trunk/Src/wptPassphraseCB.cpp

/* wptPassphraseCB.cpp - GPGME Passphrase Callback
 *      Copyright (C) 2001, 2002, 2003 Timo Schulz
 *
 * This file is part of WinPT.
 *
 * WinPT 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.
 *  
 * WinPT 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 WinPT; if not, write to the Free Software Foundation, 
 * Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 
 */

#include <windows.h>
#include <ctype.h>

#include "../resource.h"
#include "wptNLS.h"
#include "wptW32API.h"
#include "wptVersion.h"
#include "wptGPG.h"
#include "wptCommonCtl.h"
#include "wptContext.h"
#include "wptDlgs.h"
#include "wptUTF8.h"
#include "wptErrors.h"
#include "wptTypes.h"
#include "wptAgent.h"
#include "wptRegistry.h"


#define item_ctrl_id( cmd ) \
    ((cmd) == GPG_CMD_DECRYPT? IDC_DECRYPT_PWD : IDC_DECRYPT_SIGN_PWD)


BOOL CALLBACK
passphrase_callback_proc (HWND dlg, UINT msg, WPARAM wparam, LPARAM lparam)
{    
    static passphrase_cb_s * c;
    static int hide = 1;
    gpgme_key_t key;
    const char * s, * id;
    char info[768] = {0};
    void * ctx = NULL, * item;
    unsigned int pkalgo;

    switch( msg )  {
    case WM_INITDIALOG:
        hide = 1;
        c = (passphrase_cb_s *)lparam;
        if (!c)
            BUG (0);
        SetWindowText (dlg, c->title);
        if (c->gpg_cmd == GPG_CMD_DECRYPT) {
            SetDlgItemText( dlg, IDC_DECRYPT_LISTINF,
                _("Encrypted with the following public key(s)") );
            CheckDlgButton( dlg, IDC_DECRYPT_HIDE, BST_CHECKED );
        }
        else if( c->gpg_cmd == GPG_CMD_SIGN )
            CheckDlgButton( dlg, IDC_DECRYPT_SIGN_HIDE, BST_CHECKED );
        if( c->enc_to && c->gpg_cmd == GPG_CMD_DECRYPT ) {
            gpgme_recipients_enum_open( c->enc_to, &ctx );
            while ( (s = gpgme_recipients_enum_read( c->enc_to, &ctx )) ) {
                pkalgo = *s; s++;
                get_pubkey( s, &key );
                if( key ) {
                    char * uid = NULL;
                    id = gpgme_key_get_string_attr( key, GPGME_ATTR_USERID, NULL, 0 );
                    if( !id )
                        id = _("Invalid User ID");
                    uid = utf8_to_wincp (id, strlen (id));                 
                    _snprintf( info, sizeof info - 1, "%s (%s, 0x%s)", uid,
                                gpgme_key_expand_attr( GPGME_ATTR_ALGO, pkalgo ), s+8 );
                    free( uid );
                }
                else
                    _snprintf( info, sizeof info - 1, _("Unknown (key ID 0x%s)"),
                               s? s + 8 : "DEADBEEF" );
                listbox_add_string( GetDlgItem( dlg, IDC_DECRYPT_LIST ), info );
            }
            gpgme_recipients_enum_close( c->enc_to, &ctx );
        }
        SetDlgItemText( dlg, c->gpg_cmd == GPG_CMD_DECRYPT?
                        IDC_DECRYPT_PWDINFO : IDC_DECRYPT_SIGN_PWDINFO,
                        _("Please enter your passphrase") );
        if( c->gpg_cmd == GPG_CMD_DECRYPT ) {
            SetFocus( GetDlgItem( dlg, IDC_DECRYPT_PWD ) );
            SetDlgItemText( dlg, IDC_DECRYPT_MSG, c->info );
        }
        else {
            SetFocus( GetDlgItem( dlg, IDC_DECRYPT_SIGN_PWD ) );
            SetDlgItemText( dlg, IDC_DECRYPT_SIGN_MSG, c->info );
        }
        center_window( dlg );
        SetForegroundWindow( dlg );
        set_active_window( dlg );
        return FALSE;

