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
596 * decrypt, if the key was encrypted. */
597 ret
= ber_read_id_len(p
, key
->keyblob_len
, &id
, &len
, &flags
);
599 if (ret
< 0 || id
!= 16) {
600 errmsg
= "ASN.1 decoding failure";
601 retval
= key
->encrypted ? SSH2_WRONG_PASSPHRASE
: NULL
;
605 /* Expect a load of INTEGERs. */
606 if (key
->type
== OSSH_RSA
)
608 else if (key
->type
== OSSH_DSA
)
611 num_integers
= 0; /* placate compiler warnings */
614 * Space to create key blob in.
616 blobsize
= 256+key
->keyblob_len
;
617 blob
= snewn(blobsize
, unsigned char);
619 if (key
->type
== OSSH_DSA
)
620 memcpy(blob
+4, "ssh-dss", 7);
621 else if (key
->type
== OSSH_RSA
)
622 memcpy(blob
+4, "ssh-rsa", 7);
626 for (i
= 0; i
< num_integers
; i
++) {
627 ret
= ber_read_id_len(p
, key
->keyblob
+key
->keyblob_len
-p
,
630 if (ret
< 0 || id
!= 2 ||
631 key
->keyblob
+key
->keyblob_len
-p
< len
) {
632 errmsg
= "ASN.1 decoding failure";
633 retval
= key
->encrypted ? SSH2_WRONG_PASSPHRASE
: NULL
;
639 * The first integer should be zero always (I think
640 * this is some sort of version indication).
642 if (len
!= 1 || p
[0] != 0) {
643 errmsg
= "version number mismatch";
646 } else if (key
->type
== OSSH_RSA
) {
648 * Integers 1 and 2 go into the public blob but in the
649 * opposite order; integers 3, 4, 5 and 8 go into the
650 * private blob. The other two (6 and 7) are ignored.
653 /* Save the details for after we deal with number 2. */
656 } else if (i
!= 6 && i
!= 7) {
657 PUT_32BIT(blob
+blobptr
, len
);
658 memcpy(blob
+blobptr
+4, p
, len
);
661 PUT_32BIT(blob
+blobptr
, modlen
);
662 memcpy(blob
+blobptr
+4, modptr
, modlen
);
667 } else if (key
->type
== OSSH_DSA
) {
669 * Integers 1-4 go into the public blob; integer 5 goes
670 * into the private blob.
672 PUT_32BIT(blob
+blobptr
, len
);
673 memcpy(blob
+blobptr
+4, p
, len
);
679 /* Skip past the number. */
684 * Now put together the actual key. Simplest way to do this is
685 * to assemble our own key blobs and feed them to the createkey
686 * functions; this is a bit faffy but it does mean we get all
687 * the sanity checks for free.
689 assert(privptr
> 0); /* should have bombed by now if not */
690 retkey
= snew(struct ssh2_userkey
);
691 retkey
->alg
= (key
->type
== OSSH_RSA ?
&ssh_rsa
: &ssh_dss
);
692 retkey
->data
= retkey
->alg
->createkey(blob
, privptr
,
693 blob
+privptr
, blobptr
-privptr
);
696 errmsg
= "unable to create key data structure";
700 retkey
->comment
= dupstr("imported-openssh-key");
701 errmsg
= NULL
; /* no error */
706 smemclr(blob
, blobsize
);
709 smemclr(key
->keyblob
, key
->keyblob_size
);
711 smemclr(key
, sizeof(*key
));
713 if (errmsg_p
) *errmsg_p
= errmsg
;
717 int openssh_write(const Filename
*filename
, struct ssh2_userkey
*key
,
720 unsigned char *pubblob
, *privblob
, *spareblob
;
721 int publen
, privlen
, sparelen
= 0;
722 unsigned char *outblob
;
724 struct mpint_pos numbers
[9];
725 int nnumbers
, pos
, len
, seqlen
, i
;
726 char *header
, *footer
;
733 * Fetch the key blobs.
