How to Build Digital Signatures from Hash Functions

By Ahto Truu

In modern societies, more and more paper documents and ink signatures are replaced with their electronic equivalents. Now the ascent of quantum computing threatens to render all current digital signature systems insecure. Hash functions, however, seem to be quite resilient to quantum attacks and thus a promising building block for future cryptographic protocols.

The talk will recap the essentials of the existing digital signature systems as well as cryptographic hash functions and then show how the former can be built from the latter. Curiously enough, a digital signature system based on hash functions was one of the first to be invented when the idea of asymmetric cryptography was introduced to the world!

In addition to reviewing the most important historical systems, the talk will also cover a brand new one developed over the past few years.