        case WM_SYSCOMMAND:
            if( LOWORD( wparam ) == SC_CLOSE ) {
                SetDlgItemText( dlg, item_ctrl_id( c->gpg_cmd ), "" );
                c->cancel = 1;
                EndDialog( dlg, TRUE );
            }
            return FALSE;

        case WM_COMMAND:
            switch( HIWORD( wparam ) ) {
            case BN_CLICKED:
                if ( LOWORD( wparam ) == IDC_DECRYPT_HIDE
                    || LOWORD( wparam ) == IDC_DECRYPT_SIGN_HIDE ) {
                    HWND hwnd;
                    hide ^= 1;
                    hwnd = GetDlgItem( dlg, item_ctrl_id( c->gpg_cmd ) );
                    SendMessage( hwnd, EM_SETPASSWORDCHAR, hide? '*' : 0, 0 );
                    SetFocus( hwnd );
                }
            }

            switch (LOWORD (wparam)) {
            case IDOK:  
                /* fixme: the item is even cached when the passphrase is not
                          correct, which means that the user needs to delete all
                          cached entries to continue. */
                GetDlgItemText (dlg, item_ctrl_id (c->gpg_cmd), c->pwd, sizeof (c->pwd) -1);
                if (reg_prefs.cache_time > 0 && !c->is_card && !strstr (c->keyid, "missing")) {
                    if (agent_get_cache (c->keyid, &item))
                        agent_unlock_cache_entry (&item);
                    else
                        agent_put_cache (c->keyid, c->pwd, reg_prefs.cache_time);
                }
                EndDialog (dlg, TRUE);
                return TRUE;
                
            case IDCANCEL:
                SetDlgItemText (dlg, item_ctrl_id (c->gpg_cmd), "" );
                c->cancel = 1;
                EndDialog (dlg, FALSE);
                return FALSE;
            }
            break;
    }
    
    return FALSE;
} /* passphrase_callback_proc */


static const char *
parse_gpg_keyid( const char * desc )
{
    static char keyid[16+1];
    char * p;
    
    p = strrchr( desc, '\n' );
    if( !p )
        return NULL;
    /* the format of the desc buffer looks like this:
       request_keyid[16] main_keyid[16] keytype[1] keylength[4]
       we use the main keyid to use only one cache entry. */
    strncpy( keyid, desc+(p-desc+1+17), 16 );
    return keyid;
} /* parse_gpg_keyid */


static void
parse_gpg_description( char * desc, int size )
{
    char * buffer = NULL, ch, uid[128] = {0}, * uid2 = NULL;
    char usedkey[16+1] = {0}, mainkey[16+1] = {0};
    const char * buf;
    int i, algo, try_again = 0;

    if( stristr( desc, "[User ID hint missing]" ) 
        || stristr( desc, "[passphrase info missing]" ) ) {
        _snprintf( desc, size-1, 
                   _("You need a passphrase to unlock the secret key for\n"
                     "user: [UserID hint missing]\n"
                     "      [passphrase info missing]\n") );
        return;
    }

    buffer = new char[size+1];
    if( !buffer )
        BUG( NULL );
    strcpy( buffer, desc );
    buf = buffer;
    if( strstr( buf, "TRY_AGAIN" ) ) {
        buf += strlen( "TRY_AGAIN\n" );
        try_again = 1;
    }
    else if( strstr( buf, "ENTER_PASSPHRASE" ) )
        buf += strlen( "ENTER_PASSPHRASE\n" );
    else
        BUG( NULL );
    buf += 17;
    for( i = 0; i < sizeof uid-1; i++ ) {
        ch = *buf++;
        if( ch == '\n' ) {
            uid[i] = '\0';
            break;
        }
        uid[i] = ch;
    }
    memcpy( usedkey, buf, 16 );
    usedkey[16] = '\0';
    buf += 17;
    memcpy( mainkey, buf, 16 );
    mainkey[16] = '\0';
    buf += 17;
    if( !buf )
        BUG( NULL );
    algo = atol( buf );
    free_if_alloc( buffer );

    uid2 = utf8_to_wincp (uid, strlen (uid));

