mirror of
git://git.gnupg.org/gnupg.git
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332 lines
8.5 KiB
C
332 lines
8.5 KiB
C
/* findkey.c - locate the secret key
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* Copyright (C) 2001 Free Software Foundation, Inc.
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*
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* This file is part of GnuPG.
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*
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* GnuPG is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* GnuPG is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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*/
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#include <config.h>
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#include <errno.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <ctype.h>
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#include <assert.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include <assert.h>
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#include "agent.h"
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/* Helper to pass data to the check callback of the unprotect function. */
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struct try_unprotect_arg_s {
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const unsigned char *protected_key;
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unsigned char *unprotected_key;
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};
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int
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agent_write_private_key (const unsigned char *grip,
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const void *buffer, size_t length, int force)
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{
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int i;
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char *fname;
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FILE *fp;
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char hexgrip[40+4+1];
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for (i=0; i < 20; i++)
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sprintf (hexgrip+2*i, "%02X", grip[i]);
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strcpy (hexgrip+40, ".key");
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fname = make_filename (opt.homedir, GNUPG_PRIVATE_KEYS_DIR, hexgrip, NULL);
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if (force)
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fp = fopen (fname, "wb");
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else
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{
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if (!access (fname, F_OK))
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{
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log_error ("secret key file `%s' already exists\n", fname);
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xfree (fname);
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return seterr (General_Error);
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}
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fp = fopen (fname, "wbx"); /* FIXME: the x is a GNU extension - let
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configure check whether this actually
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works */
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}
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if (!fp)
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{
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log_error ("can't create `%s': %s\n", fname, strerror (errno));
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xfree (fname);
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return seterr (File_Create_Error);
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}
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if (fwrite (buffer, length, 1, fp) != 1)
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{
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log_error ("error writing `%s': %s\n", fname, strerror (errno));
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fclose (fp);
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remove (fname);
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xfree (fname);
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return seterr (File_Create_Error);
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}
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if ( fclose (fp) )
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{
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log_error ("error closing `%s': %s\n", fname, strerror (errno));
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remove (fname);
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xfree (fname);
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return seterr (File_Create_Error);
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}
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xfree (fname);
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return 0;
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}
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/* Callback function to try the unprotection from the passpharse query
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code. */
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static int
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try_unprotect_cb (struct pin_entry_info_s *pi)
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{
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struct try_unprotect_arg_s *arg = pi->check_cb_arg;
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size_t dummy;
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assert (!arg->unprotected_key);
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return agent_unprotect (arg->protected_key, pi->pin,
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&arg->unprotected_key, &dummy);
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}
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/* Unprotect the canconical encoded S-expression key in KEYBUF. GRIP
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should be the hex encoded keygrip of that key to be used with the
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cahing mechanism. */
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static int
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unprotect (unsigned char **keybuf, const unsigned char *grip, int ignore_cache)
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{
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struct pin_entry_info_s *pi;
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struct try_unprotect_arg_s arg;
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int rc, i;
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unsigned char *result;
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size_t resultlen;
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char hexgrip[40+1];
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for (i=0; i < 20; i++)
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sprintf (hexgrip+2*i, "%02X", grip[i]);
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hexgrip[40] = 0;
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/* first try to get it from the cache - if there is none or we can't
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unprotect it, we fall back to ask the user */
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if (!ignore_cache)
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{
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void *cache_marker;
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const char *pw = agent_get_cache (hexgrip, &cache_marker);
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if (pw)
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{
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rc = agent_unprotect (*keybuf, pw, &result, &resultlen);
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agent_unlock_cache_entry (&cache_marker);
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if (!rc)
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{
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xfree (*keybuf);
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*keybuf = result;
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return 0;
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}
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rc = 0;
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}
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}
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pi = gcry_calloc_secure (1, sizeof (*pi) + 100);
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pi->max_length = 100;
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pi->min_digits = 0; /* we want a real passphrase */
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pi->max_digits = 8;
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pi->max_tries = 3;
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pi->check_cb = try_unprotect_cb;
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arg.protected_key = *keybuf;
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arg.unprotected_key = NULL;
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pi->check_cb_arg = &arg;
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rc = agent_askpin (NULL, pi);
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if (!rc)
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{
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assert (arg.unprotected_key);
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agent_put_cache (hexgrip, pi->pin, 0);
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xfree (*keybuf);
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*keybuf = arg.unprotected_key;
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}
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xfree (pi);
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return rc;
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}
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/* Return the secret key as an S-Exp after locating it using the grip.
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Returns NULL if key is not available or the operation should be
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diverted to a token. In the latter case shadow_info will point to
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an allocated S-Expression with the shadow_info part from the file.
