CS255 Introduction to Cryptography

Course Syllabus

Winter 2024

Optional readings can be found in the textbooks denoted by KL and AC in the syllabus below. The optional AC book, by Boneh and Shoup, is more advanced (and free) and is intended for students wishing to go deeper. The online version of the course is another resource for the material covered in class.


Lecture 1:
Mon 1/8/24
Overview of cryptography. What is a cipher?
Reading: AC ch.2;   KL ch 2.
Basic symmetric-key encryption
Lecture 2:
Wed 1/10/24
One time pad and stream ciphers
Perfect secrecy and the one time pad;
semantic security and stream ciphers.
Reading: AC ch.3;   KL 3.2.1-3.4.2.
Mon 1/15/24
MLK: no classes
Lecture 3:
Wed 1/17/24
Block ciphers
Iterated Even-Mansour ciphers and the AES block cipher.
Reading: AC ch. 4.1, 4.2;   KL ch 6.1-6.2.
Lecture 4:
Mon 1/22/24
How to use a block cipher   [pdfpptx]
Pseudo Random Permutations (PRP); Pseudo Random Functions (PRF);
semantic security, and basic modes of operation
Reading: AC. ch. 4.4, 5;   KL ch 3.5
Lecture 5:
Wed 1/24/24
CPA Security plus attacks on block ciphers   [pdfpptx]
Nonce-based encryption, CBC and randomized counter mode,
differential & linear cryptanalysis, side channels, and quantum attacks.
Reading: AC ch. 4.3;   KL ch 3.4.2,3.6
Message integrity
Lecture 6:
Mon 1/29/24
Message integrity: definition and applications
Reading: AC ch. 6;   KL ch 4.1-4.3
Lecture 7:
Wed 1/31/24
Collision resistant hashing
Merkle-Damgard and Davies-Meyer; MACs from collision resistance;
case studies: SHA and HMAC.
Reading: AC ch. 8.1-8.9;   KL ch 5.1-5.3
Lecture 8:
Mon 2/5/24
Authenticated encryption: security against active attacks
Properties and secure constructions
Reading: AC ch. 9;   KL ch 4.5
Public key cryptography
Lecture 9:
Wed 2/7/24
Arithmetic modulo primes and finite cyclic groups
Reading: KL ch 8.
Summary of relevant facts: pdf.
Lecture 10:
Mon 2/12/24
Cryptography using finite cyclic groups
anonymous key exchange (Diffie-Hellman); the CDH and discrete-log assumptions
Reading: AC ch. 10;   KL ch 9, 11.4.1
Lecture 11:
Wed 2/14/24
ElGamal public key encryption
semantically secure ElGamal encryption; CCA security
Reading: AC ch. 11;   KL ch 9, 11.4.1
Lecture 12:
Mon 2/19/24
Public key encryption using a trapdoor function   [pdfpptx]
The RSA trapdoor permutation and its applications
Reading: AC ch. 10.2, 10.3;   KL ch 11.5
Summary of relevant facts: pdf.
Wed 2/21/24
President's day: no classes.
Digital signatures
Lecture 13:
Mon 2/26/24
Digital signatures: definitions and applications
How to sign using RSA.
Reading: AC ch. 13;   KL ch 12.1-12.4
Lecture 14:
Wed 2/28/24
More signature schemes and applications   [pdf]
hash based signatures;
certificates, certificate transparency, certificate revocation.
Reading: AC ch. 13.8, ch. 14;   KL ch 12.5-12.8
Lecture 15:
Mon 3/4/24
Identification protocols   [pdfpptx]
password protocols, salts; one time passwords (S/Key and SecurID);
challenge response authentication.
Reading: AC ch. 18;
Lecture 16:
Wed 3/6/24
Authenticated key exchange and SSL/TLS session setup   [pdf]
Reading: AC ch. 21;
Lecture 17:
Mon 3/11/24
Zero knowledge proofs
Reading: AC ch. 19;
Lecture 18:
Wed 3/13/24
The crypto wars: should we have end-to-end encryption?
Guest lecture by Jennifer Granick of the ACLU