16 February 2015, Theoretical Computer Science Seminar, Andreas Huelsing

Abstract: Hash-based signatures are currently the most confidence-inspiring replacement for the signature schemes used today. Their security is solely based on the security of the used hash function(s) and can be related to the same by means of standard-model security reductions. Today's hash-based signature schemes have performance close to that of RSA & Co and are currently subject to standardization. The only drawback of hash-based signature schemes in practice is that they are stateful, i.e., the secret key has to be updated after each signature. However, recent results show that this problem can actually be solved while maintaining practical performance and reliable security. This talk will discuss the basics of hash-based signature schemes. It will cover one-time and many-time signature schemes, Lamports scheme, the Winternitz OTS, Merkle's scheme, and XMSS. Finally, it will be explained how to build practical stateless hash-based signature schemes, explaining the concept of few-time signature schemes and introducing SPHINCS.

For more information, contact Christian Schaffner (c.schaffner at uva.nl)