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;
569 unsigned char *p, *q;
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 const struct ssh_signkey *alg;
679 const struct ec_curve *curve;
680 int algnamelen, curvenamelen;
682 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
685 if (ret < 0 || id != 2 || key->keyblob+key->keyblob_len-p < len ||
686 len != 1 || p[0] != 1) {
687 errmsg = "ASN.1 decoding failure";
688 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
692 /* Read private key OCTET STRING */
693 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
696 if (ret < 0 || id != 4 || key->keyblob+key->keyblob_len-p < len) {
697 errmsg = "ASN.1 decoding failure";
698 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
705 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
708 if (ret < 0 || id != 0 || key->keyblob+key->keyblob_len-p < len) {
709 errmsg = "ASN.1 decoding failure";
710 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
713 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
716 if (ret < 0 || id != 6 || key->keyblob+key->keyblob_len-p < len) {
717 errmsg = "ASN.1 decoding failure";
718 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
721 alg = ec_alg_by_oid(len, p, &curve);
723 errmsg = "Unsupported ECDSA curve.";
728 /* Read BIT STRING point */
729 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
732 if (ret < 0 || id != 1 || key->keyblob+key->keyblob_len-p < len) {
733 errmsg = "ASN.1 decoding failure";
734 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
737 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
740 if (ret < 0 || id != 3 || key->keyblob+key->keyblob_len-p < len ||
741 len != ((((curve->fieldBits + 7) / 8) * 2) + 2)) {
742 errmsg = "ASN.1 decoding failure";
743 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
746 p += 1; len -= 1; /* Skip 0x00 before point */
748 /* Construct the key */
749 retkey = snew(struct ssh2_userkey);
751 errmsg = "out of memory";
755 blob = snewn((4+19 + 4+8 + 4+len) + (4+privlen), unsigned char);
758 errmsg = "out of memory";
764 algnamelen = strlen(alg->name);
765 PUT_32BIT(q, algnamelen); q += 4;
766 memcpy(q, alg->name, algnamelen); q += algnamelen;
768 curvenamelen = strlen(curve->name);
769 PUT_32BIT(q, curvenamelen); q += 4;
770 memcpy(q, curve->name, curvenamelen); q += curvenamelen;
772 PUT_32BIT(q, len); q += 4;
773 memcpy(q, p, len); q += len;
775 PUT_32BIT(q, privlen);
776 memcpy(q+4, priv, privlen);
778 retkey->data = retkey->alg->createkey(retkey->alg,
784 errmsg = "unable to create key data structure";
788 } else if (key->keytype == OP_RSA || key->keytype == OP_DSA) {
791 * Space to create key blob in.
793 blobsize = 256+key->keyblob_len;
794 blob = snewn(blobsize, unsigned char);
796 if (key->keytype == OP_DSA)
797 memcpy(blob+4, "ssh-dss", 7);
798 else if (key->keytype == OP_RSA)
799 memcpy(blob+4, "ssh-rsa", 7);
803 for (i = 0; i < num_integers; i++) {
804 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
807 if (ret < 0 || id != 2 ||
808 key->keyblob+key->keyblob_len-p < len) {
809 errmsg = "ASN.1 decoding failure";
810 retval = key->encrypted ? SSH2_WRONG_PASSPHRASE : NULL;
816 * The first integer should be zero always (I think
817 * this is some sort of version indication).
819 if (len != 1 || p[0] != 0) {
820 errmsg = "version number mismatch";
823 } else if (key->keytype == OP_RSA) {
825 * Integers 1 and 2 go into the public blob but in the
826 * opposite order; integers 3, 4, 5 and 8 go into the
827 * private blob. The other two (6 and 7) are ignored.
830 /* Save the details for after we deal with number 2. */
833 } else if (i != 6 && i != 7) {
834 PUT_32BIT(blob+blobptr, len);
835 memcpy(blob+blobptr+4, p, len);
838 PUT_32BIT(blob+blobptr, modlen);
839 memcpy(blob+blobptr+4, modptr, modlen);
844 } else if (key->keytype == OP_DSA) {
846 * Integers 1-4 go into the public blob; integer 5 goes
847 * into the private blob.
849 PUT_32BIT(blob+blobptr, len);
850 memcpy(blob+blobptr+4, p, len);
856 /* Skip past the number. */
861 * Now put together the actual key. Simplest way to do this is
862 * to assemble our own key blobs and feed them to the createkey
863 * functions; this is a bit faffy but it does mean we get all
864 * the sanity checks for free.
866 assert(privptr > 0); /* should have bombed by now if not */
867 retkey = snew(struct ssh2_userkey);
868 retkey->alg = (key->keytype == OP_RSA ? &ssh_rsa : &ssh_dss);
869 retkey->data = retkey->alg->createkey(retkey->alg, blob, privptr,
874 errmsg = "unable to create key data structure";
879 assert(0 && "Bad key type from load_openssh_pem_key");
883 * The old key format doesn't include a comment in the private
886 retkey->comment = dupstr("imported-openssh-key");
888 errmsg = NULL; /* no error */
893 smemclr(blob, blobsize);
896 smemclr(key->keyblob, key->keyblob_size);
898 smemclr(key, sizeof(*key));
900 if (errmsg_p) *errmsg_p = errmsg;
904 int openssh_pem_write(const Filename *filename, struct ssh2_userkey *key,
907 unsigned char *pubblob, *privblob, *spareblob;
908 int publen, privlen, sparelen = 0;
909 unsigned char *outblob;
911 struct mpint_pos numbers[9];
912 int nnumbers, pos, len, seqlen, i;
913 char *header, *footer;
920 * Fetch the key blobs.
922 pubblob = key->alg->public_blob(key->data, &publen);
923 privblob = key->alg->private_blob(key->data, &privlen);
924 spareblob = outblob = NULL;
930 * Encode the OpenSSH key blob, and also decide on the header
933 if (key->alg == &ssh_rsa || key->alg == &ssh_dss) {
935 * The RSA and DSS handlers share some code because the two
936 * key types have very similar ASN.1 representations, as a
937 * plain SEQUENCE of big integers. So we set up a list of
938 * bignums per key type and then construct the actual blob in
939 * common code after that.