    if( strcmp( usedkey, mainkey ) )
        _snprintf( desc, size-1, 
                   _("You need a passphrase to unlock the secret key for\n"
                     "user: \"%s\"\n"
                     "%s key, ID %s (main key ID %s)\n"),
                   uid2, gpgme_key_expand_attr( GPGME_ATTR_ALGO, algo ),
                   usedkey+8, mainkey+8 );
    else if( !strcmp( usedkey, mainkey ) )
        _snprintf( desc, size-1, 
                   _("You need a passphrase to unlock the secret key for\n"
                     "user: \"%s\"\n"
                     "%s key, ID %s\n"),
                     uid2, gpgme_key_expand_attr( GPGME_ATTR_ALGO, algo ),
                     usedkey+8 );
    free( uid2 );
} /* parse_gpg_describtion */


static int inline
is_hexstring( const char * p )
{
    size_t i;
    for( i=0; i < strlen( p ); i++ ) {
        if( !isxdigit( p[i] ) )
            return -1;
    }
    return 0;
}


const char *
passphrase_cb( void * opaque, const char * desc, void * r_hd )
{   
    passphrase_cb_s * c = (passphrase_cb_s *)opaque;
    void * item;
    const char * pass, * keyid;
    int rc = 0;

    if( !c )
        return NULL;

    if( desc ) {
        keyid = parse_gpg_keyid( desc );
        pass = agent_get_cache( keyid, &item );
        if( pass ) {
            agent_unlock_cache_entry( &item );
            c->pwd_init = 0;
            return pass;
        }
    }

    if( c->pwd_init ) {
        c->keyid = keyid;
        /* if the desc has a length of 32 and only hex digits, we assume a 
           smart card has been used. */ 
        /*log_box( "", 0, "%s %d %d", desc,strlen( desc), is_hexstring( desc ) );*/
        if( desc && strlen( desc ) == 32 && !is_hexstring( desc ) ) {
            char buf[16];
            memset( buf, 0, sizeof buf );
            strncpy( buf, desc+20, 8 );
            _snprintf( c->info, sizeof c->info-1,
                    _("Please enter the PIN to unlock your secret card key\n"
                      "Card: %s"), buf );
            c->is_card = 1;
        }
        else if( desc ) {
            strcpy( c->info, desc );
            parse_gpg_description( c->info, sizeof c->info - 1 );
        }
        if( c->gpg_cmd == GPG_CMD_DECRYPT ) {
            rc = DialogBoxParam( glob_hinst, (LPCSTR)IDD_WINPT_DECRYPT,
                                (HWND)c->hwnd, passphrase_callback_proc, 
                                (LPARAM)c );
        }
        else if( c->gpg_cmd == GPG_CMD_SIGN ) {
            rc = DialogBoxParam( glob_hinst, (LPCSTR)IDD_WINPT_DECRYPT_SIGN,
                                (HWND)c->hwnd, passphrase_callback_proc, 
                                (LPARAM)c );
        }
        if( rc == -1 )
            return NULL;
        c->pwd_init = 0;
    }

    if( c->cancel )
        return NULL;

