A key generator (51, 61) generates, from an IP-key (11) for entering a closed IP network (1), a set (52, 62) of session keys (53, 63) indexed for identification, an index pointer (71, 72) points an index (i, j) to identify a session key (53, 63), the set (52, 62) of session keys has a divergence barrier...http://www.google.ca/patents/US6917685?utm_source=gb-gplus-sharePatent US6917685 - IP key management mechanism with divergence barrier increasing entropy against computational crypto-analyses
