An operator console for data communication is divided into two separate units which can be connected electrically together, namely a keyboard (10) having a logical unit (21), with a memory (211) and a ciphering/deciphering circuit (22), and a security module (11). Connected between the input side of...http://www.google.com.au/patents/US4870612?utm_source=gb-gplus-sharePatent US4870612 - Operator console with paired modules including means for ciphering and deciphering messages therebetween based on a mutually known, exclusive internal security code
