Login script

os.loadAPI("hash")

local userNameText, passwordStarText, plainTextpassword, attempts, attemptsBeforeFailure, cursorIsOn, typingUserName = "", "", "", 0, 3, true, true
local timerUUID = os.startTimer(0.25)
local messageToUser = ""
local messageToUserTicksLeft = 0

for i,v in pairs(rs.getSides()) do
    if (peripheral.getType(v) == "modem") then
        if (rednet.isOpen(v)) then
            rednet.close(v)
        end
    end
end -- To be sure nobody is listening

function checkLogin(userName, password)
    -- passwordHash = hash.hash(password)
    passwordHash = hash.sha256(password)
    if fs.exists("loginPasswords.secure.txt") then
        local passwordFile = fs.open("loginPasswords.secure.txt", "r")
        local passwordTable = textutils.unserialize(passwordFile.readAll()) or {}
        passwordFile.close()
        return passwordTable[userName] == passwordHash
    else
        error("No saved Passwords! Please run \"EditUsers\" and follow its steps.")
    end
end

while true do
    term.clear()
    term.setCursorPos(1, 1)
    print("Welcome to computer #", os.getComputerID(), ". Please login.")
    if (cursorIsOn) then
        if (typingUserName) then
            print("Username: ", userNameText, "_")
            print("Password: ", passwordStarText)
        else
            print("Username: ", userNameText)
            print("Password: ", passwordStarText, "_")
        end
    else
        print("Username: ", userNameText)
        print("Password: ", passwordStarText)
    end
    print("\n", messageToUser)

    local event, return1, return2, return3 = os.pullEventRaw()
    if (event == "char") then
        if (typingUserName) then
            userNameText = userNameText .. return1
        else
            passwordStarText = passwordStarText .. "*"
            plainTextpassword = plainTextpassword .. return1
        end
    elseif (event == "key") then
        if (return1 == 28) then
            if (typingUserName) then
                typingUserName = false
            else
                if (checkLogin(userNameText, plainTextpassword)) then
                    if (fs.exists("loginStartup")) then
                        shell.run("loginStartup")
                        return
                    end
                else
                    attempts = attempts + 1
                    if (attempts >= attemptsBeforeFailure) then
                        print("Login Failed. Shutting Down.")
                        sleep(5)
                        os.shutdown()
                    else
                        messageToUser = "Login Failure #" .. attempts .. "/" .. attemptsBeforeFailure
                        messageToUserTicksLeft = 6
                    end
                end
            end
        elseif (return1 == 14) then -- delete key
            if (typingUserName) then
                userNameText = string.sub(userNameText, 1, string.len(userNameText) - 1)
            else
                passwordStarText = string.sub(passwordStarText, 1, string.len(passwordStarText) - 1)
                plainTextpassword = string.sub(plainTextpassword, 1, string.len(plainTextpassword) - 1)
            end
        end
    elseif(event == "timer" and timerUUID == return1) then
        if (messageToUserTicksLeft > 0) then
            messageToUserTicksLeft = messageToUserTicksLeft - 1
            if (messageToUserTicksLeft == 0) then
                messageToUser = ""
            end
        end
        cursorIsOn = not cursorIsOn
        timerUUID = os.startTimer(0.25)
    end
end

os.unloadAPI("hash")