2 * Code for PuTTY to import and export private key files in other
3 * SSH clients' formats.
14 #define PUT_32BIT(cp, value) do { \
15 (cp)[3] = (unsigned char)(value); \
16 (cp)[2] = (unsigned char)((value) >> 8); \
17 (cp)[1] = (unsigned char)((value) >> 16); \
18 (cp)[0] = (unsigned char)((value) >> 24); } while (0)
20 #define GET_32BIT(cp) \
21 (((unsigned long)(unsigned char)(cp)[0] << 24) | \
22 ((unsigned long)(unsigned char)(cp)[1] << 16) | \
23 ((unsigned long)(unsigned char)(cp)[2] << 8) | \
24 ((unsigned long)(unsigned char)(cp)[3]))
26 int openssh_encrypted(char *filename);
27 struct ssh2_userkey *openssh_read(char *filename, char *passphrase);
28 int openssh_write(char *filename, struct ssh2_userkey *key, char *passphrase);
30 int sshcom_encrypted(char *filename, char **comment);
31 struct ssh2_userkey *sshcom_read(char *filename, char *passphrase);
32 int sshcom_write(char *filename, struct ssh2_userkey *key, char *passphrase);
35 * Given a key type, determine whether we know how to import it.
37 int import_possible(int type)
39 if (type == SSH_KEYTYPE_OPENSSH)
41 if (type == SSH_KEYTYPE_SSHCOM)
47 * Given a key type, determine what native key type
48 * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once
51 int import_target_type(int type)
54 * There are no known foreign SSH1 key formats.
56 return SSH_KEYTYPE_SSH2;
60 * Determine whether a foreign key is encrypted.
62 int import_encrypted(char *filename, int type, char **comment)
64 if (type == SSH_KEYTYPE_OPENSSH) {
65 *comment = dupstr(filename); /* OpenSSH doesn't do key comments */
66 return openssh_encrypted(filename);
68 if (type == SSH_KEYTYPE_SSHCOM) {
69 return sshcom_encrypted(filename, comment);
77 int import_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase)
85 struct ssh2_userkey *import_ssh2(char *filename, int type, char *passphrase)
87 if (type == SSH_KEYTYPE_OPENSSH)
88 return openssh_read(filename, passphrase);
89 if (type == SSH_KEYTYPE_SSHCOM)
90 return sshcom_read(filename, passphrase);
97 int export_ssh1(char *filename, int type, struct RSAKey *key, char *passphrase)
103 * Export an SSH2 key.
105 int export_ssh2(char *filename, int type,
106 struct ssh2_userkey *key, char *passphrase)
108 if (type == SSH_KEYTYPE_OPENSSH)
109 return openssh_write(filename, key, passphrase);
110 if (type == SSH_KEYTYPE_SSHCOM)
111 return sshcom_write(filename, key, passphrase);
115 /* ----------------------------------------------------------------------
116 * Helper routines. (The base64 ones are defined in sshpubk.c.)
119 #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \
120 ((c) >= 'a' && (c) <= 'z') || \
121 ((c) >= '0' && (c) <= '9') || \
122 (c) == '+' || (c) == '/' || (c) == '=' \
126 * Read an ASN.1/BER identifier and length pair.
128 * Flags are a combination of the #defines listed below.
130 * Returns -1 if unsuccessful; otherwise returns the number of
131 * bytes used out of the source data.
134 /* ASN.1 tag classes. */
135 #define ASN1_CLASS_UNIVERSAL (0 << 6)
136 #define ASN1_CLASS_APPLICATION (1 << 6)
137 #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6)
138 #define ASN1_CLASS_PRIVATE (3 << 6)
139 #define ASN1_CLASS_MASK (3 << 6)
141 /* Primitive versus constructed bit. */
142 #define ASN1_CONSTRUCTED (1 << 5)
144 int ber_read_id_len(void *source, int sourcelen,
145 int *id, int *length, int *flags)
147 unsigned char *p = (unsigned char *) source;
152 *flags = (*p & 0xE0);
153 if ((*p & 0x1F) == 0x1F) {
156 *id = (*id << 7) | (*p & 0x7F);
161 *id = (*id << 7) | (*p & 0x7F);
178 *length = (*length << 8) | (*p++);
185 return p - (unsigned char *) source;
189 * Write an ASN.1/BER identifier and length pair. Returns the
190 * number of bytes consumed. Assumes dest contains enough space.
191 * Will avoid writing anything if dest is NULL, but still return
192 * amount of space required.
194 int ber_write_id_len(void *dest, int id, int length, int flags)
196 unsigned char *d = (unsigned char *)dest;
201 * Identifier is one byte.
204 if (d) *d++ = id | flags;
208 * Identifier is multiple bytes: the first byte is 11111
209 * plus the flags, and subsequent bytes encode the value of
210 * the identifier, 7 bits at a time, with the top bit of
211 * each byte 1 except the last one which is 0.
