blink

--[[
-- SHA-256 implementation in CC-Lua
-- HMAC and PBKDF2 with SHA-256
-- By Anavrins
]]--

if not hash and not os.loadAPI( "hash" ) then
    local handle = http.get( "http://pastebin.com/raw/6UV4qfNF" )
    local file = fs.open( "hash", "w" )
    file.write( handle.readAll() )
    file.close()
    handle.close()
    os.loadAPI( "hash" )
end

--[[
    Base64 in Pure Lua
]]
local enc, dec
-- working lua base64 codec (c) 2006-2008 by Alex Kloss
-- compatible with lua 5.1
-- http://www.it-rfc.de
-- licensed under the terms of the LGPL2

-- bitshift functions (<<, >> equivalent)
-- shift left
do
    local function lsh(value,shift)
        return (value*(2^shift)) % 256
    end

    -- shift right
    local function rsh(value,shift)
        return math.floor(value/2^shift) % 256
    end

    -- return single bit (for OR)
    local function bit(x,b)
        return (x % 2^b - x % 2^(b-1) > 0)
    end

    -- logic OR for number values
    local function lor(x,y)
        result = 0
        for p=1,8 do result = result + (((bit(x,p) or bit(y,p)) == true) and 2^(p-1) or 0) end
        return result
    end

    -- encryption table
    local base64chars = {[0]='A',[1]='B',[2]='C',[3]='D',[4]='E',[5]='F',[6]='G',[7]='H',[8]='I',[9]='J',[10]='K',[11]='L',[12]='M',[13]='N',[14]='O',[15]='P',[16]='Q',[17]='R',[18]='S',[19]='T',[20]='U',[21]='V',[22]='W',[23]='X',[24]='Y',[25]='Z',[26]='a',[27]='b',[28]='c',[29]='d',[30]='e',[31]='f',[32]='g',[33]='h',[34]='i',[35]='j',[36]='k',[37]='l',[38]='m',[39]='n',[40]='o',[41]='p',[42]='q',[43]='r',[44]='s',[45]='t',[46]='u',[47]='v',[48]='w',[49]='x',[50]='y',[51]='z',[52]='0',[53]='1',[54]='2',[55]='3',[56]='4',[57]='5',[58]='6',[59]='7',[60]='8',[61]='9',[62]='-',[63]='_'}

    -- function encode
    -- encodes input string to base64.
    function enc(data)
        local bytes = {}
        local result = ""
        for spos=0,string.len(data)-1,3 do
            for byte=1,3 do bytes[byte] = string.byte(string.sub(data,(spos+byte))) or 0 end
            result = string.format('%s%s%s%s%s',result,base64chars[rsh(bytes[1],2)],base64chars[lor(lsh((bytes[1] % 4),4), rsh(bytes[2],4))] or "=",((#data-spos) > 1) and base64chars[lor(lsh(bytes[2] % 16,2), rsh(bytes[3],6))] or "=",((#data-spos) > 2) and base64chars[(bytes[3] % 64)] or "=")
        end
        return result
    end

    -- decryption table
    local base64bytes = {['A']=0,['B']=1,['C']=2,['D']=3,['E']=4,['F']=5,['G']=6,['H']=7,['I']=8,['J']=9,['K']=10,['L']=11,['M']=12,['N']=13,['O']=14,['P']=15,['Q']=16,['R']=17,['S']=18,['T']=19,['U']=20,['V']=21,['W']=22,['X']=23,['Y']=24,['Z']=25,['a']=26,['b']=27,['c']=28,['d']=29,['e']=30,['f']=31,['g']=32,['h']=33,['i']=34,['j']=35,['k']=36,['l']=37,['m']=38,['n']=39,['o']=40,['p']=41,['q']=42,['r']=43,['s']=44,['t']=45,['u']=46,['v']=47,['w']=48,['x']=49,['y']=50,['z']=51,['0']=52,['1']=53,['2']=54,['3']=55,['4']=56,['5']=57,['6']=58,['7']=59,['8']=60,['9']=61,['-']=62,['_']=63,['=']=nil}