    return c->pwd;
} /* passphrase_cb */


void
set_gpg_passphrase_cb( gpgme_ctx_t c, passphrase_cb_s * ctx, int cmd, 
                       HWND hwnd, const char * title )
{
    ctx->gpg_cmd = cmd;
    ctx->is_card = 0;
    ctx->cancel = 0;
    ctx->hwnd = hwnd;
    ctx->pwd_init = 1;
    if( strlen( title ) > 256 )
        BUG( NULL ); /* check bounds */
    strcpy( ctx->title, title );
    gpgme_set_passphrase_cb( c, passphrase_cb, ctx );
} /* set_gpg_passphrase_cb */
1	twoaday	2	/* wptPassphraseCB.cpp - GPGME Passphrase Callback
2			* Copyright (C) 2001, 2002, 2003 Timo Schulz
3			*
4			* This file is part of WinPT.
5			*
6			* WinPT is free software; you can redistribute it and/or
7			* modify it under the terms of the GNU General Public License
8			* as published by the Free Software Foundation; either version 2
9			* of the License, or (at your option) any later version.
10			*
11			* WinPT is distributed in the hope that it will be useful,
12			* but WITHOUT ANY WARRANTY; without even the implied warranty of
13			* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14			* General Public License for more details.
15			*
16			* You should have received a copy of the GNU General Public License
17			* along with WinPT; if not, write to the Free Software Foundation,
18			* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
19			*/
20
21			#include <windows.h>
22			#include <ctype.h>
23
24			#include "../resource.h"
25			#include "wptNLS.h"
26			#include "wptW32API.h"
27			#include "wptVersion.h"
28			#include "wptGPG.h"
29			#include "wptCommonCtl.h"
30			#include "wptContext.h"
31			#include "wptDlgs.h"
32			#include "wptUTF8.h"
33			#include "wptErrors.h"
34			#include "wptTypes.h"
35			#include "wptAgent.h"
36			#include "wptRegistry.h"
37
38
39			#define item_ctrl_id( cmd ) \
40			((cmd) == GPG_CMD_DECRYPT? IDC_DECRYPT_PWD : IDC_DECRYPT_SIGN_PWD)
41
42
43			BOOL CALLBACK
44	twoaday	4	passphrase_callback_proc (HWND dlg, UINT msg, WPARAM wparam, LPARAM lparam)
45	twoaday	2	{
46			static passphrase_cb_s * c;
47	twoaday	4	static int hide = 1;
48	twoaday	2	gpgme_key_t key;
49			const char * s, * id;
50			char info[768] = {0};
51			void * ctx = NULL, * item;
52			unsigned int pkalgo;
53
54			switch( msg ) {
55			case WM_INITDIALOG:
56	twoaday	4	hide = 1;
57	twoaday	2	c = (passphrase_cb_s *)lparam;
58	twoaday	4	if (!c)
59			BUG (0);
60			SetWindowText (dlg, c->title);
61			if (c->gpg_cmd == GPG_CMD_DECRYPT) {
62	twoaday	2	SetDlgItemText( dlg, IDC_DECRYPT_LISTINF,
63			_("Encrypted with the following public key(s)") );
64			CheckDlgButton( dlg, IDC_DECRYPT_HIDE, BST_CHECKED );
65			}
66			else if( c->gpg_cmd == GPG_CMD_SIGN )
67			CheckDlgButton( dlg, IDC_DECRYPT_SIGN_HIDE, BST_CHECKED );
68			if( c->enc_to && c->gpg_cmd == GPG_CMD_DECRYPT ) {
69			gpgme_recipients_enum_open( c->enc_to, &ctx );
70			while ( (s = gpgme_recipients_enum_read( c->enc_to, &ctx )) ) {
71			pkalgo = *s; s++;
72			get_pubkey( s, &key );
73			if( key ) {
74			char * uid = NULL;
75			id = gpgme_key_get_string_attr( key, GPGME_ATTR_USERID, NULL, 0 );
76			if( !id )
77			id = _("Invalid User ID");
78			uid = utf8_to_wincp (id, strlen (id));
79			_snprintf( info, sizeof info - 1, "%s (%s, 0x%s)", uid,
80			gpgme_key_expand_attr( GPGME_ATTR_ALGO, pkalgo ), s+8 );
81			free( uid );
82			}
83			else
84			_snprintf( info, sizeof info - 1, _("Unknown (key ID 0x%s)"),
85			s? s + 8 : "DEADBEEF" );
86			listbox_add_string( GetDlgItem( dlg, IDC_DECRYPT_LIST ), info );
87			}
88			gpgme_recipients_enum_close( c->enc_to, &ctx );
