A security apparatus including a number input device (302), an address register (312) responsive to the number input device, an encryption schema memory (316) addressable by the address register to produce an output code and a relative address code, and address incrementing logic (310) responsive the...http://www.google.de/patents/US6236728?utm_source=gb-gplus-sharePatent US6236728 - Security apparatus for data transmission with dynamic random encryption
