2 * Code for PuTTY to import and export private key files in other
3 * SSH clients' formats.
15 int openssh_encrypted(const Filename
*filename
);
16 struct ssh2_userkey
*openssh_read(const Filename
*filename
, char *passphrase
,
17 const char **errmsg_p
);
18 int openssh_write(const Filename
*filename
, struct ssh2_userkey
*key
,
21 int sshcom_encrypted(const Filename
*filename
, char **comment
);
22 struct ssh2_userkey
*sshcom_read(const Filename
*filename
, char *passphrase
,
23 const char **errmsg_p
);
24 int sshcom_write(const Filename
*filename
, struct ssh2_userkey
*key
,
28 * Given a key type, determine whether we know how to import it.
30 int import_possible(int type
)
32 if (type
== SSH_KEYTYPE_OPENSSH
)
34 if (type
== SSH_KEYTYPE_SSHCOM
)
40 * Given a key type, determine what native key type
41 * (SSH_KEYTYPE_SSH1 or SSH_KEYTYPE_SSH2) it will come out as once
44 int import_target_type(int type
)
47 * There are no known foreign SSH-1 key formats.
49 return SSH_KEYTYPE_SSH2
;
53 * Determine whether a foreign key is encrypted.
55 int import_encrypted(const Filename
*filename
, int type
, char **comment
)
57 if (type
== SSH_KEYTYPE_OPENSSH
) {
58 /* OpenSSH doesn't do key comments */
59 *comment
= dupstr(filename_to_str(filename
));
60 return openssh_encrypted(filename
);
62 if (type
== SSH_KEYTYPE_SSHCOM
) {
63 return sshcom_encrypted(filename
, comment
);
69 * Import an SSH-1 key.
71 int import_ssh1(const Filename
*filename
, int type
,
72 struct RSAKey
*key
, char *passphrase
, const char **errmsg_p
)
78 * Import an SSH-2 key.
80 struct ssh2_userkey
*import_ssh2(const Filename
*filename
, int type
,
81 char *passphrase
, const char **errmsg_p
)
83 if (type
== SSH_KEYTYPE_OPENSSH
)
84 return openssh_read(filename
, passphrase
, errmsg_p
);
85 if (type
== SSH_KEYTYPE_SSHCOM
)
86 return sshcom_read(filename
, passphrase
, errmsg_p
);
91 * Export an SSH-1 key.
93 int export_ssh1(const Filename
*filename
, int type
, struct RSAKey
*key
,
100 * Export an SSH-2 key.
102 int export_ssh2(const Filename
*filename
, int type
,
103 struct ssh2_userkey
*key
, char *passphrase
)
105 if (type
== SSH_KEYTYPE_OPENSSH
)
106 return openssh_write(filename
, key
, passphrase
);
107 if (type
== SSH_KEYTYPE_SSHCOM
)
108 return sshcom_write(filename
, key
, passphrase
);
113 * Strip trailing CRs and LFs at the end of a line of text.
115 void strip_crlf(char *str
)
117 char *p
= str
+ strlen(str
);
119 while (p
> str
&& (p
[-1] == '\r' || p
[-1] == '\n'))
123 /* ----------------------------------------------------------------------
124 * Helper routines. (The base64 ones are defined in sshpubk.c.)
127 #define isbase64(c) ( ((c) >= 'A' && (c) <= 'Z') || \
128 ((c) >= 'a' && (c) <= 'z') || \
129 ((c) >= '0' && (c) <= '9') || \
130 (c) == '+' || (c) == '/' || (c) == '=' \
134 * Read an ASN.1/BER identifier and length pair.
136 * Flags are a combination of the #defines listed below.
138 * Returns -1 if unsuccessful; otherwise returns the number of
139 * bytes used out of the source data.
142 /* ASN.1 tag classes. */
143 #define ASN1_CLASS_UNIVERSAL (0 << 6)
144 #define ASN1_CLASS_APPLICATION (1 << 6)
145 #define ASN1_CLASS_CONTEXT_SPECIFIC (2 << 6)
146 #define ASN1_CLASS_PRIVATE (3 << 6)
147 #define ASN1_CLASS_MASK (3 << 6)
149 /* Primitive versus constructed bit. */
150 #define ASN1_CONSTRUCTED (1 << 5)
152 static int ber_read_id_len(void *source
, int sourcelen
,
153 int *id
, int *length
, int *flags
)
155 unsigned char *p
= (unsigned char *) source
;
160 *flags
= (*p
& 0xE0);
161 if ((*p
& 0x1F) == 0x1F) {
167 *id
= (*id
<< 7) | (*p
& 0x7F);
185 *length
= (*length
<< 8) | (*p
++);
192 return p
- (unsigned char *) source
;
196 * Write an ASN.1/BER identifier and length pair. Returns the
197 * number of bytes consumed. Assumes dest contains enough space.
198 * Will avoid writing anything if dest is NULL, but still return
199 * amount of space required.
201 static int ber_write_id_len(void *dest
, int id
, int length
, int flags
)
203 unsigned char *d
= (unsigned char *)dest
;
208 * Identifier is one byte.
211 if (d
) *d
++ = id
| flags
;
215 * Identifier is multiple bytes: the first byte is 11111
216 * plus the flags, and subsequent bytes encode the value of
217 * the identifier, 7 bits at a time, with the top bit of
218 * each byte 1 except the last one which is 0.
221 if (d
) *d
++ = 0x1F | flags
;
222 for (n
= 1; (id
>> (7*n
)) > 0; n
++)
223 continue; /* count the bytes */
226 if (d
) *d
++ = (n ?
0x80 : 0) | ((id
>> (7*n
)) & 0x7F);
232 * Length is one byte.
