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;
369 int base64_chars = 0;
371 ret = snew(struct openssh_pem_key);
373 ret->keyblob_len = ret->keyblob_size = 0;
375 fp = f_open(filename, "r", FALSE);
377 errmsg = "unable to open key file";
381 if (!(line = fgetline(fp))) {
382 errmsg = "unexpected end of file";
386 if (0 != strncmp(line, "-----BEGIN ", 11) ||
387 0 != strcmp(line+strlen(line)-16, "PRIVATE KEY-----")) {
388 errmsg = "file does not begin with OpenSSH key header";
392 * Parse the BEGIN line. For old-format keys, this tells us the
393 * type of the key; for new-format keys, all it tells us is the
394 * format, and we'll find out the key type once we parse the
397 if (!strcmp(line, "-----BEGIN RSA PRIVATE KEY-----")) {
398 ret->keytype = OP_RSA;
399 } else if (!strcmp(line, "-----BEGIN DSA PRIVATE KEY-----")) {
400 ret->keytype = OP_DSA;
401 } else if (!strcmp(line, "-----BEGIN EC PRIVATE KEY-----")) {
402 ret->keytype = OP_ECDSA;
403 } else if (!strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
404 errmsg = "this is a new-style OpenSSH key";
407 errmsg = "unrecognised key type";
410 smemclr(line, strlen(line));
414 ret->encrypted = FALSE;
415 memset(ret->iv, 0, sizeof(ret->iv));
419 if (!(line = fgetline(fp))) {
420 errmsg = "unexpected end of file";
424 if (0 == strncmp(line, "-----END ", 9) &&
425 0 == strcmp(line+strlen(line)-16, "PRIVATE KEY-----")) {
430 if ((p = strchr(line, ':')) != NULL) {
432 errmsg = "header found in body of key data";
436 while (*p && isspace((unsigned char)*p)) p++;
437 if (!strcmp(line, "Proc-Type")) {
438 if (p[0] != '4' || p[1] != ',') {
439 errmsg = "Proc-Type is not 4 (only 4 is supported)";
443 if (!strcmp(p, "ENCRYPTED"))
444 ret->encrypted = TRUE;
445 } else if (!strcmp(line, "DEK-Info")) {
448 if (!strncmp(p, "DES-EDE3-CBC,", 13)) {
449 ret->encryption = OP_E_3DES;
451 } else if (!strncmp(p, "AES-128-CBC,", 12)) {
452 ret->encryption = OP_E_AES;
455 errmsg = "unsupported cipher";
458 p = strchr(p, ',') + 1;/* always non-NULL, by above checks */
459 for (i = 0; i < ivlen; i++) {
460 if (1 != sscanf(p, "%2x", &j)) {
461 errmsg = "expected more iv data in DEK-Info";
468 errmsg = "more iv data than expected in DEK-Info";
476 while (isbase64(*p)) {
477 base64_bit[base64_chars++] = *p;
478 if (base64_chars == 4) {
479 unsigned char out[3];
484 len = base64_decode_atom(base64_bit, out);
487 errmsg = "invalid base64 encoding";
491 if (ret->keyblob_len + len > ret->keyblob_size) {
492 ret->keyblob_size = ret->keyblob_len + len + 256;
493 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
497 memcpy(ret->keyblob + ret->keyblob_len, out, len);
498 ret->keyblob_len += len;
500 smemclr(out, sizeof(out));
506 smemclr(line, strlen(line));
514 if (ret->keyblob_len == 0 || !ret->keyblob) {
515 errmsg = "key body not present";
519 if (ret->encrypted && ret->keyblob_len % 8 != 0) {
520 errmsg = "encrypted key blob is not a multiple of "
525 smemclr(base64_bit, sizeof(base64_bit));
526 if (errmsg_p) *errmsg_p = NULL;
531 smemclr(line, strlen(line));
535 smemclr(base64_bit, sizeof(base64_bit));
538 smemclr(ret->keyblob, ret->keyblob_size);
541 smemclr(ret, sizeof(*ret));
544 if (errmsg_p) *errmsg_p = errmsg;
549 int openssh_pem_encrypted(const Filename *filename)
551 struct openssh_pem_key *key = load_openssh_pem_key(filename, NULL);
556 ret = key->encrypted;
557 smemclr(key->keyblob, key->keyblob_size);
559 smemclr(key, sizeof(*key));
564 struct ssh2_userkey *openssh_pem_read(const Filename *filename,
566 const char **errmsg_p)
568 struct openssh_pem_key *key = load_openssh_pem_key(filename, errmsg_p);
569 struct ssh2_userkey *retkey;
570 unsigned char *p, *q;
571 int ret, id, len, flags;
573 struct ssh2_userkey *retval = NULL;
576 int blobsize = 0, blobptr, privptr;
585 if (key->encrypted) {
587 * Derive encryption key from passphrase and iv/salt:
589 * - let block A equal MD5(passphrase || iv)
590 * - let block B equal MD5(A || passphrase || iv)
591 * - block C would be MD5(B || passphrase || iv) and so on
592 * - encryption key is the first N bytes of A || B
594 * (Note that only 8 bytes of the iv are used for key
595 * derivation, even when the key is encrypted with AES and
596 * hence there are 16 bytes available.)
598 struct MD5Context md5c;
599 unsigned char keybuf[32];
602 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
603 MD5Update(&md5c, (unsigned char *)key->iv, 8);
604 MD5Final(keybuf, &md5c);
607 MD5Update(&md5c, keybuf, 16);
608 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
609 MD5Update(&md5c, (unsigned char *)key->iv, 8);
610 MD5Final(keybuf+16, &md5c);
613 * Now decrypt the key blob.
615 if (key->encryption == OP_E_3DES)
616 des3_decrypt_pubkey_ossh(keybuf, (unsigned char *)key->iv,
617 key->keyblob, key->keyblob_len);
620 assert(key->encryption == OP_E_AES);
621 ctx = aes_make_context();
622 aes128_key(ctx, keybuf);
623 aes_iv(ctx, (unsigned char *)key->iv);
624 aes_ssh2_decrypt_blk(ctx, key->keyblob, key->keyblob_len);
625 aes_free_context(ctx);
628 smemclr(&md5c, sizeof(md5c));
629 smemclr(keybuf, sizeof(keybuf));
633 * Now we have a decrypted key blob, which contains an ASN.1
634 * encoded private key. We must now untangle the ASN.1.
