summaryrefslogtreecommitdiff
path: root/cmdline/apt-key.in
blob: 5bd8d1249a1bc1ee9bae53d179b883c0bfdf3e5c (plain)
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
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
#!/bin/sh

set -e
unset GREP_OPTIONS
export IFS="$(printf "\n\b")"

MASTER_KEYRING='&keyring-master-filename;'
eval "$(apt-config shell MASTER_KEYRING APT::Key::MasterKeyring)"
ARCHIVE_KEYRING='&keyring-filename;'
eval "$(apt-config shell ARCHIVE_KEYRING APT::Key::ArchiveKeyring)"
REMOVED_KEYS='&keyring-removed-filename;'
eval "$(apt-config shell REMOVED_KEYS APT::Key::RemovedKeys)"
ARCHIVE_KEYRING_URI='&keyring-uri;'
eval "$(apt-config shell ARCHIVE_KEYRING_URI APT::Key::ArchiveKeyringURI)"

aptkey_echo() { echo "$@"; }

requires_root() {
	if [ "$(id -u)" -ne 0 ]; then
		echo >&2 "ERROR: This command can only be used by root."
		exit 1
	fi
}

command_available() {
    if [ -x "$1" ]; then return 0; fi
    # command -v "$1" >/dev/null 2>&1 # not required by policy, see #747320
    # which "$1" >/dev/null 2>&1 # is in debianutils (essential) but not on non-debian systems
    local OLDIFS="$IFS"
    IFS=:
    for p in $PATH; do
	if [ -x "${p}/${1}" ]; then
	    IFS="$OLDIFS"
	    return 0
	fi
    done
    IFS="$OLDIFS"
    return 1
}

escape_shell() {
    echo "$@" | sed -e "s#'#'\"'\"'#g"
}

get_fingerprints_of_keyring() {
    aptkey_execute "$GPG_SH" --keyring "$1" --with-colons --fingerprint | while read publine; do
	# search for a public key
	if [ "${publine%%:*}" != 'pub' ]; then continue; fi
	# search for the associated fingerprint (should be the very next line)
	while read fprline; do
	   if [ "${fprline%%:*}" = 'sub' ]; then break; # should never happen
	   elif [ "${fprline%%:*}" != 'fpr' ]; then continue; fi
	   echo "$fprline" | cut -d':' -f 10
	done
	# order in the keyring shouldn't be important
    done | sort
}

add_keys_with_verify_against_master_keyring() {
    ADD_KEYRING="$1"
    MASTER="$2"

    if [ ! -f "$ADD_KEYRING" ]; then
	echo >&2 "ERROR: '$ADD_KEYRING' not found"
	return
    fi
    if [ ! -f "$MASTER" ]; then
	echo >&2 "ERROR: '$MASTER' not found"
	return
    fi

    # when adding new keys, make sure that the archive-master-keyring
    # is honored. so:
    #   all keys that are exported must have a valid signature
    #   from a key in the $distro-master-keyring
    add_keys="$(get_fingerprints_of_keyring "$ADD_KEYRING")"
    all_add_keys="$(aptkey_execute "$GPG_SH" --keyring "$ADD_KEYRING" --with-colons --list-keys | grep ^[ps]ub | cut -d: -f5)"
    master_keys="$(aptkey_execute "$GPG_SH" --keyring "$MASTER" --with-colons --list-keys | grep ^pub | cut -d: -f5)"

    # ensure there are no colisions LP: #857472
    for all_add_key in $all_add_keys; do
	for master_key in $master_keys; do
            if [ "$all_add_key" = "$master_key" ]; then
                echo >&2 "Keyid collision for '$all_add_key' detected, operation aborted"
                return 1
            fi
        done
    done

