In Chapter 7, A Survey of Chosen-Prefix Collision Attacks, Marc Stevens surveys the technical advances, impact and usage of collision attacks for the most widely used cryptographic hash functions. Cryptographic hash function are the Swiss army knives within cryptography and are used in many applications including digital signature schemes, message authentication codes, password hashing, cryptocurrencies and content-addressable storage. Stevens was one of the driving forces in turning initial weaknesses in the compression function into practical attacks against various widely deployed protocols relying on hash function collision resistance for their security. In Chapter 7 he explains how each scenario involves the development of slightly different ideas to exploit weaknesses in especially MD5.

We describe recent applications of expander graphs in cryptography, particularly supersingular isogeny graphs. The security of these cryptographic constructions relies on the assumption that computing paths in these graphs is practically infeasible, even with a quantum computer. One of these cryptographic constructions is currently considered for standardization by NIST. We also recall a related construction based on Lubotzky-Philips-Sarnak's celebrated Ramanujan graphs. We describe an efficient path-finding algorithm for these graphs which was motivated by the cryptographic application, and we mention connections to the problem of optimal quantum circuit synthesis.