214 if (d) *d++ = 0x1F | flags;
215 for (n = 1; (id >> (7*n)) > 0; n++)
216 continue; /* count the bytes */
219 if (d) *d++ = (n ? 0x80 : 0) | ((id >> (7*n)) & 0x7F);
225 * Length is one byte.
228 if (d) *d++ = length;
232 * Length is multiple bytes. The first is 0x80 plus the
233 * number of subsequent bytes, and the subsequent bytes
234 * encode the actual length.
236 for (n = 1; (length >> (8*n)) > 0; n++)
237 continue; /* count the bytes */
239 if (d) *d++ = 0x80 | n;
242 if (d) *d++ = (length >> (8*n)) & 0xFF;
249 static int put_string(void *target, void *data, int len)
251 unsigned char *d = (unsigned char *)target;
254 memcpy(d+4, data, len);
258 static int put_mp(void *target, void *data, int len)
260 unsigned char *d = (unsigned char *)target;
261 unsigned char *i = (unsigned char *)data;
266 memcpy(d+5, data, len);
270 memcpy(d+4, data, len);
275 /* Simple structure to point to an mp-int within a blob. */
276 struct mpint_pos { void *start; int bytes; };
278 int ssh2_read_mpint(void *data, int len, struct mpint_pos *ret)
281 unsigned char *d = (unsigned char *) data;
285 bytes = GET_32BIT(d);
296 return len; /* ensure further calls fail as well */
299 /* ----------------------------------------------------------------------
300 * Code to read and write OpenSSH private keys.
303 enum { OSSH_DSA, OSSH_RSA };
308 unsigned char *keyblob;
309 int keyblob_len, keyblob_size;
312 struct openssh_key *load_openssh_key(char *filename)
314 struct openssh_key *ret;
320 int base64_chars = 0;
322 ret = smalloc(sizeof(*ret));
324 ret->keyblob_len = ret->keyblob_size = 0;
326 memset(ret->iv, 0, sizeof(ret->iv));
328 fp = fopen(filename, "r");
330 errmsg = "Unable to open key file";
333 if (!fgets(buffer, sizeof(buffer), fp) ||
334 0 != strncmp(buffer, "-----BEGIN ", 11) ||
335 0 != strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n")) {
336 errmsg = "File does not begin with OpenSSH key header";
339 if (!strcmp(buffer, "-----BEGIN RSA PRIVATE KEY-----\n"))
340 ret->type = OSSH_RSA;
341 else if (!strcmp(buffer, "-----BEGIN DSA PRIVATE KEY-----\n"))
342 ret->type = OSSH_DSA;
344 errmsg = "Unrecognised key type";
350 if (!fgets(buffer, sizeof(buffer), fp)) {
351 errmsg = "Unexpected end of file";
354 if (0 == strncmp(buffer, "-----END ", 9) &&
355 0 == strcmp(buffer+strlen(buffer)-17, "PRIVATE KEY-----\n"))
357 if ((p = strchr(buffer, ':')) != NULL) {
359 errmsg = "Header found in body of key data";
363 while (*p && isspace((unsigned char)*p)) p++;
364 if (!strcmp(buffer, "Proc-Type")) {
365 if (p[0] != '4' || p[1] != ',') {
366 errmsg = "Proc-Type is not 4 (only 4 is supported)";
370 if (!strcmp(p, "ENCRYPTED\n"))
372 } else if (!strcmp(buffer, "DEK-Info")) {
375 if (strncmp(p, "DES-EDE3-CBC,", 13)) {
376 errmsg = "Ciphers other than DES-EDE3-CBC not supported";
380 for (i = 0; i < 8; i++) {
381 if (1 != sscanf(p, "%2x", &j))
387 errmsg = "Expected 16-digit iv in DEK-Info";
395 while (isbase64(*p)) {
396 base64_bit[base64_chars++] = *p;
397 if (base64_chars == 4) {
398 unsigned char out[3];
403 len = base64_decode_atom(base64_bit, out);
406 errmsg = "Invalid base64 encoding";
410 if (ret->keyblob_len + len > ret->keyblob_size) {
411 ret->keyblob_size = ret->keyblob_len + len + 256;
412 ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size);
415 memcpy(ret->keyblob + ret->keyblob_len, out, len);
416 ret->keyblob_len += len;
418 memset(out, 0, sizeof(out));
426 if (ret->keyblob_len == 0 || !ret->keyblob) {
427 errmsg = "Key body not present";
431 if (ret->encrypted && ret->keyblob_len % 8 != 0) {
432 errmsg = "Encrypted key blob is not a multiple of cipher block size";
436 memset(buffer, 0, sizeof(buffer));
437 memset(base64_bit, 0, sizeof(base64_bit));
441 memset(buffer, 0, sizeof(buffer));
442 memset(base64_bit, 0, sizeof(base64_bit));
445 memset(ret->keyblob, 0, ret->keyblob_size);
448 memset(&ret, 0, sizeof(ret));
454 int openssh_encrypted(char *filename)
456 struct openssh_key *key = load_openssh_key(filename);
461 ret = key->encrypted;
462 memset(key->keyblob, 0, key->keyblob_size);
464 memset(&key, 0, sizeof(key));
469 struct ssh2_userkey *openssh_read(char *filename, char *passphrase)
471 struct openssh_key *key = load_openssh_key(filename);
472 struct ssh2_userkey *retkey;
474 int ret, id, len, flags;
476 struct ssh2_userkey *retval = NULL;
479 int blobsize, blobptr, privptr;
488 if (key->encrypted) {
490 * Derive encryption key from passphrase and iv/salt:
492 * - let block A equal MD5(passphrase || iv)
493 * - let block B equal MD5(A || passphrase || iv)
494 * - block C would be MD5(B || passphrase || iv) and so on
495 * - encryption key is the first N bytes of A || B
497 struct MD5Context md5c;
498 unsigned char keybuf[32];
501 MD5Update(&md5c, passphrase, strlen(passphrase));
502 MD5Update(&md5c, key->iv, 8);
503 MD5Final(keybuf, &md5c);
506 MD5Update(&md5c, keybuf, 16);
507 MD5Update(&md5c, passphrase, strlen(passphrase));
508 MD5Update(&md5c, key->iv, 8);
509 MD5Final(keybuf+16, &md5c);
512 * Now decrypt the key blob.