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With IGNORE_CACHE passed as true the passphrase is not taken from
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the cache.*/
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GCRY_SEXP
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agent_key_from_file (const unsigned char *grip, unsigned char **shadow_info,
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int ignore_cache)
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{
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int i, rc;
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char *fname;
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FILE *fp;
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struct stat st;
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unsigned char *buf;
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size_t len, buflen, erroff;
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GCRY_SEXP s_skey;
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char hexgrip[40+4+1];
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if (shadow_info)
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*shadow_info = NULL;
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for (i=0; i < 20; i++)
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sprintf (hexgrip+2*i, "%02X", grip[i]);
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strcpy (hexgrip+40, ".key");
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fname = make_filename (opt.homedir, GNUPG_PRIVATE_KEYS_DIR, hexgrip, NULL);
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fp = fopen (fname, "rb");
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if (!fp)
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{
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log_error ("can't open `%s': %s\n", fname, strerror (errno));
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xfree (fname);
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return NULL;
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}
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if (fstat (fileno(fp), &st))
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{
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log_error ("can't stat `%s': %s\n", fname, strerror (errno));
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xfree (fname);
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fclose (fp);
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return NULL;
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}
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buflen = st.st_size;
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buf = xmalloc (buflen+1);
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if (fread (buf, buflen, 1, fp) != 1)
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{
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log_error ("error reading `%s': %s\n", fname, strerror (errno));
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xfree (fname);
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fclose (fp);
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xfree (buf);
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return NULL;
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}
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rc = gcry_sexp_sscan (&s_skey, &erroff, buf, buflen);
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xfree (fname);
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fclose (fp);
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xfree (buf);
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if (rc)
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{
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log_error ("failed to build S-Exp (off=%u): %s\n",
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(unsigned int)erroff, gcry_strerror (rc));
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return NULL;
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}
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len = gcry_sexp_sprint (s_skey, GCRYSEXP_FMT_CANON, NULL, 0);
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assert (len);
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buf = xtrymalloc (len);
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if (!buf)
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{
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gcry_sexp_release (s_skey);
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return NULL;
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}
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len = gcry_sexp_sprint (s_skey, GCRYSEXP_FMT_CANON, buf, len);
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assert (len);
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gcry_sexp_release (s_skey);
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switch (agent_private_key_type (buf))
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{
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case PRIVATE_KEY_CLEAR:
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break; /* no unprotection needed */
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case PRIVATE_KEY_PROTECTED:
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rc = unprotect (&buf, grip, ignore_cache);
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if (rc)
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log_error ("failed to unprotect the secret key: %s\n",
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gnupg_strerror (rc));
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break;
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case PRIVATE_KEY_SHADOWED:
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if (shadow_info)
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{
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const unsigned char *s;
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size_t n;
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rc = agent_get_shadow_info (buf, &s);
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if (!rc)
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{
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n = gcry_sexp_canon_len (s, 0, NULL,NULL);
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assert (n);
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*shadow_info = xtrymalloc (n);
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if (!*shadow_info)
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rc = GNUPG_Out_Of_Core;
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else
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{
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memcpy (*shadow_info, s, n);
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rc = 0;
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}
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}
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if (rc)
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log_error ("get_shadow_info failed: %s\n", gnupg_strerror (rc));
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}
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rc = -1; /* ugly interface: we return an error but keep a value
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in shadow_info. */
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break;
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default:
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log_error ("invalid private key format\n");
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rc = GNUPG_Bad_Secret_Key;
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break;
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}
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if (rc)
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{
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xfree (buf);
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return NULL;
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}
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/* arggg FIXME: does scan support secure memory? */
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rc = gcry_sexp_sscan (&s_skey, &erroff,
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buf, gcry_sexp_canon_len (buf, 0, NULL, NULL));
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xfree (buf);
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if (rc)
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{
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log_error ("failed to build S-Exp (off=%u): %s\n",
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(unsigned int)erroff, gcry_strerror (rc));
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return NULL;
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}
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return s_skey;
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}
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/* Return the secret key as an S-Exp after locating it using the grip.
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Returns NULL if key is not available. 0 = key is available */
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int
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agent_key_available (const unsigned char *grip)
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{
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int i;
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char *fname;
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char hexgrip[40+4+1];
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for (i=0; i < 20; i++)
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sprintf (hexgrip+2*i, "%02X", grip[i]);
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strcpy (hexgrip+40, ".key");
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fname = make_filename (opt.homedir, GNUPG_PRIVATE_KEYS_DIR, hexgrip, NULL);
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i = !access (fname, R_OK)? 0 : -1;
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xfree (fname);
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return i;
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}
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