In a data encryption/decryption system providing for security of data communications channels, a sub-system for generating, transporting encryption/decryption keys and for introducing those keys into the system while at the same time providing a high level of security for the keys and, hence, the encryption/decryption...http://www.google.com.hk/patents/US4281216?utm_source=gb-gplus-share專利 US4281216 - Key management for encryption/decryption systems