636 * We expect the whole key blob to be formatted as a SEQUENCE
637 * (0x30 followed by a length code indicating that the rest of
638 * the blob is part of the sequence). Within that SEQUENCE we
639 * expect to see a bunch of INTEGERs. What those integers mean
640 * depends on the key type:
642 * - For RSA, we expect the integers to be 0, n, e, d, p, q,
643 * dmp1, dmq1, iqmp in that order. (The last three are d mod
644 * (p-1), d mod (q-1), inverse of q mod p respectively.)
646 * - For DSA, we expect them to be 0, p, q, g, y, x in that
649 * - In ECDSA the format is totally different: we see the
650 * SEQUENCE, but beneath is an INTEGER 1, OCTET STRING priv
651 * EXPLICIT [0] OID curve, EXPLICIT [1] BIT STRING pubPoint
656 /* Expect the SEQUENCE header. Take its absence as a failure to
657 * decrypt, if the key was encrypted. */
658 ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
660 if (ret < 0 || id != 16) {
661 errmsg = "ASN.1 decoding failure";
662 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
666 /* Expect a load of INTEGERs. */
667 if (key->keytype == OP_RSA)
669 else if (key->keytype == OP_DSA)
672 num_integers = 0; /* placate compiler warnings */
675 if (key->keytype == OP_ECDSA) {
676 /* And now for something completely different */
679 const struct ssh_signkey *alg;
680 const struct ec_curve *curve;
681 int algnamelen, curvenamelen;
683 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
686 if (ret < 0 || id != 2 || key->keyblob+key->keyblob_len-p < len ||
687 len != 1 || p[0] != 1) {
688 errmsg = "ASN.1 decoding failure";
689 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
693 /* Read private key OCTET STRING */
694 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
697 if (ret < 0 || id != 4 || key->keyblob+key->keyblob_len-p < len) {
698 errmsg = "ASN.1 decoding failure";
699 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
706 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
709 if (ret < 0 || id != 0 || key->keyblob+key->keyblob_len-p < len) {
710 errmsg = "ASN.1 decoding failure";
711 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
714 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
717 if (ret < 0 || id != 6 || key->keyblob+key->keyblob_len-p < len) {
718 errmsg = "ASN.1 decoding failure";
719 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
722 alg = ec_alg_by_oid(len, p, &curve);
724 errmsg = "Unsupported ECDSA curve.";
729 /* Read BIT STRING point */
730 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
733 if (ret < 0 || id != 1 || key->keyblob+key->keyblob_len-p < len) {
734 errmsg = "ASN.1 decoding failure";
735 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
738 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
741 if (ret < 0 || id != 3 || key->keyblob+key->keyblob_len-p < len ||
742 len != ((((curve->fieldBits + 7) / 8) * 2) + 2)) {
743 errmsg = "ASN.1 decoding failure";
744 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
747 p += 1; len -= 1; /* Skip 0x00 before point */
749 /* Construct the key */
750 retkey = snew(struct ssh2_userkey);
752 errmsg = "out of memory";
756 blob = snewn((4+19 + 4+8 + 4+len) + (4+privlen), unsigned char);
759 errmsg = "out of memory";
765 algnamelen = strlen(alg->name);
766 PUT_32BIT(q, algnamelen); q += 4;
767 memcpy(q, alg->name, algnamelen); q += algnamelen;
769 curvenamelen = strlen(curve->name);
770 PUT_32BIT(q, curvenamelen); q += 4;
771 memcpy(q, curve->name, curvenamelen); q += curvenamelen;
773 PUT_32BIT(q, len); q += 4;
774 memcpy(q, p, len); q += len;
776 PUT_32BIT(q, privlen);
777 memcpy(q+4, priv, privlen);
779 retkey->data = retkey->alg->createkey(retkey->alg,
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(retkey->alg, 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 const 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) {
1061 const unsigned char *oid;
1066 * Structure of asn1:
1069 * OCTET STRING (private key)
1073 * BIT STRING (0x00 public key point)
1075 oid = ec_alg_oid(key->alg, &oidlen);
1076 pointlen = (((struct ec_key *)key->data)->publicKey.curve->fieldBits
1079 len = ber_write_id_len(NULL, 2, 1, 0);
1081 len += ber_write_id_len(NULL, 4, privlen - 4, 0);
1083 len += ber_write_id_len(NULL, 0, oidlen +
1084 ber_write_id_len(NULL, 6, oidlen, 0),
1085 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1086 len += ber_write_id_len(NULL, 6, oidlen, 0);
1088 len += ber_write_id_len(NULL, 1, 2 + pointlen +
1089 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1090 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1091 len += ber_write_id_len(NULL, 3, 2 + pointlen, 0);
1092 len += 2 + pointlen;
1095 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1097 outblob = snewn(len, unsigned char);
1101 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1102 pos += ber_write_id_len(outblob+pos, 2, 1, 0);
1104 pos += ber_write_id_len(outblob+pos, 4, privlen - 4, 0);
1105 memcpy(outblob+pos, privblob + 4, privlen - 4);
1107 pos += ber_write_id_len(outblob+pos, 0, oidlen +
1108 ber_write_id_len(NULL, 6, oidlen, 0),
1109 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1110 pos += ber_write_id_len(outblob+pos, 6, oidlen, 0);
1111 memcpy(outblob+pos, oid, oidlen);
1113 pos += ber_write_id_len(outblob+pos, 1, 2 + pointlen +
1114 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1115 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1116 pos += ber_write_id_len(outblob+pos, 3, 2 + pointlen, 0);
1118 memcpy(outblob+pos, pubblob+39, 1 + pointlen);
1119 pos += 1 + pointlen;
1121 header = "-----BEGIN EC PRIVATE KEY-----\n";
1122 footer = "-----END EC PRIVATE KEY-----\n";
1124 assert(0); /* zoinks! */
1125 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
1131 * For the moment, we still encrypt our OpenSSH keys using
1135 struct MD5Context md5c;
1136 unsigned char keybuf[32];
1139 * Round up to the cipher block size, ensuring we have at
1140 * least one byte of padding (see below).
