Systems, methods, and other embodiments associated with key generation for networks are described. One example method includes configuring a key server with a pseudo-random function (PRF). The key server may provide keying material to gateways. The method may also include controlling the key server to generate a cryptography data structure (e.g., D-matrix) based, at least in part, on the PRF and a seed value. The method may also include controlling the key server to selectively distribute a portion of the cryptography data structure and/or data derived from the cryptography data structure to a gateway. The gateway may then encrypt communications based, at least in part, on the portion of the cryptography data structure. The method may also include selectively distributing an epoch value to members of the set of gateways that may then decrypt an encrypted communication based, at least in part, on the epoch value.