235 if (d
) *d
++ = length
;
239 * Length is multiple bytes. The first is 0x80 plus the
240 * number of subsequent bytes, and the subsequent bytes
241 * encode the actual length.
243 for (n
= 1; (length
>> (8*n
)) > 0; n
++)
244 continue; /* count the bytes */
246 if (d
) *d
++ = 0x80 | n
;
249 if (d
) *d
++ = (length
>> (8*n
)) & 0xFF;
256 static int put_string(void *target
, void *data
, int len
)
258 unsigned char *d
= (unsigned char *)target
;
261 memcpy(d
+4, data
, len
);
265 static int put_mp(void *target
, void *data
, int len
)
267 unsigned char *d
= (unsigned char *)target
;
268 unsigned char *i
= (unsigned char *)data
;
273 memcpy(d
+5, data
, len
);
277 memcpy(d
+4, data
, len
);
282 /* Simple structure to point to an mp-int within a blob. */
283 struct mpint_pos
{ void *start
; int bytes
; };
285 static int ssh2_read_mpint(void *data
, int len
, struct mpint_pos
*ret
)
288 unsigned char *d
= (unsigned char *) data
;
292 bytes
= GET_32BIT(d
);
303 return len
; /* ensure further calls fail as well */
306 /* ----------------------------------------------------------------------
307 * Code to read and write OpenSSH private keys.
310 enum { OSSH_DSA
, OSSH_RSA
};
311 enum { OSSH_ENC_3DES
, OSSH_ENC_AES
};
314 int encrypted
, encryption
;
316 unsigned char *keyblob
;
317 int keyblob_len
, keyblob_size
;
320 static struct openssh_key
*load_openssh_key(const Filename
*filename
,
321 const char **errmsg_p
)
323 struct openssh_key
*ret
;
329 int base64_chars
= 0;
331 ret
= snew(struct openssh_key
);
333 ret
->keyblob_len
= ret
->keyblob_size
= 0;
335 memset(ret
->iv
, 0, sizeof(ret
->iv
));
337 fp
= f_open(filename
, "r", FALSE
);
339 errmsg
= "unable to open key file";
343 if (!(line
= fgetline(fp
))) {
344 errmsg
= "unexpected end of file";
348 if (0 != strncmp(line
, "-----BEGIN ", 11) ||
349 0 != strcmp(line
+strlen(line
)-16, "PRIVATE KEY-----")) {
350 errmsg
= "file does not begin with OpenSSH key header";
353 if (!strcmp(line
, "-----BEGIN RSA PRIVATE KEY-----"))
354 ret
->type
= OSSH_RSA
;
355 else if (!strcmp(line
, "-----BEGIN DSA PRIVATE KEY-----"))
356 ret
->type
= OSSH_DSA
;
358 errmsg
= "unrecognised key type";
361 smemclr(line
, strlen(line
));
367 if (!(line
= fgetline(fp
))) {
368 errmsg
= "unexpected end of file";
372 if (0 == strncmp(line
, "-----END ", 9) &&
373 0 == strcmp(line
+strlen(line
)-16, "PRIVATE KEY-----"))
375 if ((p
= strchr(line
, ':')) != NULL
) {
377 errmsg
= "header found in body of key data";
381 while (*p
&& isspace((unsigned char)*p
)) p
++;
382 if (!strcmp(line
, "Proc-Type")) {
383 if (p
[0] != '4' || p
[1] != ',') {
384 errmsg
= "Proc-Type is not 4 (only 4 is supported)";
388 if (!strcmp(p
, "ENCRYPTED"))
390 } else if (!strcmp(line
, "DEK-Info")) {
393 if (!strncmp(p
, "DES-EDE3-CBC,", 13)) {
394 ret
->encryption
= OSSH_ENC_3DES
;
396 } else if (!strncmp(p
, "AES-128-CBC,", 12)) {
397 ret
->encryption
= OSSH_ENC_AES
;
400 errmsg
= "unsupported cipher";
403 p
= strchr(p
, ',') + 1;/* always non-NULL, by above checks */
404 for (i
= 0; i
< ivlen
; i
++) {
405 if (1 != sscanf(p
, "%2x", &j
)) {
406 errmsg
= "expected more iv data in DEK-Info";
413 errmsg
= "more iv data than expected in DEK-Info";
421 while (isbase64(*p
)) {
422 base64_bit
[base64_chars
++] = *p
;
423 if (base64_chars
== 4) {
424 unsigned char out
[3];
429 len
= base64_decode_atom(base64_bit
, out
);
432 errmsg
= "invalid base64 encoding";
436 if (ret
->keyblob_len
+ len
> ret
->keyblob_size
) {
437 ret
->keyblob_size
= ret
->keyblob_len
+ len
+ 256;
438 ret
->keyblob
= sresize(ret
->keyblob
, ret
->keyblob_size
,
442 memcpy(ret
->keyblob
+ ret
->keyblob_len
, out
, len
);
443 ret
->keyblob_len
+= len
;
445 smemclr(out
, sizeof(out
));
451 smemclr(line
, strlen(line
));
459 if (ret
->keyblob_len
== 0 || !ret
->keyblob
) {
460 errmsg
= "key body not present";
464 if (ret
->encrypted
&& ret
->keyblob_len
% 8 != 0) {
465 errmsg
= "encrypted key blob is not a multiple of cipher block size";
469 smemclr(base64_bit
, sizeof(base64_bit
));
470 if (errmsg_p
) *errmsg_p
= NULL
;
475 smemclr(line
, strlen(line
));
479 smemclr(base64_bit
, sizeof(base64_bit
));
482 smemclr(ret
->keyblob
, ret
->keyblob_size
);
485 smemclr(ret
, sizeof(*ret
));
488 if (errmsg_p
) *errmsg_p
= errmsg
;
493 int openssh_encrypted(const Filename
*filename
)
495 struct openssh_key
*key
= load_openssh_key(filename
, NULL
);
500 ret
= key
->encrypted
;
501 smemclr(key
->keyblob
, key
->keyblob_size
);
503 smemclr(key
, sizeof(*key
));
508 struct ssh2_userkey
*openssh_read(const Filename
*filename
, char *passphrase
,
509 const char **errmsg_p
)
511 struct openssh_key
*key
= load_openssh_key(filename
, errmsg_p
);
512 struct ssh2_userkey
*retkey
;
514 int ret
, id
, len
, flags
;
516 struct ssh2_userkey
*retval
= NULL
;
519 int blobsize
= 0, blobptr
, privptr
;
528 if (key
->encrypted
) {
530 * Derive encryption key from passphrase and iv/salt:
532 * - let block A equal MD5(passphrase || iv)
533 * - let block B equal MD5(A || passphrase || iv)
534 * - block C would be MD5(B || passphrase || iv) and so on
535 * - encryption key is the first N bytes of A || B
537 * (Note that only 8 bytes of the iv are used for key
538 * derivation, even when the key is encrypted with AES and
539 * hence there are 16 bytes available.)