735 pubblob
= key
->alg
->public_blob(key
->data
, &publen
);
736 privblob
= key
->alg
->private_blob(key
->data
, &privlen
);
737 spareblob
= outblob
= NULL
;
740 * Find the sequence of integers to be encoded into the OpenSSH
741 * key blob, and also decide on the header line.
743 if (key
->alg
== &ssh_rsa
) {
745 struct mpint_pos n
, e
, d
, p
, q
, iqmp
, dmp1
, dmq1
;
746 Bignum bd
, bp
, bq
, bdmp1
, bdmq1
;
748 pos
= 4 + GET_32BIT(pubblob
);
749 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &e
);
750 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &n
);
752 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &d
);
753 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &p
);
754 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &q
);
755 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &iqmp
);
757 assert(e
.start
&& iqmp
.start
); /* can't go wrong */
759 /* We also need d mod (p-1) and d mod (q-1). */
760 bd
= bignum_from_bytes(d
.start
, d
.bytes
);
761 bp
= bignum_from_bytes(p
.start
, p
.bytes
);
762 bq
= bignum_from_bytes(q
.start
, q
.bytes
);
765 bdmp1
= bigmod(bd
, bp
);
766 bdmq1
= bigmod(bd
, bq
);
771 dmp1
.bytes
= (bignum_bitcount(bdmp1
)+8)/8;
772 dmq1
.bytes
= (bignum_bitcount(bdmq1
)+8)/8;
773 sparelen
= dmp1
.bytes
+ dmq1
.bytes
;
774 spareblob
= snewn(sparelen
, unsigned char);
775 dmp1
.start
= spareblob
;
776 dmq1
.start
= spareblob
+ dmp1
.bytes
;
777 for (i
= 0; i
< dmp1
.bytes
; i
++)
778 spareblob
[i
] = bignum_byte(bdmp1
, dmp1
.bytes
-1 - i
);
779 for (i
= 0; i
< dmq1
.bytes
; i
++)
780 spareblob
[i
+dmp1
.bytes
] = bignum_byte(bdmq1
, dmq1
.bytes
-1 - i
);
784 numbers
[0].start
= zero
; numbers
[0].bytes
= 1; zero
[0] = '\0';
795 header
= "-----BEGIN RSA PRIVATE KEY-----\n";
796 footer
= "-----END RSA PRIVATE KEY-----\n";
797 } else if (key
->alg
== &ssh_dss
) {
799 struct mpint_pos p
, q
, g
, y
, x
;
801 pos
= 4 + GET_32BIT(pubblob
);
802 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &p
);
803 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &q
);
804 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &g
);
805 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &y
);
807 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &x
);
809 assert(y
.start
&& x
.start
); /* can't go wrong */
811 numbers
[0].start
= zero
; numbers
[0].bytes
= 1; zero
[0] = '\0';
819 header
= "-----BEGIN DSA PRIVATE KEY-----\n";
820 footer
= "-----END DSA PRIVATE KEY-----\n";
822 assert(0); /* zoinks! */
823 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
827 * Now count up the total size of the ASN.1 encoded integers,
828 * so as to determine the length of the containing SEQUENCE.
831 for (i
= 0; i
< nnumbers
; i
++) {
832 len
+= ber_write_id_len(NULL
, 2, numbers
[i
].bytes
, 0);
833 len
+= numbers
[i
].bytes
;
836 /* Now add on the SEQUENCE header. */
837 len
+= ber_write_id_len(NULL
, 16, seqlen
, ASN1_CONSTRUCTED
);
838 /* Round up to the cipher block size, ensuring we have at least one
839 * byte of padding (see below). */
842 outlen
= (outlen
+8) &~ 7;
845 * Now we know how big outblob needs to be. Allocate it.
847 outblob
= snewn(outlen
, unsigned char);
850 * And write the data into it.
