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 memset(line
, 0, 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 memset(out
, 0, sizeof(out
));
451 memset(line
, 0, strlen(line
));
456 if (ret
->keyblob_len
== 0 || !ret
->keyblob
) {
457 errmsg
= "key body not present";
461 if (ret
->encrypted
&& ret
->keyblob_len
% 8 != 0) {
462 errmsg
= "encrypted key blob is not a multiple of cipher block size";
466 memset(base64_bit
, 0, sizeof(base64_bit
));
467 if (errmsg_p
) *errmsg_p
= NULL
;
472 memset(line
, 0, strlen(line
));
476 memset(base64_bit
, 0, sizeof(base64_bit
));
479 memset(ret
->keyblob
, 0, ret
->keyblob_size
);
482 memset(ret
, 0, sizeof(*ret
));
485 if (errmsg_p
) *errmsg_p
= errmsg
;
489 int openssh_encrypted(const Filename
*filename
)
491 struct openssh_key
*key
= load_openssh_key(filename
, NULL
);
496 ret
= key
->encrypted
;
497 memset(key
->keyblob
, 0, key
->keyblob_size
);
499 memset(key
, 0, sizeof(*key
));
504 struct ssh2_userkey
*openssh_read(const Filename
*filename
, char *passphrase
,
505 const char **errmsg_p
)
507 struct openssh_key
*key
= load_openssh_key(filename
, errmsg_p
);
508 struct ssh2_userkey
*retkey
;
510 int ret
, id
, len
, flags
;
512 struct ssh2_userkey
*retval
= NULL
;
515 int blobsize
= 0, blobptr
, privptr
;
524 if (key
->encrypted
) {
526 * Derive encryption key from passphrase and iv/salt:
528 * - let block A equal MD5(passphrase || iv)
529 * - let block B equal MD5(A || passphrase || iv)
530 * - block C would be MD5(B || passphrase || iv) and so on
531 * - encryption key is the first N bytes of A || B
533 * (Note that only 8 bytes of the iv are used for key
534 * derivation, even when the key is encrypted with AES and
535 * hence there are 16 bytes available.)
537 struct MD5Context md5c
;
538 unsigned char keybuf
[32];
541 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
542 MD5Update(&md5c
, (unsigned char *)key
->iv
, 8);
543 MD5Final(keybuf
, &md5c
);
546 MD5Update(&md5c
, keybuf
, 16);
547 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
548 MD5Update(&md5c
, (unsigned char *)key
->iv
, 8);
549 MD5Final(keybuf
+16, &md5c
);
552 * Now decrypt the key blob.
554 if (key
->encryption
== OSSH_ENC_3DES
)
555 des3_decrypt_pubkey_ossh(keybuf
, (unsigned char *)key
->iv
,
556 key
->keyblob
, key
->keyblob_len
);
559 assert(key
->encryption
== OSSH_ENC_AES
);
560 ctx
= aes_make_context();
561 aes128_key(ctx
, keybuf
);
562 aes_iv(ctx
, (unsigned char *)key
->iv
);
563 aes_ssh2_decrypt_blk(ctx
, key
->keyblob
, key
->keyblob_len
);
564 aes_free_context(ctx
);
567 memset(&md5c
, 0, sizeof(md5c
));
568 memset(keybuf
, 0, sizeof(keybuf
));
572 * Now we have a decrypted key blob, which contains an ASN.1
573 * encoded private key. We must now untangle the ASN.1.
575 * We expect the whole key blob to be formatted as a SEQUENCE
576 * (0x30 followed by a length code indicating that the rest of
577 * the blob is part of the sequence). Within that SEQUENCE we
578 * expect to see a bunch of INTEGERs. What those integers mean
579 * depends on the key type:
581 * - For RSA, we expect the integers to be 0, n, e, d, p, q,
582 * dmp1, dmq1, iqmp in that order. (The last three are d mod
583 * (p-1), d mod (q-1), inverse of q mod p respectively.)
585 * - For DSA, we expect them to be 0, p, q, g, y, x in that
591 /* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */
592 ret
= ber_read_id_len(p
, key
->keyblob_len
, &id
, &len
, &flags
);
594 if (ret
< 0 || id
!= 16) {
595 errmsg
= "ASN.1 decoding failure";
596 retval
= SSH2_WRONG_PASSPHRASE
;
600 /* Expect a load of INTEGERs. */
601 if (key
->type
== OSSH_RSA
)
603 else if (key
->type
== OSSH_DSA
)
606 num_integers
= 0; /* placate compiler warnings */
609 * Space to create key blob in.
