Encrypted Chat for ComputerCraft

--[[
        Encrypted Chat for ComputerCraft

    This chat system is connection based and uses the Diffie-Hellman-Merkle key exchange and the AES Encryption API
    by SquidDev to encrypt messages.

    It is very simple and probably dirty made but it works quite well :)

    ~Piorjade

]]--

shell.run("wget https://git.io/aeslua aeslua")
os.loadAPI("aeslua")
fs.delete("aeslua")
rednet.open("top")
Y = 20752
P = 2340971
print(math.pow(10, 13))
X = math.random(math.pow(10, 13))

print("your secret number is: "..X)

print("Connect or host? (c/h)")
local answer = ""
repeat
    write("> ")
    answer = read()
until answer == "c" or answer == "h"

if answer == "c" then
    print("")
    write("Enter ID: ")
    id = tonumber(read())
    print("Waiting for "..id.." to respond....")
    rednet.send(id, {"connect",math.pow(Y, X%P)}, "encrypted_chat")
    local sender, msg, protocol
    repeat
        sender, msg, protocol = rednet.receive()
        print(tostring(sender).." "..tostring(msg).." "..tostring(protocol))
    until sender == id and protocol == "encrypted_chat" and msg[1] == "connect"
    local sender_number = msg[2]
    local sender_library = msg[3]
    local encryption_number = math.pow(sender_number, X%P)

    print("You are now sending messages to "..id)
    local window1 = window.create(term.current(), 1, 1, 51, 18)
    window1.setBackgroundColor(colors.black)
    window1.setTextColor(colors.yellow)
    window1.clear()
    local window2 = window.create(term.current(), 1, 19, 51, 1)
    window2.setBackgroundColor(colors.gray)
    window2.clear()

    local function receive()
        while true do
            local _, msg, prot = rednet.receive()
            if id == _ and prot == "encrypted_chat" then
                local str = aeslua.decrypt(tostring(encryption_number), msg, aeslua.AES128, aeslua.CBCMODE, sender_library)
                term.redirect(window1)
                term.setCursorBlink(false)
                print(id.."> "..str)
                window2.restoreCursor()
                term.redirect(window2)
                term.setCursorBlink(true)
            end
        end
    end

    local function send()
        while true do
            write("> ")
            local omsg = read()
            if omsg == "/exit" then break end
            msg = aeslua.encrypt(tostring(encryption_number), omsg, aeslua.AES128, aeslua.CBCMODE, sender_library)
            rednet.send(id, msg, "encrypted_chat")
            term.clear()
            term.setCursorPos(1,1)
            term.redirect(window1)
            print("You> "..omsg)
            term.redirect(window2)
        end
    end

    local evt = {}
    local c1 = coroutine.create(receive)
    local c2 = coroutine.create(send)
    while true do
        coroutine.resume(c1, unpack(evt))
        coroutine.resume(c2, unpack(evt))
        evt = {os.pullEventRaw()}
        if coroutine.status(c2) == "dead" then
            rednet.send(id, aeslua.encrypt(tostring(encryption_number), "**exited**", aeslua.AES128, aeslua.CBCMODE, sender_library), "encrypted_chat")
            break
        end
    end
    print("Thanks for using the program!")
else
    local library = {}
    for i = 1, 16 do library[i] = math.random(1, 255) end
    print("")
    write("Enter ID: ")
    id = tonumber(read())
    print("Waiting for "..id.." to connect..")
    local sender, msg, protocol
    repeat
        sender, msg, protocol = rednet.receive()
    until sender == id and protocol == "encrypted_chat" and msg[1] == "connect"
    local sender_number = msg[2]
    local encryption_number = math.pow(sender_number, X%P)
    rednet.send(sender, {"connect", math.pow(Y, X%P), library}, "encrypted_chat")
    print("You are now chatting with "..id)


    local window1 = window.create(term.current(), 1, 1, 51, 18)
    window1.setBackgroundColor(colors.black)
    window1.setTextColor(colors.yellow)
    window1.clear()
    local window2 = window.create(term.current(), 1, 19, 51, 1)
    window2.setBackgroundColor(colors.gray)
    window2.clear()

    local function receive()
        while true do
            local _, msg, prot = rednet.receive()
            if id == _ and prot == "encrypted_chat" then
                local str = aeslua.decrypt(tostring(encryption_number), msg, aeslua.AES128, aeslua.CBCMODE, library)
                term.redirect(window1)
                term.setCursorBlink(false)
                print(id.."> "..str)
                window2.restoreCursor()
                term.redirect(window2)
                term.setCursorBlink(true)
            end
        end
    end

    local function send()
        while true do
            write("> ")
            local omsg = read()
            if omsg == "/exit" then break end
            msg = aeslua.encrypt(tostring(encryption_number), omsg, aeslua.AES128, aeslua.CBCMODE, library)
            rednet.send(id, msg, "encrypted_chat")
            term.clear()
            term.setCursorPos(1,1)
            term.redirect(window1)
            print("You> "..omsg)
            term.redirect(window2)
        end
    end

    local evt = {}
    local c1 = coroutine.create(receive)
    local c2 = coroutine.create(send)
    while true do
        coroutine.resume(c1, unpack(evt))
        coroutine.resume(c2, unpack(evt))
        evt = {os.pullEventRaw()}
        if coroutine.status(c2) == "dead" then
            rednet.send(id, aeslua.encrypt(tostring(encryption_number), "**exited**", aeslua.AES128, aeslua.CBCMODE, library), "encrypted_chat")
            break
        end
    end
    print("Thanks for using the program!")
end