X-Git-Url: https://git.saurik.com/apt.git/blobdiff_plain/f99a02461efe5183a00d5e73da197b85f93cf57a..5b1997c095acf183077ec49b2a8cbb1174e3c280:/cmdline/apt-key.in

diff --git a/cmdline/apt-key.in b/cmdline/apt-key.in
index 463e4b4b4..881f8a990 100644
--- a/cmdline/apt-key.in
+++ b/cmdline/apt-key.in
@@ -3,28 +3,6 @@
 set -e
 unset GREP_OPTIONS
 
-GPG_CMD="gpg --ignore-time-conflict --no-options --no-default-keyring"
-
-# gpg needs a trustdb to function, but it can't be invalid (not even empty)
-# so we create a temporary directory to store our fresh readable trustdb in
-TRUSTDBDIR="$(mktemp -d)"
-CURRENTTRAP="${CURRENTTRAP} rm -rf '${TRUSTDBDIR}';"
-trap "${CURRENTTRAP}" 0 HUP INT QUIT ILL ABRT FPE SEGV PIPE TERM
-chmod 700 "$TRUSTDBDIR"
-# We also don't use a secret keyring, of course, but gpg panics and
-# implodes if there isn't one available - and writeable for imports
-SECRETKEYRING="${TRUSTDBDIR}/secring.gpg"
-touch $SECRETKEYRING
-GPG_CMD="$GPG_CMD --secret-keyring $SECRETKEYRING"
-GPG_CMD="$GPG_CMD --trustdb-name ${TRUSTDBDIR}/trustdb.gpg"
-
-# now create the trustdb with an (empty) dummy keyring
-$GPG_CMD --quiet --check-trustdb --keyring $SECRETKEYRING
-# and make sure that gpg isn't trying to update the file
-GPG_CMD="$GPG_CMD --no-auto-check-trustdb --trust-model always"
-
-GPG="$GPG_CMD"
-
 APT_DIR="/"
 eval $(apt-config shell APT_DIR Dir)
 
@@ -36,23 +14,28 @@ REMOVED_KEYS='&keyring-removed-filename;'
 eval $(apt-config shell REMOVED_KEYS APT::Key::RemovedKeys)
 ARCHIVE_KEYRING_URI='&keyring-uri;'
 eval $(apt-config shell ARCHIVE_KEYRING_URI APT::Key::ArchiveKeyringURI)
-TMP_KEYRING=${APT_DIR}/var/lib/apt/keyrings/maybe-import-keyring.gpg
+
+aptkey_echo() { echo "$@"; }
 
 requires_root() {
 	if [ "$(id -u)" -ne 0 ]; then
-		echo >&1 "ERROR: This command can only be used by root."
+		echo >&2 "ERROR: This command can only be used by root."
 		exit 1
 	fi
 }
 
-# gpg defaults to mode 0600 for new keyrings. Create one with 0644 instead.
-init_keyring() {
-    for path; do
-        if ! [ -e "$path" ]; then
-            touch -- "$path"
-            chmod 0644 -- "$path"
-        fi
-    done
+get_fingerprints_of_keyring() {
+    $GPG_CMD --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() {
@@ -60,11 +43,11 @@ add_keys_with_verify_against_master_keyring() {
     MASTER=$2
 
     if [ ! -f "$ADD_KEYRING" ]; then
-	echo "ERROR: '$ADD_KEYRING' not found"
+	echo >&2 "ERROR: '$ADD_KEYRING' not found"
 	return
-    fi 
+    fi
     if [ ! -f "$MASTER" ]; then
-	echo "ERROR: '$MASTER' not found"
+	echo >&2 "ERROR: '$MASTER' not found"
 	return
     fi
 
@@ -72,7 +55,7 @@ add_keys_with_verify_against_master_keyring() {
     # is honored. so:
     #   all keys that are exported must have a valid signature
     #   from a key in the $distro-master-keyring
-    add_keys=`$GPG_CMD --keyring $ADD_KEYRING --with-colons --list-keys | grep ^pub | cut -d: -f5`
+    add_keys="$(get_fingerprints_of_keyring "$ADD_KEYRING")"
     all_add_keys=`$GPG_CMD --keyring $ADD_KEYRING --with-colons --list-keys | grep ^[ps]ub | cut -d: -f5`
     master_keys=`$GPG_CMD --keyring $MASTER --with-colons --list-keys | grep ^pub | cut -d: -f5`
 
