Abstract: Apparatus, methods, and articles of manufacture are claimed for securing, maintaining, monitoring and controlling computer networks and clients located therein by use of client hash code tables, which are stored on a server. Clients subsequently provide client state codes which are compared to the hash code tables to ensure only acceptable client modifications have taken place. In the event of unacceptable client modifications, mechanisms are used to notify appropriate resources.

Abstract: An apparatus and method for providing real-time tracking of virus information as reported from various computers on a distributed computer network. Each client computer on the distributed network contacts an anti-virus scanning site. The site provides a small program or applet that resides in temporary memory of the client computer. The client-user invokes the scan with supplied pattern updates for detecting recent viruses. When the scan has been completed, the user is prompted to supply a country of origin. The name of the virus, its frequency of occurrence, and the country are forwarded as a virus scan log to a virus tracking server, which receives the virus information and thereafter stores it in a database server, which is used to further calculate virus trace display information. A tracking user contacts the virus tracking server and receives map information, which traces the virus activity.

Abstract: Improved cryptographic techniques are provided by which a device that performs private key operations (e.g., signatures and/or decryptions), and whose private key operations are protected by a password, is immunized against offline dictionary attacks in case of capture by forcing the device to confirm a password guess with a designated entity or party in order to perform a private key operation, and by which the initiating device may dynamically delegate the password-checking function (i.e., confirmation of the password guess) from the originally designated entity or party to another designated entity or party.

Abstract: In a data multiplexing device which multiplexes and transmits the transport stream packets of program data consisting of a plurality of data elements constructed in the form of transport stream packets, a program distribution system, a program transmission system, a pay broadcast system, a program transmission method, a conditional access system, and a data reception device according to the present invention, by generating a scramble key Ks corresponding to one or more data elements among the plurality of data elements constituting a program and by scrambling each data element, an audience can subscribe for each data element.

Abstract: A method of producing a stream of digital data. The method includes determining a plurality of portions within the stream of digital data, such that a portion of the stream of digital data is encrypted with an encryption key that is capable of being decrypted by a decryption key and the portion including therein another decryption key capable of decrypting a subsequent portion of the stream of digital data, and the subsequent portion of the stream of digital data is encrypted with another encryption key that is capable of being decrypted by the another decryption key. The method also includes transmitting the stream of digital data, including the portion and the subsequent portion.

Abstract: A two-dimensional inverse discrete cosine transform (2-D IDCT) processor comprises cosine angle index generators, pipelined multipliers and a symmetrical kernel. The 2-D IDCT processor of the invention has a five-stage pipelined structure for carrying out a coefficient-by-coefficient 2-D IDCT algorithm and can be operated at a clock rate of more than 50 MHz to achieve a pixel rate of about 400 MHz.