• Instructor:

  • Logistics:

  • Class timing: Monday (11:00 am - 12:30 pm) and Wednesday (11:00 am - 12:30 pm)
  • Venue: CSA 252

  • Course Description (1st half) :

One way Functions (Permutations), Hard-core Predicates, Pseudo-random Generators, (Strong) Pseudo-random Functions (Permutations)

Secret Key Encryptions (SKE): Various security notions such as perfect security, semantic security, indistinguishability based Security, CPA Security, CCA Security, Constructions, Block Cipher Mode of Operations.

Message Authentication Codes (MAC): Various Secrity notions such as CMA Security, (weak/strong) CMVA security, Domain Extension, CBC-MAC.

Advanced Encryption Schemes: Authenticated Encryptions.

  • Grading:

The course evaluation for the first half will be done as follows

  • Scribe (10): Every student must scribe at least one lecture. The scribe submission deadline is one week after the corresponding lecture. The template tex file for a scribe can be downloaded from here. As you have guessed, the submission must be in Latex. Get first-hand ideas about scribing from various course webpages. Such as this.
  • "Chalk & Talk" Session (10): The goal of this session is to cover breadth of the course. Every student has to make a 30 mins presentation on a topic not covered in the class. Topics will be suggested in the lectures. We will have two sessions every week on Friday between 12:00 noon - 1:00 pm.
  • Final Exam (30): It will be a written exam conducted on 27.02.16 between 2 - 5 pm.

  • Reading Material and References (2nd half):

Reference Books:

  • Jonathan Katz and Yehuda Lindell, Introduction to Modern Cryptography, second edition 2014, CRC Press. You should definitely have a copy of this book. We will mostly follow this book.
  • Cryptography: Theory and Practice by Douglas Stinson, Third edition, CRC Press.
  • Handbook of Applied Cryptography by Alfred Menezes, Paul Oorschot and Scott Vanstone. Available Online .
  • Foundations of Cryptography by Oded Goldreich. Available Online .
  • Cryptography, An Introduction by Nigel Smart. Available Online .
Some useful Course Notes/Lectures:

  • Other Info:

  • Office Hours: Monday Wednsday 12:30 - 1:00 pm or by appointment

Lecture Details

Will be updated as and when the course progresses.

Lecture # and Date
Lecture contents
Slides / Reading material (KL: Katz-Lindell 2nd Edition)
Problem Set (KL: Katz-Lindell 2nd Edition)
Lecture 1 (06-01-2016) Introduction, Classical Crypto vs. Modern Crypto, Three Pillars of Modern crypto (definition/assumption/proof), Classical ciphers and pitfalls. Inroad towards Modern Crypto. [pptx] / Chapter 1 of KL
Lecture 2 (10-01-2016) Perfect Security: Definition, Construction (Vernam Cipher), Proof; Drawbacks of OTP [pptx] / Chapter 2 of KL Jayam [pdf], Gaurav [pdf]
Lecture 3 (12-01-2016) Proof for the inherent drawback on key length, Equivalent Alternative Definitions for Perfect Security, Shannon's Theorem, Relaxing perfect security. Introduction to Computational Security. [pptx] / Chapter 2 of KL Atlanta [pdf], Pratik [pdf] Chapter 2 Questions from KL
Lecture 4 (18-01-2016) Computational Security: Necessity of the relaxations in threat and break models. Definitions of PPT and negligible functions, Security Parameter. Sematic Security, Indistinguishability-based Security and its variant, Pseudorandom distributions. [pptx / KL pp. 43-59 Shipra [pdf], Seba Ann [pdf]
Lecture 5 (20-01-2016) Pseudo-random Generators (PRGs): Definition, No PRG against unbounded distinguisher; coa-secure Scheme from PRG, Proof by Reduction, Proof of coa-secure scheme; coa-mult security and proof that no deterministic enc can be coa-mult secure. [pptx] /KL pp. 60-72 Nidhi (ls) [pdf], Sruthi [pdf], Indu [pdf] KL 3.1-3.8
Lecture 6 (25-01-2016) CPA, cpa security for single and multiple messages, why cpa security stronger than coa-mult. Need of randomized encryption scheme, PRF, definition, PRP, Strong PRP. [pptx] /KL pp. 73-81 Subhajit [pdf], Bhavana [pdf]. KL 3.9-3.17
Lecture 7 (27-01-2016) cpa-secure scheme from PRF, proof of security, Block-cipher mode of operations: ECB, CBC, OFB, CTR [pptx]/ KL 82-95 Sudeep [pdf],Aditi [pdf] KL 3.19-3.23, 3.25-3.27, 3.29
Lecture 8 (01-02-2016) Chosen Ciphertext Attacks (CCA), Padding Oracle Attack on CBC-mode encryption, cca-security, Break of cpa-secure (PRF-based) schemes. Malleability. Introduction to MACs. Issues of Message Authetication and Message Integrity. (strong and weak) cma-security for MACs. [pptx] / KL 96-100,107-116. Arya [pdf], Kaushik [pdf] KL 3.18, 3.28
Lecture 9 (04-02-2016) MAC, Various Security Notions (cma, strong cma, cmva, strong cmva), cma-secure MAC from PRF, Domain Extension, Authenticated Encryption: Definition (cpa-security + Cipher Integrity), Construction from cpa-secure SKE and scma-secure MAC. Three approaches: authenticate-and-encrypt, authenticate-then-encrypt, encrypt-then-authenticate. [pptx] / KL 389-399,405-404, 387-89 Tapesh [pdf] KL Chapter 4 questions
Tutorial I (by Ajith) (08-02-2016) Questions from the topics covered [pdf]
Tutorial II (by Ajith) (13-02-2016; 11-12:30pm) Questions from the topics covered [pdf]
Lecture 10 (15-02-2016) strong cma-security and deterministic MACs, Autheticated Encryption based on encrypt-then-authenticate, proof of security, why the proof does not work for authenticate-then-encrypt approach. AE implies CCA security. Looking back and Ahead. [pptx] Puran [pdf], Kshitij [pdf], Mukesh (ls) [pdf] KL Chapter 4 questions
Lecture 11 (17-02-2016) PRG implies PRF (GGM Tree Construction). Hybrid Arguments. Proof. [pptx] Sayantan [pdf], Sameer (ls) [pdf] , Sriram (ls) [pdf], Jigyasa (ns), Padma Bhushan (ls) [pdf] KL 7.14,7.15
Lecture 12 (20-02-2016; 10:30-12:30 pm) One-way Functions (OWF), One-way Permutations (OWP), Hard-core Predicates, OWF (OWP) implies Hard-core Predicates (Goldreich-Levin Theorem). [pptx] Pranav [pdf], Prateek (ls) [pdf], Biswajit (ls) [pdf], Kuntal [pdf], Anupam [pdf] KL Chapter 7 Questions
Tutorial III (by Ajith) (21-02-2016; 11:00-12:30 pm) Questions from the topics covered [pdf]
Lecture 13 (22-02-2016) One-way Functions (OWP) and Hard-core Predicates implies PRG. [pptx] Ishan [pdf], Prokash (ns), Nihesh [pdf], Soumya (ns) KL Chapter 7 Questions
Lecture 14 (24-02-2016) Candidate OWF/OWP from Number Theory, RSA Assumption. [pptx]