541 struct MD5Context md5c
;
542 unsigned char keybuf
[32];
545 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
546 MD5Update(&md5c
, (unsigned char *)key
->iv
, 8);
547 MD5Final(keybuf
, &md5c
);
550 MD5Update(&md5c
, keybuf
, 16);
551 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
552 MD5Update(&md5c
, (unsigned char *)key
->iv
, 8);
553 MD5Final(keybuf
+16, &md5c
);
556 * Now decrypt the key blob.
558 if (key
->encryption
== OSSH_ENC_3DES
)
559 des3_decrypt_pubkey_ossh(keybuf
, (unsigned char *)key
->iv
,
560 key
->keyblob
, key
->keyblob_len
);
563 assert(key
->encryption
== OSSH_ENC_AES
);
564 ctx
= aes_make_context();
565 aes128_key(ctx
, keybuf
);
566 aes_iv(ctx
, (unsigned char *)key
->iv
);
567 aes_ssh2_decrypt_blk(ctx
, key
->keyblob
, key
->keyblob_len
);
568 aes_free_context(ctx
);
571 smemclr(&md5c
, sizeof(md5c
));
572 smemclr(keybuf
, sizeof(keybuf
));
576 * Now we have a decrypted key blob, which contains an ASN.1
577 * encoded private key. We must now untangle the ASN.1.
579 * We expect the whole key blob to be formatted as a SEQUENCE
580 * (0x30 followed by a length code indicating that the rest of
581 * the blob is part of the sequence). Within that SEQUENCE we
582 * expect to see a bunch of INTEGERs. What those integers mean
583 * depends on the key type:
585 * - For RSA, we expect the integers to be 0, n, e, d, p, q,
586 * dmp1, dmq1, iqmp in that order. (The last three are d mod
587 * (p-1), d mod (q-1), inverse of q mod p respectively.)
589 * - For DSA, we expect them to be 0, p, q, g, y, x in that
595 /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */
596 ret
= ber_read_id_len(p
, key
->keyblob_len
, &id
, &len
, &flags
);
598 if (ret
< 0 || id
!= 16) {
599 errmsg
= "ASN.1 decoding failure";
600 retval
= SSH2_WRONG_PASSPHRASE
;
604 /* Expect a load of INTEGERs. */
605 if (key
->type
== OSSH_RSA
)
607 else if (key
->type
== OSSH_DSA
)
610 num_integers
= 0; /* placate compiler warnings */
613 * Space to create key blob in.
615 blobsize
= 256+key
->keyblob_len
;
616 blob
= snewn(blobsize
, unsigned char);
618 if (key
->type
== OSSH_DSA
)
619 memcpy(blob
+4, "ssh-dss", 7);
620 else if (key
->type
== OSSH_RSA
)
621 memcpy(blob
+4, "ssh-rsa", 7);
625 for (i
= 0; i
< num_integers
; i
++) {
626 ret
= ber_read_id_len(p
, key
->keyblob
+key
->keyblob_len
-p
,
629 if (ret
< 0 || id
!= 2 ||
630 key
->keyblob
+key
->keyblob_len
-p
< len
) {
631 errmsg
= "ASN.1 decoding failure";
632 retval
= SSH2_WRONG_PASSPHRASE
;
638 * The first integer should be zero always (I think
639 * this is some sort of version indication).
641 if (len
!= 1 || p
[0] != 0) {
642 errmsg
= "version number mismatch";
645 } else if (key
->type
== OSSH_RSA
) {
647 * Integers 1 and 2 go into the public blob but in the
648 * opposite order; integers 3, 4, 5 and 8 go into the
649 * private blob. The other two (6 and 7) are ignored.
652 /* Save the details for after we deal with number 2. */
655 } else if (i
!= 6 && i
!= 7) {
656 PUT_32BIT(blob
+blobptr
, len
);
657 memcpy(blob
+blobptr
+4, p
, len
);
660 PUT_32BIT(blob
+blobptr
, modlen
);
661 memcpy(blob
+blobptr
+4, modptr
, modlen
);
666 } else if (key
->type
== OSSH_DSA
) {
668 * Integers 1-4 go into the public blob; integer 5 goes
669 * into the private blob.