1142 outlen = (len+8) &~ 7;
1144 unsigned char *tmp = snewn(outlen, unsigned char);
1145 memcpy(tmp, outblob, len);
1146 smemclr(outblob, len);
1152 * Padding on OpenSSH keys is deterministic. The number of
1153 * padding bytes is always more than zero, and always at most
1154 * the cipher block length. The value of each padding byte is
1155 * equal to the number of padding bytes. So a plaintext that's
1156 * an exact multiple of the block size will be padded with 08
1157 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
1158 * plaintext one byte less than a multiple of the block size
1159 * will be padded with just 01.
1161 * This enables the OpenSSL key decryption function to strip
1162 * off the padding algorithmically and return the unpadded
1163 * plaintext to the next layer: it looks at the final byte, and
1164 * then expects to find that many bytes at the end of the data
1165 * with the same value. Those are all removed and the rest is
1169 while (pos < outlen) {
1170 outblob[pos++] = outlen - len;
1174 * Invent an iv. Then derive encryption key from passphrase
1177 * - let block A equal MD5(passphrase || iv)
1178 * - let block B equal MD5(A || passphrase || iv)
1179 * - block C would be MD5(B || passphrase || iv) and so on
1180 * - encryption key is the first N bytes of A || B
1182 for (i = 0; i < 8; i++) iv[i] = random_byte();
1185 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1186 MD5Update(&md5c, iv, 8);
1187 MD5Final(keybuf, &md5c);
1190 MD5Update(&md5c, keybuf, 16);
1191 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1192 MD5Update(&md5c, iv, 8);
1193 MD5Final(keybuf+16, &md5c);
1196 * Now encrypt the key blob.
1198 des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
1200 smemclr(&md5c, sizeof(md5c));
1201 smemclr(keybuf, sizeof(keybuf));
1204 * If no encryption, the blob has exactly its original
1211 * And save it. We'll use Unix line endings just in case it's
1212 * subsequently transferred in binary mode.
1214 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1219 fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
1220 for (i = 0; i < 8; i++)
1221 fprintf(fp, "%02X", iv[i]);
1222 fprintf(fp, "\n\n");
1224 base64_encode(fp, outblob, outlen, 64);
1231 smemclr(outblob, outlen);
1235 smemclr(spareblob, sparelen);
1239 smemclr(privblob, privlen);
1243 smemclr(pubblob, publen);
1249 /* ----------------------------------------------------------------------
1250 * Code to read and write OpenSSH private keys in the new-style format.
1254 ON_E_NONE, ON_E_AES256CBC
1255 } openssh_new_cipher;
1257 ON_K_NONE, ON_K_BCRYPT
1260 struct openssh_new_key {
1261 openssh_new_cipher cipher;
1262 openssh_new_kdf kdf;
1266 /* This points to a position within keyblob, not a
1267 * separately allocated thing */
1268 const unsigned char *salt;
1272 int nkeys, key_wanted;
1273 /* This too points to a position within keyblob */
1274 unsigned char *privatestr;
1277 unsigned char *keyblob;
1278 int keyblob_len, keyblob_size;
1281 static struct openssh_new_key *load_openssh_new_key(const Filename *filename,
1282 const char **errmsg_p)
1284 struct openssh_new_key *ret;
1290 int base64_chars = 0;
1291 const void *filedata;
1293 const void *string, *kdfopts, *bcryptsalt, *pubkey;
1294 int stringlen, kdfoptlen, bcryptsaltlen, pubkeylen;
1295 unsigned bcryptrounds, nkeys, key_index;
1297 ret = snew(struct openssh_new_key);
1298 ret->keyblob = NULL;
1299 ret->keyblob_len = ret->keyblob_size = 0;
1301 fp = f_open(filename, "r", FALSE);
1303 errmsg = "unable to open key file";
1307 if (!(line = fgetline(fp))) {
1308 errmsg = "unexpected end of file";
1312 if (0 != strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
1313 errmsg = "file does not begin with OpenSSH new-style key header";
1316 smemclr(line, strlen(line));
1321 if (!(line = fgetline(fp))) {
1322 errmsg = "unexpected end of file";
1326 if (0 == strcmp(line, "-----END OPENSSH PRIVATE KEY-----")) {
1333 while (isbase64(*p)) {
1334 base64_bit[base64_chars++] = *p;
1335 if (base64_chars == 4) {
1336 unsigned char out[3];
1341 len = base64_decode_atom(base64_bit, out);
1344 errmsg = "invalid base64 encoding";
1348 if (ret->keyblob_len + len > ret->keyblob_size) {
1349 ret->keyblob_size = ret->keyblob_len + len + 256;
1350 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
1354 memcpy(ret->keyblob + ret->keyblob_len, out, len);
1355 ret->keyblob_len += len;
1357 smemclr(out, sizeof(out));
1362 smemclr(line, strlen(line));
1370 if (ret->keyblob_len == 0 || !ret->keyblob) {
1371 errmsg = "key body not present";
1375 filedata = ret->keyblob;
1376 filelen = ret->keyblob_len;
1378 if (filelen < 15 || 0 != memcmp(filedata, "openssh-key-v1\0", 15)) {
1379 errmsg = "new-style OpenSSH magic number missing\n";
1382 filedata = (const char *)filedata + 15;
1385 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1386 errmsg = "encountered EOF before cipher name\n";
1389 if (match_ssh_id(stringlen, string, "none")) {
1390 ret->cipher = ON_E_NONE;
1391 } else if (match_ssh_id(stringlen, string, "aes256-cbc")) {
1392 ret->cipher = ON_E_AES256CBC;
1394 errmsg = "unrecognised cipher name\n";
1398 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1399 errmsg = "encountered EOF before kdf name\n";
1402 if (match_ssh_id(stringlen, string, "none")) {
1403 ret->kdf = ON_K_NONE;
1404 } else if (match_ssh_id(stringlen, string, "bcrypt")) {
1405 ret->kdf = ON_K_BCRYPT;
1407 errmsg = "unrecognised kdf name\n";
1411 if (!(kdfopts = get_ssh_string(&filelen, &filedata, &kdfoptlen))) {
1412 errmsg = "encountered EOF before kdf options\n";
1417 if (kdfoptlen != 0) {
1418 errmsg = "expected empty options string for 'none' kdf";
1423 if (!(bcryptsalt = get_ssh_string(&kdfoptlen, &kdfopts,
1425 errmsg = "bcrypt options string did not contain salt\n";
1428 if (!get_ssh_uint32(&kdfoptlen, &kdfopts, &bcryptrounds)) {
1429 errmsg = "bcrypt options string did not contain round count\n";
1432 ret->kdfopts.bcrypt.salt = bcryptsalt;
1433 ret->kdfopts.bcrypt.saltlen = bcryptsaltlen;
1434 ret->kdfopts.bcrypt.rounds = bcryptrounds;
1439 * At this point we expect a uint32 saying how many keys are
1440 * stored in this file. OpenSSH new-style key files can
1441 * contain more than one. Currently we don't have any user
1442 * interface to specify which one we're trying to extract, so
1443 * we just bomb out with an error if more than one is found in
1444 * the file. However, I've put in all the mechanism here to
1445 * extract the nth one for a given n, in case we later connect
1446 * up some UI to that mechanism. Just arrange that the
1447 * 'key_wanted' field is set to a value in the range [0,
1448 * nkeys) by some mechanism.