941 if (key->alg == &ssh_rsa) {
943 struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
944 Bignum bd, bp, bq, bdmp1, bdmq1;
947 * These blobs were generated from inside PuTTY, so we needn't
948 * treat them as untrusted.
950 pos = 4 + GET_32BIT(pubblob);
951 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
952 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
954 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
955 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
956 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
957 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
959 assert(e.start && iqmp.start); /* can't go wrong */
961 /* We also need d mod (p-1) and d mod (q-1). */
962 bd = bignum_from_bytes(d.start, d.bytes);
963 bp = bignum_from_bytes(p.start, p.bytes);
964 bq = bignum_from_bytes(q.start, q.bytes);
967 bdmp1 = bigmod(bd, bp);
968 bdmq1 = bigmod(bd, bq);
973 dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
974 dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
975 sparelen = dmp1.bytes + dmq1.bytes;
976 spareblob = snewn(sparelen, unsigned char);
977 dmp1.start = spareblob;
978 dmq1.start = spareblob + dmp1.bytes;
979 for (i = 0; i < dmp1.bytes; i++)
980 spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
981 for (i = 0; i < dmq1.bytes; i++)
982 spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
986 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
997 header = "-----BEGIN RSA PRIVATE KEY-----\n";
998 footer = "-----END RSA PRIVATE KEY-----\n";
999 } else { /* ssh-dss */
1001 struct mpint_pos p, q, g, y, x;
1004 * These blobs were generated from inside PuTTY, so we needn't
1005 * treat them as untrusted.
1007 pos = 4 + GET_32BIT(pubblob);
1008 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
1009 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
1010 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
1011 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
1013 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
1015 assert(y.start && x.start); /* can't go wrong */
1017 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
1025 header = "-----BEGIN DSA PRIVATE KEY-----\n";
1026 footer = "-----END DSA PRIVATE KEY-----\n";
1030 * Now count up the total size of the ASN.1 encoded integers,
1031 * so as to determine the length of the containing SEQUENCE.
1034 for (i = 0; i < nnumbers; i++) {
1035 len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
1036 len += numbers[i].bytes;
1039 /* Now add on the SEQUENCE header. */
1040 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1043 * Now we know how big outblob needs to be. Allocate it.
1045 outblob = snewn(len, unsigned char);
1048 * And write the data into it.
1051 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1052 for (i = 0; i < nnumbers; i++) {
1053 pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
1054 memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
1055 pos += numbers[i].bytes;
1057 } else if (key->alg == &ssh_ecdsa_nistp256 ||
1058 key->alg == &ssh_ecdsa_nistp384 ||
1059 key->alg == &ssh_ecdsa_nistp521) {
1060 const unsigned char *oid;
1065 * Structure of asn1:
1068 * OCTET STRING (private key)
1072 * BIT STRING (0x00 public key point)
1074 oid = ec_alg_oid(key->alg, &oidlen);
1075 pointlen = (((struct ec_key *)key->data)->publicKey.curve->fieldBits
1078 len = ber_write_id_len(NULL, 2, 1, 0);
1080 len += ber_write_id_len(NULL, 4, privlen - 4, 0);
1082 len += ber_write_id_len(NULL, 0, oidlen +
1083 ber_write_id_len(NULL, 6, oidlen, 0),
1084 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1085 len += ber_write_id_len(NULL, 6, oidlen, 0);
1087 len += ber_write_id_len(NULL, 1, 2 + pointlen +
1088 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1089 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1090 len += ber_write_id_len(NULL, 3, 2 + pointlen, 0);
1091 len += 2 + pointlen;
1094 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
1096 outblob = snewn(len, unsigned char);
1100 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
1101 pos += ber_write_id_len(outblob+pos, 2, 1, 0);
1103 pos += ber_write_id_len(outblob+pos, 4, privlen - 4, 0);
1104 memcpy(outblob+pos, privblob + 4, privlen - 4);
1106 pos += ber_write_id_len(outblob+pos, 0, oidlen +
1107 ber_write_id_len(NULL, 6, oidlen, 0),
1108 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1109 pos += ber_write_id_len(outblob+pos, 6, oidlen, 0);
1110 memcpy(outblob+pos, oid, oidlen);
1112 pos += ber_write_id_len(outblob+pos, 1, 2 + pointlen +
1113 ber_write_id_len(NULL, 3, 2 + pointlen, 0),
1114 ASN1_CLASS_CONTEXT_SPECIFIC | ASN1_CONSTRUCTED);
1115 pos += ber_write_id_len(outblob+pos, 3, 2 + pointlen, 0);
1117 memcpy(outblob+pos, pubblob+39, 1 + pointlen);
1118 pos += 1 + pointlen;
1120 header = "-----BEGIN EC PRIVATE KEY-----\n";
1121 footer = "-----END EC PRIVATE KEY-----\n";
1123 assert(0); /* zoinks! */
1124 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
1130 * For the moment, we still encrypt our OpenSSH keys using
1134 struct MD5Context md5c;
1135 unsigned char keybuf[32];
1138 * Round up to the cipher block size, ensuring we have at
1139 * least one byte of padding (see below).
1141 outlen = (len+8) &~ 7;
1143 unsigned char *tmp = snewn(outlen, unsigned char);
1144 memcpy(tmp, outblob, len);
1145 smemclr(outblob, len);
1151 * Padding on OpenSSH keys is deterministic. The number of
1152 * padding bytes is always more than zero, and always at most
1153 * the cipher block length. The value of each padding byte is
1154 * equal to the number of padding bytes. So a plaintext that's
1155 * an exact multiple of the block size will be padded with 08
1156 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
1157 * plaintext one byte less than a multiple of the block size
1158 * will be padded with just 01.