    for add_key in $add_keys; do
        # export the add keyring one-by-one
	local TMP_KEYRING="${GPGHOMEDIR}/tmp-keyring.gpg"
	aptkey_execute "$GPG_SH" --batch --yes --keyring "$ADD_KEYRING" --output "$TMP_KEYRING" --export "$add_key"
	if ! aptkey_execute "$GPG_SH" --batch --yes --keyring "$TMP_KEYRING" --import "$MASTER" > "${GPGHOMEDIR}/gpgoutput.log" 2>&1; then
	    cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
	    false
	fi
	# check if signed with the master key and only add in this case
	ADDED=0
	for master_key in $master_keys; do
	    if aptkey_execute "$GPG_SH" --keyring "$TMP_KEYRING" --check-sigs --with-colons "$add_key" \
	       | grep '^sig:!:' | cut -d: -f5 | grep -q "$master_key"; then
		aptkey_execute "$GPG_SH" --batch --yes --keyring "$ADD_KEYRING" --export "$add_key" \
		   | aptkey_execute "$GPG" --batch --yes --import
		ADDED=1
	    fi
	done
	if [ $ADDED = 0 ]; then
	    echo >&2 "Key '$add_key' not added. It is not signed with a master key"
	fi
	rm -f "${TMP_KEYRING}"
    done
}

# update the current archive signing keyring from a network URI
# the archive-keyring keys needs to be signed with the master key
# (otherwise it does not make sense from a security POV)
net_update() {
    local APT_DIR='/'
    eval $(apt-config shell APT_DIR Dir)

    # Disabled for now as code is insecure (LP: #1013639 (and 857472, 1013128))
    APT_KEY_NET_UPDATE_ENABLED=""
    eval $(apt-config shell APT_KEY_NET_UPDATE_ENABLED APT::Key::Net-Update-Enabled)
    if [ -z "$APT_KEY_NET_UPDATE_ENABLED" ]; then
        exit 1
    fi

    if [ -z "$ARCHIVE_KEYRING_URI" ]; then
	echo >&2 "ERROR: Your distribution is not supported in net-update as no uri for the archive-keyring is set"
	exit 1
    fi
    # in theory we would need to depend on wget for this, but this feature
    # isn't useable in debian anyway as we have no keyring uri nor a master key
    if ! command_available 'wget'; then
	echo >&2 "ERROR: an installed wget is required for a network-based update"
	exit 1
    fi
    if [ ! -d "${APT_DIR}/var/lib/apt/keyrings" ]; then
	mkdir -p "${APT_DIR}/var/lib/apt/keyrings"
    fi
    keyring="${APT_DIR}/var/lib/apt/keyrings/$(basename "$ARCHIVE_KEYRING_URI")"
    old_mtime=0
    if [ -e $keyring ]; then
	old_mtime=$(stat -c %Y "$keyring")
    fi
    (cd  "${APT_DIR}/var/lib/apt/keyrings"; wget --timeout=90 -q -N "$ARCHIVE_KEYRING_URI")
    if [ ! -e "$keyring" ]; then
	return
    fi
    new_mtime=$(stat -c %Y "$keyring")
    if [ $new_mtime -ne $old_mtime ]; then
	aptkey_echo "Checking for new archive signing keys now"
	add_keys_with_verify_against_master_keyring "$keyring" "$MASTER_KEYRING"
    fi
}

update() {
    if [ ! -f "$ARCHIVE_KEYRING" ]; then
	echo >&2 "ERROR: Can't find the archive-keyring"
	echo >&2 "Is the &keyring-package; package installed?"
	exit 1
    fi

    # add new keys from the package;

    # we do not use add_keys_with_verify_against_master_keyring here,
    # because "update" is run on regular package updates.  A
    # attacker might as well replace the master-archive-keyring file
    # in the package and add his own keys. so this check wouldn't
    # add any security. we *need* this check on net-update though
    import_keyring_into_keyring "$ARCHIVE_KEYRING" '' && cat "${GPGHOMEDIR}/gpgoutput.log"

    if [ -r "$REMOVED_KEYS" ]; then
	# remove no-longer supported/used keys
	get_fingerprints_of_keyring "$REMOVED_KEYS" | while read key; do
	    foreach_keyring_do 'remove_key_from_keyring' "$key"
	done
    else
	echo >&2 "Warning: removed keys keyring  $REMOVED_KEYS missing or not readable"
    fi
}

remove_key_from_keyring() {
    local KEYRINGFILE="$1"
    shift
    # non-existent keyrings have by definition no keys
    if [ ! -e "$KEYRINGFILE" ]; then
       return
    fi

    for KEY in "$@"; do
	local FINGERPRINTS="${GPGHOMEDIR}/keyringfile.keylst"
	get_fingerprints_of_keyring "$KEYRINGFILE" > "$FINGERPRINTS"