    -- function decode
    -- decode base64 input to string
    function dec(data)
        local chars = {}
        local result=""
        for dpos=0,string.len(data)-1,4 do
            for char=1,4 do chars[char] = base64bytes[(string.sub(data,(dpos+char),(dpos+char)) or "=")] end
            result = string.format('%s%s%s%s',result,string.char(lor(lsh(chars[1],2), rsh(chars[2],4))),(chars[3] ~= nil) and string.char(lor(lsh(chars[2],4), rsh(chars[3],2))) or "",(chars[4] ~= nil) and string.char(lor(lsh(chars[3],6) % 192, (chars[4]))) or "")
        end
        return result
    end
end

--[[
Blink by KingofGamesYami
]]--

local compID = os.getComputerID()

local devicePairs, deviceKeys, cache = {}, {}, {}

local function getUUID()
    local uuid = math.random( 1, 2147483647 )
    cache[ uuid ] = true
    return uuid
end

local function getKey( a, b )
    return enc( hash.hmac( a, b ):toHex() )
end

if fs.exists( ".devicepairing" ) then
    local file = fs.open( ".devicepairing", "r" )
    devicePairs = textutils.unserialize( file.readAll() )
    file.close()
end

local modem = peripheral.find( "modem", function( name, obj )
    if obj.isWireless() then
        return true
    end
end )

if not modem then
    error( "No wireless modem connected!", 2 )
end

modem.open( 27 ) -- let's play genocide bingo! (+1 if you get the reference)

function pair( deviceID, str )
    devicePairs[ deviceID ] = str
    local file = fs.open( ".devicepairing", "w" )
    file.write( textutils.serialize( devicePairs ) )
    file.close()
end

function send( deviceID, message, timeout )
    if not modem.isOpen( 27 ) then
        modem.open( 27 )
    end
    modem.transmit( 27, 27, {blink=true, type="verifyKey", to=deviceID, from = compID, uuid = getUUID()} )
    local str, id
    if timeout then
        id = os.startTimer( timeout )
    end
    while true do
        local event, side, received, reply, message, distance = os.pullEvent()
        if event == "modem_message" and received == 27 and type( message ) == "table" and message.blink and message.type == "keyResponse" and message.from == deviceID then
            str = message.body
            break
        elseif event == "timer" and side == id then
            return false
        end
    end
    modem.transmit( 27, 27, {blink = true, type = "message", to = deviceID, from = compID, body = message, verification = getKey( devicePairs[ compID ], str ), uuid = getUUID() } )
    return true
end

function receive( deviceID )
    local event, body, from
    repeat
        event, body, from = os.pullEvent( "blink_message" )
    until from == deviceID
    return from, body
end

function setDeviceKey( str )
    return pair( compID, str )
end

function run()
    while true do
        local event, side, received, reply, message, distance = os.pullEvent( "modem_message" )
        print( type( message ) == "table" and message.type )
        if received == 27 and type( message ) == "table" and message.blink and message.to == compID and not cache[ message.uuid ] then
            cache[ message.uuid ] = true
            if message.type == "verifyKey" and devicePairs[ message.from ] then
                local str = hash.digest( tostring{} ):toHex()
                modem.transmit( 27, 27, {blink = true, type = "keyResponse", from = compID, to = message.from, body = str, uuid = getUUID() } )
                deviceKeys[ message.from ] = getKey( devicePairs[ message.from ], str )
            elseif message.type == "message" and message.verification == deviceKeys[ message.from ] then
                os.queueEvent( "blink_message", message.body, message.from )
                deviceKeys[ message.from ] = nil
            end
        elseif received == 27 and type( message ) == "table" and message.blink and not cache[ message.uuid ] then
            cache[ message.uuid ] = true
            modem.transmit( 27, 27, message )
        end
    end
end