gnupg/g10/revoke.c

/* revoke.c
 *	Copyright (C) 1998, 1999, 2000 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 <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <ctype.h>

#include "options.h"
#include "packet.h"
#include "errors.h"
#include "keydb.h"
#include <gcrypt.h>
#include "util.h"
#include "main.h"
#include "ttyio.h"
#include "status.h"
#include "i18n.h"


struct revocation_reason_info {
    int code;
    char *desc;
};


int
revocation_reason_build_cb( PKT_signature *sig, void *opaque )
{
    struct revocation_reason_info *reason = opaque;
    char *ud = NULL;
    byte *buffer;
    size_t buflen = 1;

    if( reason->desc ) {
	ud = native_to_utf8( reason->desc );
	buflen += strlen(ud);
    }
    buffer = gcry_xmalloc( buflen );
    *buffer = reason->code;
    if( ud ) {
	memcpy(buffer+1, ud, strlen(ud) );
	gcry_free( ud );
    }

    build_sig_subpkt( sig, SIGSUBPKT_REVOC_REASON, buffer, buflen );
    gcry_free( buffer );
    return 0;
}



/****************
 * Generate a revocation certificate for UNAME
 */
int
gen_revoke( const char *uname )
{
    int rc = 0;
    armor_filter_context_t afx;
    compress_filter_context_t zfx;
    PACKET pkt;
    PKT_secret_key *sk; /* used as pointer into a kbnode */
    PKT_public_key *pk = NULL;
    PKT_signature *sig = NULL;
    u32 sk_keyid[2];
    IOBUF out = NULL;
    KBNODE keyblock = NULL;
    KBNODE node;
    KBPOS kbpos;
    struct revocation_reason_info *reason = NULL;

    if( opt.batch ) {
	log_error(_("sorry, can't do this in batch mode\n"));
	return GPGERR_GENERAL;
    }


    memset( &afx, 0, sizeof afx);
    memset( &zfx, 0, sizeof zfx);
    init_packet( &pkt );


    /* search the userid */
    rc = find_secret_keyblock_byname( &kbpos, uname );
    if( rc ) {
	log_error(_("secret key for user `%s' not found\n"), uname );
	goto leave;
    }

    /* read the keyblock */
    rc = read_keyblock( &kbpos, &keyblock );
    if( rc ) {
	log_error(_("error reading the certificate: %s\n"), gpg_errstr(rc) );
	goto leave;
    }

    /* get the keyid from the keyblock */
    node = find_kbnode( keyblock, PKT_SECRET_KEY );
    if( !node ) { /* maybe better to use log_bug ? */
	log_error(_("Oops; secret key not found anymore!\n"));
	rc = GPGERR_GENERAL;
	goto leave;
    }

    /* fixme: should make a function out of this stuff,
     * it's used all over the source */
    sk = node->pkt->pkt.secret_key;
    keyid_from_sk( sk, sk_keyid );
    tty_printf("\nsec  %4u%c/%08lX %s   ",
	      nbits_from_sk( sk ),
	      pubkey_letter( sk->pubkey_algo ),
	      sk_keyid[1], datestr_from_sk(sk) );
    {
	size_t n;
	char *p = get_user_id( sk_keyid, &n );
	tty_print_utf8_string( p, n );
	gcry_free(p);
	tty_printf("\n");
    }
    pk = gcry_xcalloc( 1, sizeof *pk );
    rc = get_pubkey( pk, sk_keyid );
    if( rc ) {
	log_error(_("no corresponding public key: %s\n"), gpg_errstr(rc) );
	goto leave;
    }
    if( cmp_public_secret_key( pk, sk ) ) {
	log_error(_("public key does not match secret key!\n") );
	rc = GPGERR_GENERAL;
	goto leave;
    }

    tty_printf("\n");
    if( !cpr_get_answer_is_yes("gen_revoke.okay",
			_("Create a revocation certificate for this key? ")) ){
	rc = 0;
	goto leave;
    }

    /* get the reason for the revocation */
    reason = ask_revocation_reason( 1, 0, 1 );
    if( !reason ) { /* user decided to cancel */
	rc = 0;
	goto leave;
    }

    switch( is_secret_key_protected( sk ) ) {
      case -1:
	log_error(_("unknown protection algorithm\n"));
	rc = GPGERR_PUBKEY_ALGO;
	break;
      case 0:
	tty_printf(_("NOTE: This key is not protected!\n"));
	break;
      default:
	rc = check_secret_key( sk, 0 );
	break;
    }
    if( rc )
	goto leave;


    if( !opt.armor )
	tty_printf(_("ASCII armored output forced.\n"));

    if( (rc = open_outfile( NULL, 0, &out )) )
	goto leave;

    afx.what = 1;
    afx.hdrlines = "Comment: A revocation certificate should follow\n";
    iobuf_push_filter( out, armor_filter, &afx );