671 PUT_32BIT(blob
+blobptr
, len
);
672 memcpy(blob
+blobptr
+4, p
, len
);
678 /* Skip past the number. */
683 * Now put together the actual key. Simplest way to do this is
684 * to assemble our own key blobs and feed them to the createkey
685 * functions; this is a bit faffy but it does mean we get all
686 * the sanity checks for free.
688 assert(privptr
> 0); /* should have bombed by now if not */
689 retkey
= snew(struct ssh2_userkey
);
690 retkey
->alg
= (key
->type
== OSSH_RSA ?
&ssh_rsa
: &ssh_dss
);
691 retkey
->data
= retkey
->alg
->createkey(blob
, privptr
,
692 blob
+privptr
, blobptr
-privptr
);
695 errmsg
= "unable to create key data structure";
699 retkey
->comment
= dupstr("imported-openssh-key");
700 errmsg
= NULL
; /* no error */
705 smemclr(blob
, blobsize
);
708 smemclr(key
->keyblob
, key
->keyblob_size
);
710 smemclr(key
, sizeof(*key
));
712 if (errmsg_p
) *errmsg_p
= errmsg
;
716 int openssh_write(const Filename
*filename
, struct ssh2_userkey
*key
,
719 unsigned char *pubblob
, *privblob
, *spareblob
;
720 int publen
, privlen
, sparelen
= 0;
721 unsigned char *outblob
;
723 struct mpint_pos numbers
[9];
724 int nnumbers
, pos
, len
, seqlen
, i
;
725 char *header
, *footer
;
732 * Fetch the key blobs.
734 pubblob
= key
->alg
->public_blob(key
->data
, &publen
);
735 privblob
= key
->alg
->private_blob(key
->data
, &privlen
);
736 spareblob
= outblob
= NULL
;
739 * Find the sequence of integers to be encoded into the OpenSSH
740 * key blob, and also decide on the header line.
742 if (key
->alg
== &ssh_rsa
) {
744 struct mpint_pos n
, e
, d
, p
, q
, iqmp
, dmp1
, dmq1
;
745 Bignum bd
, bp
, bq
, bdmp1
, bdmq1
;
747 pos
= 4 + GET_32BIT(pubblob
);
748 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &e
);
749 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &n
);
751 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &d
);
752 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &p
);
753 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &q
);
754 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &iqmp
);
756 assert(e
.start
&& iqmp
.start
); /* can't go wrong */
758 /* We also need d mod (p-1) and d mod (q-1). */
759 bd
= bignum_from_bytes(d
.start
, d
.bytes
);
760 bp
= bignum_from_bytes(p
.start
, p
.bytes
);
761 bq
= bignum_from_bytes(q
.start
, q
.bytes
);
764 bdmp1
= bigmod(bd
, bp
);
765 bdmq1
= bigmod(bd
, bq
);
770 dmp1
.bytes
= (bignum_bitcount(bdmp1
)+8)/8;
771 dmq1
.bytes
= (bignum_bitcount(bdmq1
)+8)/8;
772 sparelen
= dmp1
.bytes
+ dmq1
.bytes
;
773 spareblob
= snewn(sparelen
, unsigned char);
774 dmp1
.start
= spareblob
;
775 dmq1
.start
= spareblob
+ dmp1
.bytes
;
776 for (i
= 0; i
< dmp1
.bytes
; i
++)
777 spareblob
[i
] = bignum_byte(bdmp1
, dmp1
.bytes
-1 - i
);
778 for (i
= 0; i
< dmq1
.bytes
; i
++)
779 spareblob
[i
+dmp1
.bytes
] = bignum_byte(bdmq1
, dmq1
.bytes
-1 - i
);
783 numbers
[0].start
= zero
; numbers
[0].bytes
= 1; zero
[0] = '\0';
794 header
= "-----BEGIN RSA PRIVATE KEY-----\n";
795 footer
= "-----END RSA PRIVATE KEY-----\n";
796 } else if (key
->alg
== &ssh_dss
) {
798 struct mpint_pos p
, q
, g
, y
, x
;
800 pos
= 4 + GET_32BIT(pubblob
);
801 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &p
);
802 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &q
);
803 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &g
);
804 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &y
);
806 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &x
);
808 assert(y
.start
&& x
.start
); /* can't go wrong */
810 numbers
[0].start
= zero
; numbers
[0].bytes
= 1; zero
[0] = '\0';
818 header
= "-----BEGIN DSA PRIVATE KEY-----\n";
819 footer
= "-----END DSA PRIVATE KEY-----\n";
821 assert(0); /* zoinks! */
822 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
826 * Now count up the total size of the ASN.1 encoded integers,
827 * so as to determine the length of the containing SEQUENCE.
830 for (i
= 0; i
< nnumbers
; i
++) {
831 len
+= ber_write_id_len(NULL
, 2, numbers
[i
].bytes
, 0);
832 len
+= numbers
[i
].bytes
;
835 /* Now add on the SEQUENCE header. */
836 len
+= ber_write_id_len(NULL
, 16, seqlen
, ASN1_CONSTRUCTED
);
837 /* Round up to the cipher block size, ensuring we have at least one
838 * byte of padding (see below). */
841 outlen
= (outlen
+8) &~ 7;
844 * Now we know how big outblob needs to be. Allocate it.
846 outblob
= snewn(outlen
, unsigned char);
849 * And write the data into it.
852 pos
+= ber_write_id_len(outblob
+pos
, 16, seqlen
, ASN1_CONSTRUCTED
);
853 for (i
= 0; i
< nnumbers
; i
++) {
854 pos
+= ber_write_id_len(outblob
+pos
, 2, numbers
[i
].bytes
, 0);
855 memcpy(outblob
+pos
, numbers
[i
].start
, numbers
[i
].bytes
);
856 pos
+= numbers
[i
].bytes
;
860 * Padding on OpenSSH keys is deterministic. The number of
861 * padding bytes is always more than zero, and always at most
862 * the cipher block length. The value of each padding byte is
863 * equal to the number of padding bytes. So a plaintext that's
864 * an exact multiple of the block size will be padded with 08
865 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
866 * plaintext one byte less than a multiple of the block size
867 * will be padded with just 01.
