(privblob, privlen);
2696 smemclr(pubblob, publen);