    /* create it */
    rc = make_keysig_packet( &sig, pk, NULL, NULL, sk, 0x20, 0,
						  revocation_reason_build_cb,
						  reason );
    if( rc ) {
	log_error(_("make_keysig_packet failed: %s\n"), gpg_errstr(rc));
	goto leave;
    }
    init_packet( &pkt );
    pkt.pkttype = PKT_SIGNATURE;
    pkt.pkt.signature = sig;

    rc = build_packet( out, &pkt );
    if( rc ) {
	log_error(_("build_packet failed: %s\n"), gpg_errstr(rc) );
	goto leave;
    }

    /* and issue a usage notice */
    tty_printf(_("Revocation certificate created.\n\n"
"Please move it to a medium which you can hide away; if Mallory gets\n"
"access to this certificate he can use it to make your key unusable.\n"
"It is smart to print this certificate and store it away, just in case\n"
"your media become unreadable.  But have some caution:  The print system of\n"
"your machine might store the data and make it available to others!\n"));



  leave:
    if( pk )
	free_public_key( pk );
    if( sig )
	free_seckey_enc( sig );
    release_kbnode( keyblock );
    if( rc )
	iobuf_cancel(out);
    else
	iobuf_close(out);
    release_revocation_reason_info( reason );
    return rc;
}



struct revocation_reason_info *
ask_revocation_reason( int key_rev, int cert_rev, int hint )
{
    int code;
    char *description = NULL;
    struct revocation_reason_info *reason;
    const char *text_1 = _("Key has been compromised");
    const char *text_2 = _("Key is superseded");
    const char *text_3 = _("Key is no longer used");
    const char *text_4 = _("User ID is non longer valid");
    const char *code_text = NULL;

    do {
	gcry_free(description);
	description = NULL;

	tty_printf(_("Please select the reason for the revocation:\n"));
	if( key_rev )
	    tty_printf("  1 = %s\n", text_1 );
	if( key_rev )
	    tty_printf("  2 = %s\n", text_2 );
	if( key_rev )
	    tty_printf("  3 = %s\n", text_3 );
	if( cert_rev )
	    tty_printf("  4 = %s\n", text_4 );
	tty_printf(    "  0 = %s\n", _("Cancel") );
	if( hint )
	    tty_printf(_("(Probably you want to select %d here)\n"), hint );

	for(code = 0; !code;) {
	    int n;
	    char *answer = cpr_get("ask_revocation_reason.code",
						_("Your decision? "));
	    trim_spaces( answer );
	    cpr_kill_prompt();
	    if( *answer == 'q' || *answer == 'Q' )
		n = 0;
	    else if( !isdigit( *answer ) )
		n = -1;
	    else if( hint && !*answer )
		n = hint;
	    else
		n = atoi(answer);
	    gcry_free(answer);
	    if( !n )
		return NULL; /* cancel */
	    else if( key_rev && n == 1 ) {
		code = 0x02; /* key has  been compromised */
		code_text = text_1;
	    }
	    else if( key_rev && n == 2 ) {
		code = 0x01; /* key is superseded */
		code_text = text_2;
	    }
	    else if( key_rev && n == 3 ) {
		code = 0x03; /* key is no longer used */
		code_text = text_3;
	    }
	    else if( cert_rev && n == 4 ) {
		code = 0x20; /* uid is non longer valid */
		code_text = text_4;
	    }
	    else
		tty_printf(_("Invalid selection.\n"));
	}

	tty_printf(_("Enter an optional description; "
		     "end it with an empty line:\n") );
	for(;;) {
	    char *answer = cpr_get("ask_revocation_reason.text", "> " );
	    trim_trailing_ws( answer, strlen(answer) );
	    cpr_kill_prompt();
	    if( !*answer ) {
		gcry_free(answer);
		break;
	    }

	    {
		char *p = make_printable_string( answer, strlen(answer), 0 );
		gcry_free(answer);
		answer = p;
	    }

	    if( !description )
		description = gcry_xstrdup(answer);
	    else {
		char *p = gcry_xmalloc( strlen(description) + strlen(answer) + 2 );
		strcpy(stpcpy(stpcpy( p, description),"\n"),answer);
		gcry_free(description);
		description = p;
	    }
	    gcry_free(answer);
	}

	tty_printf(_("Reason for revocation: %s\n"), code_text );
	if( !description )
	    tty_printf(_("(No description given)\n") );
	else
	    tty_printf("%s\n", description );

    } while( !cpr_get_answer_is_yes("ask_revocation_reason.okay",
					    _("Is this okay? "))  );

    reason = gcry_xmalloc( sizeof *reason );
    reason->code = code;
    reason->desc = description;
    return reason;
}

void
release_revocation_reason_info( struct revocation_reason_info *reason )
{
    if( reason ) {
	gcry_free( reason->desc );
	gcry_free( reason );
    }
}