853 pos
+= ber_write_id_len(outblob
+pos
, 16, seqlen
, ASN1_CONSTRUCTED
);
854 for (i
= 0; i
< nnumbers
; i
++) {
855 pos
+= ber_write_id_len(outblob
+pos
, 2, numbers
[i
].bytes
, 0);
856 memcpy(outblob
+pos
, numbers
[i
].start
, numbers
[i
].bytes
);
857 pos
+= numbers
[i
].bytes
;
861 * Padding on OpenSSH keys is deterministic. The number of
862 * padding bytes is always more than zero, and always at most
863 * the cipher block length. The value of each padding byte is
864 * equal to the number of padding bytes. So a plaintext that's
865 * an exact multiple of the block size will be padded with 08
866 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
867 * plaintext one byte less than a multiple of the block size
868 * will be padded with just 01.
870 * This enables the OpenSSL key decryption function to strip
871 * off the padding algorithmically and return the unpadded
872 * plaintext to the next layer: it looks at the final byte, and
873 * then expects to find that many bytes at the end of the data
874 * with the same value. Those are all removed and the rest is
878 while (pos
< outlen
) {
879 outblob
[pos
++] = outlen
- len
;
885 * For the moment, we still encrypt our OpenSSH keys using
890 * Invent an iv. Then derive encryption key from passphrase
893 * - let block A equal MD5(passphrase || iv)
894 * - let block B equal MD5(A || passphrase || iv)
895 * - block C would be MD5(B || passphrase || iv) and so on
896 * - encryption key is the first N bytes of A || B
898 struct MD5Context md5c
;
899 unsigned char keybuf
[32];
901 for (i
= 0; i
< 8; i
++) iv
[i
] = random_byte();
904 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
905 MD5Update(&md5c
, iv
, 8);
906 MD5Final(keybuf
, &md5c
);
909 MD5Update(&md5c
, keybuf
, 16);
910 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
911 MD5Update(&md5c
, iv
, 8);
912 MD5Final(keybuf
+16, &md5c
);
915 * Now encrypt the key blob.
917 des3_encrypt_pubkey_ossh(keybuf
, iv
, outblob
, outlen
);
919 smemclr(&md5c
, sizeof(md5c
));
920 smemclr(keybuf
, sizeof(keybuf
));
924 * And save it. We'll use Unix line endings just in case it's
925 * subsequently transferred in binary mode.
927 fp
= f_open(filename
, "wb", TRUE
); /* ensure Unix line endings */
932 fprintf(fp
, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
933 for (i
= 0; i
< 8; i
++)
934 fprintf(fp
, "%02X", iv
[i
]);
937 base64_encode(fp
, outblob
, outlen
, 64);
944 smemclr(outblob
, outlen
);
948 smemclr(spareblob
, sparelen
);
952 smemclr(privblob
, privlen
);
956 smemclr(pubblob
, publen
);
962 /* ----------------------------------------------------------------------
963 * Code to read ssh.com private keys.
967 * The format of the base64 blob is largely SSH-2-packet-formatted,
968 * except that mpints are a bit different: they're more like the
969 * old SSH-1 mpint. You have a 32-bit bit count N, followed by
970 * (N+7)/8 bytes of data.
972 * So. The blob contains:
974 * - uint32 0x3f6ff9eb (magic number)
975 * - uint32 size (total blob size)
976 * - string key-type (see below)
977 * - string cipher-type (tells you if key is encrypted)
978 * - string encrypted-blob
980 * (The first size field includes the size field itself and the
981 * magic number before it. All other size fields are ordinary SSH-2
982 * strings, so the size field indicates how much data is to
985 * The encrypted blob, once decrypted, contains a single string
986 * which in turn contains the payload. (This allows padding to be
987 * added after that string while still making it clear where the
988 * real payload ends. Also it probably makes for a reasonable
991 * The payload blob, for an RSA key, contains:
994 * - mpint n (yes, the public and private stuff is intermixed)
995 * - mpint u (presumably inverse of p mod q)
996 * - mpint p (p is the smaller prime)
997 * - mpint q (q is the larger)
999 * For a DSA key, the payload blob contains:
1007 * Alternatively, if the parameters are `predefined', that
1008 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
1009 * containing some predefined parameter specification. *shudder*,
1010 * but I doubt we'll encounter this in real life.