611 blobsize
= 256+key
->keyblob_len
;
612 blob
= snewn(blobsize
, unsigned char);
614 if (key
->type
== OSSH_DSA
)
615 memcpy(blob
+4, "ssh-dss", 7);
616 else if (key
->type
== OSSH_RSA
)
617 memcpy(blob
+4, "ssh-rsa", 7);
621 for (i
= 0; i
< num_integers
; i
++) {
622 ret
= ber_read_id_len(p
, key
->keyblob
+key
->keyblob_len
-p
,
625 if (ret
< 0 || id
!= 2 ||
626 key
->keyblob
+key
->keyblob_len
-p
< len
) {
627 errmsg
= "ASN.1 decoding failure";
628 retval
= SSH2_WRONG_PASSPHRASE
;
634 * The first integer should be zero always (I think
635 * this is some sort of version indication).
637 if (len
!= 1 || p
[0] != 0) {
638 errmsg
= "version number mismatch";
641 } else if (key
->type
== OSSH_RSA
) {
643 * Integers 1 and 2 go into the public blob but in the
644 * opposite order; integers 3, 4, 5 and 8 go into the
645 * private blob. The other two (6 and 7) are ignored.
648 /* Save the details for after we deal with number 2. */
651 } else if (i
!= 6 && i
!= 7) {
652 PUT_32BIT(blob
+blobptr
, len
);
653 memcpy(blob
+blobptr
+4, p
, len
);
656 PUT_32BIT(blob
+blobptr
, modlen
);
657 memcpy(blob
+blobptr
+4, modptr
, modlen
);
662 } else if (key
->type
== OSSH_DSA
) {
664 * Integers 1-4 go into the public blob; integer 5 goes
665 * into the private blob.
667 PUT_32BIT(blob
+blobptr
, len
);
668 memcpy(blob
+blobptr
+4, p
, len
);
674 /* Skip past the number. */
679 * Now put together the actual key. Simplest way to do this is
680 * to assemble our own key blobs and feed them to the createkey
681 * functions; this is a bit faffy but it does mean we get all
682 * the sanity checks for free.
684 assert(privptr
> 0); /* should have bombed by now if not */
685 retkey
= snew(struct ssh2_userkey
);
686 retkey
->alg
= (key
->type
== OSSH_RSA ?
&ssh_rsa
: &ssh_dss
);
687 retkey
->data
= retkey
->alg
->createkey(blob
, privptr
,
688 blob
+privptr
, blobptr
-privptr
);
691 errmsg
= "unable to create key data structure";
695 retkey
->comment
= dupstr("imported-openssh-key");
696 errmsg
= NULL
; /* no error */
701 memset(blob
, 0, blobsize
);
704 memset(key
->keyblob
, 0, key
->keyblob_size
);
706 memset(key
, 0, sizeof(*key
));
708 if (errmsg_p
) *errmsg_p
= errmsg
;
712 int openssh_write(const Filename
*filename
, struct ssh2_userkey
*key
,
715 unsigned char *pubblob
, *privblob
, *spareblob
;
716 int publen
, privlen
, sparelen
= 0;
717 unsigned char *outblob
;
719 struct mpint_pos numbers
[9];
720 int nnumbers
, pos
, len
, seqlen
, i
;
721 char *header
, *footer
;
728 * Fetch the key blobs.
730 pubblob
= key
->alg
->public_blob(key
->data
, &publen
);
731 privblob
= key
->alg
->private_blob(key
->data
, &privlen
);
732 spareblob
= outblob
= NULL
;
735 * Find the sequence of integers to be encoded into the OpenSSH
736 * key blob, and also decide on the header line.