        # strip leading 0x, if present:
        KEY="${KEY#0x}"

	# check if the key is in this keyring
	if ! grep -iq "^[0-9A-F]*${KEY}$" "$FINGERPRINTS"; then
	    continue
	fi
	if [ ! -w "$KEYRINGFILE" ]; then
	    echo >&2 "Key ${KEY} is in keyring ${KEYRINGFILE}, but can't be removed as it is read only."
	    continue
	fi
	# check if it is the only key in the keyring and if so remove the keyring altogether
	if [ '1' = "$(uniq "$FINGERPRINTS" | wc -l)" ]; then
	    mv -f "$KEYRINGFILE" "${KEYRINGFILE}~" # behave like gpg
	    return
	fi
	# we can't just modify pointed to files as these might be in /usr or something
	local REALTARGET
	if [ -L "$KEYRINGFILE" ]; then
	    REALTARGET="$(readlink -f "$KEYRINGFILE")"
	    mv -f "$KEYRINGFILE" "${KEYRINGFILE}.dpkg-tmp"
	    cp -a "$REALTARGET" "$KEYRINGFILE"
	fi
	# delete the key from the keyring
	aptkey_execute "$GPG_SH" --keyring "$KEYRINGFILE" --batch --delete-keys --yes "$KEY"
	if [ -n "$REALTARGET" ]; then
	    # the real backup is the old link, not the copy we made
	    mv -f "${KEYRINGFILE}.dpkg-tmp" "${KEYRINGFILE}~"
	fi
    done
}

foreach_keyring_do() {
   local ACTION="$1"
   shift
   # if a --keyring was given, just work on this one
   if [ -n "$FORCED_KEYRING" ]; then
	$ACTION "$FORCED_KEYRING" "$@"
   else
	# otherwise all known keyrings are up for inspection
	if [ -s "$TRUSTEDFILE" ]; then
	    $ACTION "$TRUSTEDFILE" "$@"
	fi
	local TRUSTEDPARTS="/etc/apt/trusted.gpg.d"
	eval "$(apt-config shell TRUSTEDPARTS Dir::Etc::TrustedParts/d)"
	if [ -d "$TRUSTEDPARTS" ]; then
	    TRUSTEDPARTS="$(readlink -f "$TRUSTEDPARTS")"
	    local TRUSTEDPARTSLIST="$(cd /; find "$TRUSTEDPARTS" -mindepth 1 -maxdepth 1 -name '*.gpg')"
	    for trusted in $(echo "$TRUSTEDPARTSLIST" | sort); do
		if [ -s "$trusted" ]; then
		    $ACTION "$trusted" "$@"
		fi
	    done
	fi
   fi
}

run_cmd_on_keyring() {
    local KEYRINGFILE="$1"
    shift
    # fingerprint and co will fail if key isn't in this keyring
    aptkey_execute "$GPG_SH" --keyring "$KEYRINGFILE" --batch "$@" 2>/dev/null || true
}