1012 * The key type strings are ghastly. The RSA key I looked at had a
1015 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
1017 * and the DSA key wasn't much better:
1019 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
1021 * It isn't clear that these will always be the same. I think it
1022 * might be wise just to look at the `if-modn{sign{rsa' and
1023 * `dl-modp{sign{dsa' prefixes.
1025 * Finally, the encryption. The cipher-type string appears to be
1026 * either `none' or `3des-cbc'. Looks as if this is SSH-2-style
1027 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
1028 * from the passphrase by means of yet another hashing faff:
1030 * - first 16 bytes are MD5(passphrase)
1031 * - next 16 bytes are MD5(passphrase || first 16 bytes)
1032 * - if there were more, they'd be MD5(passphrase || first 32),
1036 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
1039 char comment
[256]; /* allowing any length is overkill */
1040 unsigned char *keyblob
;
1041 int keyblob_len
, keyblob_size
;
1044 static struct sshcom_key
*load_sshcom_key(const Filename
*filename
,
1045 const char **errmsg_p
)
1047 struct sshcom_key
*ret
;
1054 int base64_chars
= 0;
1056 ret
= snew(struct sshcom_key
);
1057 ret
->comment
[0] = '\0';
1058 ret
->keyblob
= NULL
;
1059 ret
->keyblob_len
= ret
->keyblob_size
= 0;
1061 fp
= f_open(filename
, "r", FALSE
);
1063 errmsg
= "unable to open key file";
1066 if (!(line
= fgetline(fp
))) {
1067 errmsg
= "unexpected end of file";
1071 if (0 != strcmp(line
, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
1072 errmsg
= "file does not begin with ssh.com key header";
1075 smemclr(line
, strlen(line
));
1081 if (!(line
= fgetline(fp
))) {
1082 errmsg
= "unexpected end of file";
1086 if (!strcmp(line
, "---- END SSH2 ENCRYPTED PRIVATE KEY ----"))
1088 if ((p
= strchr(line
, ':')) != NULL
) {
1090 errmsg
= "header found in body of key data";
1094 while (*p
&& isspace((unsigned char)*p
)) p
++;
1095 hdrstart
= p
- line
;
1098 * Header lines can end in a trailing backslash for
1101 len
= hdrstart
+ strlen(line
+hdrstart
);
1103 while (line
[len
-1] == '\\') {
1107 line2
= fgetline(fp
);
1109 errmsg
= "unexpected end of file";
1114 line2len
= strlen(line2
);
1115 line
= sresize(line
, len
+ line2len
+ 1, char);
1116 strcpy(line
+ len
- 1, line2
);
1117 len
+= line2len
- 1;
1120 smemclr(line2
, strlen(line2
));
1124 p
= line
+ hdrstart
;
1126 if (!strcmp(line
, "Comment")) {
1127 /* Strip quotes in comment if present. */
1128 if (p
[0] == '"' && p
[strlen(p
)-1] == '"') {
1130 p
[strlen(p
)-1] = '\0';
1132 strncpy(ret
->comment
, p
, sizeof(ret
->comment
));
1133 ret
->comment
[sizeof(ret
->comment
)-1] = '\0';
1139 while (isbase64(*p
)) {
1140 base64_bit
[base64_chars
++] = *p
;
1141 if (base64_chars
== 4) {
1142 unsigned char out
[3];
1146 len
