US 4,882,752 A · Computer security system

Abstract

A security system for distributed computer systems with a central computer and remotely located interactive terminals. The security system includes a master security control processor (SCP) which is associated with the central computer, and one or more slave SCPs, each of which is associated with one of the interactive terminals. Clearance at several security levels is required before communications between one of the remote terminals and the central computer is authorized. The security levels are implemented after communications are established to maintain only authorized access to the central computer. One of several unauthorized access modes are implemented when an unauthorized interactive terminal or SCP is identified. All data communicated between the master and slave SCPs is encrypted for security.

Claims32

Dependent claims

A multi-level computer security system of the type having a master access control unit having a master unit database memory for storing codes characteristic of authorized slave access control units and adapted to selectively interface a central computer to a data transmission path and at least one slave access control unit adapted to interface a peripheral unit to the data transmission path, for controlling communications between the peripheral unit and the central computer over the data transmission path and preventing unauthorized access to the central computer;

wherein the system is characterized by a first security level procedure at which the slave access control unit transmits a slave unit identification code over the data transmission path to the master access control unit which, when received, is compared by the master access control unit to slave unit identification codes of authorized slave access control units stored in the master unit database memory, and a first security level clearance granted by the master access control unit upon a favorable comparison, and a second security level procedure at which the master access control unit requests from the slave access control unit over the data transmission path a slave unit sync code which must be received over the data transmission path by the master access control unit during a predetermined sync window and which, when received, is compared by the master access control unit to sync codes of authorized slave units stored in the master unit database memory, and a second security level clearance grated upon a favorable comparison of the received sync code and the sync codes stored in memory if the sync code was received during the sync window, the security system permitting data transmission between the peripheral unit and the central computer through the master and slave access control units and over the data transmission path only if the first and second security clearances are granted, and wherein the master access control unit periodically requests the slave unit sync code from the slave access control unit during data transmission after the first and second security clearance are granted, and terminates data transmission between the peripheral unit and the central computer unless a valid sync code is received during the sync window.

A computer security system of the type having at least one slave access control unit adapted to interface a peripheral unit to a data transmission path and including memory means for storing cipher data and authorization code data, and a master access control unit adapted to selectively interface a central computer to the data transmission path and for granting security level clearances to the slave access control unit as a function of authorization codes received from the slave access control unit over the data transmission path and permitting data transmission between the peripheral unit and central computer through the master and slave access control unit over the data transmission path when security level clearance is granted by the master access control unit and prohibiting data transmission over the data transmission path when security level clearance is denied, thereby preventing unauthorized access to the central computer by the peripheral unit;

wherein the system is characterized by the slave access control unit including electrically erasable programmable read only memory means for storing the cipher data and authorization code data, erase control means capable of erasing data stored in the erasable member means in response to erase commands from the master access control unit over the data transmission path, and a first unauthorized access mode in which the master access control unit generates and supplies an erase command to the slave access control unit when security level clearance is denied, thereby causing the data in the erasable memory means to be erased.

A computer security system of the type having a master access control unit which is adapted to selectively interface a central computer to a data transmission path and at least one slave access control unit which is adapted to interface a peripheral unit to the data transmission path, for controlling communications between the peripheral unit and central computer over the data transmission path and preventing unauthorized access to the central computer, both the master and slave access control units including cipher means for securing data transmission between the central computer and peripheral unit;

which cipher means of the master and slave access control units is characterized by memory means for storing data representative of a cipher key formed by a plurality of indexed cipher locations, each location including data representative of a mathematical operator and a number and wherein corresponding indexed cipher locations of the master access control unit and slave access control unit have complementary mathematical operators and identical numbers, means for randomly selectively one of the indexed locations, and computing means for mathematically operating on data by the mathematic operator and number of the selected corresponding indexed cipher locations so as to encipher data to be transmitted over the transmission path and to decipher data received over the data transmission path.

Dependencies are inferred from the claim text.

Computer security system

Life of this patent

Computer security system

Life of this patent

Abstract

Claims32