1450 if (!get_ssh_uint32(&filelen, &filedata, &nkeys)) {
1451 errmsg = "encountered EOF before key count\n";
1455 errmsg = "multiple keys in new-style OpenSSH key file "
1460 ret->key_wanted = 0;
1462 for (key_index = 0; key_index < nkeys; key_index++) {
1463 if (!(pubkey = get_ssh_string(&filelen, &filedata, &pubkeylen))) {
1464 errmsg = "encountered EOF before kdf options\n";
1470 * Now we expect a string containing the encrypted part of the
1473 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1474 errmsg = "encountered EOF before private key container\n";
1477 ret->privatestr = (unsigned char *)string;
1478 ret->privatelen = stringlen;
1481 * And now we're done, until asked to actually decrypt.
1484 smemclr(base64_bit, sizeof(base64_bit));
1485 if (errmsg_p) *errmsg_p = NULL;
1490 smemclr(line, strlen(line));
1494 smemclr(base64_bit, sizeof(base64_bit));
1497 smemclr(ret->keyblob, ret->keyblob_size);
1498 sfree(ret->keyblob);
1500 smemclr(ret, sizeof(*ret));
1503 if (errmsg_p) *errmsg_p = errmsg;
1508 int openssh_new_encrypted(const Filename *filename)
1510 struct openssh_new_key *key = load_openssh_new_key(filename, NULL);
1515 ret = (key->cipher != ON_E_NONE);
1516 smemclr(key->keyblob, key->keyblob_size);
1517 sfree(key->keyblob);
1518 smemclr(key, sizeof(*key));
1523 struct ssh2_userkey *openssh_new_read(const Filename *filename,
1525 const char **errmsg_p)
1527 struct openssh_new_key *key = load_openssh_new_key(filename, errmsg_p);
1528 struct ssh2_userkey *retkey;
1530 struct ssh2_userkey *retval = NULL;
1532 unsigned char *blob;
1534 unsigned checkint0, checkint1;
1535 const void *priv, *string;
1536 int privlen, stringlen, key_index;
1537 const struct ssh_signkey *alg;
1544 if (key->cipher != ON_E_NONE) {
1545 unsigned char keybuf[48];
1549 * Construct the decryption key, and decrypt the string.
1551 switch (key->cipher) {
1555 case ON_E_AES256CBC:
1556 keysize = 48; /* 32 byte key + 16 byte IV */
1559 assert(0 && "Bad cipher enumeration value");
1561 assert(keysize <= sizeof(keybuf));
1564 memset(keybuf, 0, keysize);
1567 openssh_bcrypt(passphrase,
1568 key->kdfopts.bcrypt.salt,
1569 key->kdfopts.bcrypt.saltlen,
1570 key->kdfopts.bcrypt.rounds,
1574 assert(0 && "Bad kdf enumeration value");
1576 switch (key->cipher) {
1579 case ON_E_AES256CBC:
1580 if (key->privatelen % 16 != 0) {
1581 errmsg = "private key container length is not a"
1582 " multiple of AES block size\n";
1586 void *ctx = aes_make_context();
1587 aes256_key(ctx, keybuf);
1588 aes_iv(ctx, keybuf + 32);
1589 aes_ssh2_decrypt_blk(ctx, key->privatestr,
1591 aes_free_context(ctx);
1595 assert(0 && "Bad cipher enumeration value");
1600 * Now parse the entire encrypted section, and extract the key
1601 * identified by key_wanted.
1603 priv = key->privatestr;
1604 privlen = key->privatelen;
1606 if (!get_ssh_uint32(&privlen, &priv, &checkint0) ||
1607 !get_ssh_uint32(&privlen, &priv, &checkint1) ||
1608 checkint0 != checkint1) {
1609 errmsg = "decryption check failed";
1614 for (key_index = 0; key_index < key->nkeys; key_index++) {
1615 const unsigned char *thiskey;
1619 * Read the key type, which will tell us how to scan over
1620 * the key to get to the next one.
1622 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1623 errmsg = "expected key type in private string";
1628 * Preliminary key type identification, and decide how
1629 * many pieces of key we expect to see. Currently
1630 * (conveniently) all key types can be seen as some number
1631 * of strings, so we just need to know how many of them to
1632 * skip over. (The numbers below exclude the key comment.)