= base64_decode_atom(base64_bit
, out
);
1149 errmsg
= "invalid base64 encoding";
1153 if (ret
->keyblob_len
+ len
> ret
->keyblob_size
) {
1154 ret
->keyblob_size
= ret
->keyblob_len
+ len
+ 256;
1155 ret
->keyblob
= sresize(ret
->keyblob
, ret
->keyblob_size
,
1159 memcpy(ret
->keyblob
+ ret
->keyblob_len
, out
, len
);
1160 ret
->keyblob_len
+= len
;
1166 smemclr(line
, strlen(line
));
1171 if (ret
->keyblob_len
== 0 || !ret
->keyblob
) {
1172 errmsg
= "key body not present";
1176 if (errmsg_p
) *errmsg_p
= NULL
;
1181 smemclr(line
, strlen(line
));
1187 smemclr(ret
->keyblob
, ret
->keyblob_size
);
1188 sfree(ret
->keyblob
);
1190 smemclr(ret
, sizeof(*ret
));
1193 if (errmsg_p
) *errmsg_p
= errmsg
;
1197 int sshcom_encrypted(const Filename
*filename
, char **comment
)
1199 struct sshcom_key
*key
= load_sshcom_key(filename
, NULL
);
1200 int pos
, len
, answer
;
1207 * Check magic number.
1209 if (GET_32BIT(key
->keyblob
) != 0x3f6ff9eb)
1210 return 0; /* key is invalid */
1213 * Find the cipher-type string.
1217 if (key
->keyblob_len
< pos
+4)
1218 goto done
; /* key is far too short */
1219 pos
+= 4 + GET_32BIT(key
->keyblob
+ pos
); /* skip key type */
1220 if (key
->keyblob_len
< pos
+4)
1221 goto done
; /* key is far too short */
1222 len
= GET_32BIT(key
->keyblob
+ pos
); /* find cipher-type length */
1223 if (key
->keyblob_len
< pos
+4+len
)
1224 goto done
; /* cipher type string is incomplete */
1225 if (len
!= 4 || 0 != memcmp(key
->keyblob
+ pos
+ 4, "none", 4))
1229 *comment
= dupstr(key
->comment
);
1230 smemclr(key
->keyblob
, key
->keyblob_size
);
1231 sfree(key
->keyblob
);
1232 smemclr(key
, sizeof(*key
));
1237 static int sshcom_read_mpint(void *data
, int len
, struct mpint_pos
*ret
)
1241 unsigned char *d
= (unsigned char *) data
;
1245 bits
= GET_32BIT(d
);
1247 bytes
= (bits
+ 7) / 8;
1258 return len
; /* ensure further calls fail as well */
1261 static int sshcom_put_mpint(void *target
, void *data
, int len
)
1263 unsigned char *d
= (unsigned char *)target
;
1264 unsigned char *i
= (unsigned char *)data
;
1265 int bits
= len
* 8 - 1;
1268 if (*i
& (1 << (bits
& 7)))
1274 PUT_32BIT(d
, bits
+1);
1275 memcpy(d
+4, i
, len
);
1279 struct ssh2_userkey
*sshcom_read(const Filename
*filename
, char *passphrase
,
1280 const char **errmsg_p
)
1282 struct sshcom_key
*key
= load_sshcom_key(filename
, errmsg_p
);
1285 const char prefix_rsa
[] = "if-modn{sign{rsa";
1286 const char prefix_dsa
[] = "dl-modp{sign{dsa";
1287 enum { RSA
, DSA
} type
;
1291 struct ssh2_userkey
*ret
= NULL
, *retkey
;
1292 const struct ssh_signkey
*alg
;
1293 unsigned char *blob
= NULL
;
1294 int blobsize
= 0, publen
, privlen
;
1300 * Check magic number.
1302 if (GET_32BIT(key
->keyblob
) != SSHCOM_MAGIC_NUMBER
) {
1303 errmsg
= "key does not begin with magic number";
1308 * Determine the key type.
