Group key exchanges with failures

Abstract

Described are a method for generating a session key on demand in a network, a computer program element, a computer program product stored on a computer usable medium, and a computer device for executing the computer program product. The method generates a session key sk on demand in a network among n participating network devices with up to a number t of faulty devices. Each participating network device sends and receives a series of messages and performs the steps of: a) choosing a private and public key d, eaccording to a public key encryption scheme, and broadcasting the public key eto each participating network device; b) choosing a local contribution value yfrom a multiplicative group Gof size q; c) in each case of receiving the public key efrom one of the participating network devices, encrypting the local contribution value yunder the received public key eto an encrypted contribution value yand responding to the one participating network device the encrypted contribution value y; d) receiving encrypted contribution values yand deriving decrypted contribution values yby applying the private key d; e) deriving a blinded session key bskfrom the decrypted contribution values yand the local contribution value y; f) agreeing on one of the blinded session keys bskby using an agreement protocol; and g) deriving the session key sk from the agreed-on blinded session key bskby applying one of the decrypted contribution values yand the contribution value y.