In QNap's infinite wisdom, they decided to change how the underlying encryption works to provide a extra layer of security. Sadly, it breaks the ability to get the data out in the event of a failure of the NAS itself. Fortunately it's not a effective deterrent. You'll still need the password used to encrypt the volume. The key file wont help.First thing is to convert the password to a key file you can use with vanilla crypto setup. Replace the string __PASSWORD__HERE__ with your password

First thing is to convert the password to a key file you can use with vanilla crypto setup. Replace the string __PASSWORD__HERE__ with your password

#include <unistd.h> 
#include <stdio.h>
#include <stdlib.h>
#include <crypt.h>

int main()
{
    printf("%s",crypt("__PASSWORD__HERE__","$1$YCCaQNAP$"));
    exit(0);
}
Then compile it via
gcc qnap_encryption_convert.c -lcrypt
and then generate the key file
./a.out > qnap.key
You'll need to figure out which lv you need to use. Mine was lv4, but it might vary for you. You'll then have to activate, unlock and mount
lvchange -a y /dev/vg4/lv4
cryptsetup -v luksOpen /dev/vg4/lv4 lv4 --key-file=qnap.key
mount /dev/mapper/lv4 /mnt/whatever
and your data should be there. Booya!