514 des3_decrypt_pubkey_ossh(keybuf, key->iv,
515 key->keyblob, key->keyblob_len);
517 memset(&md5c, 0, sizeof(md5c));
518 memset(keybuf, 0, sizeof(keybuf));
522 * Now we have a decrypted key blob, which contains an ASN.1
523 * encoded private key. We must now untangle the ASN.1.
525 * We expect the whole key blob to be formatted as a SEQUENCE
526 * (0x30 followed by a length code indicating that the rest of
527 * the blob is part of the sequence). Within that SEQUENCE we
528 * expect to see a bunch of INTEGERs. What those integers mean
529 * depends on the key type:
531 * - For RSA, we expect the integers to be 0, n, e, d, p, q,
532 * dmp1, dmq1, iqmp in that order. (The last three are d mod
533 * (p-1), d mod (q-1), inverse of q mod p respectively.)
535 * - For DSA, we expect them to be 0, p, q, g, y, x in that
541 /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */
542 ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
544 if (ret < 0 || id != 16) {
545 errmsg = "ASN.1 decoding failure";
546 retval = SSH2_WRONG_PASSPHRASE;
550 /* Expect a load of INTEGERs. */
551 if (key->type == OSSH_RSA)
553 else if (key->type == OSSH_DSA)
557 * Space to create key blob in.
559 blobsize = 256+key->keyblob_len;
560 blob = smalloc(blobsize);
562 if (key->type == OSSH_DSA)
563 memcpy(blob+4, "ssh-dss", 7);
564 else if (key->type == OSSH_RSA)
565 memcpy(blob+4, "ssh-rsa", 7);
569 for (i = 0; i < num_integers; i++) {
570 ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
573 if (ret < 0 || id != 2 ||
574 key->keyblob+key->keyblob_len-p < len) {
575 errmsg = "ASN.1 decoding failure";
581 * The first integer should be zero always (I think
582 * this is some sort of version indication).
584 if (len != 1 || p[0] != 0) {
585 errmsg = "Version number mismatch";
588 } else if (key->type == OSSH_RSA) {
590 * Integers 1 and 2 go into the public blob but in the
591 * opposite order; integers 3, 4, 5 and 8 go into the
592 * private blob. The other two (6 and 7) are ignored.
595 /* Save the details for after we deal with number 2. */
598 } else if (i != 6 && i != 7) {
599 PUT_32BIT(blob+blobptr, len);
600 memcpy(blob+blobptr+4, p, len);
603 PUT_32BIT(blob+blobptr, modlen);
604 memcpy(blob+blobptr+4, modptr, modlen);
609 } else if (key->type == OSSH_DSA) {
611 * Integers 1-4 go into the public blob; integer 5 goes
612 * into the private blob.
614 PUT_32BIT(blob+blobptr, len);
615 memcpy(blob+blobptr+4, p, len);
621 /* Skip past the number. */
626 * Now put together the actual key. Simplest way to do this is
627 * to assemble our own key blobs and feed them to the createkey
628 * functions; this is a bit faffy but it does mean we get all
629 * the sanity checks for free.
631 assert(privptr > 0); /* should have bombed by now if not */
632 retkey = smalloc(sizeof(struct ssh2_userkey));
633 retkey->alg = (key->type == OSSH_RSA ? &ssh_rsa : &ssh_dss);
634 retkey->data = retkey->alg->createkey(blob, privptr,
635 blob+privptr, blobptr-privptr);
638 errmsg = "unable to create key data structure";
642 retkey->comment = dupstr("imported-openssh-key");
643 errmsg = NULL; /* no error */
648 memset(blob, 0, blobsize);
651 memset(key->keyblob, 0, key->keyblob_size);
653 memset(&key, 0, sizeof(key));
658 int openssh_write(char *filename, struct ssh2_userkey *key, char *passphrase)
660 unsigned char *pubblob, *privblob, *spareblob;
661 int publen, privlen, sparelen;
662 unsigned char *outblob;
664 struct mpint_pos numbers[9];
665 int nnumbers, pos, len, seqlen, i;
666 char *header, *footer;
673 * Fetch the key blobs.
