Hash Functions Explained: Essential Concepts in Cryptography 🔐

Welcome to "V3a: Hash Functions: Fundamental Concepts," the first lecture in Alfred Menezes's "Crypto 101: Building Blocks" course, focusing on hash functions, a vital component of cryptography. This video introduces key concepts that are essential for understanding hash functions, their properties, and their role in modern cryptographic protocols. Designed for computer science students, software engineers, applied cryptographers, and cybersecurity professionals, this lecture offers a solid foundation in one of cryptography's most important building blocks.

In this video, we cover the critical security properties of hash functions: preimage resistance, second-preimage resistance, and collision resistance. These properties ensure that hash functions are secure and reliable when used to generate fixed-size outputs from arbitrary input data. You will also learn about iterated hash functions, which are the foundation of many widely used algorithms such as MD5, SHA-1, SHA-256, SHA-384, and SHA-512.

Additionally, we discuss the practical applications of hash functions in various cryptographic protocols like digital signatures, blockchain technologies, and data integrity checks. We also explore the risks associated with outdated hash functions, such as MD5 and SHA-1, which are vulnerable to generic attacks. By the end of this lecture, you'll have a clear understanding of hash functions and their importance in securing digital systems.

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
01:12 Slide 107: Definitions and terminology
01:47 Slide 108: What is a hash function?
02:16 Slide 109: Example: SHA-256
03:34 Slide 110: Definition of a hash function
04:42 Slide 111: Toy hash function
05:52 Slide 112: Some applications of hash functions
06:16 Slide 113: Preimage resistance (PR)
09:17 Slide 114: 2nd preimage resistance (2PR)
11:16 Slide 115: Collision resistance (CR)
13:18 Slide 116: Some other applications of hash functions
13:26 Coming up