import_keyring_into_keyring() {
    local FROM="${1:-${GPGHOMEDIR}/pubring.gpg}"
    local TO="${2:-${GPGHOMEDIR}/pubring.gpg}"
    shift 2
    rm -f "${GPGHOMEDIR}/gpgoutput.log"
    # the idea is simple: We take keys from one keyring and copy it to another
    # we do this with so many checks in between to ensure that WE control the
    # creation, so we know that the (potentially) created $TO keyring is a
    # simple keyring rather than a keybox as gpg2 would create it which in turn
    # can't be read by gpgv.
    # BEWARE: This is designed more in the way to work with the current
    # callers, than to have a well defined it would be easy to add new callers to.
    if [ ! -s "$TO" ]; then
	if [ -s "$FROM" ]; then
	    if [ -z "$2" ]; then
		if ! aptkey_execute "$GPG_SH" --keyring "$FROM" --export ${1:+"$1"} > "$TO" 2> "${GPGHOMEDIR}/gpgoutput.log"; then
		    cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
		    false
		else
		    chmod 0644 -- "$TO"
		fi
	    else
		create_new_keyring "$TO"
	    fi
	else
	    create_new_keyring "$TO"
	fi
    elif [ -s "$FROM" ]; then
	local EXPORTLIMIT="$1"
	if [ -n "$1$2" ]; then shift; fi
	if ! aptkey_execute "$GPG_SH" --keyring "$FROM" --export ${EXPORTLIMIT:+"$EXPORTLIMIT"} \
	   | aptkey_execute "$GPG_SH" --keyring "$TO" --batch --import "$@" > "${GPGHOMEDIR}/gpgoutput.log" 2>&1; then
	    cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
	    false
	fi
    fi
}

merge_all_trusted_keyrings_into_pubring() {
    # does the same as:
    # foreach_keyring_do 'import_keys_from_keyring' "${GPGHOMEDIR}/pubring.gpg"
    # but without using gpg, just cat and find
    local PUBRING="$(readlink -f "${GPGHOMEDIR}/pubring.gpg")"
    # if a --keyring was given, just use this one
    if [ -n "$FORCED_KEYRING" ]; then
	if [ -s "$FORCED_KEYRING" ]; then
	    cp --dereference "$FORCED_KEYRING" "$PUBRING"
	fi
    else
	# otherwise all known keyrings are merged
	local TRUSTEDPARTS="/etc/apt/trusted.gpg.d"
	eval $(apt-config shell TRUSTEDPARTS Dir::Etc::TrustedParts/d)
	if [ -d "$TRUSTEDPARTS" ]; then
	    rm -f "$PUBRING"
	    if [ -s "$TRUSTEDFILE" ]; then
		cat "$TRUSTEDFILE" > "$PUBRING"
	    fi
	    TRUSTEDPARTS="$(readlink -f "$TRUSTEDPARTS")"
	    (cd /; find "$TRUSTEDPARTS" -mindepth 1 -maxdepth 1 -name '*.gpg' -exec cat {} + >> "$PUBRING";)
	elif [ -s "$TRUSTEDFILE" ]; then
	    cp --dereference "$TRUSTEDFILE" "$PUBRING"
	fi
    fi

    if [ ! -s "$PUBRING" ]; then
	touch "$PUBRING"
    fi
}

import_keys_from_keyring() {
    import_keyring_into_keyring "$1" "$2"
}

merge_keys_into_keyrings() {
    import_keyring_into_keyring "$2" "$1" '' --import-options 'merge-only'
}

merge_back_changes() {
    if [ -n "$FORCED_KEYRING" ]; then
	# if the keyring was forced merge is already done
	return
    fi
    if [ -s "${GPGHOMEDIR}/pubring.gpg" ]; then
	# merge all updated keys
	foreach_keyring_do 'merge_keys_into_keyrings' "${GPGHOMEDIR}/pubring.gpg"
    fi
    # look for keys which were added or removed
    get_fingerprints_of_keyring "${GPGHOMEDIR}/pubring.orig.gpg" > "${GPGHOMEDIR}/pubring.orig.keylst"
    get_fingerprints_of_keyring "${GPGHOMEDIR}/pubring.gpg" > "${GPGHOMEDIR}/pubring.keylst"
    comm -3 "${GPGHOMEDIR}/pubring.keylst" "${GPGHOMEDIR}/pubring.orig.keylst" > "${GPGHOMEDIR}/pubring.diff"
    # key isn't part of new keyring, so remove
    cut -f 2 "${GPGHOMEDIR}/pubring.diff" | while read key; do
	if [ -z "$key" ]; then continue; fi
	foreach_keyring_do 'remove_key_from_keyring' "$key"
    done
    # key is only part of new keyring, so we need to import it
    cut -f 1 "${GPGHOMEDIR}/pubring.diff" | while read key; do
	if [ -z "$key" ]; then continue; fi
	import_keyring_into_keyring '' "$TRUSTEDFILE" "$key"
    done
}