@@ -85,24 +68,28 @@ add_keys_with_verify_against_master_keyring() {
             fi
         done
     done
-    
+
     for add_key in $add_keys; do
         # export the add keyring one-by-one
-        rm -f $TMP_KEYRING
-        $GPG_CMD --keyring $ADD_KEYRING --output $TMP_KEYRING --export $add_key 
-        # check if signed with the master key and only add in this case
-        ADDED=0
+	local TMP_KEYRING="${GPGHOMEDIR}/tmp-keyring.gpg"
+	$GPG_CMD --batch --yes --keyring "$ADD_KEYRING" --output "$TMP_KEYRING" --export "$add_key"
+	if ! $GPG_CMD --batch --yes --keyring "$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 $GPG_CMD --keyring $MASTER --keyring $TMP_KEYRING --check-sigs --with-colons $add_key | grep '^sig:!:' | cut -d: -f5 | grep -q $master_key; then
-		$GPG --import $TMP_KEYRING
+	    if $GPG_CMD --keyring $TMP_KEYRING --check-sigs --with-colons $add_key | grep '^sig:!:' | cut -d: -f5 | grep -q $master_key; then
+		$GPG_CMD --batch --yes --keyring "$ADD_KEYRING" --export "$add_key" | $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
-    rm -f $TMP_KEYRING
 }
 
 # update the current archive signing keyring from a network URI
@@ -120,7 +107,6 @@ net_update() {
 	echo >&2 "ERROR: Your distribution is not supported in net-update as no uri for the archive-keyring is set"
 	exit 1
     fi
-    requires_root
     # 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 ! which wget >/dev/null 2>&1; then
@@ -141,7 +127,7 @@ net_update() {
     fi
     new_mtime=$(stat -c %Y $keyring)
     if [ $new_mtime -ne $old_mtime ]; then
-	echo "Checking for new archive signing keys now"
+	aptkey_echo "Checking for new archive signing keys now"
 	add_keys_with_verify_against_master_keyring $keyring $MASTER_KEYRING
     fi
 }
@@ -152,7 +138,6 @@ update() {
 	echo >&2 "Is the &keyring-package; package installed?"
 	exit 1
     fi
-    requires_root
 
     # add new keys from the package;
 
@@ -161,75 +146,222 @@ update() {
     # 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
-    $GPG_CMD --quiet --batch --keyring $ARCHIVE_KEYRING --export | $GPG --import
+    import_keyring_into_keyring "$ARCHIVE_KEYRING" '' && cat "${GPGHOMEDIR}/gpgoutput.log"
 
     if [ -r "$REMOVED_KEYS" ]; then
 	# remove no-longer supported/used keys
-	keys=`$GPG_CMD --keyring $REMOVED_KEYS --with-colons --list-keys | grep ^pub | cut -d: -f5`
-	for key in $keys; do
-	    if $GPG --list-keys --with-colons | grep ^pub | cut -d: -f5 | grep -q $key; then
-		$GPG --quiet --batch --delete-key --yes ${key}
-	    fi
+	get_fingerprints_of_keyring "$REMOVED_KEYS" | while read key; do
+	    foreach_keyring_do 'remove_key_from_keyring' "$key"
 	done
     else
-	echo "Warning: removed keys keyring  $REMOVED_KEYS missing or not readable" >&2
+	echo >&2 "Warning: removed keys keyring  $REMOVED_KEYS missing or not readable"
     fi
 }
 
 remove_key_from_keyring() {
-    local GPG="$GPG_CMD --keyring $1"
-    # check if the key is in this keyring: the key id is in the 5 column at the end
-    if ! $GPG --with-colons --list-keys 2>&1 | grep -q "^pub:[^:]*:[^:]*:[^:]*:[0-9A-F]\+$2:"; then
-	return
-    fi
-    if [ ! -w "$1" ]; then
-	echo >&2 "Key ${2} is in keyring ${1}, but can't be removed as it is read only."
-	return
-    fi
-    # check if it is the only key in the keyring and if so remove the keyring alltogether
-    if [ '1' = "$($GPG --with-colons --list-keys | grep "^pub:[^:]*:[^:]*:[^:]*:[0-9A-F]\+:" | wc -l)" ]; then
-	mv -f "$1" "${1}~" # 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 "$1" ]; then
-	REALTARGET="$(readlink -f "$1")"
-	mv -f "$1" "${1}.dpkg-tmp"
-	cp -a "$REALTARGET" "$1"
-	ls "$(dirname $1)"
+    local KEYRINGFILE="$1"
+    shift
+    # non-existent keyrings have by definition no keys
+    if [ ! -e "$KEYRINGFILE" ]; then
+       return
     fi
-    # delete the key from the keyring
-    $GPG --batch --delete-key --yes "$2"
-    if [ -n "$REALTARGET" ]; then
-	# the real backup is the old link, not the copy we made
-	mv -f "${1}.dpkg-tmp" "${1}~"
-    fi
-}
 
