Cryptography

**Instructor:**

Nadia Heninger
(nadiah at cis dot upenn.edu, 464 Levine GRW)

Office hours: Tuesday 1-2pm

**TA:**

Luke Valenta
(lukev at cis dot upenn.edu, DSL, Moore 102)

Office hours: Wednesday 4pm-5pm, Levine 3rd floor bump space

**Lectures:**

Tuesday/Thursday 10:30am-12pm

**Teaching Resources:**

Grades/Homework on Canvas

Announcements/Questions on Piazza

**Grading:**

30% Homework

30% Midterm

30% Final project

10% Participation, brownie points, and grading

This course is a graduate-level introduction to cryptography, both theory and applications. A tentative list of topics includes:

- Symmetric cryptography: block ciphers, stream ciphers, modes of operation
- Message integrity, hash functions
- Public-key cryptography: number-theoretic notions, public-key encryption schemes, digital signatures
- Cryptographic security: key management, network security protocols, random number generation, side-channel attacks
- Magical crypto tricks: secret sharing, commitments, zero-knowledge proofs
- Research topics: privacy-enhancing technologies, lattices, etc.

Topic
| References
| Assignments
| |

8/27 | Introduction, one-time pad |
Katz & Lindell Ch. 1, 2 Boneh & Shoup Ch. 2.2 Further reading:Communication theory of secrecy systems Shannon 1949 | Homework 1 assigned |

9/1 | Probability and entropy review |
Katz & Lindell Appendix A Boneh & Shoup Appendix B Hoffstein, Pipher, & Silverman Ch. 4.3, 4.6 Further reading:A mathematical theory of communication Shannon 1948 Alistair Sinclair scribe notes on Chernoff bounds | |

9/3 | Semantic security, pseudorandom generators, stream ciphers |
Katz & Lindell Ch. 3 Boneh & Shoup Ch. 2.3, 3 | |

9/8 | Stream ciphers, chosen plaintext attacks, pseudorandom functions |
Katz & Lindell Ch. 3.5, 3.6 Boneh & Shoup Ch. 4 Further reading/Research directions:All Your Biases Belong To Us: Breaking RC4 in WPA-TKIP and TLS by Vanhoef and Piessens Attacks Only Get Better: Password Recovery Attacks Against RC4 in TLS by Garman, Paterson, and Van der Merwe On the security of RC4 in TLS and WPA by AlFardan, Bernstein, Paterson, Poettering, and Schuldt 2013 Spritz-a spongy RC4-like stream cipher and hash function by Rivest and Schuldt 2014 The ChaCha family of stream ciphers by Bernstein |
Homework 1 due Homework 2 assigned |

9/10 | Block ciphers, modes of operation, block cipher attacks |
Katz & Lindell Ch. 5 Here come the xor ninjas by Duong and Rizzo 2011 Compression and information leakage of plaintext by Kelsey 2002 The CRIME attack by Rizzo and Duong 2012 | |

9/15 | Chosen ciphertext attacks, malleability, padding oracles, message authentication codes | Katz & Lindell Ch. 4.4-4.6 Boneh & Shoup Ch. 6 Security Flaws Induced by CBC Padding Applications to SSL, IPSEC, WTLS... by Vaudenay 2002 | |

9/17 | Hash functions, birthday attacks | Katz & Lindell Ch. 4 Boneh & Shoup Ch. 8.1-8.6 |
Homework 2 due
(extended to 11:59pm on 09/18) Homework 3 assigned |

9/22 | Hash functions in practice, length extension attacks, HMAC | Katz & Lindell Ch. 4.7-4.8 Boneh & Shoup Ch. 8.7 Further reading/research directionsMD5 to be considered harmful today by Sotirov, Stevens, Appelbaum, Lenstra, Molnar, Osvik, de Weger 2009 Counter-cryptanalysis by Stevens 2013 New collision attacks on SHA-1 based on optimal joint local-collision analysis by Stevens 2013 | |

9/24 | Authenticated encryption, computational number theory: modular arithmetic, GCDs, ideals | Katz & Lindell Ch. 7 A Computational Introduction to Number Theory and Algebra by Shoup | |

9/29 | Groups, discrete log HAC Ch. 3.6.3 | ||

10/1 | Diffie-Hellman, ElGamal | New Directions in Cryptography by Diffie and Hellman 1976 Katz & Lindell Ch. 7.3, 8.2.1, 9, 10 |
Homework 3 due Homework 4 assigned |

10/6 | Arithmetic modulo composites, Chinese Remainder Theorem, Pohlig-Hellman discrete log |
Katz & Lindell Ch. 7.1.5, 7.2, 8.1.2, 8.2.2, 10.4 HAC Ch. 3.6.4 | |

