1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
/* pksign.c - public key signing (well, acually using a secret key)
* Copyright (C) 2001 Free Software Foundation, Inc.
*
* This file is part of GnuPG.
*
* GnuPG is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* GnuPG is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include <config.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <assert.h>
#include <unistd.h>
#include <sys/stat.h>
#include "agent.h"
static int
do_encode_md (const unsigned char *digest, size_t digestlen, int algo,
unsigned int nbits, GCRY_MPI *r_val)
{
int nframe = (nbits+7) / 8;
byte *frame;
int i, n;
byte asn[100];
size_t asnlen;
asnlen = DIM(asn);
if (gcry_md_algo_info (algo, GCRYCTL_GET_ASNOID, asn, &asnlen))
{
log_error ("no object identifier for algo %d\n", algo);
return GNUPG_Internal_Error;
}
if (digestlen + asnlen + 4 > nframe )
{
log_error ("can't encode a %d bit MD into a %d bits frame\n",
(int)(digestlen*8), (int)nbits);
return GNUPG_Internal_Error;
}
/* We encode the MD in this way:
*
* 0 1 PAD(n bytes) 0 ASN(asnlen bytes) MD(len bytes)
*
* PAD consists of FF bytes.
*/
frame = xtrymalloc (nframe);
if (!frame)
return GNUPG_Out_Of_Core;
n = 0;
frame[n++] = 0;
frame[n++] = 1; /* block type */
i = nframe - digestlen - asnlen -3 ;
assert ( i > 1 );
memset ( frame+n, 0xff, i ); n += i;
frame[n++] = 0;
memcpy ( frame+n, asn, asnlen ); n += asnlen;
memcpy ( frame+n, digest, digestlen ); n += digestlen;
assert ( n == nframe );
if (DBG_CRYPTO)
log_printhex ("encoded hash:", frame, nframe);
gcry_mpi_scan (r_val, GCRYMPI_FMT_USG, frame, &nframe);
xfree (frame);
return 0;
}
/* SIGN whatever information we have accumulated in CTRL and write it
back to OUTFP. */
int
agent_pksign (CTRL ctrl, FILE *outfp, int ignore_cache)
{
GCRY_SEXP s_skey = NULL, s_hash = NULL, s_sig = NULL;
GCRY_MPI frame = NULL;
unsigned char *shadow_info = NULL;
int rc;
char *buf = NULL;
size_t len;
if (!ctrl->have_keygrip)
return seterr (No_Secret_Key);
s_skey = agent_key_from_file (ctrl->keygrip, &shadow_info, ignore_cache);
if (!s_skey && !shadow_info)
{
log_error ("failed to read the secret key\n");
rc = seterr (No_Secret_Key);
goto leave;
}
if (!s_skey)
{ /* divert operation to the smartcard */
unsigned char *sigbuf;
rc = divert_pksign (ctrl->digest.value,
ctrl->digest.valuelen,
ctrl->digest.algo,
shadow_info, &sigbuf);
if (rc)
{
log_error ("smartcard signing failed: %s\n", gnupg_strerror (rc));
goto leave;
}
len = gcry_sexp_canon_len (sigbuf, 0, NULL, NULL);
assert (len);
buf = sigbuf;
}
else
{ /* no smartcard, but a private key */
/* put the hash into a sexp */
rc = do_encode_md (ctrl->digest.value,
ctrl->digest.valuelen,
ctrl->digest.algo,
gcry_pk_get_nbits (s_skey),
&frame);
if (rc)
goto leave;
if ( gcry_sexp_build (&s_hash, NULL, "%m", frame) )
BUG ();
if (DBG_CRYPTO)
{
log_debug ("skey: ");
gcry_sexp_dump (s_skey);
}
/* sign */
rc = gcry_pk_sign (&s_sig, s_hash, s_skey);
if (rc)
{
log_error ("signing failed: %s\n", gcry_strerror (rc));
rc = map_gcry_err (rc);
goto leave;
}
if (DBG_CRYPTO)
{
log_debug ("result: ");
gcry_sexp_dump (s_sig);
}
len = gcry_sexp_sprint (s_sig, GCRYSEXP_FMT_CANON, NULL, 0);
assert (len);
buf = xmalloc (len);
len = gcry_sexp_sprint (s_sig, GCRYSEXP_FMT_CANON, buf, len);
assert (len);
}
/* FIXME: we must make sure that no buffering takes place or we are
in full control of the buffer memory (easy to do) - should go
into assuan. */
fwrite (buf, 1, len, outfp);
leave:
gcry_sexp_release (s_skey);
gcry_sexp_release (s_hash);
gcry_sexp_release (s_sig);
gcry_mpi_release (frame);
xfree (buf);
xfree (shadow_info);
return rc;
}
|