1160 * This enables the OpenSSL key decryption function to strip
1161 * off the padding algorithmically and return the unpadded
1162 * plaintext to the next layer: it looks at the final byte, and
1163 * then expects to find that many bytes at the end of the data
1164 * with the same value. Those are all removed and the rest is
1168 while (pos < outlen) {
1169 outblob[pos++] = outlen - len;
1173 * Invent an iv. Then derive encryption key from passphrase
1176 * - let block A equal MD5(passphrase || iv)
1177 * - let block B equal MD5(A || passphrase || iv)
1178 * - block C would be MD5(B || passphrase || iv) and so on
1179 * - encryption key is the first N bytes of A || B
1181 for (i = 0; i < 8; i++) iv[i] = random_byte();
1184 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1185 MD5Update(&md5c, iv, 8);
1186 MD5Final(keybuf, &md5c);
1189 MD5Update(&md5c, keybuf, 16);
1190 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
1191 MD5Update(&md5c, iv, 8);
1192 MD5Final(keybuf+16, &md5c);
1195 * Now encrypt the key blob.
1197 des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
1199 smemclr(&md5c, sizeof(md5c));
1200 smemclr(keybuf, sizeof(keybuf));
1203 * If no encryption, the blob has exactly its original
1210 * And save it. We'll use Unix line endings just in case it's
1211 * subsequently transferred in binary mode.
1213 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1218 fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
1219 for (i = 0; i < 8; i++)
1220 fprintf(fp, "%02X", iv[i]);
1221 fprintf(fp, "\n\n");
1223 base64_encode(fp, outblob, outlen, 64);
1230 smemclr(outblob, outlen);
1234 smemclr(spareblob, sparelen);
1238 smemclr(privblob, privlen);
1242 smemclr(pubblob, publen);
1248 /* ----------------------------------------------------------------------
1249 * Code to read and write OpenSSH private keys in the new-style format.
1253 ON_E_NONE, ON_E_AES256CBC
1254 } openssh_new_cipher;
1256 ON_K_NONE, ON_K_BCRYPT
1259 struct openssh_new_key {
1260 openssh_new_cipher cipher;
1261 openssh_new_kdf kdf;
1265 /* This points to a position within keyblob, not a
1266 * separately allocated thing */
1267 const unsigned char *salt;
1271 int nkeys, key_wanted;
1272 /* This too points to a position within keyblob */
1273 unsigned char *privatestr;
1276 unsigned char *keyblob;
1277 int keyblob_len, keyblob_size;
1280 static struct openssh_new_key *load_openssh_new_key(const Filename *filename,
1281 const char **errmsg_p)
1283 struct openssh_new_key *ret;
1288 int base64_chars = 0;
1289 const void *filedata;
1291 const void *string, *kdfopts, *bcryptsalt, *pubkey;
1292 int stringlen, kdfoptlen, bcryptsaltlen, pubkeylen;
1293 unsigned bcryptrounds, nkeys, key_index;
1295 ret = snew(struct openssh_new_key);
1296 ret->keyblob = NULL;
1297 ret->keyblob_len = ret->keyblob_size = 0;
1299 fp = f_open(filename, "r", FALSE);
1301 errmsg = "unable to open key file";
1305 if (!(line = fgetline(fp))) {
1306 errmsg = "unexpected end of file";
1310 if (0 != strcmp(line, "-----BEGIN OPENSSH PRIVATE KEY-----")) {
1311 errmsg = "file does not begin with OpenSSH new-style key header";
1314 smemclr(line, strlen(line));
1319 if (!(line = fgetline(fp))) {
1320 errmsg = "unexpected end of file";
1324 if (0 == strcmp(line, "-----END OPENSSH PRIVATE KEY-----")) {
1331 while (isbase64(*p)) {
1332 base64_bit[base64_chars++] = *p;
1333 if (base64_chars == 4) {
1334 unsigned char out[3];
1339 len = base64_decode_atom(base64_bit, out);
1342 errmsg = "invalid base64 encoding";
1346 if (ret->keyblob_len + len > ret->keyblob_size) {
1347 ret->keyblob_size = ret->keyblob_len + len + 256;
1348 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
1352 memcpy(ret->keyblob + ret->keyblob_len, out, len);
1353 ret->keyblob_len += len;
1355 smemclr(out, sizeof(out));
1360 smemclr(line, strlen(line));
1368 if (ret->keyblob_len == 0 || !ret->keyblob) {
1369 errmsg = "key body not present";
1373 filedata = ret->keyblob;
1374 filelen = ret->keyblob_len;
1376 if (filelen < 15 || 0 != memcmp(filedata, "openssh-key-v1\0", 15)) {
1377 errmsg = "new-style OpenSSH magic number missing\n";
1380 filedata = (const char *)filedata + 15;
1383 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1384 errmsg = "encountered EOF before cipher name\n";
1387 if (match_ssh_id(stringlen, string, "none")) {
1388 ret->cipher = ON_E_NONE;
1389 } else if (match_ssh_id(stringlen, string, "aes256-cbc")) {
1390 ret->cipher = ON_E_AES256CBC;
1392 errmsg = "unrecognised cipher name\n";
1396 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1397 errmsg = "encountered EOF before kdf name\n";
1400 if (match_ssh_id(stringlen, string, "none")) {
1401 ret->kdf = ON_K_NONE;
1402 } else if (match_ssh_id(stringlen, string, "bcrypt")) {
1403 ret->kdf = ON_K_BCRYPT;
1405 errmsg = "unrecognised kdf name\n";
1409 if (!(kdfopts = get_ssh_string(&filelen, &filedata, &kdfoptlen))) {
1410 errmsg = "encountered EOF before kdf options\n";
1415 if (kdfoptlen != 0) {
1416 errmsg = "expected empty options string for 'none' kdf";
1421 if (!(bcryptsalt = get_ssh_string(&kdfoptlen, &kdfopts,
1423 errmsg = "bcrypt options string did not contain salt\n";
1426 if (!get_ssh_uint32(&kdfoptlen, &kdfopts, &bcryptrounds)) {
1427 errmsg = "bcrypt options string did not contain round count\n";
1430 ret->kdfopts.bcrypt.salt = bcryptsalt;
1431 ret->kdfopts.bcrypt.saltlen = bcryptsaltlen;
1432 ret->kdfopts.bcrypt.rounds = bcryptrounds;
1437 * At this point we expect a uint32 saying how many keys are
1438 * stored in this file. OpenSSH new-style key files can
1439 * contain more than one. Currently we don't have any user
1440 * interface to specify which one we're trying to extract, so
1441 * we just bomb out with an error if more than one is found in
1442 * the file. However, I've put in all the mechanism here to
1443 * extract the nth one for a given n, in case we later connect
1444 * up some UI to that mechanism. Just arrange that the
1445 * 'key_wanted' field is set to a value in the range [0,
1446 * nkeys) by some mechanism.
