Security level identification method for computer based information

Claim 1

In a computer information system of the type having a plurality of input/output devices adapted to read from and/or write information to input/output medium means for input and/or output of information, the information and the medium being associated with one or more of a plurality of security levels, the information being coded as to the level of security associated therewith, the improvement comprising the method of providing multi-level security comprising the steps of: a. coding the input/output medium by applying one of a plurality of machine and visually detectable indicia indicating the level of security of information to be read and/or written thereon; b. detecting the security level of the input/output medium through a detector means located in the input/output device for reading the machine and visually detectable indicia and providing the computer information system with a security code corresponding to the security level coded on the input/output medium through the indicia applied thereto; c. determining from the computer the security level of information which is to be subject to output from the computer or the security level of the user who wishes to use input information from the medium; d. Comparing the security level determined in step c with the input/output medium security level detected in step b; e. permitting the information to be read from or written to the input/output medium only if the security level of the information and the security code of the media are compatible.