Disk Formatting.

local file = fs.open( ".stored", "r" )
local data = file.readAll()
file.close()
local users = textutils.unserialize( data )

local function generatePass()
    local pass = ""
    for i = 1, 16 do
        math.randomseed( os.time() ^ ( math.random() * 10000 ) % math.random() )
        pass = pass .. string.char( math.random( 32, 126 ) )
    end
    return pass
end

local function saveUsers()
    local file = fs.open( ".stored", "w" )
    file.write( textutils.serialize( users ) )
    file.close()
end

while true do
    local side
    local event = { os.pullEvent() }
    if event[ 1 ] == "disk" then
        side = event[ 2 ]
        local path = disk.getMountPath( side )
        local user = disk.getID( side )
        if disk.getLabel( side ) then
            disk.eject( side )
        elseif disk.hasData( side ) and fs.exists( fs.combine( path, "startup" ) ) then
            disk.eject( side )
        elseif disk.hasData( side ) and fs.exists( fs.combine( path, ".password" ) ) then
            local file = fs.open( fs.combine( path, ".password" ), "r" )
            local pass = file.readAll()
            file.close()
            if users[ user ] == pass then
                local new = generatePass()
                users[ user ] = new
                local file = fs.open( fs.combine( path, ".password" ), "w" )
                file.write( new )
                file.close()
                saveUsers()
                rs.setOutput( "left", true )
                os.startTmer( 5 )
            else
                print( "access denied" )
            end
        else
            disk.eject( side )
        end
    elseif event[ 1 ] == "timer" then
        rs.setOutput( "left", false )
        if disk.isPresent( side ) then
            disk.eject( side )
        end
    end
end