This is a small programm to use with Immibis's Peripherals RFID reader

Run RFID write in your computer and you will be guided through the coding of the card
Run RFID door to activat the door lock

Make sure to set the sides of the reader, writer and redstone wire to the sides you use in your build

Program:
Spoiler

--If you want this to start at every boot of a computer run the following line of code in the startup
-- shell.run("RFID","door")

--The door stays open as long as you stay in the area of the reader
--			  !!! Make sure there is no creeper behind you !!!
-- Set up your own door system

doorPass = "wsxedcrfvbgtnhzmjuzvrnzcif" --Max Length 82 chars
cardLabel = "Ident: Front Door"  --Max Length 20 chars
--Make sure the following sides are equal to your build

readerSide = "left"
writerSide = "right"
redstoneSide = "bottom"

--(Don´t change)
tArgs = {...}
lastTimer = {}

-- Check the arguments given
if #tArgs < 1 then
print("Usage:")
print("RFID write")
print("RFID door")
return
end

mode = tArgs[1]
shell.run("clear")

if mode == "write" then
writer = peripheral.wrap(writerSide)
print("Enter writing mode")
print("Insert card in the writer")
while not writer.isPresent() do --Waits until a card is in the writer
  sleep(0)
end

if writer.encode(doorPass, cardLabel) then --Start write to card
  print("Start writing Pass to card")
else --Error handling
  if writer.isCoded() then
   print("Card is already coded\nInsert a blank card")
  elseif #cardLabel > 20 then
   print("Card Label is too long max. 20 char")
  elseif #doorPass > 82 then
   print("Data is too long max. 82 char")
  else
   print("Leave the card in the writer")
  end
  return
end
os.pullEvent("rfid_written") --Wait until the card is written
print("RFID card is coded")
print("Take the card out of the writer")

while writer.isCoded() do --Ends the program when the card is taken out of the writer
  sleep(0)
end
shell.run("clear")

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elseif mode == "door" then
reader = peripheral.wrap(readerSide)
print("Door Contol is running")
while true do
  reader.scan() --Creats an "rfid_detected" when a card is in range
  event, p1 = os.pullEvent()
  if event == "rfid_detected" then
   if p1 == doorPass then
	rs.setOutput(redstoneSide, true)
	lastTimer = os.startTimer(1)
   end
  elseif event == "timer" and lastTimer == p1 then
   rs.setOutput(redstoneSide, false)
  end
end
end

http://pastebin.com/Jnw5B9h1