Patent ID: 8867747

Claim:
A method comprising: configuring a key server (KS) with a pseudo-random function (PRF), the KS being associated with a set of gateways for which the KS provides keying material; controlling the KS to generate a cryptographic data structure for a symmetrical key generation system (KGS) based, at least in part, on the PRY and a seed value; controlling the KS to generate an epoch value; controlling the KS to selectively distribute the epoch value and KGS user secret data derived from the cryptographic data structure to a member of the set of gateways; wherein the KGS user secret data and the epoch value are for generating keys for encrypted communications; wherein a different set of KGS user secret data is provided to different members of the set of gateways; revoking at least one member of the set of gateways; generating a new epoch value; and distributing the new epoch value to a selected group of the set of gateways that does not include the revoked member, where the selected group of the set of gateways communicate using encryption among the selected group, and where encryption is based on keys generated, at least in part, on the KGS user secret data and the new epoch value.