cs 394b introduction - kaustweb.kaust.edu.sa/faculty/marcocanini/classes/cs394b/s18/... ·...

CS394BIntroductionMarcoCanini

CS394B– S18 1

ThisClass• Courseisacombination:classesinaflippedclassroomstyleandpaperpresentations/discussions

• Learntechnicalaspectsofblockchain technologiesanddistributedconsensus• Havetheconceptualfoundationstoengineersecuresoftwarethatinteractswiththeblockchain• Beabletointegrateideasfromtheblockchain intheirownprojects

• Comprehendandcritiquerelevantresearchpapersintheareaofblockchain systems• Presentresearchideasbothorallyinaconcisewayandwithintheallottedtimeaswellasinwriting

• Defendtheresearchapproach,designdecisions,andtheevaluationmethodsinadiscussion• Moderateadiscussionafteraresearchpresentation

CS394B– S18 2

AbouttheInstructor

• MarcoCanini• AssistantProfessoratKAUSTsinceAug’16• https://mcanini.github.io

• Researchinterestsspan• DistributedandNetworkedsystemsinthecontextofcloudcomputing,large-scaledataanalytics,andmachinelearning

• HeadofSANDSLab• Software-definedAdvancedNetworkedandDistributedSystemsLaboratory

CS394B– S18 3

Myresearch

4

SoftwareEngineering

Networking

FormalMethods

ProgrammingLanguages

OptimizationTheory

Idesign,build,measureandanalyzelarge-scalenetworkedsystemsthatspanmultipleautonomous,

potentiallyuntrustedentities

Security

MachineLearning

Goal: Discoverandapplyfundamentalprinciplesandvaluableknowledgeonhowtobuildscalable,dependable

andfuture-proofsystems,worthyofsociety’strust

DistributedSystems

CS394B– S18

Challenges

#1Challenge:Complexity

Hardtoreasonaboutbehaviorassystemsscaletolargenumbersofcomponentsandusers

• Poorlyunderstoodconnections• Needpredictabilitytoensurescalableperformance,reliableoperation,etc.

5CS394B– S18

SystemsApproach

• Formulateproblem• Getidea• Buildprototype• Measure&analyze• Adjustprototype…repeatpreviousstep

Principlesofsystemconstruction• modularity,hierarchy,layering,abstraction,endtoend

6CS394B– S18

Newapproachesareneeded

Systemsbasedondesigndecisionsmadeinthelastdecadecanhardlycopewithtoday’sscale,volumeorvelocity,letalonethefuture

Weneednewtechniques,designsandsolutions:• Improveperformancebyatleast10x,insomecases100x

• Ensurepredictabilityofperformanceandhighreliability

• Lowercomplexity ofmanaginglarge-scalesystems andprocessingbigdata

7CS394B– S18

SANDSLabVision

Makeiteasytoproduceandmanagekeynetworkedsystemsthatareworthyofsociety’strustandachievespecificobjectives:• Highperformanceandscalability• Highdependabilityandfuture-proof• Lowpower• …

WebuildprototypesthatdirectlyimprovethelivesofrealusersWelearngeneralprinciplesandlessonsofwhatworksinpractice

8CS394B– S18

Example:Dynam-IX

• DynamicInterconnectioneXchange

• https://dynam-ix.github.io/

CS394B– S18 9

WhatAboutYou?

• Pleaseintroduceyourself!• Whyareyouinthisclass?• Howcanwemakeitaveryusefulone?

