ChatProgram.lua

local component = require("component")
local event = require("event")
local modem = component.modem
local keyboard = require("keyboard")
local data = component.data

--local serverAddress = "7709c111-2724-4327-a98e-280aaf2cd439"
local serverAddress = "9955471e-b28f-4001-9d66-79c28c75be2d"
local computerAddress = "defb88c6-fe9b-4fd7-a236-c1b956c9023e"
local compOrServer
local addressToUse
local sendID
local receiveID
local key = "Two One Nine Two"
local IV = "Thats my Kung Fu"
local decryptedMessage

local function CheckModem()
  for k,v in component.list("modem") do
    if k == serverAddress then
      compOrServer = "server"
      break
    elseif k == computerAddress then
      compOrServer = "computer"
      break
    end
  end
end

local function CompOrServer(compOrServer)
  if compOrServer == "computer" then
    addressToUse = serverAddress
    sendID = "Computer: "
    receiveID = "Server: "
  elseif compOrServer == "server" then
    addressToUse = computerAddress
    sendID = "Server: "
    receiveID = "Computer: "
  end
end

local function OpenPort()
  modem.open(42)
  openStatus = modem.isOpen(42)
  if openStatus then
    print("Successfully opened port 42.")
  else
    print("Was unable to open port 42, closing program...")
    os.exit()
  end
end

local function EncryptMessage(message, key, IV)
  encryptedMessage = data.encrypt(message, key, IV)
  if encryptedMessage == message then
    print("Encryption of message has failed, exiting program.")
    modem.close(42)
    os.exit()
  end
  return encryptedMessage
end

local function SendMessage(key, IV)
  io.write(sendID)
  message = io.read()
  encryptedMessage = EncryptMessage(message, key, IV)
  print("Sending " .. encryptedMessage .. " to " .. addressToUse .. " on port 42")
  modem.send(addressToUse, 42, encryptedMessage)
end

local function DecryptMessage(encryptedMessage, key, IV)
  decryptedMessage = data.decrypt(encryptedMessage, key, IV)
  if encryptedMessage == decryptedMessage then
    print("Message decryption has failed, exiting program.")
    modem.close(42)
    os.exit()
  end
  return decryptedMessage
end

OpenPort()
CheckModem()
CompOrServer(compOrServer)
print("Hold ctrl to send a message. Hold alt to exit.")
while true do
  local type, _, from, port, _, message = event.pull()
  if type == "modem_message" then
    if message ~= nil then
      decryptedMessage = DecryptMessage(message, key, IV)
      print(receiveID .. tostring(decryptedMessage))
    end
  elseif type == "key_down" then
    if keyboard.isAltDown() then
      modem.close(42)
      print("Closing port 42 and exiting program...")
      os.exit()
    elseif keyboard.isControlDown() then
      SendMessage(key, IV)
    --else
      --os.sleep(0.5)
    end
  end
end