simple

function format(text)
  text = string.upper(text)
  local bytevals = {}
  for totab=1,#text,1 do
    bytevals[totab] = string.byte(text,totab,totab)
  end
  return bytevals
end

function unformat(text)
  local myString = "-"
  for tostr=1,#text,1 do
    myString = myString .. string.char(text[tostr])
  end
  return myString
end

function round1(text)
  for bshift=2,#text,1 do
    text[bshift] = bit.blshift(text[bshift],2)
  end
  return text
end

function deround1(text)
  for bshift=2,#text,1 do
    text[bshift] = bit.brshift(text[bshift],2)
  end
  return text
end

function round2(text,cyphert)
  myEnc = cyphert
  if #cyphert < #text then
    encLen = #cyphert
    divisor = math.ceil(#text/encLen)
    for me=1,divisor,1 do
      for space = 1,encLen,1 do
        getLoc = me % encLen
        myEnc[space + me*4] = myEnc[space]
      end
    end
  end
  for xorin=1,#text,1 do
    text[xorin] = bit.bxor(text[xorin],myEnc[xorin])
  end
  return text
end
------CYPHER-TEXT--------
encText = {12,200,2,21}

-----ENCRYPT-------------
c1 = format("Longr")
c2 = round1(c1)
c3 = round2(c2,encText)
print("ENCRYPTED: ",table.concat(c3,","))

----DECRYPT--------------
c4 = round2(c3,encText)
c5 = deround1(c4)
c6 = unformat(c5)
print("DECRYPTED: ",c6)