CS394B– S18 10

Aboutthisclass

CS394B– S18 11

CourseSchedule

• Webpage:http://web.kaust.edu.sa/Faculty/MarcoCanini/classes/CS394B/S18/• Piazza:https://piazza.com/kaust.edu.sa/spring2018/cs394b

• Meetings• 4PM– 5:30PM(Sun forlecturesanddiscussions)

• Payattentiontotheonlineannouncementsandschedule• Onaverage,onemeetingperweek• Makeupswillbeaddedonaneed-to-addbasis,typicallyWed

CS394B– S18 12

Prerequisites

• CS240(ComputingSystemsandConcurrency)• BasicsofOSorganization,threads,memorymanagement,filesystems,scheduling,networking,etc.• EquivalentcourseofCS240isacceptableaswell

• Goodprogrammingskills• Distributedsystems– helpful• Cryptography– helpful• Probability– helpful

CS394B– S18 13

Flippedclassroom

• Courselecturesareonline• WefollowthecourseBitcoinandCryptocurrencyTechnologiesbyArvindNarayanan,JosephBonneau,EdwardFelten andAndrewMillerhttp://bitcoinbook.cs.princeton.edu/

• Youmustwatchthevideomaterialbeforethemeeting• Wegodeepintoeachtopicduringmeetings• Sendmequestionsinadvanceregardingthematerial

CS394B– S18 14

Textbook

• Textbooknotrequiredbutcanbeveryhelpful• ArvindNarayanan,JosephBonneau,EdwardFelten,AndrewMillerandStevenGoldfeder,BitcoinandCryptocurrencyTechnologies• Apre-publicationdraftofthebookisavailablefordownloadonthewebsite:http://bitcoinbook.cs.princeton.edu/

CS394B– S18 15

CourseRequirements

PaperReviews 15%Paper Presentation 15%ActiveParticipation 5%Assignments 25%Project 40%

Checkpoint#1:initialproposal 5%Checkpoint#2:midtermprogressreport 10%Presentation 10%Finalreport 15%

CS394B– S18 16

PaperReviews

• Paperreviewsaccountfor20% ofthetotalgrade• 6-8summariestowrite• Whatgoesinagoodsummary?• Highlightstrengths• Highlightweaknesses• Describetheentirepaperin3-5sentences

CS394B– S18 17

Papers

• Readcritically!• Istheproblemreal?• Whatisthesolution’smainidea(nugget)?• Whyissolutiondifferentfrompreviouswork?• Areassumptionsdifferent?• Isworkloaddifferent?• Isproblemnew?

• Doesthepaper(ordoyou)identifyanyfundamental/hardtrade-offs?• Doyouthinktheworkwillbeinfluentialin10years?• Whyorwhynot?

CS394B– S18 18

PaperReviews

• Reviewsmustbesubmittedelectronically24hoursbeforetheclass• SendthereviewviaPiazzaasprivatenotetoInstructors

• Youcanmissatmosttwowithoutanypenalty• Eachmissingonebeyondthatwillresultin25%decreaseingradeforthissegment• Meaning,missingsixormorewillresultin0%forthe“PaperReviews”segmentofyourgrade

• Reviewsarepeer-reviewed• Anotherstudentwillreadandgiveconstructivefeedbackonyourreview• Thegoalistomakebetterreviews• Goodfeedbackwillbeconsideredpositivelyduringgrading

• Read(ifyouhaven’talready!)• HowtoReadaPaper byS.Keshav• Howtoreadaresearchpaper byMichaelMitzenmacher• WritingReviewsforSystemsConferences byTimothyRoscoe

CS394B– S18 19

HowtoReview

• Youwillseeasectionfordescribingapapersummary,itsstrengths,itsweaknesses,anddetailedcomments• Inthesummarysection,pleasedirectlyaddress:

1. Whatproblemthepaperisaddressing(1-2sentencesorbullets)2. Thecorenovelideasortechnicalcontributionsofthework(1-2sentencesorbullets).Put

anotherway,what'sthe30secondelevatorpitch,or,fiveyearsfromnow,whatshouldonerememberaboutthispaper?

3. Alongerdescription(3-5sentences)thatsummarizesthepaper'sapproach,mechanisms,andfindings.

• Fortheothersections,pleaseinclude2-4bulletpointsforthestrengthsandweaknesses,whileamuchlongerexpositioninthedetailedcomments.• Remembertobeconstructive:don'tonlyfocusonthepaper'sshortcomings,butalsoonwhatitcouldhavedonedifferentlyorasthenextsteps.Imaginethatyouarehavingaconversationwiththeauthors:Whatwouldyoutellthem?