1311 if (key
->keyblob_len
< pos
+4 ||
1312 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1313 errmsg
= "key blob does not contain a key type string";
1316 if (len
> sizeof(prefix_rsa
) - 1 &&
1317 !memcmp(key
->keyblob
+pos
+4, prefix_rsa
, sizeof(prefix_rsa
) - 1)) {
1319 } else if (len
> sizeof(prefix_dsa
) - 1 &&
1320 !memcmp(key
->keyblob
+pos
+4, prefix_dsa
, sizeof(prefix_dsa
) - 1)) {
1323 errmsg
= "key is of unknown type";
1329 * Determine the cipher type.
1331 if (key
->keyblob_len
< pos
+4 ||
1332 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1333 errmsg
= "key blob does not contain a cipher type string";
1336 if (len
== 4 && !memcmp(key
->keyblob
+pos
+4, "none", 4))
1338 else if (len
== 8 && !memcmp(key
->keyblob
+pos
+4, "3des-cbc", 8))
1341 errmsg
= "key encryption is of unknown type";
1347 * Get hold of the encrypted part of the key.
1349 if (key
->keyblob_len
< pos
+4 ||
1350 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1351 errmsg
= "key blob does not contain actual key data";
1354 ciphertext
= (char *)key
->keyblob
+ pos
+ 4;
1356 if (cipherlen
== 0) {
1357 errmsg
= "length of key data is zero";
1362 * Decrypt it if necessary.
1366 * Derive encryption key from passphrase and iv/salt:
1368 * - let block A equal MD5(passphrase)
1369 * - let block B equal MD5(passphrase || A)
1370 * - block C would be MD5(passphrase || A || B) and so on
1371 * - encryption key is the first N bytes of A || B
1373 struct MD5Context md5c
;
1374 unsigned char keybuf
[32], iv
[8];
1376 if (cipherlen
% 8 != 0) {
1377 errmsg
= "encrypted part of key is not a multiple of cipher block"
1383 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1384 MD5Final(keybuf
, &md5c
);
1387 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1388 MD5Update(&md5c
, keybuf
, 16);
1389 MD5Final(keybuf
+16, &md5c
);
1392 * Now decrypt the key blob.
1394 memset(iv
, 0, sizeof(iv
));
1395 des3_decrypt_pubkey_ossh(keybuf
, iv
, (unsigned char *)ciphertext
,
1398 smemclr(&md5c
, sizeof(md5c
));
1399 smemclr(keybuf
, sizeof(keybuf
));
1402 * Hereafter we return WRONG_PASSPHRASE for any parsing
1403 * error. (But only if we've just tried to decrypt it!
1404 * Returning WRONG_PASSPHRASE for an unencrypted key is
1408 ret
= SSH2_WRONG_PASSPHRASE
;
1412 * Strip away the containing string to get to the real meat.
1414 len
= GET_32BIT(ciphertext
);
1415 if (len
< 0 || len
> cipherlen
-4) {
1416 errmsg
= "containing string was ill-formed";
1423 * Now we break down into RSA versus DSA. In either case we'll
1424 * construct public and private blobs in our own format, and
1425 * end up feeding them to alg->createkey().