1448 if (!get_ssh_uint32(&filelen, &filedata, &nkeys)) {
1449 errmsg = "encountered EOF before key count\n";
1453 errmsg = "multiple keys in new-style OpenSSH key file "
1458 ret->key_wanted = 0;
1460 for (key_index = 0; key_index < nkeys; key_index++) {
1461 if (!(pubkey = get_ssh_string(&filelen, &filedata, &pubkeylen))) {
1462 errmsg = "encountered EOF before kdf options\n";
1468 * Now we expect a string containing the encrypted part of the
1471 if (!(string = get_ssh_string(&filelen, &filedata, &stringlen))) {
1472 errmsg = "encountered EOF before private key container\n";
1475 ret->privatestr = (unsigned char *)string;
1476 ret->privatelen = stringlen;
1479 * And now we're done, until asked to actually decrypt.
1482 smemclr(base64_bit, sizeof(base64_bit));
1483 if (errmsg_p) *errmsg_p = NULL;
1488 smemclr(line, strlen(line));
1492 smemclr(base64_bit, sizeof(base64_bit));
1495 smemclr(ret->keyblob, ret->keyblob_size);
1496 sfree(ret->keyblob);
1498 smemclr(ret, sizeof(*ret));
1501 if (errmsg_p) *errmsg_p = errmsg;
1506 int openssh_new_encrypted(const Filename *filename)
1508 struct openssh_new_key *key = load_openssh_new_key(filename, NULL);
1513 ret = (key->cipher != ON_E_NONE);
1514 smemclr(key->keyblob, key->keyblob_size);
1515 sfree(key->keyblob);
1516 smemclr(key, sizeof(*key));
1521 struct ssh2_userkey *openssh_new_read(const Filename *filename,
1523 const char **errmsg_p)
1525 struct openssh_new_key *key = load_openssh_new_key(filename, errmsg_p);
1526 struct ssh2_userkey *retkey;
1528 struct ssh2_userkey *retval = NULL;
1530 unsigned char *blob;
1532 unsigned checkint0, checkint1;
1533 const void *priv, *string;
1534 int privlen, stringlen, key_index;
1535 const struct ssh_signkey *alg;
1542 if (key->cipher != ON_E_NONE) {
1543 unsigned char keybuf[48];
1547 * Construct the decryption key, and decrypt the string.
1549 switch (key->cipher) {
1553 case ON_E_AES256CBC:
1554 keysize = 48; /* 32 byte key + 16 byte IV */
1557 assert(0 && "Bad cipher enumeration value");
1559 assert(keysize <= sizeof(keybuf));
1562 memset(keybuf, 0, keysize);
1565 openssh_bcrypt(passphrase,
1566 key->kdfopts.bcrypt.salt,
1567 key->kdfopts.bcrypt.saltlen,
1568 key->kdfopts.bcrypt.rounds,
1572 assert(0 && "Bad kdf enumeration value");
1574 switch (key->cipher) {
1577 case ON_E_AES256CBC:
1578 if (key->privatelen % 16 != 0) {
1579 errmsg = "private key container length is not a"
1580 " multiple of AES block size\n";
1584 void *ctx = aes_make_context();
1585 aes256_key(ctx, keybuf);
1586 aes_iv(ctx, keybuf + 32);
1587 aes_ssh2_decrypt_blk(ctx, key->privatestr,
1589 aes_free_context(ctx);
1593 assert(0 && "Bad cipher enumeration value");
1598 * Now parse the entire encrypted section, and extract the key
1599 * identified by key_wanted.
1601 priv = key->privatestr;
1602 privlen = key->privatelen;
1604 if (!get_ssh_uint32(&privlen, &priv, &checkint0) ||
1605 !get_ssh_uint32(&privlen, &priv, &checkint1) ||
1606 checkint0 != checkint1) {
1607 errmsg = "decryption check failed";
1612 for (key_index = 0; key_index < key->nkeys; key_index++) {
1613 const unsigned char *thiskey;
1617 * Read the key type, which will tell us how to scan over
1618 * the key to get to the next one.
1620 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1621 errmsg = "expected key type in private string";
1626 * Preliminary key type identification, and decide how
1627 * many pieces of key we expect to see. Currently
1628 * (conveniently) all key types can be seen as some number
1629 * of strings, so we just need to know how many of them to
1630 * skip over. (The numbers below exclude the key comment.)
1633 /* find_pubkey_alg needs a zero-terminated copy of the
1635 char *name_zt = dupprintf("%.*s", stringlen, (char *)string);
1636 alg = find_pubkey_alg(name_zt);
1641 errmsg = "private key type not recognised\n";
1648 * Skip over the pieces of key.
1650 for (i = 0; i < alg->openssh_private_npieces; i++) {
1651 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1652 errmsg = "ran out of data in mid-private-key";
1657 thiskeylen = (int)((const unsigned char *)priv -
1658 (const unsigned char *)thiskey);
1659 if (key_index == key->key_wanted) {
1660 retkey = snew(struct ssh2_userkey);
1662 retkey->data = alg->openssh_createkey(alg, &thiskey, &thiskeylen);
1663 if (!retkey->data) {
1665 errmsg = "unable to create key data structure";
1671 * Read the key comment.
