METHOD AND MEANS TO LIMIT ACCESS TO COMPUTER SYSTEMS

Abstract: In a preferred embodiment, a method of limiting access to computer system (12) which method includes scrambling identification card information (24) with time information so that the resulting code can be used for only a limited period of time, thus preventing unauthorized persons from using the code at a later time.

Description: Description Method and Means to Limit Access to Computer Systems Technical Field The present invention relates to electronic computer systems generally and, more particularly, to a novel method and means of limiting access to such computer systems and especially those systems which require the input of a security code, or password, as part of the procedure to access such systems. Background Art Electronic data bases are widely used in a broad range of activities and typically are maintained in various memory devices of computer systems. Such data bases may be used for work-in-process control in manufacturing, pricing and inventory control in selling, ticket issuance, and data storage in research, to name only a very small number of actual uses. Often, and especially in larger data systems, the computer system in which the data bases are maintained has included in it a number of CRT terminals which may be used to both input and access data to and from the memory devices. This arrangement greatly facilitates the operation of an organization by allowing rapid input and access by a number of persons. While this is advantageous, there are many situations in which it is desired to limit access to the data bases and programs to only those persons to whom such access is authorized. Conventionally, access to data bases is limited by means of having a potential user type in a security code at one of the CRT terminals to "unlock" access to the data bases. A problem with this method is that an unauthorized person may simply observe the keys pressed to enter the security code. As an alternative method, the potential user may insert a personal identification card with a bar code, magnetic code, or other coded identification in a slot card reader. One problem with either method is that, later, an unauthorized person can simply put the CRT terminal in "TEST MODE" to read the security code and then use the security code to gain access to the data bases. It is therefore necessary to ensure that the security code is deleted, or the terminal locked out, whenever the authorized person leaves the terminal. Frequently, the program requires that the user log out when finished, but often the users forget to log out. One conventional technique to achieve automatic log out is to have a "time out" period built into the computer program with which the terminal is locked out after a predetermined interval of time during which there has been no entry on the keyboard. A disadvantage of this technique is that the "time out" period must be set fairly long to allow for slow users or users may stop to think for a period of time in excess of the "time out" period. Another problem with the foregoing methods is that the authorized person may give his security code to the unauthorized person. A further problem with methods which employ an identification card with the security code encrypted on it in bar code form is that the card may simply be copied by conventional photocopying techniques or, if the bar code is encrypted according to standard symbologies, it may be forged through the use of a standard bar code printer. Accordingly, it is a principal object of the invention to provide a method and means to prevent copying or forging of a transmission to a host computer. It is a further object of the invention to provide a method and means to check the validity of an identification card and to prevent copying or forging of the card. Yet an additional object of the invention is to provide such method and means which can be easily retrofitted to existing systems with minor hardware changes and little or no changes to existing host computer software. Other objects of the present invention, as well as particular features and advantages thereof, will be elucidated in, or be apparent from, the following description and the accompanying drawing figure. Disclosure of Invention The present invention achieves the above objects, among others, by providing, in a preferred embodiment, a method of limiting access to computer systems which method includes scrambling identification card information with time information so that the resulting code can be used for only a limited period of time, thus preventing unauthorized persons from using the code at a later time. Brief Description of the Drawings The invention will be better understood if reference is made to the accompanying drawing in which: The sole drawing figure is a schematic diagram of a computer system including one aspect of the present invention. Best Mode for Carrying Out the Invention Referring now to the drawing, the sole drawing figure schematically illustrates a data base input/retrieval system or the like, generally indicated by the reference numeral 10, which includes the present invention. System 10 includes a host computer 12, in the memory of which it may be assumed that a data base is stored. Connected to host computer 12 are one or more CRT terminals 14 (only one shown) each with an associated keyboard 16. Connected to CRT terminal 14 is a wedge, or keyboard emulator, 18 to which is connected data input devices, here, for illustrative purposes, a bar code reader wand 20 and a slot card reader/decoder 22. Slot card reader/decoder 22 may be of the type which reads bar codes on cards inserted therein or it may be of the type which reads magnetic codes embedded in cards. The former type of card is illustrated as identification