869 * This enables the OpenSSL key decryption function to strip
870 * off the padding algorithmically and return the unpadded
871 * plaintext to the next layer: it looks at the final byte, and
872 * then expects to find that many bytes at the end of the data
873 * with the same value. Those are all removed and the rest is
877 while (pos
< outlen
) {
878 outblob
[pos
++] = outlen
- len
;
884 * For the moment, we still encrypt our OpenSSH keys using
889 * Invent an iv. Then derive encryption key from passphrase
892 * - let block A equal MD5(passphrase || iv)
893 * - let block B equal MD5(A || passphrase || iv)
894 * - block C would be MD5(B || passphrase || iv) and so on
895 * - encryption key is the first N bytes of A || B
897 struct MD5Context md5c
;
898 unsigned char keybuf
[32];
900 for (i
= 0; i
< 8; i
++) iv
[i
] = random_byte();
903 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
904 MD5Update(&md5c
, iv
, 8);
905 MD5Final(keybuf
, &md5c
);
908 MD5Update(&md5c
, keybuf
, 16);
909 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
910 MD5Update(&md5c
, iv
, 8);
911 MD5Final(keybuf
+16, &md5c
);
914 * Now encrypt the key blob.
916 des3_encrypt_pubkey_ossh(keybuf
, iv
, outblob
, outlen
);
918 smemclr(&md5c
, sizeof(md5c
));
919 smemclr(keybuf
, sizeof(keybuf
));
923 * And save it. We'll use Unix line endings just in case it's
924 * subsequently transferred in binary mode.
926 fp
= f_open(filename
, "wb", TRUE
); /* ensure Unix line endings */
931 fprintf(fp
, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
932 for (i
= 0; i
< 8; i
++)
933 fprintf(fp
, "%02X", iv
[i
]);
936 base64_encode(fp
, outblob
, outlen
, 64);
943 smemclr(outblob
, outlen
);
947 smemclr(spareblob
, sparelen
);
951 smemclr(privblob
, privlen
);
955 smemclr(pubblob
, publen
);
961 /* ----------------------------------------------------------------------
962 * Code to read ssh.com private keys.
966 * The format of the base64 blob is largely SSH-2-packet-formatted,
967 * except that mpints are a bit different: they're more like the
968 * old SSH-1 mpint. You have a 32-bit bit count N, followed by
969 * (N+7)/8 bytes of data.
971 * So. The blob contains:
973 * - uint32 0x3f6ff9eb (magic number)
974 * - uint32 size (total blob size)
975 * - string key-type (see below)
976 * - string cipher-type (tells you if key is encrypted)
977 * - string encrypted-blob
979 * (The first size field includes the size field itself and the
980 * magic number before it. All other size fields are ordinary SSH-2
981 * strings, so the size field indicates how much data is to
984 * The encrypted blob, once decrypted, contains a single string
985 * which in turn contains the payload. (This allows padding to be
986 * added after that string while still making it clear where the
987 * real payload ends. Also it probably makes for a reasonable
990 * The payload blob, for an RSA key, contains:
993 * - mpint n (yes, the public and private stuff is intermixed)
994 * - mpint u (presumably inverse of p mod q)
995 * - mpint p (p is the smaller prime)
996 * - mpint q (q is the larger)
998 * For a DSA key, the payload blob contains:
1006 * Alternatively, if the parameters are `predefined', that
1007 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
1008 * containing some predefined parameter specification. *shudder*,
1009 * but I doubt we'll encounter this in real life.
1011 * The key type strings are ghastly. The RSA key I looked at had a
1014 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
1016 * and the DSA key wasn't much better:
1018 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
1020 * It isn't clear that these will always be the same. I think it
1021 * might be wise just to look at the `if-modn{sign{rsa' and
1022 * `dl-modp{sign{dsa' prefixes.