675 pubblob = key->alg->public_blob(key->data, &publen);
676 privblob = key->alg->private_blob(key->data, &privlen);
677 spareblob = outblob = NULL;
680 * Find the sequence of integers to be encoded into the OpenSSH
681 * key blob, and also decide on the header line.
683 if (key->alg == &ssh_rsa) {
685 struct mpint_pos n, e, d, p, q, iqmp, dmp1, dmq1;
686 Bignum bd, bp, bq, bdmp1, bdmq1;
688 pos = 4 + GET_32BIT(pubblob);
689 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
690 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
692 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
693 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
694 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
695 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
697 assert(e.start && iqmp.start); /* can't go wrong */
699 /* We also need d mod (p-1) and d mod (q-1). */
700 bd = bignum_from_bytes(d.start, d.bytes);
701 bp = bignum_from_bytes(p.start, p.bytes);
702 bq = bignum_from_bytes(q.start, q.bytes);
705 bdmp1 = bigmod(bd, bp);
706 bdmq1 = bigmod(bd, bq);
711 dmp1.bytes = (bignum_bitcount(bdmp1)+8)/8;
712 dmq1.bytes = (bignum_bitcount(bdmq1)+8)/8;
713 sparelen = dmp1.bytes + dmq1.bytes;
714 spareblob = smalloc(sparelen);
715 dmp1.start = spareblob;
716 dmq1.start = spareblob + dmp1.bytes;
717 for (i = 0; i < dmp1.bytes; i++)
718 spareblob[i] = bignum_byte(bdmp1, dmp1.bytes-1 - i);
719 for (i = 0; i < dmq1.bytes; i++)
720 spareblob[i+dmp1.bytes] = bignum_byte(bdmq1, dmq1.bytes-1 - i);
724 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
735 header = "-----BEGIN RSA PRIVATE KEY-----\n";
736 footer = "-----END RSA PRIVATE KEY-----\n";
737 } else if (key->alg == &ssh_dss) {
739 struct mpint_pos p, q, g, y, x;
741 pos = 4 + GET_32BIT(pubblob);
742 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
743 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
744 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
745 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
747 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
749 assert(y.start && x.start); /* can't go wrong */
751 numbers[0].start = zero; numbers[0].bytes = 1; zero[0] = '\0';
759 header = "-----BEGIN DSA PRIVATE KEY-----\n";
760 footer = "-----END DSA PRIVATE KEY-----\n";
762 assert(0); /* zoinks! */
766 * Now count up the total size of the ASN.1 encoded integers,
767 * so as to determine the length of the containing SEQUENCE.
770 for (i = 0; i < nnumbers; i++) {
771 len += ber_write_id_len(NULL, 2, numbers[i].bytes, 0);
772 len += numbers[i].bytes;
775 /* Now add on the SEQUENCE header. */
776 len += ber_write_id_len(NULL, 16, seqlen, ASN1_CONSTRUCTED);
777 /* Round up to the cipher block size, ensuring we have at least one
778 * byte of padding (see below). */
781 outlen = (outlen+8) &~ 7;
784 * Now we know how big outblob needs to be. Allocate it.
786 outblob = smalloc(outlen);
789 * And write the data into it.
792 pos += ber_write_id_len(outblob+pos, 16, seqlen, ASN1_CONSTRUCTED);
793 for (i = 0; i < nnumbers; i++) {
794 pos += ber_write_id_len(outblob+pos, 2, numbers[i].bytes, 0);
795 memcpy(outblob+pos, numbers[i].start, numbers[i].bytes);
796 pos += numbers[i].bytes;
800 * Padding on OpenSSH keys is deterministic. The number of
801 * padding bytes is always more than zero, and always at most
802 * the cipher block length. The value of each padding byte is
803 * equal to the number of padding bytes. So a plaintext that's
804 * an exact multiple of the block size will be padded with 08
805 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
806 * plaintext one byte less than a multiple of the block size
807 * will be padded with just 01.