738 if (key
->alg
== &ssh_rsa
) {
740 struct mpint_pos n
, e
, d
, p
, q
, iqmp
, dmp1
, dmq1
;
741 Bignum bd
, bp
, bq
, bdmp1
, bdmq1
;
743 pos
= 4 + GET_32BIT(pubblob
);
744 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &e
);
745 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &n
);
747 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &d
);
748 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &p
);
749 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &q
);
750 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &iqmp
);
752 assert(e
.start
&& iqmp
.start
); /* can't go wrong */
754 /* We also need d mod (p-1) and d mod (q-1). */
755 bd
= bignum_from_bytes(d
.start
, d
.bytes
);
756 bp
= bignum_from_bytes(p
.start
, p
.bytes
);
757 bq
= bignum_from_bytes(q
.start
, q
.bytes
);
760 bdmp1
= bigmod(bd
, bp
);
761 bdmq1
= bigmod(bd
, bq
);
766 dmp1
.bytes
= (bignum_bitcount(bdmp1
)+8)/8;
767 dmq1
.bytes
= (bignum_bitcount(bdmq1
)+8)/8;
768 sparelen
= dmp1
.bytes
+ dmq1
.bytes
;
769 spareblob
= snewn(sparelen
, unsigned char);
770 dmp1
.start
= spareblob
;
771 dmq1
.start
= spareblob
+ dmp1
.bytes
;
772 for (i
= 0; i
< dmp1
.bytes
; i
++)
773 spareblob
[i
] = bignum_byte(bdmp1
, dmp1
.bytes
-1 - i
);
774 for (i
= 0; i
< dmq1
.bytes
; i
++)
775 spareblob
[i
+dmp1
.bytes
] = bignum_byte(bdmq1
, dmq1
.bytes
-1 - i
);
779 numbers
[0].start
= zero
; numbers
[0].bytes
= 1; zero
[0] = '\0';
790 header
= "-----BEGIN RSA PRIVATE KEY-----\n";
791 footer
= "-----END RSA PRIVATE KEY-----\n";
792 } else if (key
->alg
== &ssh_dss
) {
794 struct mpint_pos p
, q
, g
, y
, x
;
796 pos
= 4 + GET_32BIT(pubblob
);
797 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &p
);
798 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &q
);
799 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &g
);
800 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &y
);
802 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &x
);
804 assert(y
.start
&& x
.start
); /* can't go wrong */
806 numbers
[0].start
= zero
; numbers
[0].bytes
= 1; zero
[0] = '\0';
814 header
= "-----BEGIN DSA PRIVATE KEY-----\n";
815 footer
= "-----END DSA PRIVATE KEY-----\n";
817 assert(0); /* zoinks! */
818 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
822 * Now count up the total size of the ASN.1 encoded integers,
823 * so as to determine the length of the containing SEQUENCE.
826 for (i
= 0; i
< nnumbers
; i
++) {
827 len
+= ber_write_id_len(NULL
, 2, numbers
[i
].bytes
, 0);
828 len
+= numbers
[i
].bytes
;
831 /* Now add on the SEQUENCE header. */
832 len
+= ber_write_id_len(NULL
, 16, seqlen
, ASN1_CONSTRUCTED
);
833 /* Round up to the cipher block size, ensuring we have at least one
834 * byte of padding (see below). */
837 outlen
= (outlen
+8) &~ 7;
840 * Now we know how big outblob needs to be. Allocate it.
842 outblob
= snewn(outlen
, unsigned char);
845 * And write the data into it.
848 pos
+= ber_write_id_len(outblob
+pos
, 16, seqlen
, ASN1_CONSTRUCTED
);
849 for (i
= 0; i
< nnumbers
; i
++) {
850 pos
+= ber_write_id_len(outblob
+pos
, 2, numbers
[i
].bytes
, 0);
851 memcpy(outblob
+pos
, numbers
[i
].start
, numbers
[i
].bytes
);
852 pos
+= numbers
[i
].bytes
;
856 * Padding on OpenSSH keys is deterministic. The number of
857 * padding bytes is always more than zero, and always at most
858 * the cipher block length. The value of each padding byte is
859 * equal to the number of padding bytes. So a plaintext that's
860 * an exact multiple of the block size will be padded with 08
861 * 08 08 08 08 08 08 08 (assuming a 64-bit block cipher); a
862 * plaintext one byte less than a multiple of the block size
863 * will be padded with just 01.
865 * This enables the OpenSSL key decryption function to strip
866 * off the padding algorithmically and return the unpadded
867 * plaintext to the next layer: it looks at the final byte, and
868 * then expects to find that many bytes at the end of the data
869 * with the same value. Those are all removed and the rest is
873 while (pos
< outlen
) {
874 outblob
[pos
++] = outlen
- len
;
880 * For the moment, we still encrypt our OpenSSH keys using
885 * Invent an iv. Then derive encryption key from passphrase
888 * - let block A equal MD5(passphrase || iv)
889 * - let block B equal MD5(A || passphrase || iv)
890 * - block C would be MD5(B || passphrase || iv) and so on
891 * - encryption key is the first N bytes of A || B
893 struct MD5Context md5c
;
894 unsigned char keybuf
[32];
896 for (i
= 0; i
< 8; i
++) iv
[i
] = random_byte();
899 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
900 MD5Update(&md5c
, iv
, 8);
901 MD5Final(keybuf
, &md5c
);
904 MD5Update(&md5c
, keybuf
, 16);
905 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
906 MD5Update(&md5c
, iv
, 8);
907 MD5Final(keybuf
+16, &md5c
);
910 * Now encrypt the key blob.