card 24. The purpose of keyboard emulator 18 is to provide an input to host computer 12 which the host computer reads as an input from the keyboard, without having to change the software in the host computer for different input devices. Keyboard emulator 18 is also connected to keyboard 16 to lock the keyboard unless an identification card 24 is inserted into reader/decoder 22. Identification card 24 may be any type of identification card, but it is preferably one that includes an encrypted security code such as that described in US Application Serial No. 07/338,373, filed April 13, 1989, by James S. Bianco, titled IDENTIFICATION MEANS WITH ENCRYPTED SECURITY CODE AND METHOD OF MAKING AND USING SAME, the disclosure of which application is made a part hereof by reference. Using such an identification card increases the degree of security. In many cases, access to the data bases in host computer 12 is freely available to anyone who ' uses CRT terminal 14. Data may be inputted through keyboard 16 or by means of reading a bar code with wand 20. Likewise, data may be retrieved by inputting the appropriate commands on keyboard 16. In other cases, secured access may be desired and it is in these cases, that, in conventional systems, a potential user may be required to enter a unique security code on keyboard 16 or to enter the code by means of inserting identification card 24 into slot card reader/decoder 22, or both the entry of a security code and the insertion of an identification card may be required. When host computer 12 receives the security code, it provides access to the data bases. As noted above, a substantial limitation of the conventional systems is that, after the authorized user leaves CRT terminal 14, an unauthorized person can put the CRT terminal in "TEST MODE", read the security code, and use the security code later for unauthorized access to the data bases. The present invention defeats this mode of unauthorized access as follows: Reader/decoder 22 is programmed to scramble the security code, using conventional encoding techniques, the scrambling algorithm changing as a function of the current date and time. Host computer 12 is likewise programmed to decode the scrambled security code, with the unscrambling algorithm changing, in the same manner, as a function of the date and the time. The algorithms may change at the end of any selected interval of time, say, each hour or even each minute. Host computer.12 is programmed to accept scrambled codes in a time interval somewhat greater than the time interval of changes to avoid rejecting a potential authorized user at the point of change. If an "out-of-date" code is received, host computer 12 is programmed to not unlock CRT terminal 14, since the code was probably copied by an unauthorized user. The unauthorized user can still read the scrambled code on CRT terminal 14 in the manner described above, but the code is valid only for a limited period of time and, if the length of that period of time is selected to be short enough, having the scrambled code would be of no value to the unauthorized user. It will be understood from the foregoing that time domain encryption of an identification code prevents duplication of a transmitted security code, while the use of a specially encrypted security code prevents forging of the transmitted security code. It will further be appreciated that the present invention can easily be incorporated into existing computer systems by relatively simple reprogramming and minor equipment changes. It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matter contained in the above description or shown on the accompanying drawing figures shall be interpreted as illustrative only and not in a limiting sense. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Claims: Claims 1. A method of limiting access to a computer system, said system being accessible by means of a security code, comprising: (a) reading an identification code on identifying indicia by machine means connected to said computer system; (b) scrambling said identification code as a function of current time to produce said security code; (c) transmitting directly from said machine means to said computer system said security code; (d) descrambling, in said computer system, said security code to determine if said security code is valid for the then current date and time; and (e) permitting said security code, if valid, to be used for access to said computer system for a selected interval of time only. 2. A method, as defined in Claim 1, wherein said identification code is included as part of an identification card. 3. A method, as defined in Claim 2, wherein said identification code is in the form of a bar code, 4. A method, as defined in Claim 3, wherein a portion of said identification code is encrypted according to a unique symbology. 5. A method, as defined in Claim 3, wherein said identifying indicia comprises: (a) a first decipherable code containing first information encrypted according to a standard symbology; and (b) a second decipherable code containing second information encrypted according to a unique symbology, said second information including at least a portion of said first information; and said method further comprises the step of said machine means decoding said first and second decipherable codes to determine if said identification code is valid and permitting access to said computer system only if said identification code is valid. 6. Every novel system, apparatus, method, or article disclosed herein.

Inventors: BIANCO JAMES S, CEPPETELLI MICHAEL A, MADSEN JAMES T, BIANCO, JAMES, S., CEPPETELLI, MICHAEL, A., MADSEN, JAMES, T.
Applicants: BIANCO JAMES S, BIANCO, JAMES, S.
Application year: 1991
Main classification: H04K1
IPC codes: G06F21, G06K7, G06K19, G07F7