1673 if (!(string = get_ssh_string(&privlen, &priv, &stringlen))) {
1674 errmsg = "ran out of data at key comment";
1677 if (key_index == key->key_wanted) {
1679 retkey->comment = dupprintf("%.*s", stringlen,
1680 (const char *)string);
1685 errmsg = "key index out of range";
1690 * Now we expect nothing left but padding.
1692 for (i = 0; i < privlen; i++) {
1693 if (((const unsigned char *)priv)[i] != (unsigned char)(i+1)) {
1694 errmsg = "padding at end of private string did not match";
1699 errmsg = NULL; /* no error */
1704 smemclr(blob, blobsize);
1707 smemclr(key->keyblob, key->keyblob_size);
1708 sfree(key->keyblob);
1709 smemclr(key, sizeof(*key));
1711 if (errmsg_p) *errmsg_p = errmsg;
1715 int openssh_new_write(const Filename *filename, struct ssh2_userkey *key,
1718 unsigned char *pubblob, *privblob, *outblob, *p;
1719 unsigned char *private_section_start, *private_section_length_field;
1720 int publen, privlen, commentlen, maxsize, padvalue, i;
1723 unsigned char bcrypt_salt[16];
1724 const int bcrypt_rounds = 16;
1728 * Fetch the key blobs and find out the lengths of things.
1730 pubblob = key->alg->public_blob(key->data, &publen);
1731 i = key->alg->openssh_fmtkey(key->data, NULL, 0);
1732 privblob = snewn(i, unsigned char);
1733 privlen = key->alg->openssh_fmtkey(key->data, privblob, i);
1734 assert(privlen == i);
1735 commentlen = strlen(key->comment);
1738 * Allocate enough space for the full binary key format. No need
1739 * to be absolutely precise here.
1741 maxsize = (16 + /* magic number */
1742 32 + /* cipher name string */
1743 32 + /* kdf name string */
1744 64 + /* kdf options string */
1746 4+publen + /* public key string */
1747 4 + /* string header for private section */
1748 8 + /* checkint x 2 */
1749 4+strlen(key->alg->name) + /* key type string */
1750 privlen + /* private blob */
1751 4+commentlen + /* comment string */
1752 16); /* padding at end of private section */
1753 outblob = snewn(maxsize, unsigned char);
1756 * Construct the cleartext version of the blob.
1761 memcpy(p, "openssh-key-v1\0", 15);
1764 /* Cipher and kdf names, and kdf options. */
1766 memset(bcrypt_salt, 0, sizeof(bcrypt_salt)); /* prevent warnings */
1767 p += put_string_z(p, "none");
1768 p += put_string_z(p, "none");
1769 p += put_string_z(p, "");
1772 for (i = 0; i < (int)sizeof(bcrypt_salt); i++)
1773 bcrypt_salt[i] = random_byte();
1774 p += put_string_z(p, "aes256-cbc");
1775 p += put_string_z(p, "bcrypt");
1778 p += put_string(p, bcrypt_salt, sizeof(bcrypt_salt));
1779 p += put_uint32(p, bcrypt_rounds);
1780 PUT_32BIT_MSB_FIRST(q, (unsigned)(p - (q+4)));
1783 /* Number of keys. */
1784 p += put_uint32(p, 1);
1787 p += put_string(p, pubblob, publen);
1789 /* Begin private section. */
1790 private_section_length_field = p;
1792 private_section_start = p;
1796 for (i = 0; i < 4; i++)
1797 checkint = (checkint << 8) + random_byte();
1798 p += put_uint32(p, checkint);
1799 p += put_uint32(p, checkint);
1801 /* Private key. The main private blob goes inline, with no string
1803 p += put_string_z(p, key->alg->name);
1804 memcpy(p, privblob, privlen);
1808 p += put_string_z(p, key->comment);
1810 /* Pad out the encrypted section. */
1814 } while ((p - private_section_start) & 15);
1816 assert(p - outblob < maxsize);
1818 /* Go back and fill in the length field for the private section. */
1819 PUT_32BIT_MSB_FIRST(private_section_length_field,
1820 p - private_section_start);
1824 * Encrypt the private section. We need 48 bytes of key
1825 * material: 32 bytes AES key + 16 bytes iv.
1827 unsigned char keybuf[48];
1830 openssh_bcrypt(passphrase,
1831 bcrypt_salt, sizeof(bcrypt_salt), bcrypt_rounds,
1832 keybuf, sizeof(keybuf));
1834 ctx = aes_make_context();
1835 aes256_key(ctx, keybuf);
1836 aes_iv(ctx, keybuf + 32);
1837 aes_ssh2_encrypt_blk(ctx, private_section_start,
1838 p - private_section_start);
1839 aes_free_context(ctx);
1841 smemclr(keybuf, sizeof(keybuf));
1845 * And save it. We'll use Unix line endings just in case it's
1846 * subsequently transferred in binary mode.
1848 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
1851 fputs("-----BEGIN OPENSSH PRIVATE KEY-----\n", fp);
1852 base64_encode(fp, outblob, p - outblob, 64);
1853 fputs("-----END OPENSSH PRIVATE KEY-----\n", fp);
1859 smemclr(outblob, maxsize);
1863 smemclr(privblob, privlen);
1867 smemclr(pubblob, publen);
1873 /* ----------------------------------------------------------------------
1874 * The switch function openssh_auto_write(), which chooses one of the
1875 * concrete OpenSSH output formats based on the key type.
1877 int openssh_auto_write(const Filename *filename, struct ssh2_userkey *key,
1881 * The old OpenSSH format supports a fixed list of key types. We
1882 * assume that anything not in that fixed list is newer, and hence
1883 * will use the new format.
1885 if (key->alg == &ssh_dss ||
1886 key->alg == &ssh_rsa ||
1887 key->alg == &ssh_ecdsa_nistp256 ||
1888 key->alg == &ssh_ecdsa_nistp384 ||
1889 key->alg == &ssh_ecdsa_nistp521)
1890 return openssh_pem_write(filename, key, passphrase);
1892 return openssh_new_write(filename, key, passphrase);
1895 /* ----------------------------------------------------------------------
1896 * Code to read ssh.com private keys.