912 des3_encrypt_pubkey_ossh(keybuf
, iv
, outblob
, outlen
);
914 memset(&md5c
, 0, sizeof(md5c
));
915 memset(keybuf
, 0, sizeof(keybuf
));
919 * And save it. We'll use Unix line endings just in case it's
920 * subsequently transferred in binary mode.
922 fp
= f_open(*filename
, "wb", TRUE
); /* ensure Unix line endings */
927 fprintf(fp
, "Proc-Type: 4,ENCRYPTED\nDEK-Info: DES-EDE3-CBC,");
928 for (i
= 0; i
< 8; i
++)
929 fprintf(fp
, "%02X", iv
[i
]);
932 base64_encode(fp
, outblob
, outlen
, 64);
939 memset(outblob
, 0, outlen
);
943 memset(spareblob
, 0, sparelen
);
947 memset(privblob
, 0, privlen
);
951 memset(pubblob
, 0, publen
);
957 /* ----------------------------------------------------------------------
958 * Code to read ssh.com private keys.
962 * The format of the base64 blob is largely SSH-2-packet-formatted,
963 * except that mpints are a bit different: they're more like the
964 * old SSH-1 mpint. You have a 32-bit bit count N, followed by
965 * (N+7)/8 bytes of data.
967 * So. The blob contains:
969 * - uint32 0x3f6ff9eb (magic number)
970 * - uint32 size (total blob size)
971 * - string key-type (see below)
972 * - string cipher-type (tells you if key is encrypted)
973 * - string encrypted-blob
975 * (The first size field includes the size field itself and the
976 * magic number before it. All other size fields are ordinary SSH-2
977 * strings, so the size field indicates how much data is to
980 * The encrypted blob, once decrypted, contains a single string
981 * which in turn contains the payload. (This allows padding to be
982 * added after that string while still making it clear where the
983 * real payload ends. Also it probably makes for a reasonable
986 * The payload blob, for an RSA key, contains:
989 * - mpint n (yes, the public and private stuff is intermixed)
990 * - mpint u (presumably inverse of p mod q)
991 * - mpint p (p is the smaller prime)
992 * - mpint q (q is the larger)
994 * For a DSA key, the payload blob contains:
1002 * Alternatively, if the parameters are `predefined', that
1003 * (0,p,g,q) sequence can be replaced by a uint32 1 and a string
1004 * containing some predefined parameter specification. *shudder*,
1005 * but I doubt we'll encounter this in real life.
1007 * The key type strings are ghastly. The RSA key I looked at had a
1010 * `if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}'
1012 * and the DSA key wasn't much better:
1014 * `dl-modp{sign{dsa-nist-sha1},dh{plain}}'
1016 * It isn't clear that these will always be the same. I think it
1017 * might be wise just to look at the `if-modn{sign{rsa' and
1018 * `dl-modp{sign{dsa' prefixes.
1020 * Finally, the encryption. The cipher-type string appears to be
1021 * either `none' or `3des-cbc'. Looks as if this is SSH-2-style
1022 * 3des-cbc (i.e. outer cbc rather than inner). The key is created
1023 * from the passphrase by means of yet another hashing faff:
1025 * - first 16 bytes are MD5(passphrase)
1026 * - next 16 bytes are MD5(passphrase || first 16 bytes)
1027 * - if there were more, they'd be MD5(passphrase || first 32),
1031 #define SSHCOM_MAGIC_NUMBER 0x3f6ff9eb
1034 char comment
[256]; /* allowing any length is overkill */
1035 unsigned char *keyblob
;
1036 int keyblob_len
, keyblob_size
;
1039 static struct sshcom_key
*load_sshcom_key(const Filename
*filename
,
1040 const char **errmsg_p
)
1042 struct sshcom_key
*ret
;
1049 int base64_chars
= 0;
1051 ret
= snew(struct sshcom_key
);
1052 ret
->comment
[0] = '\0';
1053 ret
->keyblob
= NULL
;
1054 ret
->keyblob_len
= ret
->keyblob_size
= 0;
1056 fp
= f_open(*filename
, "r", FALSE
);
1058 errmsg
= "unable to open key file";
1061 if (!(line
= fgetline(fp
))) {
1062 errmsg
= "unexpected end of file";
1066 if (0 != strcmp(line
, "---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----")) {
1067 errmsg
= "file does not begin with ssh.com key header";
1070 memset(line
