Andtypicallyit's gonnabelike 300 or 433 megahertz.
Allright, sowhen I hitthisbutton, looktotheright.
Thisisinsane.
Sowhat?
I cantelljustbylookingatthisishowit's actually a modulatingthesignalonoutsendingthisiscalledamplitudeShift.
King A S K.
What's happeningis, everytime I'm holdingonthebutton, multiplebitsaregettingsenton a singlefrequencyandithastodowiththetimethatit's onoroff, whichmeans a oneor a zero.
I mean, notonlydoesthatmeanwecanthrowoutallthegapsbetweenourcodesthatcoverallthecombinations, itactuallymeanswecanmergesomeofthosecombinationstogetherbecauseessentially, wecanoverlapthecodestomakesurewehaveeverycombinationinthere.
A sequencelikethisiscalled a deBruinsequence, andthatreducesthenumberofbitsyouhavetosenddramatically.
Andthat's becauseactuallyhave a differentgaragedooropener, whichhasthenextlevelupofsecurityinsteadofusingfixedcodes, useswhatarecalledrollingcodes.
Sothewayrollingcodesworkisthatbothyourclickerandthereceiverhaveinsidethemanalgorithmthatuses a seedwhichcouldjustbe a numbertogenerate a pseudorandomnumber.
Andthatisthecodethattheybothusedtocommunicate.
Sohere I haveanonlinepseudorandomnumbergenerator I canputin a seed, which, inmycase, I'lljustkeepitverysimple, and I canpickwhicheverourthem I want.
That's theseedthey'reusingtogeneratethenextpseudorandomnumberinthesequenceso I cancalculate a randomnumber, andthiswouldbethecodeusedbytheclickerandthegaragedoortocommunicateifanattacker's sittingoutsideortheyplant a devicethat's justlisteningtoour F andstoresthatthecodeoncewhenyoupressthebuttonwell, theyhavethatcode.
Butitjustgotusedup.
Andnowthatreceivercansay I willnote, Neverrespectthatcodeagain.
Asyoucansee, I cancontinuegeneratingnewpseudorandomnumbers, andifanyoneisoverhearingthissequence, theywon't beabletopredictwhatthenextnumberis.
What I thoughtwas, whatifyoucouldactuallyinterferewiththatsignal?
Sowhatif I put a deviceonyourgarage, yourcaranditlookedforsomethinglike a sinkword, andwheneveritsawthattherewasdatacomingin, itwouldjam a frequencyclosetothat.
Yourcargaragewouldnotbeabletoheartheactualpassword, therollingcodethatyourtransmittersentand I wouldnowrecordit.
Thenyou'relike, OK, I justpressthisbuttoninmygarageandopen.
Whatdo I do?
Probablygonnahititagain.
Yougetittotwotimes.
And I haveproducedtworollingcodes.
Well, nowthat I havetohavejammedboth, I canreplaythe 1st 1 andthe 1st 1 allowsyourgaragetoopen.
You'relike, Oh, great.
Itworkedonce I hitthebuttontwice.
Butnow I have a futurecode.
I have a codethatappearstobeinthefuture, and I canthencomebacklaterandusethatgoat.
Thesedeviceshavenotime.
Theyhavenosenseoftiming.
Alltheyhaveisthatsequence.
Sothatis a kindof a bigissuewithrollingcodesthemselves.
I haven't atebitgatethatwetriedtohackinto, andwefailedeverytimeusingthe I amme 256 possibilities.
Howlongcouldittakeyoutocrackthisthing?
I thinkwehavebooked a workout.
No, Thegameisn't moved.
Thiswasmeanttobe a videoaboutjusthoweasyitwouldbetocrack a fixedcodegate, butitturnsoutthatit's harderthanitlooks.
I just I justdidthat, Uh, for a minute, everythoughthehadit.
Uh, yeah, thegate.
It's hardtogetthefrequencyexactlyright.
It's hand.
Soandthebitrateandonebitofinformationforthatclicker, whichiscustombuiltforthatpurposeandsimplyhasthosedipswitchesisnotonebitofinformationfor a multipurposedeviceliketheMiamiThere, youhavetogetthebodrateright.
Thatisthetimingatwhichyou'resendingthesebits.
Youhavetogetthelengthofthebitsperfectlyright.
Soit's muchmorechallengingas I foundout, hackintothesesystemsthan I thought.