809 * This enables the OpenSSL key decryption function to strip
810 * off the padding algorithmically and return the unpadded
811 * plaintext to the next layer: it looks at the final byte, and
812 * then expects to find that many bytes at the end of the data
813 * with the same value. Those are all removed and the rest is
817 while (pos < outlen) {
818 outblob[pos++] = outlen - len;
826 * Invent an iv. Then derive encryption key from passphrase
829 * - let block A equal MD5(passphrase || iv)
830 * - let block B equal MD5(A || passphrase || iv)
831 * - block C would be MD5(B || passphrase || iv) and so on
832 * - encryption key is the first N bytes of A || B
834 struct MD5Context md5c;
835 unsigned char keybuf[32];
837 for (i = 0; i < 8; i++) iv[i] = random_byte();
840 MD5Update(&md5c, passphrase, strlen(passphrase));
841 MD5Update(&md5c, iv, 8);
842 MD5Final(keybuf, &md5c);
845 MD5Update(&md5c, keybuf, 16);
846 MD5Update(&md5c, passphrase, strlen(passphrase));
847 MD5Update(&md5c, iv, 8);
848 MD5Final(keybuf+16, &md5c);
851 * Now encrypt the key blob.
853 des3_encrypt_pubkey_ossh(keybuf, iv, outblob, outlen);
855 memset(&md5c, 0, sizeof(md5c));
856 memset(keybuf, 0, sizeof(keybuf));
860 * And save it. We'll use Unix line endings just in case it's
861 * subsequently transferred in binary mode.
863 fp = fopen(filename, "wb"); /* ensure Unix line endings */
868 fprintf(fp, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
869 for (i = 0; i < 8; i++)
870 fprintf(fp, "%02X", iv[i]);
873 base64_encode(fp, outblob, outlen, 64);
880 memset(outblob, 0, outlen);
884 memset(spareblob, 0, sparelen);
888 memset(privblob, 0, privlen);
892 memset(pubblob, 0, publen);
898 /* ----------------------------------------------------------------------
899 * Code to read ssh.com private keys.
903 * The format of the base64 blob is largely ssh2-packet-formatted,
904 * except that mpints are a bit different: they're more like the
905 * old ssh1 mpint. You have a 32-bit bit count N, followed by
906 * (N+7)/8 bytes of data.
908 * So. The blob contains:
910 * - uint32 0x3f6ff9eb (magic number)
911 * - uint32 size (total blob size)
912 * - string key-type (see below)
913 * - string cipher-type (tells you if key is encrypted)
914 * - string encrypted-blob
916 * (The first size field includes the size field itself and the
917 * magic number before it. All other size fields are ordinary ssh2
918 * strings, so the size field indicates how much data is to
921 * The encrypted blob, once decrypted, contains a single string
922 * which in turn contains the payload. (This allows padding to be
923 * added after that string while still making it clear where the
924 * real payload ends. Also it probably makes for a reasonable
927 * The payload blob, for an RSA key, contains:
930 * - mpint n (yes, the public and private stuff is intermixed)
931 * - mpint u (presumably inverse of p mod q)
932 * - mpint p (p is the smaller prime)
933 * - mpint q (q is the larger)
935 * For a DSA key, the payload blob contains:
943 * Alternatively, if the parameters are `predefined', that
944 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
945 * containing some predefined parameter specification. *shudder*,
946 * but I doubt we'll encounter this in real life.
948 * The key type strings are ghastly. The RSA key I looked at had a
951 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
953 * and the DSA key wasn't much better:
955 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
957 * It isn't clear that these will always be the same. I think it
958 * might be wise just to look at the `if-modn{sign{rsa' and
959 * `dl-modp{sign{dsa' prefixes.
961 * Finally, the encryption. The cipher-type string appears to be
962 * either `none' or `3des-cbc'. Looks as if this is SSH2-style
963 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
964 * from the passphrase by means of yet another hashing faff:
966 * - first 16 bytes are MD5(passphrase)
967 * - next 16 bytes are MD5(passphrase || first 16 bytes)
968 * - if there were more, they'd be MD5(passphrase || first 32),
972 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
975 char comment[256]; /* allowing any length is overkill */
976 unsigned char *keyblob;
977 int keyblob_len, keyblob_size;
980 struct sshcom_key *load_sshcom_key(char *filename)
982 struct sshcom_key *ret;
989 int base64_chars = 0;
991 ret = smalloc(sizeof(*ret));
992 ret->comment[0] = '\0';
994 ret->keyblob_len = ret->keyblob_size = 0;
996 fp = fopen(filename, "r");
998 errmsg = "Unable to open key file";
1001 if (!fgets(buffer, sizeof(buffer), fp) ||