, 0, strlen(line
));
1076 if (!(line
= fgetline(fp
))) {
1077 errmsg
= "unexpected end of file";
1081 if (!strcmp(line
, "---- END SSH2 ENCRYPTED PRIVATE KEY ----"))
1083 if ((p
= strchr(line
, ':')) != NULL
) {
1085 errmsg
= "header found in body of key data";
1089 while (*p
&& isspace((unsigned char)*p
)) p
++;
1090 hdrstart
= p
- line
;
1093 * Header lines can end in a trailing backslash for
1096 len
= hdrstart
+ strlen(line
+hdrstart
);
1098 while (line
[len
-1] == '\\') {
1102 line2
= fgetline(fp
);
1104 errmsg
= "unexpected end of file";
1109 line2len
= strlen(line2
);
1110 line
= sresize(line
, len
+ line2len
+ 1, char);
1111 strcpy(line
+ len
- 1, line2
);
1112 len
+= line2len
- 1;
1115 memset(line2
, 0, strlen(line2
));
1119 p
= line
+ hdrstart
;
1121 if (!strcmp(line
, "Comment")) {
1122 /* Strip quotes in comment if present. */
1123 if (p
[0] == '"' && p
[strlen(p
)-1] == '"') {
1125 p
[strlen(p
)-1] = '\0';
1127 strncpy(ret
->comment
, p
, sizeof(ret
->comment
));
1128 ret
->comment
[sizeof(ret
->comment
)-1] = '\0';
1134 while (isbase64(*p
)) {
1135 base64_bit
[base64_chars
++] = *p
;
1136 if (base64_chars
== 4) {
1137 unsigned char out
[3];
1141 len
= base64_decode_atom(base64_bit
, out
);
1144 errmsg
= "invalid base64 encoding";
1148 if (ret
->keyblob_len
+ len
> ret
->keyblob_size
) {
1149 ret
->keyblob_size
= ret
->keyblob_len
+ len
+ 256;
1150 ret
->keyblob
= sresize(ret
->keyblob
, ret
->keyblob_size
,
1154 memcpy(ret
->keyblob
+ ret
->keyblob_len
, out
, len
);
1155 ret
->keyblob_len
+= len
;
1161 memset(line
, 0, strlen(line
));
1166 if (ret
->keyblob_len
== 0 || !ret
->keyblob
) {
1167 errmsg
= "key body not present";
1171 if (errmsg_p
) *errmsg_p
= NULL
;
1176 memset(line
, 0, strlen(line
));
1182 memset(ret
->keyblob
, 0, ret
->keyblob_size
);
1183 sfree(ret
->keyblob
);
1185 memset(ret
, 0, sizeof(*ret
));
1188 if (errmsg_p
) *errmsg_p
= errmsg
;
1192 int sshcom_encrypted(const Filename
*filename
, char **comment
)
1194 struct sshcom_key
*key
= load_sshcom_key(filename
, NULL
);
1195 int pos
, len
, answer
;
1202 * Check magic number.
1204 if (GET_32BIT(key
->keyblob
) != 0x3f6ff9eb)
1205 return 0; /* key is invalid */
1208 * Find the cipher-type string.
1212 if (key
->keyblob_len
< pos
+4)
1213 goto done
; /* key is far too short */
1214 pos
+= 4 + GET_32BIT(key
->keyblob
+ pos
); /* skip key type */
1215 if (key
->keyblob_len
< pos
+4)
1216 goto done
; /* key is far too short */
1217 len
= GET_32BIT(key
->keyblob
+ pos
); /* find cipher-type length */
1218 if (key
->keyblob_len
< pos
+4+len
)
1219 goto done
; /* cipher type string is incomplete */
1220 if (len
!= 4 || 0 != memcmp(key
->keyblob
+ pos
+ 4, "none", 4))
1224 *comment
= dupstr(key
->comment
);
1225 memset(key
->keyblob
, 0, key
->keyblob_size
);
1226 sfree(key
->keyblob
);
1227 memset(key
, 0, sizeof(*key
));
1232 static int sshcom_read_mpint(void *data
, int len
, struct mpint_pos
*ret
)
1236 unsigned char *d
= (unsigned char *) data
;
1240 bits
= GET_32BIT(d
);
1242 bytes
= (bits
+ 7) / 8;
1253 return len
; /* ensure further calls fail as well */
1256 static int sshcom_put_mpint(void *target
, void *data
, int len
)
1258 unsigned char *d
= (unsigned char *)target
;
1259 unsigned char *i
= (unsigned char *)data
;
1260 int bits
= len
* 8 - 1;
1263 if (*i
& (1 << (bits
& 7)))
1269 PUT_32BIT(d
, bits
+1);
1270 memcpy(d
+4, i
, len
);
1274 struct ssh2_userkey
*sshcom_read(const Filename
*filename
, char *passphrase
,
1275 const char **errmsg_p
)
1277 struct sshcom_key
*key
= load_sshcom_key(filename
, errmsg_p
);
1280 const char prefix_rsa
[] = "if-modn{sign{rsa";
1281 const char prefix_dsa
[] = "dl-modp{sign{dsa";
1282 enum { RSA
, DSA
} type
;
1286 struct ssh2_userkey
*ret
= NULL
, *retkey
;
1287 const struct ssh_signkey
*alg
;
1288 unsigned char *blob
= NULL
;
1289 int blobsize
= 0, publen
, privlen
;
1295 * Check magic number.