1900 * The format of the base64 blob is largely SSH-2-packet-formatted,
1901 * except that mpints are a bit different: they're more like the
1902 * old SSH-1 mpint. You have a 32-bit bit count N, followed by
1903 * (N+7)/8 bytes of data.
1905 * So. The blob contains:
1907 * - uint32 0x3f6ff9eb (magic number)
1908 * - uint32 size (total blob size)
1909 * - string key-type (see below)
1910 * - string cipher-type (tells you if key is encrypted)
1911 * - string encrypted-blob
1913 * (The first size field includes the size field itself and the
1914 * magic number before it. All other size fields are ordinary SSH-2
1915 * strings, so the size field indicates how much data is to
1918 * The encrypted blob, once decrypted, contains a single string
1919 * which in turn contains the payload. (This allows padding to be
1920 * added after that string while still making it clear where the
1921 * real payload ends. Also it probably makes for a reasonable
1922 * decryption check.)
1924 * The payload blob, for an RSA key, contains:
1927 * - mpint n (yes, the public and private stuff is intermixed)
1928 * - mpint u (presumably inverse of p mod q)
1929 * - mpint p (p is the smaller prime)
1930 * - mpint q (q is the larger)
1932 * For a DSA key, the payload blob contains:
1940 * Alternatively, if the parameters are `predefined', that
1941 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
1942 * containing some predefined parameter specification. *shudder*,
1943 * but I doubt we'll encounter this in real life.
1945 * The key type strings are ghastly. The RSA key I looked at had a
1948 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
1950 * and the DSA key wasn't much better:
1952 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
1954 * It isn't clear that these will always be the same. I think it
1955 * might be wise just to look at the `if-modn{sign{rsa' and
1956 * `dl-modp{sign{dsa' prefixes.
1958 * Finally, the encryption. The cipher-type string appears to be
1959 * either `none' or `3des-cbc'. Looks as if this is SSH-2-style
1960 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
1961 * from the passphrase by means of yet another hashing faff:
1963 * - first 16 bytes are MD5(passphrase)
1964 * - next 16 bytes are MD5(passphrase || first 16 bytes)
1965 * - if there were more, they'd be MD5(passphrase || first 32),
1969 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
1972 char comment[256]; /* allowing any length is overkill */
1973 unsigned char *keyblob;
1974 int keyblob_len, keyblob_size;
1977 static struct sshcom_key *load_sshcom_key(const Filename *filename,
1978 const char **errmsg_p)
1980 struct sshcom_key *ret;
1987 int base64_chars = 0;
1989 ret = snew(struct sshcom_key);
1990 ret->comment[0] = '\0';
1991 ret->keyblob = NULL;
1992 ret->keyblob_len = ret->keyblob_size = 0;
1994 fp = f_open(filename, "r", FALSE);
1996 errmsg = "unable to open key file";
1999 if (!(line = fgetline(fp))) {
2000 errmsg = "unexpected end of file";
2004 if (0 != strcmp(line, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
2005 errmsg = "file does not begin with ssh.com key header";
2008 smemclr(line, strlen(line));
2014 if (!(line = fgetline(fp))) {
2015 errmsg = "unexpected end of file";
2019 if (!strcmp(line, "---- END SSH2 ENCRYPTED PRIVATE KEY ----")) {
2024 if ((p = strchr(line, ':')) != NULL) {
2026 errmsg = "header found in body of key data";
2030 while (*p && isspace((unsigned char)*p)) p++;
2031 hdrstart = p - line;
2034 * Header lines can end in a trailing backslash for
2037 len = hdrstart + strlen(line+hdrstart);
2039 while (line[len-1] == '\\') {
2043 line2 = fgetline(fp);
2045 errmsg = "unexpected end of file";
2050 line2len = strlen(line2);
2051 line = sresize(line, len + line2len + 1, char);
2052 strcpy(line + len - 1, line2);
2053 len += line2len - 1;
2056 smemclr(line2, strlen(line2));
2060 p = line + hdrstart;
2062 if (!strcmp(line, "Comment")) {
2063 /* Strip quotes in comment if present. */
2064 if (p[0] == '"' && p[strlen(p)-1] == '"') {
2066 p[strlen(p)-1] = '\0';
2068 strncpy(ret->comment, p, sizeof(ret->comment));
2069 ret->comment[sizeof(ret->comment)-1] = '\0';
2075 while (isbase64(*p)) {
2076 base64_bit[base64_chars++] = *p;
2077 if (base64_chars == 4) {
2078 unsigned char out[3];
2082 len = base64_decode_atom(base64_bit, out);
2085 errmsg = "invalid base64 encoding";
2089 if (ret->keyblob_len + len > ret->keyblob_size) {
2090 ret->keyblob_size = ret->keyblob_len + len + 256;
2091 ret->keyblob = sresize(ret->keyblob, ret->keyblob_size,
2095 memcpy(ret->keyblob + ret->keyblob_len, out, len);
2096 ret->keyblob_len += len;
2102 smemclr(line, strlen(line));
2107 if (ret->keyblob_len == 0 || !ret->keyblob) {
2108 errmsg = "key body not present";
2113 if (errmsg_p) *errmsg_p = NULL;
2121 smemclr(line, strlen(line));
2127 smemclr(ret->keyblob, ret->keyblob_size);
2128 sfree(ret->keyblob);
2130 smemclr(ret, sizeof(*ret));
2133 if (errmsg_p) *errmsg_p = errmsg;
2137 int sshcom_encrypted(const Filename *filename, char **comment)
2139 struct sshcom_key *key = load_sshcom_key(filename, NULL);
2140 int pos, len, answer;
2149 * Check magic number.
2151 if (GET_32BIT(key->keyblob) != 0x3f6ff9eb) {
2152 goto done; /* key is invalid */
2156 * Find the cipher-type string.