-remove_key() {
-    requires_root
+    local GPG="$GPG_CMD --keyring $KEYRINGFILE"
+    for KEY in "$@"; do
+	local FINGERPRINTS="${GPGHOMEDIR}/keyringfile.keylst"
+	get_fingerprints_of_keyring "$KEYRINGFILE" > "$FINGERPRINTS"
+	# check if the key is in this keyring
+	if ! grep -iq "^[0-9A-F]*${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
+	$GPG --batch --delete-keys --yes "$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
+}
 
-    # if a --keyring was given, just remove from there
-    if [ -n "$FORCED_KEYRING" ]; then
-	remove_key_from_keyring "$FORCED_KEYRING" "$1"
-    else
+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
-	local TRUSTEDFILE="/etc/apt/trusted.gpg"
-	eval $(apt-config shell TRUSTEDFILE Apt::GPGV::TrustedKeyring)
-	eval $(apt-config shell TRUSTEDFILE Dir::Etc::Trusted/f)
-	remove_key_from_keyring "$TRUSTEDFILE" "$1"
-	TRUSTEDPARTS="/etc/apt/trusted.gpg.d"
+	if [ -s "$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
+	    # strip / suffix as gpg will double-slash in that case (#665411)
+	    local STRIPPED_TRUSTEDPARTS="${TRUSTEDPARTS%/}"
+	    if [ "${STRIPPED_TRUSTEDPARTS}/" = "$TRUSTEDPARTS" ]; then
+		TRUSTEDPARTS="$STRIPPED_TRUSTEDPARTS"
+	    fi
 	    for trusted in $(run-parts --list "$TRUSTEDPARTS" --regex '^.*\.gpg$'); do
-		remove_key_from_keyring "$trusted" "$1"
+		if [ -s "$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
+    $GPG_CMD --keyring "$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 inbetween 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 ! $GPG_CMD --keyring "$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 ! $GPG_CMD --keyring "$FROM" --export ${EXPORTLIMIT:+"$EXPORTLIMIT"} | $GPG_CMD --keyring "$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="${GPGHOMEDIR}/pubring.gpg"
+    # if a --keyring was given, just use this one
+    if [ -n "$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
+	    # ignore errors mostly for non-existing $TRUSTEDFILE
+	    cat /dev/null "$TRUSTEDFILE" $(find -L "$TRUSTEDPARTS" -type f -name '*.gpg') > "$PUBRING" 2>/dev/null || true
+	elif [ -s "$TRUSTEDFILE" ]; then
+	    cp --dereference "$TRUSTEDFILE" "$PUBRING"
+	fi
+    fi
+
+    if [ ! -s "$PUBRING" ]; then
+	touch "$PUBRING"
     fi
-    echo "OK"
 }
 
+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="${FORCED_KEYRING}"
+	GPG="$GPG --keyring $TRUSTEDFILE"
+	# ignore error as this "just" means we haven't found the forced keyid and the keyring will be empty
+	import_keyring_into_keyring '' "$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" "${GPGHOMEDIR}/pubring.orig.gpg"
+	fi
+	GPG="$GPG --keyring ${GPGHOMEDIR}/pubring.gpg"
+    else
+	create_new_keyring "$TRUSTEDFILE"
+	GPG="$GPG --keyring $TRUSTEDFILE"
+    fi
+}
+
+create_new_keyring() {
+    # gpg defaults to mode 0600 for new keyrings. Create one with 0644 instead.
+    if ! [ -e "$TRUSTEDFILE" ]; then
+	if [ -w "$(dirname "$TRUSTEDFILE")" ]; then
+	    touch -- "$TRUSTEDFILE"
+	    chmod 0644 -- "$TRUSTEDFILE"
+	fi
+    fi
+}
 