1297 if (GET_32BIT(key
->keyblob
) != SSHCOM_MAGIC_NUMBER
) {
1298 errmsg
= "key does not begin with magic number";
1303 * Determine the key type.
1306 if (key
->keyblob_len
< pos
+4 ||
1307 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1308 errmsg
= "key blob does not contain a key type string";
1311 if (len
> sizeof(prefix_rsa
) - 1 &&
1312 !memcmp(key
->keyblob
+pos
+4, prefix_rsa
, sizeof(prefix_rsa
) - 1)) {
1314 } else if (len
> sizeof(prefix_dsa
) - 1 &&
1315 !memcmp(key
->keyblob
+pos
+4, prefix_dsa
, sizeof(prefix_dsa
) - 1)) {
1318 errmsg
= "key is of unknown type";
1324 * Determine the cipher type.
1326 if (key
->keyblob_len
< pos
+4 ||
1327 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1328 errmsg
= "key blob does not contain a cipher type string";
1331 if (len
== 4 && !memcmp(key
->keyblob
+pos
+4, "none", 4))
1333 else if (len
== 8 && !memcmp(key
->keyblob
+pos
+4, "3des-cbc", 8))
1336 errmsg
= "key encryption is of unknown type";
1342 * Get hold of the encrypted part of the key.
1344 if (key
->keyblob_len
< pos
+4 ||
1345 (len
= GET_32BIT(key
->keyblob
+ pos
)) > key
->keyblob_len
- pos
- 4) {
1346 errmsg
= "key blob does not contain actual key data";
1349 ciphertext
= (char *)key
->keyblob
+ pos
+ 4;
1351 if (cipherlen
== 0) {
1352 errmsg
= "length of key data is zero";
1357 * Decrypt it if necessary.
1361 * Derive encryption key from passphrase and iv/salt:
1363 * - let block A equal MD5(passphrase)
1364 * - let block B equal MD5(passphrase || A)
1365 * - block C would be MD5(passphrase || A || B) and so on
1366 * - encryption key is the first N bytes of A || B
1368 struct MD5Context md5c
;
1369 unsigned char keybuf
[32], iv
[8];
1371 if (cipherlen
% 8 != 0) {
1372 errmsg
= "encrypted part of key is not a multiple of cipher block"
1378 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1379 MD5Final(keybuf
, &md5c
);
1382 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1383 MD5Update(&md5c
, keybuf
, 16);
1384 MD5Final(keybuf
+16, &md5c
);
1387 * Now decrypt the key blob.
1389 memset(iv
, 0, sizeof(iv
));
1390 des3_decrypt_pubkey_ossh(keybuf
, iv
, (unsigned char *)ciphertext
,
1393 memset(&md5c
, 0, sizeof(md5c
));
1394 memset(keybuf
, 0, sizeof(keybuf
));
1397 * Hereafter we return WRONG_PASSPHRASE for any parsing
1398 * error. (But only if we've just tried to decrypt it!
1399 * Returning WRONG_PASSPHRASE for an unencrypted key is
1403 ret
= SSH2_WRONG_PASSPHRASE
;
1407 * Strip away the containing string to get to the real meat.
1409 len
= GET_32BIT(ciphertext
);
1410 if (len
< 0 || len
> cipherlen
-4) {
1411 errmsg
= "containing string was ill-formed";
1418 * Now we break down into RSA versus DSA. In either case we'll
1419 * construct public and private blobs in our own format, and
1420 * end up feeding them to alg->createkey().
