Cryptum

local tArgs = {...}
local pstr = 10
-- 1=File 2=Out 3=Mode(d/e)
write("Password to "..(tArgs[3]=="d" and "open" or "save").." with: ")
local pass = read("*")
local bseed = ""
for i=1,#pass do
  bseed = bseed..string.byte(pass:sub(i,i))
end
local ttef = fs.open(tArgs[1],"r")
local tte = ttef.readAll()
ttef.close()
local endt = ""
for i=1,#tte do
  math.randomseed(bseed+i)
  local shift = math.random(1,pstr)
  endt = endt..string.char(string.byte(tte:sub(i,i))+(tArgs[3]=="d" and shift or -1*shift))
  write(endt:sub(i,i))
end
local efile = fs.open(tArgs[2],"w")
efile.write(endt)
efile.close()
print("\n"..(tArgs[3]=="d" and "Decryption" or "Encryption").." Complete!")