CS394B– S18 20

PaperPresentation

• Eachstudentmustpresentatleasttwopapers;possiblythree• Paperpresentationaccountfor15% ofthetotalgrade

• Twopapersperclassand20-minutespresentationforeach• Sharp20minutes;westartclapping!• Followedbydiscussionanchoredbythepresenters

• Whatshouldgoinausefulpresentation?• Motivate• Highlightthekeyideasandinsights;skip thedetails

• Leadthediscussion• Gothroughthestrengthsandweaknessesfromthepaperreview

CS394B– S18 21

PresentationGuidelines

Youroraldescriptionofthepapershouldfollowamuchsimilarformat:1. Title,authorsandinstitutions,conference/journal2. Problem3. Coreideas4. Descriptivesummaryandmainresults5. Strengths6. Weaknesses/limitations7. Furtherdiscussion,includingproposalsforfollow-upwork

CS394B– S18 22

PaperPresentation

• Emailyourslidestotheinstructor24hoursbeforetheclass• Prepareearly• Practicealot• Also,read• HowtoGiveaBadTalk byDavidA.Patterson• PointersforLeadingPaperDiscussions byRandyH.Katz

CS394B– S18 23

Participation

• Attendallmeetings• Canmissatmosttwowithlegitimatereasons

• Readallthepapersandparticipate• Askquestions!

• Sendquestionsonvideolectures(inadvance)

CS394B– S18 24

Assignments

• 3programmingassignments• Tobedoneindividually;due11:59pmonduedate

• 20/2Assignment1due• 6/3Assignment2due• 21/3Assignment3due

• Noextensionsgiven

CS394B– S18 25

Project

• Thebiggestcomponentofthiscourse• Pickaninterestingopenproblem.Whyisitimportant?• Whathasalreadybeendone?Whyaretheynotenough?• Developahypothesisabouthowyou’dimproveit

• Intuitively,whywillyourapproachwork?• Buildasubstantialprototype

• Experiment,measure,andcompareagainstthestate-of-the-art

• Aimatproducingaconference/workshop-qualityresearchpaper• Canberelatedtoyourresearchtopicbutitisexpectedtobedistinct!

CS394B– S18 26

Projects

• Thefinalprojectaccountsfor40% oftotalgrades• Doneingroupsof2students.Findyourpeers!

• Whatcanandcannotbeaproject?• Justsurveysarenotallowed.Infact,eachprojectmustincludeasurveyofrelatedworkandbackground• Anidealprojectshouldanswerthequestionsyouaskedduringpaperreviewsandpointsyoucaredaboutforpresentations• Measurementsofnewenvironmentsorofexistingsolutionsonnewenvironmentsareacceptableupondiscussion

• Willcoverprojectsinmoredepthinthenextmeeting!

CS394B– S18 27

HowtoApproachit?

1. Findaproblemandmotivatewhythisisworthsolving2. Surveybackgroundandrelatedworktogetasenseofyour

(friendly!)competition• Mightrequireyoutogobacktothefirststep

3. Form/updateyourhypothesis4. Testyourhypothesis• Gobackto3untilyouarehappy

5. Presentyourfindingsinapresentationandinwriting• Discussknownlimitations

CS394B– S18 28

MilestonesDate Milestone DetailsASAP Form Group Find like-minded students

14/2/18 Draft Proposal Send your proposal by email

7/3/18Finalize ProposalCheckpoint #1 (5%)

After a back-and-forth discussions with the instructor

21/3/18Midterm Progress ReportCheckpoint #2 (10%)

Should read like parts of a research paper

25/3/18 Midterm PresentationsDefine and motivate a problem, survey related work, and form initial hypothesis and idea

13/5/18 Presentations (10%) Present your findings in a presentation

16/5/18 Research paper (15%) Submit a final report similar to the papers you readCS394B– S18 29

DraftProposal

• Twopagesincludingreferencesthatideally includes• Whatistheproblem?• Whyisitimportanttosolve?• Anyinitialthoughtsonwhatyouwanttodo?• Howwouldyouevaluateyoursolution?