1422 blobsize
= cipherlen
+ 256;
1423 blob
= snewn(blobsize
, unsigned char);
1426 struct mpint_pos n
, e
, d
, u
, p
, q
;
1428 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &e
);
1429 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &d
);
1430 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &n
);
1431 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &u
);
1432 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &p
);
1433 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &q
);
1435 errmsg
= "key data did not contain six integers";
1441 pos
+= put_string(blob
+pos
, "ssh-rsa", 7);
1442 pos
+= put_mp(blob
+pos
, e
.start
, e
.bytes
);
1443 pos
+= put_mp(blob
+pos
, n
.start
, n
.bytes
);
1445 pos
+= put_string(blob
+pos
, d
.start
, d
.bytes
);
1446 pos
+= put_mp(blob
+pos
, q
.start
, q
.bytes
);
1447 pos
+= put_mp(blob
+pos
, p
.start
, p
.bytes
);
1448 pos
+= put_mp(blob
+pos
, u
.start
, u
.bytes
);
1449 privlen
= pos
- publen
;
1450 } else if (type
== DSA
) {
1451 struct mpint_pos p
, q
, g
, x
, y
;
1453 if (GET_32BIT(ciphertext
) != 0) {
1454 errmsg
= "predefined DSA parameters not supported";
1457 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &p
);
1458 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &g
);
1459 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &q
);
1460 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &y
);
1461 pos
+= sshcom_read_mpint(ciphertext
+pos
, cipherlen
-pos
, &x
);
1463 errmsg
= "key data did not contain five integers";
1469 pos
+= put_string(blob
+pos
, "ssh-dss", 7);
1470 pos
+= put_mp(blob
+pos
, p
.start
, p
.bytes
);
1471 pos
+= put_mp(blob
+pos
, q
.start
, q
.bytes
);
1472 pos
+= put_mp(blob
+pos
, g
.start
, g
.bytes
);
1473 pos
+= put_mp(blob
+pos
, y
.start
, y
.bytes
);
1475 pos
+= put_mp(blob
+pos
, x
.start
, x
.bytes
);
1476 privlen
= pos
- publen
;
1480 assert(privlen
> 0); /* should have bombed by now if not */
1482 retkey
= snew(struct ssh2_userkey
);
1484 retkey
->data
= alg
->createkey(blob
, publen
, blob
+publen
, privlen
);
1485 if (!retkey
->data
) {
1487 errmsg
= "unable to create key data structure";
1490 retkey
->comment
= dupstr(key
->comment
);
1492 errmsg
= NULL
; /* no error */
1497 memset(blob
, 0, blobsize
);
1500 memset(key
->keyblob
, 0, key
->keyblob_size
);
1501 sfree(key
->keyblob
);
1502 memset(key
, 0, sizeof(*key
));
1504 if (errmsg_p
) *errmsg_p
= errmsg
;
1508 int sshcom_write(const Filename
*filename
, struct ssh2_userkey
*key
,
1511 unsigned char *pubblob
, *privblob
;
1512 int publen
, privlen
;
1513 unsigned char *outblob
;
1515 struct mpint_pos numbers
[6];
1516 int nnumbers
, initial_zero
, pos
, lenpos
, i
;
1524 * Fetch the key blobs.
1526 pubblob
= key
->alg
->public_blob(key
->data
, &publen
);
1527 privblob
= key
->alg
->private_blob(key
->data
, &privlen
);
1531 * Find the sequence of integers to be encoded into the OpenSSH
1532 * key blob, and also decide on the header line.
1534 if (key
->alg
== &ssh_rsa
) {
1536 struct mpint_pos n
, e
, d
, p
, q
, iqmp
;
1538 pos
= 4 + GET_32BIT(pubblob
);
1539 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &e
);
1540 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &n
);
1542 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &d
);
1543 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &p
);
1544 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &q
);
1545 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &iqmp
);
1547 assert(e
.start
&& iqmp
.start
); /* can't go wrong */
1558 type
= "if-modn{sign{rsa-pkcs1-sha1},encrypt{rsa-pkcs1v2-oaep}}";
1559 } else if (key
->alg
== &ssh_dss
) {
1561 struct mpint_pos p
, q
, g
, y
, x
;
1563 pos
= 4 + GET_32BIT(pubblob
);
1564 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &p
);
1565 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &q
);
1566 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &g
);
1567 pos
+= ssh2_read_mpint(pubblob
+pos
, publen
-pos
, &y
);
1569 pos
+= ssh2_read_mpint(privblob
+pos
, privlen
-pos
, &x
);
1571 assert(y
.start
&& x
.start
); /* can't go wrong */
1581 type
= "dl-modp{sign{dsa-nist-sha1},dh{plain}}";
1583 assert(0); /* zoinks! */
1584 exit(1); /* XXX: GCC doesn't understand assert() on some systems. */
1588 * Total size of key blob will be somewhere under 512 plus
1589 * combined length of integers. We'll calculate the more
1590 * precise size as we construct the blob.