1002 0 != strcmp(buffer, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n")) {
1003 errmsg = "File does not begin with ssh.com key header";
1009 if (!fgets(buffer, sizeof(buffer), fp)) {
1010 errmsg = "Unexpected end of file";
1013 if (!strcmp(buffer, "---- END SSH2 ENCRYPTED PRIVATE KEY ----\n"))
1015 if ((p = strchr(buffer, ':')) != NULL) {
1017 errmsg = "Header found in body of key data";
1021 while (*p && isspace((unsigned char)*p)) p++;
1023 * Header lines can end in a trailing backslash for
1026 while ((len = strlen(p)) > (int)(sizeof(buffer) - (p-buffer) -1) ||
1027 p[len-1] != '\n' || p[len-2] == '\\') {
1028 if (len > (int)((p-buffer) + sizeof(buffer)-2)) {
1029 errmsg = "Header line too long to deal with";
1032 if (!fgets(p+len-2, sizeof(buffer)-(p-buffer)-(len-2), fp)) {
1033 errmsg = "Unexpected end of file";
1037 p[strcspn(p, "\n")] = '\0';
1038 if (!strcmp(buffer, "Comment")) {
1039 /* Strip quotes in comment if present. */
1040 if (p[0] == '"' && p[strlen(p)-1] == '"') {
1042 p[strlen(p)-1] = '\0';
1044 strncpy(ret->comment, p, sizeof(ret->comment));
1045 ret->comment[sizeof(ret->comment)-1] = '\0';
1051 while (isbase64(*p)) {
1052 base64_bit[base64_chars++] = *p;
1053 if (base64_chars == 4) {
1054 unsigned char out[3];
1058 len = base64_decode_atom(base64_bit, out);
1061 errmsg = "Invalid base64 encoding";
1065 if (ret->keyblob_len + len > ret->keyblob_size) {
1066 ret->keyblob_size = ret->keyblob_len + len + 256;
1067 ret->keyblob = srealloc(ret->keyblob, ret->keyblob_size);
1070 memcpy(ret->keyblob + ret->keyblob_len, out, len);
1071 ret->keyblob_len += len;
1079 if (ret->keyblob_len == 0 || !ret->keyblob) {
1080 errmsg = "Key body not present";
1089 memset(ret->keyblob, 0, ret->keyblob_size);
1090 sfree(ret->keyblob);
1092 memset(&ret, 0, sizeof(ret));
1098 int sshcom_encrypted(char *filename, char **comment)
1100 struct sshcom_key *key = load_sshcom_key(filename);
1101 int pos, len, answer;
1108 * Check magic number.
1110 if (GET_32BIT(key->keyblob) != 0x3f6ff9eb)
1111 return 0; /* key is invalid */
1114 * Find the cipher-type string.
1118 if (key->keyblob_len < pos+4)
1119 goto done; /* key is far too short */
1120 pos += 4 + GET_32BIT(key->keyblob + pos); /* skip key type */
1121 if (key->keyblob_len < pos+4)
1122 goto done; /* key is far too short */
1123 len = GET_32BIT(key->keyblob + pos); /* find cipher-type length */
1124 if (key->keyblob_len < pos+4+len)
1125 goto done; /* cipher type string is incomplete */
1126 if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
1130 *comment = dupstr(key->comment);
1131 memset(key->keyblob, 0, key->keyblob_size);
1132 sfree(key->keyblob);
1133 memset(&key, 0, sizeof(key));
1138 int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
1142 unsigned char *d = (unsigned char *) data;
1146 bits = GET_32BIT(d);
1148 bytes = (bits + 7) / 8;
1159 return len; /* ensure further calls fail as well */
1162 static int sshcom_put_mpint(void *target, void *data, int len)
1164 unsigned char *d = (unsigned char *)target;
1165 unsigned char *i = (unsigned char *)data;
1166 int bits = len * 8 - 1;
1169 if (*i & (1 << (bits & 7)))
1175 PUT_32BIT(d, bits+1);
1176 memcpy(d+4, i, len);
1180 struct ssh2_userkey *sshcom_read(char *filename, char *passphrase)
1182 struct sshcom_key *key = load_sshcom_key(filename);
1185 const char prefix_rsa[] = "if-modn{sign{rsa";
1186 const char prefix_dsa[] = "dl-modp{sign{dsa";
1187 enum { RSA, DSA } type;
1191 struct ssh2_userkey *ret = NULL, *retkey;
1192 const struct ssh_signkey *alg;
1193 unsigned char *blob = NULL;
1194 int blobsize, publen, privlen;
1200 * Check magic number.
1202 if (GET_32BIT(key->keyblob) != SSHCOM_MAGIC_NUMBER) {
1203 errmsg = "Key does not begin with magic number";
1208 * Determine the key type.
1211 if (key->keyblob_len < pos+4 ||
1212 (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) {
1213 errmsg = "Key blob does not contain a key type string";
1216 if (len > sizeof(prefix_rsa) - 1 &&
1217 !memcmp(key->keyblob+pos+4, prefix_rsa, sizeof(prefix_rsa) - 1)) {
1219 } else if (len > sizeof(prefix_dsa) - 1 &&
1220 !memcmp(key->keyblob+pos+4, prefix_dsa, sizeof(prefix_dsa) - 1)) {
1223 errmsg = "Key is of unknown type";
1229 * Determine the cipher type.
1231 if (key->keyblob_len < pos+4 ||
1232 (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) {
1233 errmsg = "Key blob does not contain a cipher type string";
1236 if (len == 4 && !memcmp(key->keyblob+pos+4, "none", 4))
1238 else if (len == 8 && !memcmp(key->keyblob+pos+4, "3des-cbc", 8))
1241 errmsg = "Key encryption is of unknown type";
1247 * Get hold of the encrypted part of the key.