• Includeteammembers• Meaning,formagroupASAP

• Scheduleviaemaila15-minutemeetingtodiscuss

CS394B– S18 30

Read:TheHeilmeier’s Catechism

FinalizedProposal

• Twopagesincludingreferencesthatmust include• Whatistheproblem?• Whyisitimportanttosolve?• Anyinitialthoughtsonwhatyouwanttodo?• Howwouldyouevaluateyoursolution?

• Approvedbytheinstructorandagreeduponbyyou• Formsthebasisofexpectation

CS394B– S18 31

MidtermPresentation

• In-classshortpresentationoveroneday• Thisistomakesureyouaremakingprogress

• Mustinclude• Whatistheproblem?• Whyisitimportant?• Whatarethemostrelatedwork?• What’syourhypothesissofar?• Howare/willyouevaluateit?

CS394B– S18 32

FinalPresentationandPaper

• Presentation• Itwillfollowaformatsimilartootherpresentationsgivenintheclass

• Researchpaper• Thekeypart• Shouldbewrittensimilartothepapersyou’veread• Yourgoalistodopublishablequalitysystemsresearch• Uptofive“bestprojects”willbeearmarkedforexpeditedsubmissiontoarenownedconference,withthehelpoftheinstructor• HowtoWriteaGreat ResearchPaper bySimonPeytonJones

CS394B– S18 33

RoughOutline

• Abstract• Introduction(Highlighttheimportanceandgiveintuitionofsolution)• Motivation (Usedataandsimpleexamples)• Overview(Summarizeyouroverallsolutionsothatreaderscanfollowlater)• CoreIdea (Maincontributionw/challengesandhowyouaddressthem)• Implementation(Discussnon-obviouspartsofyourimplementation)• Evaluation (Convincereadersthatitworksandwhenitfails)• RelatedWork (Letreadersknowthatyouknowyourcompetition!)• Discussion(Knowyourlimitationsandpossibleworkarounds)• Conclusion(Summarizeandpointoutfuturework)

CS394B– S18 34

CourseTopics

• Introductorymaterial(~10videolectures)• basicsofcryptography;Merkle tree• blockchain;distributedconsensus• mining;incentives• proofofwork;proofofstake• governance;economics• security• smartcontracts;applications

• Advancedmaterial• activeresearchproblemsinthearea,includingattacks,networkscalability,alternativestoproofofwork/stake

CS394B– S18 35

BeforeWeMoveOn…

• Noextensions• Everyonemustwatchlecturesandreadpapersinadvance• Classmeetingformat• Quicksummarybytheinstructor• Topicdiscussionandaddressingquestions• Presentationofonepaper• Presentersleaddiscussionsonthepaperswe’vereadandrelatedtopics

CS394B– S18 36

DevelopingaCryptocurrency

SlidecourtesyofIttay EyalCS394B– S18 37

Bitcoin

2008:TheBitcoinwhitepaper2009:Referenceimplementation

Probablynotthisguy

SlidecourtesyofIttay Eyal CS394B– S18 38

KeyChallenges

A

B

C

1. Nostealing:OnlyAlicecanmovehermoney2. Minting:Fairmoneycreation3. Nodouble-spending:Alicecannotduplicatehermoney


60SecondsonPublicKeySignatures

Alicegenerateskeypair1. privatekey𝑘",keptsecret2. publickey𝐾",publishedwithpublickeyinfrastructure

• Alicesignsamessage𝑚withprivatekey𝑘",generatingasignature𝑠.

• Anyonecanverifythat𝑠 isasignatureof𝑚 withkey𝑘"given𝑚 and𝐾".