 usage() {
     echo "Usage: apt-key [--keyring file] [command] [arguments]"
@@ -255,18 +387,33 @@ while [ -n "$1" ]; do
 	 shift
 	 TRUSTEDFILE="$1"
 	 FORCED_KEYRING="$1"
-	 if [ -r "$TRUSTEDFILE" ] || [ "$2" = 'add' ] || [ "$2" = 'adv' ]; then
-	    GPG="$GPG --keyring $TRUSTEDFILE --primary-keyring $TRUSTEDFILE"
-	 else
-	    echo >&2 "Error: The specified keyring »$TRUSTEDFILE« is missing or not readable"
-	    exit 1
-	 fi
+	 ;;
+      --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; }
-	 shift
 	 ;;
+      --quiet)
+	 aptkey_echo() { true; }
+	 ;;
+      --debug1)
+	 # some cmds like finger redirect stderr to /dev/null …
+	aptkey_execute() { echo 'EXEC:' "$@"; "$@"; }
+	;;
+      --debug2)
+	 # … other more complicated ones pipe gpg into gpg.
+	aptkey_execute() { echo >&2 'EXEC:' "$@"; "$@"; }
+	;;
       --*)
 	 echo >&2 "Unknown option: $1"
 	 usage
@@ -274,28 +421,13 @@ while [ -n "$1" ]; do
       *)
 	 break;;
    esac
+   shift
 done
 
 if [ -z "$TRUSTEDFILE" ]; then
    TRUSTEDFILE="/etc/apt/trusted.gpg"
    eval $(apt-config shell TRUSTEDFILE Apt::GPGV::TrustedKeyring)
    eval $(apt-config shell TRUSTEDFILE Dir::Etc::Trusted/f)
-   if [ -r "$TRUSTEDFILE" ]; then
-      GPG="$GPG --keyring $TRUSTEDFILE"
-   fi
-   GPG="$GPG --primary-keyring $TRUSTEDFILE"
-   TRUSTEDPARTS="/etc/apt/trusted.gpg.d"
-   eval $(apt-config shell TRUSTEDPARTS Dir::Etc::TrustedParts/d)
-   if [ -d "$TRUSTEDPARTS" ]; then
-      # strip / suffix as gpg will double-slash in that case (#665411)
-      STRIPPED_TRUSTEDPARTS="${TRUSTEDPARTS%/}"
-      if [ "${STRIPPED_TRUSTEDPARTS}/" = "$TRUSTEDPARTS" ]; then
-	 TRUSTEDPARTS="$STRIPPED_TRUSTEDPARTS"
-      fi
-      for trusted in $(run-parts --list "$TRUSTEDPARTS" --regex '^.*\.gpg$'); do
-	 GPG="$GPG --keyring $trusted"
-      done
-   fi
 fi
 