setup_merged_keyring() {
    if [ -n "$FORCED_KEYID" ]; then
	merge_all_trusted_keyrings_into_pubring
	FORCED_KEYRING="${GPGHOMEDIR}/forcedkeyid.gpg"
	TRUSTEDFILE="${FORCED_KEYRING}"
	echo "#!/bin/sh
exec sh '($(escape_shell "${GPG}")' --keyring '$(escape_shell "${TRUSTEDFILE}")' \"\$@\"" > "${GPGHOMEDIR}/gpg.1.sh"
	GPG="${GPGHOMEDIR}/gpg.1.sh"
	# ignore error as this "just" means we haven't found the forced keyid and the keyring will be empty
	import_keyring_into_keyring '' "$TRUSTEDFILE" "$FORCED_KEYID" || true
    elif [ -z "$FORCED_KEYRING" ]; then
	merge_all_trusted_keyrings_into_pubring
	if [ -r "${GPGHOMEDIR}/pubring.gpg" ]; then
	    cp -a "${GPGHOMEDIR}/pubring.gpg" "${GPGHOMEDIR}/pubring.orig.gpg"
	else
	   touch "${GPGHOMEDIR}/pubring.gpg" "${GPGHOMEDIR}/pubring.orig.gpg"
	fi
	echo "#!/bin/sh
exec sh '$(escape_shell "${GPG}")' --keyring '$(escape_shell "${GPGHOMEDIR}/pubring.gpg")' \"\$@\"" > "${GPGHOMEDIR}/gpg.1.sh"
	GPG="${GPGHOMEDIR}/gpg.1.sh"
    else
	create_new_keyring "$TRUSTEDFILE"
	echo "#!/bin/sh
exec sh '$(escape_shell "${GPG}")' --keyring '$(escape_shell "${TRUSTEDFILE}")' \"\$@\"" > "${GPGHOMEDIR}/gpg.1.sh"
	GPG="${GPGHOMEDIR}/gpg.1.sh"
    fi
}

create_new_keyring() {
    # gpg defaults to mode 0600 for new keyrings. Create one with 0644 instead.
    if ! [ -e "$TRUSTEDFILE" ]; then
	if [ -w "$(dirname "$TRUSTEDFILE")" ]; then
	    touch -- "$TRUSTEDFILE"
	    chmod 0644 -- "$TRUSTEDFILE"
	fi
    fi
}

aptkey_execute() { sh "$@"; }

usage() {
    echo "Usage: apt-key [--keyring file] [command] [arguments]"
    echo
    echo "Manage apt's list of trusted keys"
    echo
    echo "  apt-key add <file>          - add the key contained in <file> ('-' for stdin)"
    echo "  apt-key del <keyid>         - remove the key <keyid>"
    echo "  apt-key export <keyid>      - output the key <keyid>"
    echo "  apt-key exportall           - output all trusted keys"
    echo "  apt-key update              - update keys using the keyring package"
    echo "  apt-key net-update          - update keys using the network"
    echo "  apt-key list                - list keys"
    echo "  apt-key finger              - list fingerprints"
    echo "  apt-key adv                 - pass advanced options to gpg (download key)"
    echo
    echo "If no specific keyring file is given the command applies to all keyring files."
}

