The application of hash chains and hash structures to cryptography

In this thesis we study how hash chains and other hash structures can be used in various cryptographic applications. In particular we focus on the applications of entity authentication, signatures and key establishment.\n\nWe study recursive application of hash functions to create hash chains, hash trees and other hash structures. We collate all these to form a catalogue of structures that we apply to various cryptographic applications.\n\nWe study existing work on authentication and create many entity authentication schemes based on structures from our catalogue.\n\nWe present a novel algorithm to find efficient signature schemes from any given hash structure. We study some suggestions for suitable hash structures and define a particular scalable hash structure complete with a simple message to signature map that is the most efficient such scheme of which we know.\n\nWe explore k-time signature schemes and identify two new properties, which we call perforated and porous.\n\nWe look at the application of hash structures to key establishment schemes. We compare the existing schemes and make improvements on many. We present a new key establishment scheme, and show a link between certain k-time signatures and certain key establishment schemes.\n\nWe look at the other applications of hash structures, and suggest areas in which our catalogue could be used for further development.