Multiparty key agreement protocols

A class of multiparty key agreement protocols based on secret sharing is pr esented. The trust infrastructure necessary to achieve the intended securit y goals is discussed. Entity authentication is suggested to be replaced by a less expensive group authentication. Two key agreement protocols are disc ussed. The first is the group key agreement where all principals must be ac tive to call the conference. The other allows a big enough subgroup (contro lled by the threshold parameter t) to trigger the conference. It is proved that the protocols achieve key freshness, key confidentiality, group authen tication and key confirmation. A discussion about possible modifications an d extensions of the protocol concludes the paper.