2159 if (key->keyblob_len < pos+4)
2160 goto done; /* key is far too short */
2161 len = toint(GET_32BIT(key->keyblob + pos));
2162 if (len < 0 || len > key->keyblob_len - pos - 4)
2163 goto done; /* key is far too short */
2164 pos += 4 + len; /* skip key type */
2165 len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
2166 if (len < 0 || len > key->keyblob_len - pos - 4)
2167 goto done; /* cipher type string is incomplete */
2168 if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
2173 *comment = dupstr(key->comment);
2174 smemclr(key->keyblob, key->keyblob_size);
2175 sfree(key->keyblob);
2176 smemclr(key, sizeof(*key));
2179 *comment = dupstr("");
2184 static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
2186 unsigned bits, bytes;
2187 unsigned char *d = (unsigned char *) data;
2191 bits = GET_32BIT(d);
2193 bytes = (bits + 7) / 8;
2204 return len; /* ensure further calls fail as well */
2207 static int sshcom_put_mpint(void *target, void *data, int len)
2209 unsigned char *d = (unsigned char *)target;
2210 unsigned char *i = (unsigned char *)data;
2211 int bits = len * 8 - 1;
2214 if (*i & (1 << (bits & 7)))
2220 PUT_32BIT(d, bits+1);
2221 memcpy(d+4, i, len);
2225 struct ssh2_userkey *sshcom_read(const Filename *filename, char *passphrase,
2226 const char **errmsg_p)
2228 struct sshcom_key *key = load_sshcom_key(filename, errmsg_p);
2231 const char prefix_rsa[] = "if-modn{sign{rsa";
2232 const char prefix_dsa[] = "dl-modp{sign{dsa";
2233 enum { RSA, DSA } type;
2237 struct ssh2_userkey *ret = NULL, *retkey;
2238 const struct ssh_signkey *alg;
2239 unsigned char *blob = NULL;
2240 int blobsize = 0, publen, privlen;
2246 * Check magic number.
2248 if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) {
2249 errmsg = "key does not begin with magic number";
2254 * Determine the key type.
2257 if (key->keyblob_len < pos+4 ||
2258 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2259 len > key->keyblob_len - pos - 4) {
2260 errmsg = "key blob does not contain a key type string";
2263 if (len > sizeof(prefix_rsa) - 1 &&
2264 !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) {
2266 } else if (len > sizeof(prefix_dsa) - 1 &&
2267 !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) {
2270 errmsg = "key is of unknown type";
2276 * Determine the cipher 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 cipher type string";
2284 if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4))
2286 else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8))
2289 errmsg = "key encryption is of unknown type";
2295 * Get hold of the encrypted part of the key.
2297 if (key->keyblob_len < pos+4 ||
2298 (len = toint(GET_32BIT(key->keyblob + pos))) < 0 ||
2299 len > key->keyblob_len - pos - 4) {
2300 errmsg = "key blob does not contain actual key data";
2303 ciphertext = (char *)key->keyblob + pos + 4;
2305 if (cipherlen == 0) {
2306 errmsg = "length of key data is zero";
2311 * Decrypt it if necessary.
2315 * Derive encryption key from passphrase and iv/salt:
2317 * - let block A equal MD5(passphrase)
2318 * - let block B equal MD5(passphrase || A)
2319 * - block C would be MD5(passphrase || A || B) and so on
2320 * - encryption key is the first N bytes of A || B
2322 struct MD5Context md5c;
2323 unsigned char keybuf[32], iv[8];
2325 if (cipherlen % 8 != 0) {
2326 errmsg = "encrypted part of key is not a multiple of cipher block"
2332 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2333 MD5Final(keybuf, &md5c);
2336 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2337 MD5Update(&md5c, keybuf, 16);
2338 MD5Final(keybuf+16, &md5c);
2341 * Now decrypt the key blob.
2343 memset(iv, 0, sizeof(iv));
2344 des3_decrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2347 smemclr(&md5c, sizeof(md5c));
2348 smemclr(keybuf, sizeof(keybuf));
2351 * Hereafter we return WRONG_PASSPHRASE for any parsing
2352 * error. (But only if we've just tried to decrypt it!
2353 * Returning WRONG_PASSPHRASE for an unencrypted key is
2357 ret = SSH2_WRONG_PASSPHRASE;
2361 * Strip away the containing string to get to the real meat.
2363 len = toint(GET_32BIT(ciphertext));
2364 if (len < 0 || len > cipherlen-4) {
2365 errmsg = "containing string was ill-formed";
2372 * Now we break down into RSA versus DSA. In either case we'll
2373 * construct public and private blobs in our own format, and
2374 * end up feeding them to alg->createkey().
2376 blobsize = cipherlen + 256;
2377 blob = snewn(blobsize, unsigned char);
2380 struct mpint_pos n, e, d, u, p, q;
2382 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e);
2383 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d);
2384 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n);
2385 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u);
2386 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2387 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2389 errmsg = "key data did not contain six integers";
2395 pos += put_string(blob+pos, "ssh-rsa", 7);
2396 pos += put_mp(blob+pos, e.start, e.bytes);
2397 pos += put_mp(blob+pos, n.start, n.bytes);
2399 pos += put_string(blob+pos, d.start, d.bytes);
2400 pos += put_mp(blob+pos, q.start, q.bytes);
2401 pos += put_mp(blob+pos, p.start, p.bytes);
2402 pos += put_mp(blob+pos, u.start, u.bytes);
2403 privlen = pos - publen;
2405 struct mpint_pos p, q, g, x, y;
2408 assert(type == DSA); /* the only other option from the if above */
2410 if (GET_32BIT(ciphertext) != 0) {
2411 errmsg = "predefined DSA parameters not supported";
2414 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
2415 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g);
2416 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
2417 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y);
2418 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x);
2420 errmsg = "key data did not contain five integers";
2426 pos += put_string(blob+pos, "ssh-dss", 7);
2427 pos += put_mp(blob+pos, p.start, p.bytes);
2428 pos += put_mp(blob+pos, q.start, q.bytes);
2429 pos += put_mp(blob+pos, g.start, g.bytes);
2430 pos += put_mp(blob+pos, y.start, y.bytes);
2432 pos += put_mp(blob+pos, x.start, x.bytes);
2433 privlen = pos - publen;
2436 assert(privlen > 0); /* should have bombed by now if not */
2438 retkey = snew(struct ssh2_userkey);
2440 retkey->data = alg->createkey(alg, blob, publen, blob+publen, privlen);
2441 if (!retkey->data) {
2443 errmsg = "unable to create key data structure";
2446 retkey->comment = dupstr(key->comment);
2448 errmsg = NULL; /* no error */
2453 smemclr(blob, blobsize);
2456 smemclr(key->keyblob, key->keyblob_size);
2457 sfree(key->keyblob);
2458 smemclr(key, sizeof(*key));
2460 if (errmsg_p) *errmsg_p = errmsg;
2464 int sshcom_write(const Filename *filename, struct ssh2_userkey *key,
2467 unsigned char *pubblob, *privblob;
2468 int publen, privlen;
2469 unsigned char *outblob;
2471 struct mpint_pos numbers[6];
2472 int nnumbers, initial_zero, pos, lenpos, i;
2480 * Fetch the key blobs.
