cryptsetup keyscript example

keyfile-md0

#!/bin/sh

target="${0##*/keyfile-}"

m=
cleanup() {
    [ -n "$m" ] && umount "$m" 1>&2
}

init() {
    modprobe vfat
    sleep 5
    mkdir -p /keydev 1>&2
}

search() {
    local dev=
    for dev in /dev/disk/by-partlabel/efi-* ; do
        if mount -t vfat -o ro,codepage=437,iocharset=utf8 "$dev" /keydev 1>&2; then
            m="/keydev"
            if [ -f "/keydev/${target}.key" ]; then
                cat "/keydev/${target}.key"
                return 0
            fi
            umount "$m" 1>&2
            m=
        fi
    done
}

trap cleanup EXIT
init
search