V3d: Iterated hash functions (Applied Cryptography 101)

Welcome to "V3d: Iterated Hash Functions," the fourth lecture on hash functions in Alfred Menezes's "Crypto 101: Building Blocks" course. This video delves into iterated hash functions, a fundamental cryptographic concept used in widely deployed algorithms like MD5, SHA-1, SHA-256, and SHA-512. Ideal for computer science students, software engineers, applied cryptographers, and cybersecurity professionals, this lecture offers a detailed exploration of the construction and security of iterated hash functions, which are the backbone of many cryptographic systems. In this video, we discuss Merkle’s method for constructing hash functions and the security proof of collision resistance that ensures the integrity of cryptographic data. You’ll learn how these hash functions are iteratively applied to input data to produce a fixed-size output, ensuring both efficiency and security. We also review historical hash functions such as MD4 and MD5, which are now considered vulnerable due to their susceptibility to attacks, and discuss the evolution of hash function standards like SHA-2 and SHA-3. Additionally, we cover the impact of Professor Xiaoyun Wang's groundbreaking attacks on hash functions, which revealed vulnerabilities in earlier algorithms. By the end of this lecture, you will have a comprehensive understanding of iterated hash functions, their security properties, and their role in modern cryptography. Lecture playlist: https://www.youtube.com/playlist?list=PLA1qgQLL41SRsHMtsb4up5fTytDeHV_yJ Course web page: https://cryptography101.ca/crypto101-building-blocks/ The slides are available on the course web page. Other cryptography courses: https://cryptography101.ca Slides 00:00 Introduction 00:32 Slide 139: Iterated hash functions (Merkle's meta method) 03:23 Slide 140: Collision resistance of iterated hash functions 04:48 Slide 141: Provable security 06:32 Slide 142: Proof of Merkle's Theorem 07:26 Slide 143: Proof of Merkle's Theorem (2) 08:06 Slide 144: Proof of Merkle's Theorem (3) 13:06 Slide 145: MD-x family of hash functions 14:08 Slide 146: MD5 hash function 14:55 Slide 147: MD5 hash function (2) 15:50 Slide 148: Flame malware 16:57 Slide 149: SHA-1 18:32 Slide 150: SHA-2 family 20:01 Slide 151: Summary: Collision resistance of iterated hash functions 20:46 Slide 152: SHA-3 family 21:55 Coming up