2482 pubblob = key->alg->public_blob(key->data, &publen);
2483 privblob = key->alg->private_blob(key->data, &privlen);
2487 * Find the sequence of integers to be encoded into the OpenSSH
2488 * key blob, and also decide on the header line.
2490 if (key->alg == &ssh_rsa) {
2492 struct mpint_pos n, e, d, p, q, iqmp;
2495 * These blobs were generated from inside PuTTY, so we needn't
2496 * treat them as untrusted.
2498 pos = 4 + GET_32BIT(pubblob);
2499 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
2500 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
2502 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
2503 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
2504 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
2505 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
2507 assert(e.start && iqmp.start); /* can't go wrong */
2518 type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
2519 } else if (key->alg == &ssh_dss) {
2521 struct mpint_pos p, q, g, y, x;
2524 * These blobs were generated from inside PuTTY, so we needn't
2525 * treat them as untrusted.
2527 pos = 4 + GET_32BIT(pubblob);
2528 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
2529 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
2530 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
2531 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
2533 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
2535 assert(y.start && x.start); /* can't go wrong */
2545 type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
2547 assert(0); /* zoinks! */
2548 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
2552 * Total size of key blob will be somewhere under 512 plus
2553 * combined length of integers. We'll calculate the more
2554 * precise size as we construct the blob.
2557 for (i = 0; i < nnumbers; i++)
2558 outlen += 4 + numbers[i].bytes;
2559 outblob = snewn(outlen, unsigned char);
2562 * Create the unencrypted key blob.
2565 PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
2566 pos += 4; /* length field, fill in later */
2567 pos += put_string(outblob+pos, type, strlen(type));
2569 char *ciphertype = passphrase ? "3des-cbc" : "none";
2570 pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
2572 lenpos = pos; /* remember this position */
2573 pos += 4; /* encrypted-blob size */
2574 pos += 4; /* encrypted-payload size */
2576 PUT_32BIT(outblob+pos, 0);
2579 for (i = 0; i < nnumbers; i++)
2580 pos += sshcom_put_mpint(outblob+pos,
2581 numbers[i].start, numbers[i].bytes);
2582 /* Now wrap up the encrypted payload. */
2583 PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8));
2584 /* Pad encrypted blob to a multiple of cipher block size. */
2586 int padding = -(pos - (lenpos+4)) & 7;
2588 outblob[pos++] = random_byte();
2590 ciphertext = (char *)outblob+lenpos+4;
2591 cipherlen = pos - (lenpos+4);
2592 assert(!passphrase || cipherlen % 8 == 0);
2593 /* Wrap up the encrypted blob string. */
2594 PUT_32BIT(outblob+lenpos, cipherlen);
2595 /* And finally fill in the total length field. */
2596 PUT_32BIT(outblob+4, pos);
2598 assert(pos < outlen);
2605 * Derive encryption key from passphrase and iv/salt:
2607 * - let block A equal MD5(passphrase)
2608 * - let block B equal MD5(passphrase || A)
2609 * - block C would be MD5(passphrase || A || B) and so on
2610 * - encryption key is the first N bytes of A || B
2612 struct MD5Context md5c;
2613 unsigned char keybuf[32], iv[8];
2616 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2617 MD5Final(keybuf, &md5c);
2620 MD5Update(&md5c, (unsigned char *)passphrase, strlen(passphrase));
2621 MD5Update(&md5c, keybuf, 16);
2622 MD5Final(keybuf+16, &md5c);
2625 * Now decrypt the key blob.
2627 memset(iv, 0, sizeof(iv));
2628 des3_encrypt_pubkey_ossh(keybuf, iv, (unsigned char *)ciphertext,
2631 smemclr(&md5c, sizeof(md5c));
2632 smemclr(keybuf, sizeof(keybuf));
2636 * And save it. We'll use Unix line endings just in case it's
2637 * subsequently transferred in binary mode.
2639 fp = f_open(filename, "wb", TRUE); /* ensure Unix line endings */
2642 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2643 fprintf(fp, "Comment: \"");
2645 * Comment header is broken with backslash-newline if it goes
2646 * over 70 chars. Although it's surrounded by quotes, it
2647 * _doesn't_ escape backslashes or quotes within the string.
2648 * Don't ask me, I didn't design it.
2651 int slen = 60; /* starts at 60 due to "Comment: " */
2652 char *c = key->comment;
2653 while ((int)strlen(c) > slen) {
2654 fprintf(fp, "%.*s\\\n", slen, c);
2656 slen = 70; /* allow 70 chars on subsequent lines */
2658 fprintf(fp, "%s\"\n", c);
2660 base64_encode(fp, outblob, pos, 70);
2661 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
2667 smemclr(outblob, outlen);
2671 smemclr(privblob, privlen);
2675 smemclr(pubblob, publen);