1427 blobsize
= cipherlen
+ 256;
1428 blob
= snewn(blobsize
, unsigned char);
1431 struct mpint_pos n
, e
, d
, u
, p
, q
;
1433 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &e
);
1434 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &d
);
1435 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &n
);
1436 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &u
);
1437 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &p
);
1438 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &q
);
1440 errmsg
= "key data did not contain six integers";
1446 pos
+= put_string(blob
+pos
, "ssh-rsa", 7);
1447 pos
+= put_mp(blob
+pos
, e
.start
, e
.bytes
);
1448 pos
+= put_mp(blob
+pos
, n
.start
, n
.bytes
);
1450 pos
+= put_string(blob
+pos
, d
.start
, d
.bytes
);
1451 pos
+= put_mp(blob
+pos
, q
.start
, q
.bytes
);
1452 pos
+= put_mp(blob
+pos
, p
.start
, p
.bytes
);
1453 pos
+= put_mp(blob
+pos
, u
.start
, u
.bytes
);
1454 privlen
= pos
- publen
;
1455 } else if (type
== DSA
) {
1456 struct mpint_pos p
, q
, g
, x
, y
;
1458 if (GET_32BIT(ciphertext
) != 0) {
1459 errmsg
= "predefined DSA parameters not supported";
1462 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &p
);
1463 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &g
);
1464 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &q
);
1465 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &y
);
1466 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &x
);
1468 errmsg
= "key data did not contain five integers";
1474 pos
+= put_string(blob
+pos
, "ssh-dss", 7);
1475 pos
+= put_mp(blob
+pos
, p
.start
, p
.bytes
);
1476 pos
+= put_mp(blob
+pos
, q
.start
, q
.bytes
);
1477 pos
+= put_mp(blob
+pos
, g
.start
, g
.bytes
);
1478 pos
+= put_mp(blob
+pos
, y
.start
, y
.bytes
);
1480 pos
+= put_mp(blob
+pos
, x
.start
, x
.bytes
);
1481 privlen
= pos
- publen
;
1485 assert(privlen
> 0); /* should have bombed by now if not */
1487 retkey
= snew(struct ssh2_userkey
);
1489 retkey
->data
= alg
->createkey(blob
, publen
, blob
+publen
, privlen
);
1490 if (!retkey
->data
) {
1492 errmsg
= "unable to create key data structure";
1495 retkey
->comment
= dupstr(key
->comment
);
1497 errmsg
= NULL
; /* no error */
1502 smemclr(blob
, blobsize
);
1505 smemclr(key
->keyblob
, key
->keyblob_size
);
1506 sfree(key
->keyblob
);
1507 smemclr(key
, sizeof(*key
));
1509 if (errmsg_p
) *errmsg_p
= errmsg
;
1513 int sshcom_write(const Filename
*filename
, struct ssh2_userkey
*key
,
1516 unsigned char *pubblob
, *privblob
;
1517 int publen
, privlen
;
1518 unsigned char *outblob
;
1520 struct mpint_pos numbers
[6];
1521 int nnumbers
, initial_zero
, pos
, lenpos
, i
;
1529 * Fetch the key blobs.
1531 pubblob
= key
->alg
->public_blob(key
->data
, &publen
);
1532 privblob
= key
->alg
->private_blob(key
->data
, &privlen
);
1536 * Find the sequence of integers to be encoded into the OpenSSH
1537 * key blob, and also decide on the header line.
1539 if (key
->alg
== &ssh_rsa
) {
1541 struct mpint_pos n
, e
, d
, p
, q
, iqmp
;
1543 pos
= 4 + GET_32BIT(pubblob
);
1544 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &e
);
1545 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &n
);
1547 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &d
);
1548 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &p
);
1549 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &q
);
1550 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &iqmp
);
1552 assert(e
.start
&& iqmp
.start
); /* can't go wrong */
1563 type
= "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
1564 } else if (key
->alg
== &ssh_dss
) {
1566 struct mpint_pos p
, q
, g
, y
, x
;
1568 pos
= 4 + GET_32BIT(pubblob
);
1569 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &p
);
1570 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &q
);
1571 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &g
);
1572 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &y
);
1574 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &x
);
1576 assert(y
.start
&& x
.start
); /* can't go wrong */
1586 type
= "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
1588 assert(0); /* zoinks! */
1589 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
1593 * Total size of key blob will be somewhere under 512 plus
1594 * combined length of integers. We'll calculate the more
1595 * precise size as we construct the blob.