while [ -n "$1" ]; do
   case "$1" in
      --keyring)
	 shift
	 TRUSTEDFILE="$1"
	 FORCED_KEYRING="$1"
	 ;;
      --keyid)
	 shift
	 FORCED_KEYID="$1"
	 ;;
      --secret-keyring)
	 shift
	 FORCED_SECRET_KEYRING="$1"
	 ;;
      --readonly)
	 merge_back_changes() { true; }
	 create_new_keyring() { if [ ! -r "$FORCED_KEYRING" ]; then TRUSTEDFILE='/dev/null'; FORCED_KEYRING="$TRUSTEDFILE"; fi; }
	 ;;
      --fakeroot)
	 requires_root() { true; }
	 ;;
      --quiet)
	 aptkey_echo() { true; }
	 ;;
      --debug1)
	 # some cmds like finger redirect stderr to /dev/null …
	aptkey_execute() { echo 'EXEC:' "$@"; sh "$@"; }
	;;
      --debug2)
	 # … other more complicated ones pipe gpg into gpg.
	aptkey_execute() { echo >&2 'EXEC:' "$@"; sh "$@"; }
	;;
      --*)
	 echo >&2 "Unknown option: $1"
	 usage
	 exit 1;;
      *)
	 break;;
   esac
   shift
done

if [ -z "$TRUSTEDFILE" ]; then
   TRUSTEDFILE="/etc/apt/trusted.gpg"
   eval $(apt-config shell TRUSTEDFILE Apt::GPGV::TrustedKeyring)
   eval $(apt-config shell TRUSTEDFILE Dir::Etc::Trusted/f)
fi

command="$1"
if [ -z "$command" ]; then
    usage
    exit 1
fi
shift

create_gpg_home() {
    # gpg needs (in different versions more or less) files to function correctly,
    # so we give it its own homedir and generate some valid content for it later on
    if [ -n "$TMPDIR" ]; then
	# tmpdir is a directory and current user has rwx access to it
	# same tests as in apt-pkg/contrib/fileutl.cc GetTempDir()
	if [ ! -d "$TMPDIR" ] || [ ! -r "$TMPDIR" ] || [ ! -w "$TMPDIR" ] || [ ! -x "$TMPDIR" ]; then
	    unset TMPDIR
	fi
    fi
    GPGHOMEDIR="$(mktemp -d)"
    CURRENTTRAP="${CURRENTTRAP} rm -rf '$(escape_shell "${GPGHOMEDIR}")';"
    trap "${CURRENTTRAP}" 0 HUP INT QUIT ILL ABRT FPE SEGV PIPE TERM
    chmod 700 "$GPGHOMEDIR"
}

prepare_gpg_home() {
    # crude detection if we are called from a maintainerscript where the
    # package depends on gnupg or not. We accept recommends here as
    # well as the script hopefully uses apt-key optionally then like e.g.
    # debian-archive-keyring for (upgrade) cleanup did
    if [ -n "$DPKG_MAINTSCRIPT_PACKAGE" ]; then
	if ! dpkg-query --show --showformat '${Pre-Depends}${Depends}${Recommends}\n' "$DPKG_MAINTSCRIPT_PACKAGE" 2>/dev/null | grep -q gnupg; then
	    cat >&2 <<EOF
Warning: The $DPKG_MAINTSCRIPT_NAME maintainerscript of the package $DPKG_MAINTSCRIPT_PACKAGE
Warning: seems to use apt-key (provided by apt) without depending on gnupg or gnupg2.
Warning: This will BREAK in the future and should be fixed by the package maintainer(s).
Note: Check first if apt-key functionality is needed at all - it probably isn't!
EOF
	fi
    fi
    eval "$(apt-config shell GPG_EXE Apt::Key::gpgcommand)"
    if [ -n "$GPG_EXE" ] && command_available "$GPG_EXE"; then
	true
    elif command_available 'gpg'; then
	GPG_EXE="gpg"
    elif command_available 'gpg2'; then
	GPG_EXE="gpg2"
    else
	echo >&2 "Error: gnupg or gnupg2 do not seem to be installed,"
	echo >&2 "Error: but apt-key requires gnupg or gnupg2 for this operation."
	echo >&2
	exit 255
    fi

    create_gpg_home

    # create the trustdb with an (empty) dummy keyring
    # older gpgs required it, newer gpgs even warn that it isn't needed,
    # but require it nonetheless for some commands, so we just play safe
    # here for the foreseeable future and create a dummy one
    touch "${GPGHOMEDIR}/empty.gpg"
    if ! "$GPG_EXE" --ignore-time-conflict --no-options --no-default-keyring \
       --homedir "$GPGHOMEDIR" --quiet --check-trustdb --keyring "${GPGHOMEDIR}/empty.gpg" >"${GPGHOMEDIR}/gpgoutput.log" 2>&1; then
       cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
       false
    fi

