luks-functions: remove key-slots being hardcoded for DRK handling since DUK code is now dynamic

TODO: multi LUKS volumes (Q4.2.1 non-default BRTFS deployment) not supported still with reencryption.
Not a regression, just not yet handled since no OEM known to ship such setup.

Signed-off-by: Thierry Laurion <insurgo@riseup.net>

Author: tlaurion

initrd/etc/luks-functions

@@ -363,29 +363,11 @@ luks_reencrypt() {
 		warn "DO NOT POWER DOWN MACHINE, UNPLUG AC OR REMOVE BATTERY DURING REENCRYPTION PROCESS"
 		cryptsetup reencrypt --resilience=none --force-offline-reencrypt --disable-locks \
 			--perf-no_read_workqueue --perf-no_write_workqueue \
-			"$LUKS" --key-slot 0 --key-file /tmp/luks_current_Disk_Recovery_Key_passphrase
+			"$LUKS" --key-file /tmp/luks_current_Disk_Recovery_Key_passphrase
 		#--perf-no_read_workqueue and/or --perf-no_write_workqueue improve encryption/reencrypton performance on kernel 5.10.9+
 		# bypassing dm-crypt queues.
 		#Ref https://github.com/cloudflare/linux/issues/1#issuecomment-729695518
-		#
-		#TODO: cryptsetup nows use specified --key-slot to test passphrase but moves keyslot to next available keyslot...
-		#  therefore, we cannot take for granted that DRK is under slot 0.
-		#    We could:
-		#     - not rely on keyslot anymore so that all keyslot are tested until DRK matches;
-		#     - Move DUK to slot 8?
-		#     This way
-		#      - luksChangeKey would change passphrase on same slot found
-		#      - reencrypt would rotate keyslot with next keyslot found
-		#      But then what to do with previous DUK.
-		#       We could: 
-		#         - If 2+ keyslot, iterate through slot numbers to test passphrase.
-		#          - When passphrase matching keyslot is found, keep trace of it (expected 0, might be 1)
-		#           - If DRK is 1, DUK must be 2 if we have 2 keyslots used
-		#            - We don't touch passphrase matched DRK slot
-		#             - We wipe the others
-		#              - We move DUK keyslot to 8.
-		#              Bad approach?
-
+		
 		#Validate past cryptsetup reencrypt attempts
 		if [ $? -ne 0 ]; then
 			whiptail --title 'Invalid Actual LUKS Disk Recovery Key passphrase?' --msgbox \
@@ -444,7 +426,7 @@ luks_change_passphrase()
 
 		#output and do cryptsetup luksChangeKey op
 		echo -e "\nChanging "$LUKS" LUKS encrypted disk passphrase to the new LUKS Disk Recovery Key passphrase..."
-		cryptsetup luksChangeKey "$LUKS" --key-slot 0 --key-file=/tmp/luks_current_Disk_Recovery_Key_passphrase /tmp/luks_new_Disk_Recovery_Key_passphrase
+		cryptsetup luksChangeKey "$LUKS" --key-file=/tmp/luks_current_Disk_Recovery_Key_passphrase /tmp/luks_new_Disk_Recovery_Key_passphrase
 
 		#Validate past cryptsetup attempts
 		if [ $? -ne 0 ]; then