"Chalk & Talk" Session

Please send me an email with your name as soon as you commit to a talk; otherwise your CT may not get registered and evaluated under your name.
Group #: members
Date and Time
Supplementary reading material
Group 1 (Two): Pranav and Sayantan Friday (22.01.16); 12 noon - 12:30 pm Equivalences between Various Definitions of Perfect Security [pdf]
Group 2 (One): Shruthi Friday (22.01.16); 12:30 - 13:50 pm OTP Implementation Details and Cryptanalysis of Reusing Key [pdf]
Group 3 (One): Bhavana Friday (29.01.16); 12:00 - 12:15 pm ind-security implies bitwise-security of the messages KL Chapter 3.2
Group 4 (One): Aditi Friday (29.01.16); 12:15 - 12:30 pm Equivalence of ind-security and its variant.
Group 5 (One): Nidhi Friday (05.02.16); 12:00 - 12:15 pm If PRG exists, then OWF exists. KL Chapter 7.7
Group 6 (One): Ishaan Friday (05.02.16); 12:16 - 12:30 pm If coa-secure SKE exists, then OWF exists KL Chapter 7.7
Group 7 (One): Atlanta Friday (05.02.16); 12:31 - 12:45 pm If PRF exists, then so does PRG
Group 8 (Two): Arya, Soumyo Friday (05.02.16); 12:45 - 1:15 pm A PPT D cannot distinguish a TRF from a TRP (for the same domain and co-domain) except with negl. prob.
Group 9 (Two): Shipra, Jayam Wednesday (10.02.16); 11 - 11:29 am cpa-security of CTR mode
Group 10 (Two): Puran, Kshitij Wednesday (10.02.16); 11:30 - 11:59 am Construction of a cpa-secure scheme from two given schemes one of which is cpa-secure, but not known which of the two. Proof of security.
Group 11 (Three): Pratik, Kuntal, Anupam Wednesday (10.02.16); 12:00 - 12:45 pm Domain Extension of MAC
Group 12 (Two): Prateek, tapesh Wednesday (10.02.16); 12:00 - 12:29 pm Stream Ciphers and Trivium
Group 13 (Four): Seba Ann, Indu, Mukesh, Gaurav Friday (11.02.16); 12:00 - 1:00 pm Information Theoretic MAC
Group 14 (One): Sameer Shah Friday (19.02.16); 12:00 - 12:30 pm Authenticate-then-encrypt approach instantiated with cpa-secure SKE and cma-secure MAC yields a cpa-secure scheme with WEAK ciphertext integrity.
Group 15 (Two): Biswajit, Prokash Friday (19.02.16); 12:30 - 1:00 pm F: SPRP, m: n/2 bits, k= n-bits, c = Fk(m||r), r: n/2 bit random string. Prove cca-security. Prove that it is not secure according to Definition 2 of AE.
Group 16 (Two): Sriram C., Padma Bhushan Friday (26.02.16); 12:00 - 12:30 pm PRF implies PRP (Feistel Construction).
Group 17 (One): Sudeep Friday (26.02.16); 12:30 - 12:45 pm If a one-to-one function has hard-core predicate then it must be one-way.
Group 18 (One): Jigyasa Friday (26.02.16); 12:45 - 1:00 pm If f is a OWF, then prove or disprove that g(x) = (f(x),f(f(x))) is a OWF.
Group 19 (Two): Subhajit, Kaushik Friday (26.02.16); 2:00 - 2:30 pm If there exists a PRF that maps n-length key and input to 1-bit output, then there exists a PRF that maps n2-length key and n-bit input to n-bit output.
Group 20 (One): Nihesh Friday (26.02.16); 2:30 - 2:45 pm If G: {0,1}n {0,1}n+1 is a PRG, then G is a OWF.