1024 * Finally, the encryption. The cipher-type string appears to be
1025 * either `none' or `3des-cbc'. Looks as if this is SSH-2-style
1026 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
1027 * from the passphrase by means of yet another hashing faff:
1029 * - first 16 bytes are MD5(passphrase)
1030 * - next 16 bytes are MD5(passphrase || first 16 bytes)
1031 * - if there were more, they'd be MD5(passphrase || first 32),
1035 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
1038 char comment
[256]; /* allowing any length is overkill */
1039 unsigned char *keyblob
;
1040 int keyblob_len
, keyblob_size
;
1043 static struct sshcom_key
*load_sshcom_key(const Filename
*filename
,
1044 const char **errmsg_p
)
1046 struct sshcom_key
*ret
;
1053 int base64_chars
= 0;
1055 ret
= snew(struct sshcom_key
);
1056 ret
->comment
[0] = '\0';
1057 ret
->keyblob
= NULL
;
1058 ret
->keyblob_len
= ret
->keyblob_size
= 0;
1060 fp
= f_open(filename
, "r", FALSE
);
1062 errmsg
= "unable to open key file";
1065 if (!(line
= fgetline(fp
))) {
1066 errmsg
= "unexpected end of file";
1070 if (0 != strcmp(line
, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
1071 errmsg
= "file does not begin with ssh.com key header";
1074 smemclr(line
, strlen(line
));
1080 if (!(line
= fgetline(fp
))) {
1081 errmsg
= "unexpected end of file";
1085 if (!strcmp(line
, "---- END SSH2 ENCRYPTED PRIVATE KEY ----"))
1087 if ((p
= strchr(line
, ':')) != NULL
) {
1089 errmsg
= "header found in body of key data";
1093 while (*p
&& isspace((unsigned char)*p
)) p
++;
1094 hdrstart
= p
- line
;
1097 * Header lines can end in a trailing backslash for
1100 len
= hdrstart
+ strlen(line
+hdrstart
);
1102 while (line
[len
-1] == '\\') {
1106 line2
= fgetline(fp
);
1108 errmsg
= "unexpected end of file";
1113 line2len
= strlen(line2
);
1114 line
= sresize(line
, len
+ line2len
+ 1, char);
1115 strcpy(line
+ len
- 1, line2
);
1116 len
+= line2len
- 1;
1119 smemclr(line2
, strlen(line2
));
1123 p
= line
+ hdrstart
;
1125 if (!strcmp(line
, "Comment")) {
1126 /* Strip quotes in comment if present. */
1127 if (p
[0] == '"' && p
[strlen(p
)-1] == '"') {
1129 p
[strlen(p
)-1] = '\0';
1131 strncpy(ret
->comment
, p
, sizeof(ret
->comment
));
1132 ret
->comment
[sizeof(ret
->comment
)-1] = '\0';
1138 while (isbase64(*p
)) {
1139 base64_bit
[base64_chars
++] = *p
;
1140 if (base64_chars
== 4) {
1141 unsigned char out
[3];
1145 len
= base64_decode_atom(base64_bit
, out
);
1148 errmsg
= "invalid base64 encoding";
1152 if (ret
->keyblob_len
+ len
> ret
->keyblob_size
) {
1153 ret
->keyblob_size
= ret
->keyblob_len
+ len
+ 256;
1154 ret
->keyblob
= sresize(ret
->keyblob
, ret
->keyblob_size
,
1158 memcpy(ret
->keyblob
+ ret
->keyblob_len
, out
, len
);
1159 ret
->keyblob_len
+= len
;
1165 smemclr(line
, strlen(line
));
1170 if (ret
->keyblob_len
== 0 || !ret
->keyblob
) {
1171 errmsg
= "key body not present";
1175 if (errmsg_p
) *errmsg_p
= NULL
;
1180 smemclr(line
, strlen(line
));
1186 smemclr(ret
->keyblob
, ret
->keyblob_size
);
1187 sfree(ret
->keyblob
);
1189 smemclr(ret
, sizeof(*ret
));
1192 if (errmsg_p
) *errmsg_p
= errmsg
;
1196 int sshcom_encrypted(const Filename
*filename
, char **comment
)
1198 struct sshcom_key
*key
= load_sshcom_key(filename
, NULL
);
1199 int pos
, len
, answer
;
1206 * Check magic number.
1208 if (GET_32BIT(key
->keyblob
) != 0x3f6ff9eb)
1209 return 0; /* key is invalid */
1212 * Find the cipher-type string.
1216 if (key
->keyblob_len
< pos
+4)
1217 goto done
; /* key is far too short */
1218 pos
+= 4 + GET_32BIT(key
->keyblob
+ pos
); /* skip key type */
1219 if (key
->keyblob_len
< pos
+4)
1220 goto done
; /* key is far too short */
1221 len
= GET_32BIT(key
->keyblob
+ pos
); /* find cipher-type length */
1222 if (key
->keyblob_len
< pos
+4+len
)
1223 goto done
; /* cipher type string is incomplete */
1224 if (len
!= 4 || 0 != memcmp(key
->keyblob
+ pos
+ 4, "none", 4))
1228 *comment
= dupstr(key
->comment
);
1229 smemclr(key
->keyblob
, key
->keyblob_size
);
1230 sfree(key
->keyblob
);
1231 smemclr(key
, sizeof(*key
));
1236 static int sshcom_read_mpint(void *data
, int len
, struct mpint_pos
*ret
)
1240 unsigned char *d
= (unsigned char *) data
;
1244 bits
= GET_32BIT(d
);
1246 bytes
= (bits
+ 7) / 8;
1257 return len
; /* ensure further calls fail as well */
1260 static int sshcom_put_mpint(void *target
, void *data
, int len
)
1262 unsigned char *d
= (unsigned char *)target
;
1263 unsigned char *i
= (unsigned char *)data
;
1264 int bits
= len
* 8 - 1;
1267 if (*i
& (1 << (bits
& 7)))
1273 PUT_32BIT(d
, bits
+1);
1274 memcpy(d
+4, i
, len
);
1278 struct ssh2_userkey
*sshcom_read(const Filename
*filename
, char *passphrase
,
1279 const char **errmsg_p
)
1281 struct sshcom_key
*key
= load_sshcom_key(filename
, errmsg_p
);
1284 const char prefix_rsa
[] = "if-modn{sign{rsa";
1285 const char prefix_dsa
[] = "dl-modp{sign{dsa";
1286 enum { RSA
, DSA
} type
;
1290 struct ssh2_userkey
*ret
= NULL
, *retkey
;
1291 const struct ssh_signkey
*alg
;
1292 unsigned char *blob
= NULL
;
1293 int blobsize
= 0, publen
, privlen
;
1299 * Check magic number.
1301 if (GET_32BIT(key
->keyblob
) != SSHCOM_MAGIC_NUMBER
) {
1302 errmsg
= "key does not begin with magic number";
1307 * Determine the key type.
