CPSC 418/MATH 318 Introduction to Cryptography Outline Course Technicalities, Symmetric Cryptosystems Course Technicalities Renate Scheidler 1 Department of Mathematics & Statistics Overview of Cryptography 2 Department of Computer Science Cryptography Within Information Security University of Calgary Week 1 Symmetric Cryptography 3 Cryptanalysis 4 Cryptographic Attacks Cryptographic Security Email Comic Share on Facebook Tweet Share on LinkedIn Comments 144 Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 1 / 35 Buy ×Close Share September 08, 2019's comic on: Facebook Twitter Reddit Course Technicalities Motivation Course Details Course web page: //people.ucalgary.ca/~rscheidl/418 Cryptography (from the Greek) — ‘hidden writing’ Course info, slides, assignments, handouts, course schedule, useful links What would you like to see in a secure electronic assignment submission system? Want submission: Link can be found on the D2L page (combined page for CPSC 418 and MATH 318) confidential so no one can steal it (confidentiality) protected so no one can alter it (data integrity) Delivery: authentic so no one can impersonate creator (entity authentication) Lectures (MWF 2:00-2:50 pm, ST 148) safe from intrusion on disk (access control) For CPSC 418 only: individual tutorials once a week (5 tutorials, all safe from denial by instructor or TA (non-repudiation) Mon & Wed afternoons) For CPSC 418 only: common tutorial (Wed 18:00-18:50, ICT 102) This course will work toward solutions for ensuring all of these. Examples of complete systems at end of the course. Read through the course website this week. Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 2 / 35 Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 3 / 35
Course Technicalities Course Technicalities Course Materials Software Tools Course resources : course web page Recommended textbook (entirely optional): //people.ucalgary.ca/~rscheidl/418 D. R. Stinson & M. B. Paterson Discussion forum : Piazza Cryptography — Theory and Practice I will enroll you all; watch for a welcome e-mail 4 th edition, CRC Press, 2019 Assignment submission : Gradescope Older editions of Stinson’s book are obsolete and missing modern You will need to create an account (user name is your U of C e-mail material! address) and add the course to your account using the code 9GZZ3B Slides, handouts, practice problems, L A T EX templates, tutorial Grade maintenance D2L materials (on course web page) Other sources (see “references” page) For day-to-day use, you only need the course web page and Piazza. Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 4 / 35 Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 5 / 35 Course Technicalities Course Technicalities Course Evaluation Course Content Rough schedule: 30%: 3 assignments (approx. 4 weeks time for each) 5 weeks: Encryption via conventional cryptography (what it is, what Some written problems common to CPSC 418 and MATH 318 it does, techniques, attacks) Some for CPSC 418 only (mainly programming problems, can be 1 week: Cryptographic key agreement done by MATH 318 students for bonus credit) Some for MATH 318 only (mainly mathematical and proof-oriented 1.5 weeks Data integrity via conventional cryptography problems, can be done by CPSC 418 students for bonus credit) 4 weeks: Public Key Cryptography (encryption, signatures) All work must be done individually All written work must be done in L A T EX 1 week: Cryptography in practice and real-life use examples, plus All programming problems must be coded in Python other topics (time-permitting) More about this course under “about” tab on web page 30%: midterm exam (March 18, 18:00-29:30, location TBD, closed book) 40%: final exam (scheduled by the Registrar, on all course material) CPSC 418 is part of the Computer Science BSc concentration (area of specialization) in Information Security Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 6 / 35 Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 7 / 35
Overview of Cryptography Overview of Cryptography Basic Terminology More Terminology Historically, cryptography is the art of sending messages in secret, or Definition 3 (plaintext) disguised form. The message or data to be encrypted. Definition 1 (encrypt, encipher) Definition 4 (ciphertext) To render a message unintelligible to everyone except the intended recipient. The message after encryption. Definition 2 (decrypt, decipher) Definition 5 (cipher, cryptosystem) To transform an encrypted message back into its unencrypted form. A particular method of encryption, capable of handling arbitrary messages. Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 8 / 35 Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 9 / 35 Overview of Cryptography Overview of Cryptography An Old Example An Old Example Example 6 (Caesar Cipher) Substitute each plaintext letter with the third subsequent letter of the Example 7 (Caesar Cipher) alphabet, wrapping from Z to A ; i.e. A → D , B → E , · · · , Z → C : Can you crack the code? Plaintext: I came, I saw, I conquered. Ciphertext: GTB YNJX FWJ HTTQ. Ciphertext: L FDPH, L VDZ, L FRQTXHUHG. Plaintext: Example of a class of ciphers knows as shift ciphers : shift every letter by another letter a fixed position down in the alphabet (with “wrap-around” at “Z”). Any good strategies? 2000 years old: According to Suetonius (“Lives of the Caesars”), Julius Caesar used this cipher during his campaign in Gaul (modern day France) to send encrypted dispatches back to Rome. Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 10 / 35 Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 11 / 35
Overview of Cryptography Overview of Cryptography Cryptography Within Information Security Who Uses Cryptography? Information Security Historic users: Governments (military, diplomatic service) Definition 8 (information security) A few private citizens (illicitly, e.g. for secret love letters, conspiracies) Measures to protect information and information systems from Modern users (since invention of computers): unauthorized access, use, disclosure, disruption, modification or Everyone (using a computer, smart phone, credit card, ATM, the destruction. internet, . . . ) Cryptography is ubiquitous! Examples: Cryptography provides some such measures in e-commerce, online banking/shopping/auctioning, storage of important foundational part of complete security systems sensitive data, cloud computing, and much more addresses mainly technological questions in personal computers, mobile phones, chip cards, medical devices, does not do it all! cars, sensors, and many more. Modern cryptography does MUCH more than just hiding messages! Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 12 / 35 Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 13 / 35 Overview of Cryptography Cryptography Within Information Security Overview of Cryptography Cryptography Within Information Security Security Objectives Security Mechanisms Encryption is just one of many security mechanisms that achieve one or more of the above security objective. Cryptography provides services that can achieve security objectives . Cryptographic security mechanisms discussed in this course include: Encryption systems — for confidentiality and limited data integrity Services provided by modern cryptography: Hash functions, Message Authentication Codes (MACs) — for data Data confidentiality (data only readable to legitimate parties) integrity Data integrity (data has not been modified) Digital signatures — for data origin authentication and Non-repudiation (protection against denial by one of the parties in a non-repudiation communication) Authentication exchange/protocol — for entity authentication and Authentication (communicating entity is the one claimed) access control Access Control Cryptography provides many security mechanisms, but not all Necessary, but not sufficient for information security See Anderson “Why cryptosystems fail” (1993, but still relevant today; link under “references”). Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 14 / 35 Renate Scheidler (University of Calgary) CPSC 418/MATH 318 Week 1 15 / 35
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