1635 /* find_pubkey_alg needs a zero-terminated copy of the
1637 char *name_zt = dupprintf("%.*s", stringlen, (char *)string);
1638 alg = find_pubkey_alg(name_zt);
1643 errmsg = "private key type not recognised\n";
1650 * Skip over the pieces of key.
1652 for (i = 0; i < alg->openssh_private_npieces; i++) {
1653 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1654 errmsg = "ran out of data in mid-private-key";
1659 thiskeylen = (int)((const unsigned char *)priv -
1660 (const unsigned char *)thiskey);
1661 if (key_index == key->key_wanted) {
1662 retkey = snew(struct ssh2_userkey);
1664 retkey->data = alg->openssh_createkey(alg, &thiskey, &thiskeylen);
1665 if (!retkey->data) {
1667 errmsg = "unable to create key data structure";
1673 * Read the key comment.
1675 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1676 errmsg = "ran out of data at key comment";
1679 if (key_index == key->key_wanted) {
1681 retkey->comment = dupprintf("%.*s", stringlen,
1682 (const char *)string);
1687 errmsg = "key index out of range";
1692 * Now we expect nothing left but padding.
1694 for (i = 0; i < privlen; i++) {
1695 if (((const unsigned char *)priv)[i] != (unsigned char)(i+1)) {
1696 errmsg = "padding at end of private string did not match";
1701 errmsg = NULL; /* no error */
1706 smemclr(blob, blobsize);
1709 smemclr(key->keyblob, key->keyblob_size);
1710 sfree(key->keyblob);
1711 smemclr(key, sizeof(*key));
1713 if (errmsg_p) *errmsg_p = errmsg;
1717 int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
1720 unsigned char *pubblob, *privblob, *outblob, *p;
1721 unsigned char *private_section_start, *private_section_length_field;
1722 int publen, privlen, commentlen, maxsize, padvalue, i;
1725 unsigned char bcrypt_salt[16];
1726 const int bcrypt_rounds = 16;
1730 * Fetch the key blobs and find out the lengths of things.
1732 pubblob = key->alg->public_blob(key->data, &publen);
1733 i = key->alg->openssh_fmtkey(key->data, NULL, 0);
1734 privblob = snewn(i, unsigned char);
1735 privlen = key->alg->openssh_fmtkey(key->data, privblob, i);
1736 assert(privlen == i);
1737 commentlen = strlen(key->comment);
1740 * Allocate enough space for the full binary key format. No need
1741 * to be absolutely precise here.
1743 maxsize = (16 + /* magic number */
1744 32 + /* cipher name string */
1745 32 + /* kdf name string */
1746 64 + /* kdf options string */
1748 4+publen + /* public key string */
1749 4 + /* string header for private section */
1750 8 + /* checkint x 2 */
1751 4+strlen(key->alg->name) + /* key type string */
1752 privlen + /* private blob */
1753 4+commentlen + /* comment string */
1754 16); /* padding at end of private section */
1755 outblob = snewn(maxsize, unsigned char);
1758 * Construct the cleartext version of the blob.
1763 memcpy(p, "openssh-key-v1\0", 15);
1766 /* Cipher and kdf names, and kdf options. */
1768 memset(bcrypt_salt, 0, sizeof(bcrypt_salt)); /* prevent warnings */
1769 p += put_string_z(p, "none");
1770 p += put_string_z(p, "none");
1771 p += put_string_z(p, "");
1774 for (i = 0; i < (int)sizeof(bcrypt_salt); i++)
1775 bcrypt_salt[i] = random_byte();
1776 p += put_string_z(p, "aes256-cbc");
1777 p += put_string_z(p, "bcrypt");
1780 p += put_string(p, bcrypt_salt, sizeof(bcrypt_salt));
1781 p += put_uint32(p, bcrypt_rounds);
1782 PUT_32BIT_MSB_FIRST(q, (unsigned)(p - (q+4)));
1785 /* Number of keys. */
1786 p += put_uint32(p, 1);
1789 p += put_string(p, pubblob, publen);
1791 /* Begin private section. */
1792 private_section_length_field = p;
1794 private_section_start = p;
1798 for (i = 0; i < 4; i++)
1799 checkint = (checkint << 8) + random_byte();
1800 p += put_uint32(p, checkint);
1801 p += put_uint32(p, checkint);
1803 /* Private key. The main private blob goes inline, with no string
1805 p += put_string_z(p, key->alg->name);
1806 memcpy(p, privblob, privlen);
1810 p += put_string_z(p, key->comment);
1812 /* Pad out the encrypted section. */
1816 } while ((p - private_section_start) & 15);
1818 assert(p - outblob < maxsize);
1820 /* Go back and fill in the length field for the private section. */
1821 PUT_32BIT_MSB_FIRST(private_section_length_field,
1822 p - private_section_start);
1826 * Encrypt the private section. We need 48 bytes of key
1827 * material: 32 bytes AES key + 16 bytes iv.
1829 unsigned char keybuf[48];
1832 openssh_bcrypt(passphrase,
1833 bcrypt_salt, sizeof(bcrypt_salt), bcrypt_rounds,
1834 keybuf, sizeof(keybuf));
1836 ctx = aes_make_context();
1837 aes256_key(ctx, keybuf);
1838 aes_iv(ctx, keybuf + 32);
1839 aes_ssh2_encrypt_blk(ctx, private_section_start,
1840 p - private_section_start);
1841 aes_free_context(ctx);
1843 smemclr(keybuf, sizeof(keybuf));
1847 * And save it. We'll use Unix line endings just in case it's
1848 * subsequently transferred in binary mode.
1850 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1853 fputs("-----BEGIN OPENSSH PRIVATE KEY-----\n", fp);
1854 base64_encode(fp, outblob, p - outblob, 64);
1855 fputs("-----END OPENSSH PRIVATE KEY-----\n", fp);
1861 smemclr(outblob, maxsize);
1865 smemclr(privblob, privlen);
1869 smemclr(pubblob, publen);
1875 /* ----------------------------------------------------------------------
1876 * The switch function openssh_auto_write(), which chooses one of the
1877 * concrete OpenSSH output formats based on the key type.
