Data processing terminal.

摘要

The invention concerns a data processing terminal. …In an embodiment of the invention a data processing terminal coupled via a communication line to a remote host system includes data security device 11 which includes storage means 13 for storing a master cipher key, cryptographic apparatus 12 for performing cryptographic operations, and control means 14 for controlling the writing of a master cipher key into the storage means 13, controlling the transfer of the master cipher key to the cryptographic apparatus 12 and controlling the cryptographic apparatus to perform cryptographic operations. When a new master cipher key is written into the storage means 13, the old master cipher key is automatically overwritten with an arbitrary value, after which the new master key may be written into the storage means. The cryptographic apparatus 23 of the data security device 11 includes data storage means BR17 and DR22, a working key storage means 20, and cipher means 25 for performing a cipher function on data stored in the cryptographic apparatus storage means under control of a working cipher key stored in the storage means 20, the resulting ciphered data being stored in the cryptographic apparatus storage means. A load cipher key direct function can be performed whereby a working cipher key may be loaded directly into the working key storage means 20 for use as a working cipher key in performing a cipher function. A decipher key function also can be performed whereby the master cipher key from 13 is transferred to the working key storage means 20 as a working cipher key after which an operational key enciphered under the master cipher key (received from the remote host system) is transferred to the cryptographic apparatus storage means and the control means causes the enciphered operational key to be deciphered to obtain the operational key in clear form as a working cipher key for subsequent encipher/decipher data functions by the cipher means 25.