1598 for (i
= 0; i
< nnumbers
; i
++)
1599 outlen
+= 4 + numbers
[i
].bytes
;
1600 outblob
= snewn(outlen
, unsigned char);
1603 * Create the unencrypted key blob.
1606 PUT_32BIT(outblob
+pos
, SSHCOM_MAGIC_NUMBER
); pos
+= 4;
1607 pos
+= 4; /* length field, fill in later */
1608 pos
+= put_string(outblob
+pos
, type
, strlen(type
));
1610 char *ciphertype
= passphrase ?
"3des-cbc" : "none";
1611 pos
+= put_string(outblob
+pos
, ciphertype
, strlen(ciphertype
));
1613 lenpos
= pos
; /* remember this position */
1614 pos
+= 4; /* encrypted-blob size */
1615 pos
+= 4; /* encrypted-payload size */
1617 PUT_32BIT(outblob
+pos
, 0);
1620 for (i
= 0; i
< nnumbers
; i
++)
1621 pos
+= sshcom_put_mpint(outblob
+pos
,
1622 numbers
[i
].start
, numbers
[i
].bytes
);
1623 /* Now wrap up the encrypted payload. */
1624 PUT_32BIT(outblob
+lenpos
+4, pos
- (lenpos
+8));
1625 /* Pad encrypted blob to a multiple of cipher block size. */
1627 int padding
= -(pos
- (lenpos
+4)) & 7;
1629 outblob
[pos
++] = random_byte();
1631 ciphertext
= (char *)outblob
+lenpos
+4;
1632 cipherlen
= pos
- (lenpos
+4);
1633 assert(!passphrase
|| cipherlen
% 8 == 0);
1634 /* Wrap up the encrypted blob string. */
1635 PUT_32BIT(outblob
+lenpos
, cipherlen
);
1636 /* And finally fill in the total length field. */
1637 PUT_32BIT(outblob
+4, pos
);
1639 assert(pos
< outlen
);
1646 * Derive encryption key from passphrase and iv/salt:
1648 * - let block A equal MD5(passphrase)
1649 * - let block B equal MD5(passphrase || A)
1650 * - block C would be MD5(passphrase || A || B) and so on
1651 * - encryption key is the first N bytes of A || B
1653 struct MD5Context md5c
;
1654 unsigned char keybuf
[32], iv
[8];
1657 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1658 MD5Final(keybuf
, &md5c
);
1661 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1662 MD5Update(&md5c
, keybuf
, 16);
1663 MD5Final(keybuf
+16, &md5c
);
1666 * Now decrypt the key blob.
1668 memset(iv
, 0, sizeof(iv
));
1669 des3_encrypt_pubkey_ossh(keybuf
, iv
, (unsigned char *)ciphertext
,
1672 smemclr(&md5c
, sizeof(md5c
));
1673 smemclr(keybuf
, sizeof(keybuf
));
1677 * And save it. We'll use Unix line endings just in case it's
1678 * subsequently transferred in binary mode.
1680 fp
= f_open(filename
, "wb", TRUE
); /* ensure Unix line endings */
1683 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp
);
1684 fprintf(fp
, "Comment: \"");
1686 * Comment header is broken with backslash-newline if it goes
1687 * over 70 chars. Although it's surrounded by quotes, it
1688 * _doesn't_ escape backslashes or quotes within the string.
1689 * Don't ask me, I didn't design it.
1692 int slen
= 60; /* starts at 60 due to "Comment: " */
1693 char *c
= key
->comment
;
1694 while ((int)strlen(c
) > slen
) {
1695 fprintf(fp
, "%.*s\\\n", slen
, c
);
1697 slen
= 70; /* allow 70 chars on subsequent lines */
1699 fprintf(fp
, "%s\"\n", c
);
1701 base64_encode(fp
, outblob
, pos
, 70);
1702 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp
);
1708 smemclr(outblob
, outlen
);
1712 smemclr(privblob
, privlen
);
1716 smemclr(pubblob
, publen
);