    # now tell gpg that it shouldn't try to maintain this trustdb file
    echo "#!/bin/sh
exec '$(escape_shell "${GPG_EXE}")' --ignore-time-conflict --no-options --no-default-keyring \\
--homedir '$(escape_shell "${GPGHOMEDIR}")' --no-auto-check-trustdb --trust-model always \"\$@\"" > "${GPGHOMEDIR}/gpg.0.sh"
    GPG_SH="${GPGHOMEDIR}/gpg.0.sh"
    GPG="$GPG_SH"

    # We don't usually need a secret keyring, of course, but
    # for advanced operations, we might really need a secret keyring after all
    if [ -n "$FORCED_SECRET_KEYRING" ] && [ -r "$FORCED_SECRET_KEYRING" ]; then
	if ! aptkey_execute "$GPG" -v --batch --import "$FORCED_SECRET_KEYRING" >"${GPGHOMEDIR}/gpgoutput.log" 2>&1; then
	    cat >&2 "${GPGHOMEDIR}/gpgoutput.log"
	    false
	fi
    else
       # and then, there are older versions of gpg which panic and implode
       # if there isn't one available - and writeable for imports
       # and even if not output is littered with the creation of a secring,
       # so lets call import once to have it create what it wants in silence
       echo -n | aptkey_execute "$GPG" --batch --import >/dev/null 2>&1 || true
    fi
}

if [ "$command" != 'help' ] && [ "$command" != 'verify' ]; then
    prepare_gpg_home
fi

case "$command" in
    add)
	requires_root
	setup_merged_keyring
	aptkey_execute "$GPG" --quiet --batch --import "$@"
	merge_back_changes
	aptkey_echo "OK"
        ;;
    del|rm|remove)
	requires_root
	foreach_keyring_do 'remove_key_from_keyring' "$@"
	aptkey_echo "OK"
        ;;
    update)
	requires_root
	setup_merged_keyring
	update
	merge_back_changes
	;;
    net-update)
	requires_root
	setup_merged_keyring
	net_update
	merge_back_changes
	;;
    list|finger*)
	foreach_keyring_do 'run_cmd_on_keyring' --fingerprint "$@"
	;;
    export|exportall)
	merge_all_trusted_keyrings_into_pubring
	aptkey_execute "$GPG_SH" --keyring "${GPGHOMEDIR}/pubring.gpg" --armor --export "$@"
	;;
    adv*)
	setup_merged_keyring
	aptkey_echo "Executing: $GPG $*"
	aptkey_execute "$GPG" "$@"
	merge_back_changes
	;;
    verify)
	GPGV=''
	eval $(apt-config shell GPGV Apt::Key::gpgvcommand)
	if [ -n "$GPGV" ] && command_available "$GPGV"; then true;
	elif command_available 'gpgv'; then GPGV='gpgv';
	elif command_available 'gpgv2'; then GPGV='gpgv2';
	else
	   echo >&2 'ERROR: gpgv or gpgv2 required for verification'
	   exit 29
	fi
	# for a forced keyid we need gpg --export, so full wrapping required
	if [ -n "$FORCED_KEYID" ]; then
	    prepare_gpg_home
	else
	    create_gpg_home
	fi
	setup_merged_keyring
	if [ -n "$FORCED_KEYRING" ]; then
	    "$GPGV" --homedir "${GPGHOMEDIR}" --keyring "${FORCED_KEYRING}" --ignore-time-conflict "$@"
	else
	    "$GPGV" --homedir "${GPGHOMEDIR}" --keyring "${GPGHOMEDIR}/pubring.gpg" --ignore-time-conflict "$@"
	fi
	;;
    help)
        usage
        ;;
    *)
        usage
        exit 1
        ;;
esac