1310 if (key
->keyblob_len
< pos
+4 ||
1311 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1312 errmsg
= "key blob does not contain a key type string";
1315 if (len
> sizeof(prefix_rsa
) - 1 &&
1316 !memcmp(key
->keyblob
+pos
+4, prefix_rsa
, sizeof(prefix_rsa
) - 1)) {
1318 } else if (len
> sizeof(prefix_dsa
) - 1 &&
1319 !memcmp(key
->keyblob
+pos
+4, prefix_dsa
, sizeof(prefix_dsa
) - 1)) {
1322 errmsg
= "key is of unknown type";
1328 * Determine the cipher type.
1330 if (key
->keyblob_len
< pos
+4 ||
1331 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1332 errmsg
= "key blob does not contain a cipher type string";
1335 if (len
== 4 && !memcmp(key
->keyblob
+pos
+4, "none", 4))
1337 else if (len
== 8 && !memcmp(key
->keyblob
+pos
+4, "3des-cbc", 8))
1340 errmsg
= "key encryption is of unknown type";
1346 * Get hold of the encrypted part of the key.
1348 if (key
->keyblob_len
< pos
+4 ||
1349 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1350 errmsg
= "key blob does not contain actual key data";
1353 ciphertext
= (char *)key
->keyblob
+ pos
+ 4;
1355 if (cipherlen
== 0) {
1356 errmsg
= "length of key data is zero";
1361 * Decrypt it if necessary.
1365 * Derive encryption key from passphrase and iv/salt:
1367 * - let block A equal MD5(passphrase)
1368 * - let block B equal MD5(passphrase || A)
1369 * - block C would be MD5(passphrase || A || B) and so on
1370 * - encryption key is the first N bytes of A || B
1372 struct MD5Context md5c
;
1373 unsigned char keybuf
[32], iv
[8];
1375 if (cipherlen
% 8 != 0) {
1376 errmsg
= "encrypted part of key is not a multiple of cipher block"
1382 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1383 MD5Final(keybuf
, &md5c
);
1386 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1387 MD5Update(&md5c
, keybuf
, 16);
1388 MD5Final(keybuf
+16, &md5c
);
1391 * Now decrypt the key blob.
1393 memset(iv
, 0, sizeof(iv
));
1394 des3_decrypt_pubkey_ossh(keybuf
, iv
, (unsigned char *)ciphertext
,
1397 smemclr(&md5c
, sizeof(md5c
));
1398 smemclr(keybuf
, sizeof(keybuf
));
1401 * Hereafter we return WRONG_PASSPHRASE for any parsing
1402 * error. (But only if we've just tried to decrypt it!
1403 * Returning WRONG_PASSPHRASE for an unencrypted key is
1407 ret
= SSH2_WRONG_PASSPHRASE
;
1411 * Strip away the containing string to get to the real meat.
1413 len
= GET_32BIT(ciphertext
);
1414 if (len
< 0 || len
> cipherlen
-4) {
1415 errmsg
= "containing string was ill-formed";
1422 * Now we break down into RSA versus DSA. In either case we'll
1423 * construct public and private blobs in our own format, and
1424 * end up feeding them to alg->createkey().
1426 blobsize
= cipherlen
+ 256;
1427 blob
= snewn(blobsize
, unsigned char);
1430 struct mpint_pos n
, e
, d
, u
, p
, q
;
1432 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &e
);
1433 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &d
);
1434 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &n
);
1435 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &u
);
1436 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &p
);
1437 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &q
);
1439 errmsg
= "key data did not contain six integers";
1445 pos
+= put_string(blob
+pos
, "ssh-rsa", 7);
1446 pos
+= put_mp(blob
+pos
, e
.start
, e
.bytes
);
1447 pos
+= put_mp(blob
+pos
, n
.start
, n
.bytes
);
1449 pos
+= put_string(blob
+pos
, d
.start
, d
.bytes
);
1450 pos
+= put_mp(blob
+pos
, q
.start
, q
.bytes
);
1451 pos
+= put_mp(blob
+pos
, p
.start
, p
.bytes
);
1452 pos
+= put_mp(blob
+pos
, u
.start
, u
.bytes
);
1453 privlen
= pos
- publen
;
1454 } else if (type
== DSA
) {
1455 struct mpint_pos p
, q
, g
, x
, y
;
1457 if (GET_32BIT(ciphertext
) != 0) {
1458 errmsg
= "predefined DSA parameters not supported";
1461 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &p
);
1462 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &g
);
1463 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &q
);
1464 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &y
);
1465 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &x
);
1467 errmsg
= "key data did not contain five integers";
1473 pos
+= put_string(blob
+pos
, "ssh-dss", 7);
1474 pos
+= put_mp(blob
+pos
, p
.start
, p
.bytes
);
1475 pos
+= put_mp(blob
+pos
, q
.start
, q
.bytes
);
1476 pos
+= put_mp(blob
+pos
, g
.start
, g
.bytes
);
1477 pos
+= put_mp(blob
+pos
, y
.start
, y
.bytes
);
1479 pos
+= put_mp(blob
+pos
, x
.start
, x
.bytes
);
1480 privlen
= pos
- publen
;
1484 assert(privlen
> 0); /* should have bombed by now if not */
1486 retkey
= snew(struct ssh2_userkey
);
1488 retkey
->data
= alg
->createkey(blob
, publen
, blob
+publen
, privlen
);
1489 if (!retkey
->data
) {
1491 errmsg
= "unable to create key data structure";
1494 retkey
->comment
= dupstr(key
->comment
);
1496 errmsg
= NULL
; /* no error */
1501 smemclr(blob
, blobsize
);
1504 smemclr(key
->keyblob
, key
->keyblob_size
);
1505 sfree(key
->keyblob
);
1506 smemclr(key
, sizeof(*key
));
1508 if (errmsg_p
) *errmsg_p
= errmsg
;
1512 int sshcom_write(const Filename
*filename
, struct ssh2_userkey
*key
,
1515 unsigned char *pubblob
, *privblob
;
1516 int publen
, privlen
;
1517 unsigned char *outblob
;
1519 struct mpint_pos numbers
[6];
1520 int nnumbers
, initial_zero
, pos
, lenpos
, i
;
1528 * Fetch the key blobs.
