CSCI 4407/5407, Security and Cryptography (Spring 2024)

University of Colorado Denver

Department of Computer Science and Engineering

Automatically updated on 7 January 2024

[ Instructor | Class Time and Room | Textbooks | Background Knowledge | Grades | Schedule | Academic Deadlines ]



Instructor

Dr. Ellen Gethner
Email: ellen dot gethner at ucdenver dot edu
Office hours: all on zoom

Class Time and Room (two in-person meetings only for exams; all else is online)

Monday 12:30-1:45pm March 4th and April 29th In Lawrence Street Center Room 840

Textbook

Recommended Background Knowledge

Algorithms and Discrete Structures

Subject Matter

Grades are based on four quizzes (all students), a midterm (all students), a final exam (undergrads only) and a final project (grads ony). You will all be on a team of 3-4 members. Stay tuned-- requests for team members will be solicited soon.

Schedule (subject to change)

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Week Date Topic Comments Quiz Dates
One 15 and 17 January History Codes and Ciphers: From Queen Mary of Scots to the Navajo Code Talkers of WWII. See lecture notes on Canvas-- this material is not in our textbook.
Two 22 and 24 January Background Number Theory Hierarchy of numbers; formal definition of division; divisors and proper divisors; prime numbers; GCD (You should review the Euclidean and Extended Euclidean Algorithm on your own in Ch 1); relatively prime numbers; Euler's Phi function; modular arithmetic; equivalence relation For Undergraduates Only: Prerequisite Assessment Quiz Due on Monday by 11:59pm (almost midnight). The quiz is online and can be found on canvas under Course Summary.
Three 29 and 31 Jan Group Theory, Fermat's Little Theorem Equivlance relations revisited; examples of Groups both finite and infinite; order of an element in a group; order of a group; Theorem 2.9.2; order of a subgroup of a group (Theorem 2.10.9); Grand Finale: proof of Fermat's Little Theorem (needed for RSA later on)
Four 5 and 7 Feb Beginning of Encyrption Tools Encryption Schemes, Alphabets and Words, Permutations, Block Ciphers, Simple Example of Stream Cipher, Affine Ciphers. Quiz 0 due no later than 12:30pm as an upload (one quiz per team) on canvas on Monday: open book, open notes, open friends, open internet. Write up your own solutions together with your team. Do not wait until the last minute to upload your quiz-- no late quizzes will be accepted under any circumstances!!!!!!!!!!!
Five 12 and 14 Feb Secret Sharing Schemes Affine and stream ciphers. Secret Sharing Schemes: you should read and review basic properties of square matrices (See review of determinants ). The main scheme we will cover is the Threshold Scheme (two different approaches). There is a Mathematica nobebook on Canvas with a secret sharing tutorial in this week's module.
Six 19 and 21 Feb Public Key Cryptography and RSA (Chapter 6) Global Procedure (a high level view of RSA); tranlsation of plaintext to a numerical message; Encryption process [public key=(n,e)]; Decryption process [private key=(p,q,d)]; False proof of correctness; True Proof of correctness; Digital Signature; Discussion of the security of RSA and its history. Peter Shor's 1994 quantum algorithm that led to the breakage of RSA on any classical computer: that is, integer factorization can be done in polynomial time. Quiz 1 due no later than 12:30pm as an upload (one quiz per team) on canvas on Monday: open book, open notes, open friends, open internet. Write up your own solutions together with your team. Do not wait until the last minute to upload your quiz-- no late quizzes will be accepted under any circumstances!!!!!!!!!!!
Seven 26 and 28 Feb DES: Selections from Chapter 4 in our textbook. History of DES; Encryption process; Decryption; Expander function; S-boxes and their output; Key; the function f that takes the modified key and part of the text as input; mulitple Rounds of DES; Present-day lack of Security in DES, which led to the new Encryption Standard, namely AES. Warmup for AES: the mathematics of Fields: Galois Fields, particularly the one of order 256 and its relation to the irreducible polynomial x^8 + x^4 + x^3 + x + 1 with coefficients from the field Z_2.
Eight 4 and 6 March Midterm March 4 (grad and undergrad) and Project Proposal (grad) March 6 The Midterm Exam (grad and undergrad) is in class, in person, without your team, on Monday 4 March 12:30-1:45pm in Lawrence Street Center Room 840. You may bring two pages of notes (8.5" x 11") on both sides and calculators are allowed. Do not hand in the notes.
Nine 11 and 13 March AES Guest speakers: Dalton, Michael, and Julian. Multiple Key Lengths; 10 Rounds; Input/Output sizes; ByteSubTransformation (non-linear); ShiftRow Transformation (diffuses bits over multiple rounds); MixColumn Transformation (same purpose as ShiftRow); AddRoundKey (XOR this key with the output of the previous layer)
null 18-24 March Spring Break: no classes, no office hours
Ten 25 and March Elliptic Curve Cryptosystems-- Chapter 16 (and a few warmups) Finite Fields (again); Discrete Log Problem; ElGammal Cryptosystem; Elliptic Curve Cryptosystems; Elliptic Curves mod N; Representing Plaintext on an elliptic curve; Factoring integers using elliptic curves; An Elliptic Curve ElGammal Cryptosystem; Quiz 2 due no later than 12:30pm as an upload (one quiz per team) on canvas on Monday: open book, open notes, open friends, open internet. Write up your own solutions together with your team. Do not wait until the last minute to upload your quiz-- no late quizzes will be accepted under any circumstances!!!!!!!!!!!
Eleven 1 and 3 April Flipping Coins and Playing Poker over the phone. Riemann Hypothesis Tools: Fermat's Little Theorem and Quadratic Residues
Twelve 8 and 10 April Guest Lecture; Deception Video and Slides on Canvas
Thirteen 15 and 17 April Art and Math Lecture Video on Canvas
Fourteen 22 and 24 April Grad Student Video Presentations Various topics; videos will be posted on Canvas Quiz 3 due no later than 12:30pm as an upload (one quiz per team) on canvas on Monday: open book, open notes, open friends, open internet. Write up your own solutions together with your team. Do not wait until the last minute to upload your quiz-- no late quizzes will be accepted under any circumstances!!!!!!!!!!!
Fifteen 29 April and 1 May FINAL EXAM (undergrads only): Monday, April 29th, In person from 12:30-1:45 in Lawrence Street Center Room 840. Shamir Secret Sharing is the sole topic of the final exam, which you will do as one team-- all undergrads. FINAL EXAM (undergrads only) WILL BE A JOINT EFFORT: Shamir Secret Sharing Scheme; each of you will be given one share in the scheme and you will, together, discover the secret. Open book, open notes, open software, open friends, open internet.
Sixteen Week of 6 May Office hours on Monday to be determined