10/8 | Fall break | ||

10/13 | No class | ||

10/15 | No class | ||

10/20 | RSA encryption, textbook RSA is insecure | Katz & Lindell Ch. 10.4, 10.6 Boneh & Franklin Ch. 13 A method for obtaining digital signatures and public-key cryptography by Rivest, Shamir, and Adleman 1978 Further reading/Research directions:Why Textbook ElGamal and RSA Encryption Are Insecure by Boneh, Joux, and Nguyen 2000 Chosen Ciphertext Attacks Against Protocols Based on the RSA Encryption Standard PKCS #1 by Bleichenbacher 1998 Efficient Padding Oracle Attacks on Cryptographic Hardware by Bardou, Focardi, Kawamoto, Simionato, Steel, Tsay 2012 Revisiting SSL/TLS Implementations: New Bleichenbacher Side Channels and Attacks by Meyer, Somorovsky, Weiss, Schwenk, Schinzel, Tews 2014 |
Homework 4 due Homework 5 assigned |

10/22 | RSA digital signatures | Katz & Lindell Ch. 12 | |

10/27 | Midterm exam | ||

10/29 | DSA; Constructing secure channels, TLS |
Further reading:Ferguson Schneier & Kohno Ch. 14 The Secure Sockets Layer (SSL) Protocol Version 3.0 by Freier Karlton Kocher 2011 The Transport Layer Security (TLS) Protocol Version 1.2 by Dierks and Rescorla 2008 This POODLE Bites: Exploiting The SSL 3.0 Fallback by Moeller, Duong, Kotowicz 2014 | |

11/3 | Constructing secure channels, SSH; Factoring algorithms | Katz & Lindell Ch. 9.1 | |

11/5 | Subexponential factoring, quadratic sieve | Katz & Lindell Ch. 8.1.1, 8.1.3 Katz & Lindell 8.2.4 Further Reading:A tale of two sieves by Pomerance (1996) Factoring integers with the number field sieve by Buhler, Lenstra, and Pomerance (1993) Factorization of a 768-bit RSA modulus by Kleinjung et al. (2010) | Homework 5 due |

11/10 | Index calculus algorithms for discrete log Slides |
Katz & Lindell Ch. 9.2.4 Imperfect Forward Secrecy: How Diffie-Hellman Fails in Practice by Adrian et al. Further reading:A new index calculus algorithm with complexity L(1/4 + o(1)) in small characteristic by Joux 2013 A quasi-polynomial algorithm for discrete logarithm in finite fields of small characteristic by Barbulescu Gaudry Joux and Thome 2013 | |

11/12 | Secret sharing |
How to share a secret by Shamir 1979Other resources:Secret-sharing schemes: A survey by Beimel 2011 David Wagner lecture notes | |

11/17 | Commitment schemes |
Lecture notes by Yevgeniy DodisFurther reading:A practical scheme for non-interactive verifiable secret sharing by Feldman 1987 | |

11/19 | Zero-knowledge proofs |
Lecture notes by David Wagner Lecture notes by Boaz Barak 1 2 The knowledge complexity of interactive proof systems by Goldwasser, Micali, and Rackoff 1989 Further reading/research topics: Zerocoin: Anonymous Distributed E-Cash from Bitcoin by Miers, Garman, Green, Rubin 2013 Zerocash: Decentralized Anonymous Payments from Bitcoin by Ben-Sasson, Chiesa, Garman, Green, Miers, Tromer, Virza 2014 SNARKs for C: Verifying Program Executions Succinctly and in Zero Knowledge by Ben-Sasson, Chiesa, Genkin, Tromer, Virza 2013 | |

11/24 | Lattices |
Daniele Micciancio lecture notes 1 2 Oded Regev lecture notes Factoring Polynomials with Rational Coefficients by Lenstra Lenstra and Lovasz 1982 The two faces of lattices in cryptology by Nguyen 2001 Using LLL-reduction for solving RSA and factorization problems: a survey by May 2007 | |

11/26 | Thanksgiving | ||

12/1 | Project presentations | ||

12/3 | No class | ||

12/8 | Project presentations |

- Introduction to Modern Cryptography by Katz and Lindell. A copy should be on reserve in the Rosengarten Reserve Room in the Van Pelt-Dietrich Library Center.

- A Graduate Course in Applied Cryptography by Boneh and Shoup.
- An Introduction to Mathematical Cryptography by Hoffstein, Pipher, and Silverman. A mathematically-oriented introductory text.
- Introduction to Modern Cryptography by Bellare and Rogaway. Online course notes for an introductory course.
- Cryptography Engineering by Ferguson, Schneier, and Kohno. A practice-oriented introductory text.
- The Handbook of Applied Cryptography by Menezes, van Oorschot, and Vanstone. A classic reference, available for free online.