1879 int openssh_auto_write(const Filename *filename, struct ssh2_userkey *key,
1883 * The old OpenSSH format supports a fixed list of key types. We
1884 * assume that anything not in that fixed list is newer, and hence
1885 * will use the new format.
1887 if (key->alg == &ssh_dss ||
1888 key->alg == &ssh_rsa ||
1889 key->alg == &ssh_ecdsa_nistp256 ||
1890 key->alg == &ssh_ecdsa_nistp384 ||
1891 key->alg == &ssh_ecdsa_nistp521)
1892 return openssh_pem_write(filename, key, passphrase);
1894 return openssh_new_write(filename, key, passphrase);
1897 /* ----------------------------------------------------------------------
1898 * Code to read ssh.com private keys.
1902 * The format of the base64 blob is largely SSH-2-packet-formatted,
1903 * except that mpints are a bit different: they're more like the
1904 * old SSH-1 mpint. You have a 32-bit bit count N, followed by
1905 * (N+7)/8 bytes of data.
1907 * So. The blob contains:
1909 * - uint32 0x3f6ff9eb (magic number)
1910 * - uint32 size (total blob size)
1911 * - string key-type (see below)
1912 * - string cipher-type (tells you if key is encrypted)
1913 * - string encrypted-blob
1915 * (The first size field includes the size field itself and the
1916 * magic number before it. All other size fields are ordinary SSH-2
1917 * strings, so the size field indicates how much data is to
1920 * The encrypted blob, once decrypted, contains a single string
1921 * which in turn contains the payload. (This allows padding to be
1922 * added after that string while still making it clear where the
1923 * real payload ends. Also it probably makes for a reasonable
1924 * decryption check.)
1926 * The payload blob, for an RSA key, contains:
1929 * - mpint n (yes, the public and private stuff is intermixed)
1930 * - mpint u (presumably inverse of p mod q)
1931 * - mpint p (p is the smaller prime)
1932 * - mpint q (q is the larger)
1934 * For a DSA key, the payload blob contains:
1942 * Alternatively, if the parameters are `predefined', that
1943 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
1944 * containing some predefined parameter specification. *shudder*,
1945 * but I doubt we'll encounter this in real life.
1947 * The key type strings are ghastly. The RSA key I looked at had a
1950 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
1952 * and the DSA key wasn't much better:
1954 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
1956 * It isn't clear that these will always be the same. I think it
1957 * might be wise just to look at the `if-modn{sign{rsa' and
1958 * `dl-modp{sign{dsa' prefixes.
1960 * Finally, the encryption. The cipher-type string appears to be
1961 * either `none' or `3des-cbc'. Looks as if this is SSH-2-style
1962 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
1963 * from the passphrase by means of yet another hashing faff:
1965 * - first 16 bytes are MD5(passphrase)
1966 * - next 16 bytes are MD5(passphrase || first 16 bytes)
1967 * - if there were more, they'd be MD5(passphrase || first 32),
1971 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
1974 char comment[256]; /* allowing any length is overkill */
1975 unsigned char *keyblob;
1976 int keyblob_len, keyblob_size;
1979 static struct sshcom_key *load_sshcom_key(const Filename *filename,
1980 const char **errmsg_p)
1982 struct sshcom_key *ret;
1990 int base64_chars = 0;
1992 ret = snew(struct sshcom_key);
1993 ret->comment[0] = '\0';
1994 ret->keyblob = NULL;
1995 ret->keyblob_len = ret->keyblob_size = 0;
1997 fp = f_open(filename, "r", FALSE);
1999 errmsg = "unable to open key file";
2002 if (!(line = fgetline(fp))) {
2003 errmsg = "unexpected end of file";
2007 if (0 != strcmp(line, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
2008 errmsg = "file does not begin with ssh.com key header";
2011 smemclr(line, strlen(line));
2017 if (!(line = fgetline(fp))) {
2018 errmsg = "unexpected end of file";
2022 if (!strcmp(line, "---- END SSH2 ENCRYPTED PRIVATE KEY ----")) {
2027 if ((p = strchr(line, ':')) != NULL) {
2029 errmsg = "header found in body of key data";
2033 while (*p && isspace((unsigned char)*p)) p++;
2034 hdrstart = p - line;
2037 * Header lines can end in a trailing backslash for
2040 len = hdrstart + strlen(line+hdrstart);
2042 while (line[len-1] == '\\') {
2046 line2 = fgetline(fp);
2048 errmsg = "unexpected end of file";
2053 line2len = strlen(line2);
2054 line = sresize(line, len + line2len + 1, char);
2055 strcpy(line + len - 1, line2);
2056 len += line2len - 1;
2059 smemclr(line2, strlen(line2));
2063 p = line + hdrstart;
2065 if (!strcmp(line, "Comment")) {
2066 /* Strip quotes in comment if present. */
2067 if (p[0] == '"' && p[strlen(p)-1] == '"') {
2069 p[strlen(p)-1] = '\0';
2071 strncpy(ret->comment, p, sizeof(ret->comment));
2072 ret->comment[sizeof(ret->comment)-1] = '\0';
2078 while (isbase64(*p)) {
2079 base64_bit[base64_chars++] = *p;
2080 if (base64_chars == 4) {
2081 unsigned char out[3];
2085 len = base64_decode_atom(base64_bit, out);
2088 errmsg = "invalid base64 encoding";
2092 if (ret->keyblob_len + len > ret->keyblob_size) {
2093 ret->keyblob_size = ret->keyblob_len + len + 256;
2094 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
2098 memcpy(ret->keyblob + ret->keyblob_len, out, len);
2099 ret->keyblob_len += len;
2105 smemclr(line, strlen(line));
2110 if (ret->keyblob_len == 0 || !ret->keyblob) {
2111 errmsg = "key body not present";
2116 if (errmsg_p) *errmsg_p = NULL;
2124 smemclr(line, strlen(line));
2130 smemclr(ret->keyblob, ret->keyblob_size);
2131 sfree(ret->keyblob);
2133 smemclr(ret, sizeof(*ret));
2136 if (errmsg_p) *errmsg_p = errmsg;
2140 int sshcom_encrypted(const Filename *filename, char **comment)
2142 struct sshcom_key *key = load_sshcom_key(filename, NULL);
2143 int pos, len, answer;
2152 * Check magic number.