1530 pubblob
= key
->alg
->public_blob(key
->data
, &publen
);
1531 privblob
= key
->alg
->private_blob(key
->data
, &privlen
);
1535 * Find the sequence of integers to be encoded into the OpenSSH
1536 * key blob, and also decide on the header line.
1538 if (key
->alg
== &ssh_rsa
) {
1540 struct mpint_pos n
, e
, d
, p
, q
, iqmp
;
1542 pos
= 4 + GET_32BIT(pubblob
);
1543 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &e
);
1544 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &n
);
1546 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &d
);
1547 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &p
);
1548 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &q
);
1549 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &iqmp
);
1551 assert(e
.start
&& iqmp
.start
); /* can't go wrong */
1562 type
= "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
1563 } else if (key
->alg
== &ssh_dss
) {
1565 struct mpint_pos p
, q
, g
, y
, x
;
1567 pos
= 4 + GET_32BIT(pubblob
);
1568 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &p
);
1569 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &q
);
1570 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &g
);
1571 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &y
);
1573 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &x
);
1575 assert(y
.start
&& x
.start
); /* can't go wrong */
1585 type
= "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
1587 assert(0); /* zoinks! */
1588 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
1592 * Total size of key blob will be somewhere under 512 plus
1593 * combined length of integers. We'll calculate the more
1594 * precise size as we construct the blob.
1597 for (i
= 0; i
< nnumbers
; i
++)
1598 outlen
+= 4 + numbers
[i
].bytes
;
1599 outblob
= snewn(outlen
, unsigned char);
1602 * Create the unencrypted key blob.
1605 PUT_32BIT(outblob
+pos
, SSHCOM_MAGIC_NUMBER
); pos
+= 4;
1606 pos
+= 4; /* length field, fill in later */
1607 pos
+= put_string(outblob
+pos
, type
, strlen(type
));
1609 char *ciphertype
= passphrase ?
"3des-cbc" : "none";
1610 pos
+= put_string(outblob
+pos
, ciphertype
, strlen(ciphertype
));
1612 lenpos
= pos
; /* remember this position */
1613 pos
+= 4; /* encrypted-blob size */
1614 pos
+= 4; /* encrypted-payload size */
1616 PUT_32BIT(outblob
+pos
, 0);
1619 for (i
= 0; i
< nnumbers
; i
++)
1620 pos
+= sshcom_put_mpint(outblob
+pos
,
1621 numbers
[i
].start
, numbers
[i
].bytes
);
1622 /* Now wrap up the encrypted payload. */
1623 PUT_32BIT(outblob
+lenpos
+4, pos
- (lenpos
+8));
1624 /* Pad encrypted blob to a multiple of cipher block size. */
1626 int padding
= -(pos
- (lenpos
+4)) & 7;
1628 outblob
[pos
++] = random_byte();
1630 ciphertext
= (char *)outblob
+lenpos
+4;
1631 cipherlen
= pos
- (lenpos
+4);
1632 assert(!passphrase
|| cipherlen
% 8 == 0);
1633 /* Wrap up the encrypted blob string. */
1634 PUT_32BIT(outblob
+lenpos
, cipherlen
);
1635 /* And finally fill in the total length field. */
1636 PUT_32BIT(outblob
+4, pos
);
1638 assert(pos
< outlen
);
1645 * Derive encryption key from passphrase and iv/salt:
1647 * - let block A equal MD5(passphrase)
1648 * - let block B equal MD5(passphrase || A)
1649 * - block C would be MD5(passphrase || A || B) and so on
1650 * - encryption key is the first N bytes of A || B
1652 struct MD5Context md5c
;
1653 unsigned char keybuf
[32], iv
[8];
1656 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1657 MD5Final(keybuf
, &md5c
);
1660 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1661 MD5Update(&md5c
, keybuf
, 16);
1662 MD5Final(keybuf
+16, &md5c
);
1665 * Now decrypt the key blob.
1667 memset(iv
, 0, sizeof(iv
));
1668 des3_encrypt_pubkey_ossh(keybuf
, iv
, (unsigned char *)ciphertext
,
1671 smemclr(&md5c
, sizeof(md5c
));
1672 smemclr(keybuf
, sizeof(keybuf
));
1676 * And save it. We'll use Unix line endings just in case it's
1677 * subsequently transferred in binary mode.
1679 fp
= f_open(filename
, "wb", TRUE
); /* ensure Unix line endings */
1682 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp
);
1683 fprintf(fp
, "Comment: \"");
1685 * Comment header is broken with backslash-newline if it goes
1686 * over 70 chars. Although it's surrounded by quotes, it
1687 * _doesn't_ escape backslashes or quotes within the string.
1688 * Don't ask me, I didn't design it.
1691 int slen
= 60; /* starts at 60 due to "Comment: " */
1692 char *c
= key
->comment
;
1693 while ((int)strlen(c
) > slen
) {
1694 fprintf(fp
, "%.*s\\\n", slen
, c
);
1696 slen
= 70; /* allow 70 chars on subsequent lines */
1698 fprintf(fp
, "%s\"\n", c
);
1700 base64_encode(fp
, outblob
, pos
, 70);
1701 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp
);
1707 smemclr(outblob
, outlen
);
1711 smemclr(privblob
, privlen
);
1715 smemclr(pubblob
, publen
);