Speaker: Arkadii Slinko
Affiliation: The University of Auckland
Title: Secret sharing schemes (an elementary introduction)
Date: Tuesday, 7 May 2013
Time: 4:00 pm
Location: Room 6115, Owen Glenn Building

Certain cryptographic keys, such as missile launch codes, numbered bank accounts and the secret decoding exponent in an RSA public key cryptosystem, are so important that they present a dilemma. If too many copies are distributed, one may be leaked. If too few, they might all be lost or accidentally destroyed. Secret sharing schemes invented by Shamir (1979) and Blakley (1979) address this problem, and allow arbitrarily high levels of confidentiality and reliability to be achieved. A secret sharing scheme `divides’ the secret S into `shares’ – one for every user – in such a way that S can be easily reconstructable by any authorised subset of users, but an unauthorised subset of users can extract absolutely no information about S. A secret sharing scheme, for example, can secure a secret over multiple servers and it remains recoverable despite multiple server failures.

Secret sharing schemes are a sort of cooperative games where the information and not money is being distributed among players. The set of authorised coalitions of a secret sharing scheme is a simple game so there is a rich connection to the theory of games.

In my talk I will give an elementary introduction to secret sharing.

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