2154 if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) {
2155 goto done; /* key is invalid */
2159 * Find the cipher-type string.
2162 if (key->keyblob_len < pos+4)
2163 goto done; /* key is far too short */
2164 len = toint(GET_32BIT(key->keyblob + pos));
2165 if (len < 0 || len > key->keyblob_len - pos - 4)
2166 goto done; /* key is far too short */
2167 pos += 4 + len; /* skip key type */
2168 len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
2169 if (len < 0 || len > key->keyblob_len - pos - 4)
2170 goto done; /* cipher type string is incomplete */
2171 if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
2176 *comment = dupstr(key->comment);
2177 smemclr(key->keyblob, key->keyblob_size);
2178 sfree(key->keyblob);
2179 smemclr(key, sizeof(*key));
2182 *comment = dupstr("");
2187 static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
2189 unsigned bits, bytes;
2190 unsigned char *d = (unsigned char *) data;
2194 bits = GET_32BIT(d);
2196 bytes = (bits + 7) / 8;
2207 return len; /* ensure further calls fail as well */
2210 static int sshcom_put_mpint(void *target, void *data, int len)
2212 unsigned char *d = (unsigned char *)target;
2213 unsigned char *i = (unsigned char *)data;
2214 int bits = len * 8 - 1;
2217 if (*i & (1 << (bits & 7)))
2223 PUT_32BIT(d, bits+1);
2224 memcpy(d+4, i, len);
2228 struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
2229 const char **errmsg_p)
2231 struct sshcom_key *key = load_sshcom_key(filename, errmsg_p);
2234 const char prefix_rsa[] = "if-modn{sign{rsa";
2235 const char prefix_dsa[] = "dl-modp{sign{dsa";
2236 enum { RSA, DSA } type;
2240 struct ssh2_userkey *ret = NULL, *retkey;
2241 const struct ssh_signkey *alg;
2242 unsigned char *blob = NULL;
2243 int blobsize = 0, publen, privlen;
2249 * Check magic number.
2251 if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) {
2252 errmsg = "key does not begin with magic number";
2257 * Determine the key type.
2260 if (key->keyblob_len < pos+4 ||
2261 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2262 len > key->keyblob_len - pos - 4) {
2263 errmsg = "key blob does not contain a key type string";
2266 if (len > sizeof(prefix_rsa) - 1 &&
2267 !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) {
2269 } else if (len > sizeof(prefix_dsa) - 1 &&
2270 !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) {
2273 errmsg = "key is of unknown type";
2279 * Determine the cipher type.
2281 if (key->keyblob_len < pos+4 ||
2282 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2283 len > key->keyblob_len - pos - 4) {
2284 errmsg = "key blob does not contain a cipher type string";
2287 if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4))
2289 else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8))
2292 errmsg = "key encryption is of unknown type";
2298 * Get hold of the encrypted part of the key.
2300 if (key->keyblob_len < pos+4 ||
2301 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2302 len > key->keyblob_len - pos - 4) {
2303 errmsg = "key blob does not contain actual key data";
2306 ciphertext = (char *)key->keyblob + pos + 4;
2308 if (cipherlen == 0) {
2309 errmsg = "length of key data is zero";
2314 * Decrypt it if necessary.
2318 * Derive encryption key from passphrase and iv/salt:
2320 * - let block A equal MD5(passphrase)
2321 * - let block B equal MD5(passphrase || A)
2322 * - block C would be MD5(passphrase || A || B) and so on
2323 * - encryption key is the first N bytes of A || B
2325 struct MD5Context md5c;
2326 unsigned char keybuf[32], iv[8];
2328 if (cipherlen % 8 != 0) {
2329 errmsg = "encrypted part of key is not a multiple of cipher block"
2335 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2336 MD5Final(keybuf, &md5c);
2339 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2340 MD5Update(&md5c, keybuf, 16);
2341 MD5Final(keybuf+16, &md5c);
2344 * Now decrypt the key blob.
2346 memset(iv, 0, sizeof(iv));
2347 des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2350 smemclr(&md5c, sizeof(md5c));
2351 smemclr(keybuf, sizeof(keybuf));
2354 * Hereafter we return WRONG_PASSPHRASE for any parsing
2355 * error. (But only if we've just tried to decrypt it!
2356 * Returning WRONG_PASSPHRASE for an unencrypted key is
2360 ret = SSH2_WRONG_PASSPHRASE;
2364 * Strip away the containing string to get to the real meat.
2366 len = toint(GET_32BIT(ciphertext));
2367 if (len < 0 || len > cipherlen-4) {
2368 errmsg = "containing string was ill-formed";
2375 * Now we break down into RSA versus DSA. In either case we'll
2376 * construct public and private blobs in our own format, and
2377 * end up feeding them to alg->createkey().