1249 if (key->keyblob_len < pos+4 ||
1250 (len = GET_32BIT(key->keyblob + pos)) > key->keyblob_len - pos - 4) {
1251 errmsg = "Key blob does not contain actual key data";
1254 ciphertext = key->keyblob + pos + 4;
1256 if (cipherlen == 0) {
1257 errmsg = "Length of key data is zero";
1262 * Decrypt it if necessary.
1266 * Derive encryption key from passphrase and iv/salt:
1268 * - let block A equal MD5(passphrase)
1269 * - let block B equal MD5(passphrase || A)
1270 * - block C would be MD5(passphrase || A || B) and so on
1271 * - encryption key is the first N bytes of A || B
1273 struct MD5Context md5c;
1274 unsigned char keybuf[32], iv[8];
1276 if (cipherlen % 8 != 0) {
1277 errmsg = "Encrypted part of key is not a multiple of cipher block"
1283 MD5Update(&md5c, passphrase, strlen(passphrase));
1284 MD5Final(keybuf, &md5c);
1287 MD5Update(&md5c, passphrase, strlen(passphrase));
1288 MD5Update(&md5c, keybuf, 16);
1289 MD5Final(keybuf+16, &md5c);
1292 * Now decrypt the key blob.
1294 memset(iv, 0, sizeof(iv));
1295 des3_decrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen);
1297 memset(&md5c, 0, sizeof(md5c));
1298 memset(keybuf, 0, sizeof(keybuf));
1301 * Hereafter we return WRONG_PASSPHRASE for any parsing
1302 * error. (But only if we've just tried to decrypt it!
1303 * Returning WRONG_PASSPHRASE for an unencrypted key is
1307 ret = SSH2_WRONG_PASSPHRASE;
1311 * Strip away the containing string to get to the real meat.
1313 len = GET_32BIT(ciphertext);
1314 if (len > cipherlen-4) {
1315 errmsg = "containing string was ill-formed";
1322 * Now we break down into RSA versus DSA. In either case we'll
1323 * construct public and private blobs in our own format, and
1324 * end up feeding them to alg->createkey().
1326 blobsize = cipherlen + 256;
1327 blob = smalloc(blobsize);
1330 struct mpint_pos n, e, d, u, p, q;
1332 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &e);
1333 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &d);
1334 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &n);
1335 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &u);
1336 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
1337 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
1339 errmsg = "key data did not contain six integers";
1345 pos += put_string(blob+pos, "ssh-rsa", 7);
1346 pos += put_mp(blob+pos, e.start, e.bytes);
1347 pos += put_mp(blob+pos, n.start, n.bytes);
1349 pos += put_string(blob+pos, d.start, d.bytes);
1350 pos += put_mp(blob+pos, q.start, q.bytes);
1351 pos += put_mp(blob+pos, p.start, p.bytes);
1352 pos += put_mp(blob+pos, u.start, u.bytes);
1353 privlen = pos - publen;
1354 } else if (type == DSA) {
1355 struct mpint_pos p, q, g, x, y;
1357 if (GET_32BIT(ciphertext) != 0) {
1358 errmsg = "predefined DSA parameters not supported";
1361 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &p);
1362 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &g);
1363 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &q);
1364 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &y);
1365 pos += sshcom_read_mpint(ciphertext+pos, cipherlen-pos, &x);
1367 errmsg = "key data did not contain five integers";
1373 pos += put_string(blob+pos, "ssh-dss", 7);
1374 pos += put_mp(blob+pos, p.start, p.bytes);
1375 pos += put_mp(blob+pos, q.start, q.bytes);
1376 pos += put_mp(blob+pos, g.start, g.bytes);
1377 pos += put_mp(blob+pos, y.start, y.bytes);
1379 pos += put_mp(blob+pos, x.start, x.bytes);
1380 privlen = pos - publen;
1383 assert(privlen > 0); /* should have bombed by now if not */
1385 retkey = smalloc(sizeof(struct ssh2_userkey));
1387 retkey->data = alg->createkey(blob, publen, blob+publen, privlen);
1388 if (!retkey->data) {
1390 errmsg = "unable to create key data structure";
1393 retkey->comment = dupstr(key->comment);
1395 errmsg = NULL; /* no error */
1400 memset(blob, 0, blobsize);
1403 memset(key->keyblob, 0, key->keyblob_size);
1404 sfree(key->keyblob);
1405 memset(&key, 0, sizeof(key));
1410 int sshcom_write(char *filename, struct ssh2_userkey *key, char *passphrase)
1412 unsigned char *pubblob, *privblob;
1413 int publen, privlen;
1414 unsigned char *outblob;
1416 struct mpint_pos numbers[6];
1417 int nnumbers, initial_zero, pos, lenpos, i;
1425 * Fetch the key blobs.