89			}
90			SetDlgItemText( dlg, c->gpg_cmd == GPG_CMD_DECRYPT?
91			IDC_DECRYPT_PWDINFO : IDC_DECRYPT_SIGN_PWDINFO,
92			_("Please enter your passphrase") );
93			if( c->gpg_cmd == GPG_CMD_DECRYPT ) {
94			SetFocus( GetDlgItem( dlg, IDC_DECRYPT_PWD ) );
95			SetDlgItemText( dlg, IDC_DECRYPT_MSG, c->info );
96			}
97			else {
98			SetFocus( GetDlgItem( dlg, IDC_DECRYPT_SIGN_PWD ) );
99			SetDlgItemText( dlg, IDC_DECRYPT_SIGN_MSG, c->info );
100			}
101			center_window( dlg );
102			SetForegroundWindow( dlg );
103			set_active_window( dlg );
104			return FALSE;
105
106			case WM_SYSCOMMAND:
107			if( LOWORD( wparam ) == SC_CLOSE ) {
108			SetDlgItemText( dlg, item_ctrl_id( c->gpg_cmd ), "" );
109			c->cancel = 1;
110			EndDialog( dlg, TRUE );
111			}
112			return FALSE;
113
114			case WM_COMMAND:
115			switch( HIWORD( wparam ) ) {
116			case BN_CLICKED:
117			if ( LOWORD( wparam ) == IDC_DECRYPT_HIDE
118			\|\| LOWORD( wparam ) == IDC_DECRYPT_SIGN_HIDE ) {
119			HWND hwnd;
120	twoaday	4	hide ^= 1;
121	twoaday	2	hwnd = GetDlgItem( dlg, item_ctrl_id( c->gpg_cmd ) );
122	twoaday	4	SendMessage( hwnd, EM_SETPASSWORDCHAR, hide? '*' : 0, 0 );
123	twoaday	2	SetFocus( hwnd );
124			}
125			}
126
127	twoaday	4	switch (LOWORD (wparam)) {
128			case IDOK:
129	twoaday	2	/* fixme: the item is even cached when the passphrase is not
130			correct, which means that the user needs to delete all
131			cached entries to continue. */
132	twoaday	4	GetDlgItemText (dlg, item_ctrl_id (c->gpg_cmd), c->pwd, sizeof (c->pwd) -1);
133			if (reg_prefs.cache_time > 0 && !c->is_card && !strstr (c->keyid, "missing")) {
134			if (agent_get_cache (c->keyid, &item))
135			agent_unlock_cache_entry (&item);
136	twoaday	2	else
137	twoaday	4	agent_put_cache (c->keyid, c->pwd, reg_prefs.cache_time);
138	twoaday	2	}
139	twoaday	4	EndDialog (dlg, TRUE);
140	twoaday	2	return TRUE;
141
142			case IDCANCEL:
143	twoaday	4	SetDlgItemText (dlg, item_ctrl_id (c->gpg_cmd), "" );
144	twoaday	2	c->cancel = 1;
145	twoaday	4	EndDialog (dlg, FALSE);
146	twoaday	2	return FALSE;
147			}
148			break;
149			}
150
151			return FALSE;
152			} /* passphrase_callback_proc */
153
154
155			static const char *
156			parse_gpg_keyid( const char * desc )
157			{
158			static char keyid[16+1];
159			char * p;
160
161			p = strrchr( desc, '\n' );
162			if( !p )
163			return NULL;
164			/* the format of the desc buffer looks like this:
165			request_keyid[16] main_keyid[16] keytype[1] keylength[4]
166			we use the main keyid to use only one cache entry. */
167			strncpy( keyid, desc+(p-desc+1+17), 16 );
168			return keyid;
169			} /* parse_gpg_keyid */
170
171
172			static void
173			parse_gpg_description( char * desc, int size )
174			{
175			char * buffer = NULL, ch, uid[128] = {0}, * uid2 = NULL;
176			char usedkey[16+1] = {0}, mainkey[16+1] = {0};
177			const char * buf;
178			int i, algo, try_again = 0;
179
180			if( stristr( desc, "[User ID hint missing]" )
181			\|\| stristr( desc, "[passphrase info missing]" ) ) {
182			_snprintf( desc, size-1,
183			_("You need a passphrase to unlock the secret key for\n"
184			"user: [UserID hint missing]\n"
185			" [passphrase info missing]\n") );
186			return;
187			}
188
189			buffer = new char[size+1];
190			if( !buffer )
191			BUG( NULL );
192			strcpy( buffer, desc );
193			buf = buffer;
194			if( strstr( buf, "TRY_AGAIN" ) ) {
195			buf += strlen( "TRY_AGAIN\n" );
196			try_again = 1;
197			}
198			else if( strstr( buf, "ENTER_PASSPHRASE" ) )
199			buf += strlen( "ENTER_PASSPHRASE\n" );