AddressesandTransactions

1.sgn(𝑘")

2.sgn(𝑘')2.𝐾(,amount𝑦

1.𝐾*,amount0.5𝑥

3.𝐾/,amount0.5𝑥

2.𝐾",amount𝑥

…

…

1.𝐾',amount𝑦


1. Nostealing:OnlyAlicecanmovehermoney2. Nodouble-spending:Alicecannotduplicatehermoney3. Minting:Fairmoneycreation

KeyChallenges

A

B

C


GlobalLedger

Mà A

Aà B

Bà C


GlobalLedger

Mà A

Aà B

Aà C


GlobalLedger

Mà A

Aà B

Bà C


KeyChallenges

A

B

C

1. Nostealing:OnlyAlicecanmovehermoney2. Nodouble-spending:Alicecannotduplicatehermoney3. Minting:Fairmoneycreation


60SecondsonCryptographicHashing

HashFunction

𝐻

Lorem ipsum dolorsitamet,consecteturadipiscing elit,sed doeiusmod temporincididunt ut labore etdolore magnaaliqua.Utenim adminimveniam,quis nostrudexercitationullamco laboris nisiut aliquip exeacommodo consequat.Duis aute irure dolorinreprehenderit involuptate velit esse cillumdolore eu fugiat nulla pariatur.Excepteur sintoccaecat cupidatat nonproident,sunt inculpaquiofficia deserunt mollit anim idest laborum.

56293a80e0394d252e995f2debccea8223e4b5b2b150bee212729b3b39ac4d46

Stringinput 256bitnumber(forexample)

Givena256bitnumberℎ,onecannotfindaninputstringthatresultsinℎ fasterthanrepeatedlyguessinginputs𝑥 andcalculating𝐻(𝑥).


Mining– MintingforProofofWork

Computationallydifficultpuzzle:

Find𝑥 suchthat𝐻 𝑥|𝑦 < 𝑡

Solverguessesvaluesfor𝑥 untilfindingavalidone

• Differentstrings𝑦 fordifferentpuzzles• Thetarget𝑡 determinesthedifficulty,averagetimetosolve


Mining– MintingforProofofWork

A

puzzle

solution(PoW)


KeyChallenges

1. Nostealing:OnlyAlicecanmovehermoneyCryptographicsignatures

2. Nodouble-spending:AlicecannotduplicatehermoneyGloballedger

3. Minting:FairmoneycreationMintforproofofwork


KeyChallenges

Whogivesmoneyforpuzzles?

Whorunsthepublickeyinfrastructure?

Whomaintainsthepublicledger?

Canthisbedecentralized?





ReplicatedStateMachine

• Insteadofonemachine,useareplicatedstatemachine• Multiplemachinesoperateasingleledger,PKI,andmintfairly• Asubsetcanbehavearbitrarily– akaByzantine

Butwhochoosestheparticipatingmachines?


AReplicatedStateMachine

𝐴8 → 𝐵8

Log

A B

𝐴8 → 𝐴; 𝐵8 → 𝐶8


Nakamoto’s Blockchain

Log Blockchain

block

header



Log Blockchain

block

header



Log Blockchain

hash( )< target*

*target:adeterministicfunctionofpreviousblocks



Exponentialrandominterval


IncentiveforMining

• InternalPrize:• Minting• Fees

Wins proportionaltocomputationpower


Forks

• Naturalinadistributedsystem


ForkResolution

• Longest chainwins• Transactionsarereverted• Double-spendingathreat


ForkResolution

Atransactionisconfirmed whenitisburied deepenough


KeyChallenges

Decentralized





Next…

• Followlecture1• ReadBitcoin:APeer-to-PeerElectronicCashSystem

• WemeetonWednesday

CS394B– S18 65

cs 394b introduction - kaustweb.kaust.edu.sa/faculty/marcocanini/classes/cs394b/s18/... ·...

Documents