 command="$1"
@@ -305,52 +437,140 @@ if [ -z "$command" ]; then
 fi
 shift
 
-if [ "$command" != "help" ] && ! which gpg >/dev/null 2>&1; then
-    echo >&2 "Warning: gnupg does not seem to be installed."
-    echo >&2 "Warning: apt-key requires gnupg for most operations."
-    echo >&2
+create_gpg_home() {
+    # gpg needs (in different versions more or less) files to function correctly,
+    # so we give it its own homedir and generate some valid content for it later on
+    if [ -n "$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 '${GPGHOMEDIR}';"
+    trap "${CURRENTTRAP}" 0 HUP INT QUIT ILL ABRT FPE SEGV PIPE TERM
+    chmod 700 "$GPGHOMEDIR"
+}
+
+prepare_gpg_home() {
+    eval $(apt-config shell GPG_EXE Apt::Key::gpgcommand)
+
+    if [ -n "$GPG_EXE" ] && which "$GPG_EXE" >/dev/null 2>&1; then
+	true
+    elif which gpg >/dev/null 2>&1; then
+	GPG_EXE="gpg"
+    elif which gpg2 >/dev/null 2>&1; 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
+
+    if type aptkey_execute >/dev/null 2>&1; then
+	GPG_EXE="aptkey_execute $GPG_EXE"
+    fi
+    GPG_CMD="$GPG_EXE --ignore-time-conflict --no-options --no-default-keyring"
+
+    create_gpg_home
+
+    # We don't use a secret keyring, of course, but gpg panics and
+    # implodes if there isn't one available - and writeable for imports
+    SECRETKEYRING="${GPGHOMEDIR}/secring.gpg"
+    touch $SECRETKEYRING
+    GPG_CMD="$GPG_CMD --homedir $GPGHOMEDIR"
+    # 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
+    $GPG_CMD --quiet --check-trustdb --keyring $SECRETKEYRING >/dev/null 2>&1
+    # tell gpg that it shouldn't try to maintain a trustdb file
+    GPG_CMD="$GPG_CMD --no-auto-check-trustdb --trust-model always"
+    GPG="$GPG_CMD"
+
+    # for advanced operations, we might really need a secret keyring after all
+    if [ -n "$FORCED_SECRET_KEYRING" ] && [ -r "$FORCED_SECRET_KEYRING" ]; then
+	rm -f "$SECRETKEYRING"
+	cp -a "$FORCED_SECRET_KEYRING" "$SECRETKEYRING"
+    fi
+
+    # older gpg versions need a secring file, but newer versions take it as
+    # a hint to start a migration from earlier versions. The file is empty
+    # anyhow, so nothing actually happens, but its three lines of output
+    # nobody expects to see in apt-key context, so trigger it in silence
+    echo -n | $GPG --batch --import >/dev/null 2>&1 || true
+}
+
+if [ "$command" != 'help' ] && [ "$command" != 'verify' ]; then
+    prepare_gpg_home
 fi
 
 case "$command" in
     add)
-        requires_root
-        init_keyring "$TRUSTEDFILE"
-        $GPG --quiet --batch --import "$1"
-        echo "OK"
+	requires_root
+	setup_merged_keyring
+	$GPG --quiet --batch --import "$@"
+	merge_back_changes
+	aptkey_echo "OK"
         ;;
     del|rm|remove)
-        init_keyring "$TRUSTEDFILE"
-	remove_key "$1"
+	requires_root
+	foreach_keyring_do 'remove_key_from_keyring' "$@"
+	aptkey_echo "OK"
         ;;
     update)
-        init_keyring "$TRUSTEDFILE"
+	requires_root
+	setup_merged_keyring
 	update
+	merge_back_changes
 	;;
     net-update)
-        init_keyring "$TRUSTEDFILE"
+	requires_root
+	setup_merged_keyring
 	net_update
+	merge_back_changes
 	;;
     list)
-        init_keyring "$TRUSTEDFILE"
-        $GPG --batch --list-keys
-        ;;
+	foreach_keyring_do 'run_cmd_on_keyring' --list-keys "$@"
+	;;
     finger*)
-        init_keyring "$TRUSTEDFILE"
-        $GPG --batch --fingerprint
-        ;;
-    export)
-        init_keyring "$TRUSTEDFILE"
-        $GPG --armor --export "$1"
-        ;;
-    exportall)
-        init_keyring "$TRUSTEDFILE"
-        $GPG --armor --export
-        ;;
+	foreach_keyring_do 'run_cmd_on_keyring' --fingerprint "$@"
+	;;
+    export|exportall)
+	merge_all_trusted_keyrings_into_pubring
+	$GPG_CMD --keyring "${GPGHOMEDIR}/pubring.gpg" --armor --export "$@"
+	;;
     adv*)
-        init_keyring "$TRUSTEDFILE"
-        echo "Executing: $GPG $*"
-        $GPG $*
-        ;;
+	setup_merged_keyring
+	aptkey_echo "Executing: $GPG $*"
+	$GPG "$@"
+	merge_back_changes
+	;;
+    verify)
+	GPGV=''
+	eval $(apt-config shell GPGV Apt::Key::gpgvcommand)
+	if [ -n "$GPGV" ] && which "$GPGV" >/dev/null 2>&1; then true;
+	elif which gpgv >/dev/null 2>&1; then GPGV='gpgv';
+	elif which gpgv2 >/dev/null 2>&1; then GPGV='gpgv2';
+	else
+	   echo >&2 'ERROR: gpgv or gpgv2 required for verification'
+	   exit 29
+	fi
+	# for a forced keyid we need gpg --export, so full wrapping required
+	if [ -n "$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
         ;;