1593 for (i
= 0; i
< nnumbers
; i
++)
1594 outlen
+= 4 + numbers
[i
].bytes
;
1595 outblob
= snewn(outlen
, unsigned char);
1598 * Create the unencrypted key blob.
1601 PUT_32BIT(outblob
+pos
, SSHCOM_MAGIC_NUMBER
); pos
+= 4;
1602 pos
+= 4; /* length field, fill in later */
1603 pos
+= put_string(outblob
+pos
, type
, strlen(type
));
1605 char *ciphertype
= passphrase ?
"3des-cbc" : "none";
1606 pos
+= put_string(outblob
+pos
, ciphertype
, strlen(ciphertype
));
1608 lenpos
= pos
; /* remember this position */
1609 pos
+= 4; /* encrypted-blob size */
1610 pos
+= 4; /* encrypted-payload size */
1612 PUT_32BIT(outblob
+pos
, 0);
1615 for (i
= 0; i
< nnumbers
; i
++)
1616 pos
+= sshcom_put_mpint(outblob
+pos
,
1617 numbers
[i
].start
, numbers
[i
].bytes
);
1618 /* Now wrap up the encrypted payload. */
1619 PUT_32BIT(outblob
+lenpos
+4, pos
- (lenpos
+8));
1620 /* Pad encrypted blob to a multiple of cipher block size. */
1622 int padding
= -(pos
- (lenpos
+4)) & 7;
1624 outblob
[pos
++] = random_byte();
1626 ciphertext
= (char *)outblob
+lenpos
+4;
1627 cipherlen
= pos
- (lenpos
+4);
1628 assert(!passphrase
|| cipherlen
% 8 == 0);
1629 /* Wrap up the encrypted blob string. */
1630 PUT_32BIT(outblob
+lenpos
, cipherlen
);
1631 /* And finally fill in the total length field. */
1632 PUT_32BIT(outblob
+4, pos
);
1634 assert(pos
< outlen
);
1641 * Derive encryption key from passphrase and iv/salt:
1643 * - let block A equal MD5(passphrase)
1644 * - let block B equal MD5(passphrase || A)
1645 * - block C would be MD5(passphrase || A || B) and so on
1646 * - encryption key is the first N bytes of A || B
1648 struct MD5Context md5c
;
1649 unsigned char keybuf
[32], iv
[8];
1652 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1653 MD5Final(keybuf
, &md5c
);
1656 MD5Update(&md5c
, (unsigned char *)passphrase
, strlen(passphrase
));
1657 MD5Update(&md5c
, keybuf
, 16);
1658 MD5Final(keybuf
+16, &md5c
);
1661 * Now decrypt the key blob.
1663 memset(iv
, 0, sizeof(iv
));
1664 des3_encrypt_pubkey_ossh(keybuf
, iv
, (unsigned char *)ciphertext
,
1667 memset(&md5c
, 0, sizeof(md5c
));
1668 memset(keybuf
, 0, sizeof(keybuf
));
1672 * And save it. We'll use Unix line endings just in case it's
1673 * subsequently transferred in binary mode.
1675 fp
= f_open(*filename
, "wb", TRUE
); /* ensure Unix line endings */
1678 fputs("---- BEGIN SSH2 ENCRYPTED PRIVATE KEY ----\n", fp
);
1679 fprintf(fp
, "Comment: \"");
1681 * Comment header is broken with backslash-newline if it goes
1682 * over 70 chars. Although it's surrounded by quotes, it
1683 * _doesn't_ escape backslashes or quotes within the string.
1684 * Don't ask me, I didn't design it.
1687 int slen
= 60; /* starts at 60 due to "Comment: " */
1688 char *c
= key
->comment
;
1689 while ((int)strlen(c
) > slen
) {
1690 fprintf(fp
, "%.*s\\\n", slen
, c
);
1692 slen
= 70; /* allow 70 chars on subsequent lines */
1694 fprintf(fp
, "%s\"\n", c
);
1696 base64_encode(fp
, outblob
, pos
, 70);
1697 fputs("---- END SSH2 ENCRYPTED PRIVATE KEY ----\n", fp
);
1703 memset(outblob
, 0, outlen
);
1707 memset(privblob
, 0, privlen
);
1711 memset(pubblob
, 0, publen
);