200			else
201			BUG( NULL );
202			buf += 17;
203			for( i = 0; i < sizeof uid-1; i++ ) {
204			ch = *buf++;
205			if( ch == '\n' ) {
206			uid[i] = '\0';
207			break;
208			}
209			uid[i] = ch;
210			}
211			memcpy( usedkey, buf, 16 );
212			usedkey[16] = '\0';
213			buf += 17;
214			memcpy( mainkey, buf, 16 );
215			mainkey[16] = '\0';
216			buf += 17;
217			if( !buf )
218			BUG( NULL );
219			algo = atol( buf );
220			free_if_alloc( buffer );
221
222			uid2 = utf8_to_wincp (uid, strlen (uid));
223
224			if( strcmp( usedkey, mainkey ) )
225			_snprintf( desc, size-1,
226			_("You need a passphrase to unlock the secret key for\n"
227			"user: \"%s\"\n"
228			"%s key, ID %s (main key ID %s)\n"),
229			uid2, gpgme_key_expand_attr( GPGME_ATTR_ALGO, algo ),
230			usedkey+8, mainkey+8 );
231			else if( !strcmp( usedkey, mainkey ) )
232			_snprintf( desc, size-1,
233			_("You need a passphrase to unlock the secret key for\n"
234			"user: \"%s\"\n"
235			"%s key, ID %s\n"),
236			uid2, gpgme_key_expand_attr( GPGME_ATTR_ALGO, algo ),
237			usedkey+8 );
238			free( uid2 );
239			} /* parse_gpg_describtion */
240
241
242			static int inline
243			is_hexstring( const char * p )
244			{
245			size_t i;
246			for( i=0; i < strlen( p ); i++ ) {
247			if( !isxdigit( p[i] ) )
248			return -1;
249			}
250			return 0;
251			}
252
253
254			const char *
255			passphrase_cb( void * opaque, const char * desc, void * r_hd )
256			{
257			passphrase_cb_s * c = (passphrase_cb_s *)opaque;
258			void * item;
259			const char * pass, * keyid;
260			int rc = 0;
261
262			if( !c )
263			return NULL;
264
265			if( desc ) {
266			keyid = parse_gpg_keyid( desc );
267			pass = agent_get_cache( keyid, &item );
268			if( pass ) {
269			agent_unlock_cache_entry( &item );
270			c->pwd_init = 0;
271			return pass;
272			}
273			}
274
275			if( c->pwd_init ) {
276			c->keyid = keyid;
277			/* if the desc has a length of 32 and only hex digits, we assume a
278			smart card has been used. */
279			/log_box( "", 0, "%s %d %d", desc,strlen( desc), is_hexstring( desc ) );/
280			if( desc && strlen( desc ) == 32 && !is_hexstring( desc ) ) {
281			char buf[16];
282			memset( buf, 0, sizeof buf );
283			strncpy( buf, desc+20, 8 );
284			_snprintf( c->info, sizeof c->info-1,
285			_("Please enter the PIN to unlock your secret card key\n"
286			"Card: %s"), buf );
287			c->is_card = 1;
288			}
289			else if( desc ) {
290			strcpy( c->info, desc );
291			parse_gpg_description( c->info, sizeof c->info - 1 );
292			}
293			if( c->gpg_cmd == GPG_CMD_DECRYPT ) {
294			rc = DialogBoxParam( glob_hinst, (LPCSTR)IDD_WINPT_DECRYPT,
295			(HWND)c->hwnd, passphrase_callback_proc,
296			(LPARAM)c );
297			}
298			else if( c->gpg_cmd == GPG_CMD_SIGN ) {
299			rc = DialogBoxParam( glob_hinst, (LPCSTR)IDD_WINPT_DECRYPT_SIGN,
300			(HWND)c->hwnd, passphrase_callback_proc,
301			(LPARAM)c );
302			}
303			if( rc == -1 )
304			return NULL;
305			c->pwd_init = 0;
306			}
307
308			if( c->cancel )
309			return NULL;
310
311			return c->pwd;
312			} /* passphrase_cb */
313
314
315			void
316			set_gpg_passphrase_cb( gpgme_ctx_t c, passphrase_cb_s * ctx, int cmd,
317			HWND hwnd, const char * title )
318			{
319			ctx->gpg_cmd = cmd;
320			ctx->is_card = 0;
321			ctx->cancel = 0;
322			ctx->hwnd = hwnd;
323			ctx->pwd_init = 1;
324			if( strlen( title ) > 256 )
325			BUG( NULL ); /* check bounds */
326			strcpy( ctx->title, title );
327			gpgme_set_passphrase_cb( c, passphrase_cb, ctx );
328			} /* set_gpg_passphrase_cb */