2379 blobsize = cipherlen + 256;
2380 blob = snewn(blobsize, unsigned char);
2383 struct mpint_pos n, e, d, u, p, q;
2385 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e);
2386 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d);
2387 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n);
2388 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u);
2389 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2390 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2392 errmsg = "key data did not contain six integers";
2398 pos += put_string(blob+pos, "ssh-rsa", 7);
2399 pos += put_mp(blob+pos, e.start, e.bytes);
2400 pos += put_mp(blob+pos, n.start, n.bytes);
2402 pos += put_string(blob+pos, d.start, d.bytes);
2403 pos += put_mp(blob+pos, q.start, q.bytes);
2404 pos += put_mp(blob+pos, p.start, p.bytes);
2405 pos += put_mp(blob+pos, u.start, u.bytes);
2406 privlen = pos - publen;
2408 struct mpint_pos p, q, g, x, y;
2411 assert(type == DSA); /* the only other option from the if above */
2413 if (GET_32BIT(ciphertext) != 0) {
2414 errmsg = "predefined DSA parameters not supported";
2417 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2418 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g);
2419 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2420 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y);
2421 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x);
2423 errmsg = "key data did not contain five integers";
2429 pos += put_string(blob+pos, "ssh-dss", 7);
2430 pos += put_mp(blob+pos, p.start, p.bytes);
2431 pos += put_mp(blob+pos, q.start, q.bytes);
2432 pos += put_mp(blob+pos, g.start, g.bytes);
2433 pos += put_mp(blob+pos, y.start, y.bytes);
2435 pos += put_mp(blob+pos, x.start, x.bytes);
2436 privlen = pos - publen;
2439 assert(privlen > 0); /* should have bombed by now if not */
2441 retkey = snew(struct ssh2_userkey);
2443 retkey->data = alg->createkey(alg, blob, publen, blob+publen, privlen);
2444 if (!retkey->data) {
2446 errmsg = "unable to create key data structure";
2449 retkey->comment = dupstr(key->comment);
2451 errmsg = NULL; /* no error */
2456 smemclr(blob, blobsize);
2459 smemclr(key->keyblob, key->keyblob_size);
2460 sfree(key->keyblob);
2461 smemclr(key, sizeof(*key));
2463 if (errmsg_p) *errmsg_p = errmsg;
2467 int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
2470 unsigned char *pubblob, *privblob;
2471 int publen, privlen;
2472 unsigned char *outblob;
2474 struct mpint_pos numbers[6];
2475 int nnumbers, initial_zero, pos, lenpos, i;
2483 * Fetch the key blobs.
2485 pubblob = key->alg->public_blob(key->data, &publen);
2486 privblob = key->alg->private_blob(key->data, &privlen);
2490 * Find the sequence of integers to be encoded into the OpenSSH
2491 * key blob, and also decide on the header line.
2493 if (key->alg == &ssh_rsa) {
2495 struct mpint_pos n, e, d, p, q, iqmp;
2498 * These blobs were generated from inside PuTTY, so we needn't
2499 * treat them as untrusted.
2501 pos = 4 + GET_32BIT(pubblob);
2502 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
2503 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
2505 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
2506 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
2507 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
2508 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
2510 assert(e.start && iqmp.start); /* can't go wrong */
2521 type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
2522 } else if (key->alg == &ssh_dss) {
2524 struct mpint_pos p, q, g, y, x;
2527 * These blobs were generated from inside PuTTY, so we needn't
2528 * treat them as untrusted.
2530 pos = 4 + GET_32BIT(pubblob);
2531 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
2532 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
2533 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
2534 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
2536 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
2538 assert(y.start && x.start); /* can't go wrong */
2548 type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
2550 assert(0); /* zoinks! */
2551 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
2555 * Total size of key blob will be somewhere under 512 plus
2556 * combined length of integers. We'll calculate the more
2557 * precise size as we construct the blob.
2560 for (i = 0; i < nnumbers; i++)
2561 outlen += 4 + numbers[i].bytes;
2562 outblob = snewn(outlen, unsigned char);
2565 * Create the unencrypted key blob.
2568 PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
2569 pos += 4; /* length field, fill in later */
2570 pos += put_string(outblob+pos, type, strlen(type));
2572 const char *ciphertype = passphrase ? "3des-cbc" : "none";
2573 pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
2575 lenpos = pos; /* remember this position */
2576 pos += 4; /* encrypted-blob size */
2577 pos += 4; /* encrypted-payload size */
2579 PUT_32BIT(outblob+pos, 0);
2582 for (i = 0; i < nnumbers; i++)
2583 pos += sshcom_put_mpint(outblob+pos,
2584 numbers[i].start, numbers[i].bytes);
2585 /* Now wrap up the encrypted payload. */
2586 PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8));
2587 /* Pad encrypted blob to a multiple of cipher block size. */
2589 int padding = -(pos - (lenpos+4)) & 7;
2591 outblob[pos++] = random_byte();
2593 ciphertext = (char *)outblob+lenpos+4;
2594 cipherlen = pos - (lenpos+4);
2595 assert(!passphrase || cipherlen % 8 == 0);
2596 /* Wrap up the encrypted blob string. */
2597 PUT_32BIT(outblob+lenpos, cipherlen);
2598 /* And finally fill in the total length field. */
2599 PUT_32BIT(outblob+4, pos);
2601 assert(pos < outlen);
2608 * Derive encryption key from passphrase and iv/salt:
2610 * - let block A equal MD5(passphrase)
2611 * - let block B equal MD5(passphrase || A)
2612 * - block C would be MD5(passphrase || A || B) and so on
2613 * - encryption key is the first N bytes of A || B
2615 struct MD5Context md5c;
2616 unsigned char keybuf[32], iv[8];
2619 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2620 MD5Final(keybuf, &md5c);
2623 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2624 MD5Update(&md5c, keybuf, 16);
2625 MD5Final(keybuf+16, &md5c);
2628 * Now decrypt the key blob.
2630 memset(iv, 0, sizeof(iv));
2631 des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2634 smemclr(&md5c, sizeof(md5c));
2635 smemclr(keybuf, sizeof(keybuf));
2639 * And save it. We'll use Unix line endings just in case it's
2640 * subsequently transferred in binary mode.
2642 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
2645 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2646 fprintf(fp, "Comment: \"");
2648 * Comment header is broken with backslash-newline if it goes
2649 * over 70 chars. Although it's surrounded by quotes, it
2650 * _doesn't_ escape backslashes or quotes within the string.
2651 * Don't ask me, I didn't design it.
2654 int slen = 60; /* starts at 60 due to "Comment: " */
2655 char *c = key->comment;
2656 while ((int)strlen(c) > slen) {
2657 fprintf(fp, "%.*s\\\n", slen, c);
2659 slen = 70; /* allow 70 chars on subsequent lines */
2661 fprintf(fp, "%s\"\n", c);
2663 base64_encode(fp, outblob, pos, 70);
2664 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2670 smemclr(outblob, outlen);
2674 smemclr(privblob, privlen);
2678 smemclr(pubblob, publen);