1427 pubblob = key->alg->public_blob(key->data, &publen);
1428 privblob = key->alg->private_blob(key->data, &privlen);
1432 * Find the sequence of integers to be encoded into the OpenSSH
1433 * key blob, and also decide on the header line.
1435 if (key->alg == &ssh_rsa) {
1437 struct mpint_pos n, e, d, p, q, iqmp;
1439 pos = 4 + GET_32BIT(pubblob);
1440 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &e);
1441 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &n);
1443 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &d);
1444 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &p);
1445 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &q);
1446 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &iqmp);
1448 assert(e.start && iqmp.start); /* can't go wrong */
1459 type = "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
1460 } else if (key->alg == &ssh_dss) {
1462 struct mpint_pos p, q, g, y, x;
1464 pos = 4 + GET_32BIT(pubblob);
1465 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &p);
1466 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &q);
1467 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &g);
1468 pos += ssh2_read_mpint(pubblob+pos, publen-pos, &y);
1470 pos += ssh2_read_mpint(privblob+pos, privlen-pos, &x);
1472 assert(y.start && x.start); /* can't go wrong */
1482 type = "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
1484 assert(0); /* zoinks! */
1488 * Total size of key blob will be somewhere under 512 plus
1489 * combined length of integers. We'll calculate the more
1490 * precise size as we construct the blob.
1493 for (i = 0; i < nnumbers; i++)
1494 outlen += 4 + numbers[i].bytes;
1495 outblob = smalloc(outlen);
1498 * Create the unencrypted key blob.
1501 PUT_32BIT(outblob+pos, SSHCOM_MAGIC_NUMBER); pos += 4;
1502 pos += 4; /* length field, fill in later */
1503 pos += put_string(outblob+pos, type, strlen(type));
1505 char *ciphertype = passphrase ? "3des-cbc" : "none";
1506 pos += put_string(outblob+pos, ciphertype, strlen(ciphertype));
1508 lenpos = pos; /* remember this position */
1509 pos += 4; /* encrypted-blob size */
1510 pos += 4; /* encrypted-payload size */
1512 PUT_32BIT(outblob+pos, 0);
1515 for (i = 0; i < nnumbers; i++)
1516 pos += sshcom_put_mpint(outblob+pos,
1517 numbers[i].start, numbers[i].bytes);
1518 /* Now wrap up the encrypted payload. */
1519 PUT_32BIT(outblob+lenpos+4, pos - (lenpos+8));
1520 /* Pad encrypted blob to a multiple of cipher block size. */
1522 int padding = -(pos - (lenpos+4)) & 7;
1524 outblob[pos++] = random_byte();
1526 ciphertext = outblob+lenpos+4;
1527 cipherlen = pos - (lenpos+4);
1528 assert(!passphrase || cipherlen % 8 == 0);
1529 /* Wrap up the encrypted blob string. */
1530 PUT_32BIT(outblob+lenpos, cipherlen);
1531 /* And finally fill in the total length field. */
1532 PUT_32BIT(outblob+4, pos);
1534 assert(pos < outlen);
1541 * Derive encryption key from passphrase and iv/salt:
1543 * - let block A equal MD5(passphrase)
1544 * - let block B equal MD5(passphrase || A)
1545 * - block C would be MD5(passphrase || A || B) and so on
1546 * - encryption key is the first N bytes of A || B
1548 struct MD5Context md5c;
1549 unsigned char keybuf[32], iv[8];
1552 MD5Update(&md5c, passphrase, strlen(passphrase));
1553 MD5Final(keybuf, &md5c);
1556 MD5Update(&md5c, passphrase, strlen(passphrase));
1557 MD5Update(&md5c, keybuf, 16);
1558 MD5Final(keybuf+16, &md5c);
1561 * Now decrypt the key blob.
1563 memset(iv, 0, sizeof(iv));
1564 des3_encrypt_pubkey_ossh(keybuf, iv, ciphertext, cipherlen);
1566 memset(&md5c, 0, sizeof(md5c));
1567 memset(keybuf, 0, sizeof(keybuf));
1571 * And save it. We'll use Unix line endings just in case it's
1572 * subsequently transferred in binary mode.
1574 fp = fopen(filename, "wb"); /* ensure Unix line endings */
1577 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
1578 fprintf(fp, "Comment: \"");
1580 * Comment header is broken with backslash-newline if it goes
1581 * over 70 chars. Although it's surrounded by quotes, it
1582 * _doesn't_ escape backslashes or quotes within the string.
1583 * Don't ask me, I didn't design it.
1586 int slen = 60; /* starts at 60 due to "Comment: " */
1587 char *c = key->comment;
1588 while ((int)strlen(c) > slen) {
1589 fprintf(fp, "%.*s\\\n", slen, c);
1591 slen = 70; /* allow 70 chars on subsequent lines */
1593 fprintf(fp, "%s\"\n", c);
1595 base64_encode(fp, outblob, pos, 70);
1596 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp);
1602 memset(outblob, 0, outlen);
1606 memset(privblob, 0, privlen);
1610 memset(pubblob, 0, publen);