Slide 1MenuResourcesWhy you should take this course?Why you should take this course? Reason #2: IntellectualWhy you should take this course? Reason #3: Be like Tomhttp://monticello.org/jefferson/wheelcipher/Bad reasons to take this classHow to get an A in CS588“Easy ways” to get an A in CS588Bonus Points / DemeritsChallenge ProblemsHonor CodeDecrypting the Honor CodeSlide 15What is cryptology?Cryptology and SecurityIntroductionsSlide 19CryptosystemKerckhoff’s PrincipleSymmetric CryptosystemAsymmetric CryptosystemSimple Substitution CipherMonoalphabetic CipherFrequency AnalysisPattern AnalysisGuessingSlide 29Slide 30Slide 31Slide 32Slide 33Why was it so easy?How to make it harder?Types of AttacksReally Brief History First 4000 yearsReally Brief History - last 100 yearsThemesSecurity vs. PragmaticsPerfectly Secure Cipher: One-Time PadWhy perfectly secure?Go to the beach?“One-Time” Pad’s in PracticeColossus – First Electronic Programmable ComputerColossusChargeDavid Evanshttp://www.cs.virginia.edu/evansCS588: CryptologyUniversity of VirginiaComputer ScienceCS588: Cryptology – Principles and ApplicationsLecture 1: Introduction20 January 2005 University of Virginia CS 588 2Menu•Course Introduction–Why you should or shouldn’t take this course–Course Logistics: details on Syllabus•Introduction to Cryptology–Terminology–A simple substitution cipher–Brief history of 4000 years of CryptologyRegistration survey on web: due Sunday20 January 2005 University of Virginia CS 588 3Resources•David Evans (call me “Dave” or “Coach”) [email protected] Hours (236A): Tuesday, 2:30-3:30other times by appointment or open doorResearch: Applications of cryptography, diversity for security, program analysis•AC: Matt SpearCS Lounge: Fridays, 2:30-3:30•Web: http://www.cs.virginia.edu/cs58820 January 2005 University of Virginia CS 588 4Why you should take this course?Cryptology plays a central role in human history.More than anything else, survival of humanity depends on computer security.Reason #1: Fate of Humanity20 January 2005 University of Virginia CS 588 5Why you should take this course?Reason #2: IntellectualCryptology is about making and solving puzzles.Purest form of intellectual endeavor.20 January 2005 University of Virginia CS 588 6Why you should take this course?Reason #3: Be like TomMr. Jefferson would have wanted you to.20 January 2005 University of Virginia CS 588 7http://monticello.org/jefferson/wheelcipher/20 January 2005 University of Virginia CS 588 8Bad reasons to take this class•You want to write the ultimate destructive virus.•You want to break into (UVA’s | the CIA’s | your bank’s) computer systems.20 January 2005 University of Virginia CS 588 9How to get an A in CS588Problem Sets (40-50%)4-5 throughout term (1st is due 3 Feb)Project (30-50%)Teams of 1 – 4Can involve design/implementation Can involve survey/analysisExams (30-50%)Midterm, FinalClass Contribution (0-10%)20 January 2005 University of Virginia CS 588 10“Easy ways” to get an A in CS588•Discover a security flaw important enough to get reported in the New York Times•Factor RSA-300 = 276931556780344213902868906164723309223760836398395325400503672280937582471494739461900602187562551243171865731050750745462388288171212746300721613469564396741836389979086904304472476001839015983033451909174663464663867829125664459895575157178816900228792711267471958357574416714366499722090015674047•Break into my grades file (on my home computer) and change your grade to “Haha”–Physical attacks on my house, car or office are NOT eligible! (And NOT encouraged!)–Don’t try to break into UVA’s grade records:•Too easy (probably only worth a B, or C- for social engineering attack)•Honor code violation20 January 2005 University of Virginia CS 588 11Bonus Points / Demerits(100 points = 1 problem set)+(varies) Solving a challenge problem+50 Posting in RISKS-100 Send me a virus-200 Get arrested for computer attack-1000 Get convicted for computer attack-100000 I get arrested for something you do20 January 2005 University of Virginia CS 588 12Challenge Problems•Open until solved or last day of class•Usually only first satisfactory answer gets bonus–Better, later answer might still get bonus•Solve in groups, each member getsn / n * value (e.g., 2 people = 2 / 2 = 0.7)First challenge problem will be posted on course web page tomorrow: Jefferson wheel cryptogram20 January 2005 University of Virginia CS 588 13Honor Code•If the real world followed the honor code, cryptography would be unnecessary•Read and sign the course pledge before Tuesday’s class20 January 2005 University of Virginia CS 588 14Decrypting the Honor Code•Learn from your fellow students – they are your best resource!–PS1: discuss with whoever you want, but destroy all written materials from those discussions before writing your solutions•Write down who you discussed assignments with, all external sources you used•Don’t use answers from previous courses•Be honest – you know what cheating is and isn’t•Don’t “pledge” your assignments, but let me know if you plan to cheat20 January 2005 University of Virginia CS 588 15Logistics Questions?20 January 2005 University of Virginia CS 588 16What is cryptology?•Greek: “krypto” = hide•Cryptology – science of hiding = cryptography + cryptanalysis + steganography•Cryptography – secret writing•Cryptanalysis – analyzing (breaking) secretsCryptanalysis is what attacker doesDecipher or Decryption is what legitimate receiver does• Kryptonite – breaking ciphers all night?20 January 2005 University of Virginia CS 588 17Cryptology and SecurityCryptology is a branch of mathematics.Security is about people.This course focuses on the mathematics, but always keep in mind real security is about the people.20 January 2005 University of Virginia CS 588 18IntroductionsEncryptDecryptPlaintextCiphertextPlaintextAliceBobEve(passive attacker)Insecure Channel20 January 2005 University of Virginia CS 588 19IntroductionsEncryptDecryptPlaintextCiphertextPlaintextAliceBobMalice(active attacker)Insecure Channel20 January 2005 University of Virginia CS 588 20CryptosystemCiphertext = A(Plaintext)Plaintext = A′(Ciphertext)Required property: A must be invertibleDesired properties: Without knowing A′ must be “hard” to invertA and A′ should be easy to computePossible to have lots of different A and A′Possible to reveal