A Location Based Encryption Technique and Some of Its Applications

L. Scott, D.E. Denning

Abstract:	Location based encryption enhances security by integrating position and time into encryption and decryption processes. We find that from a security perspective, it is not enough to simply enable or disable decryption based on location and time; these aspects must be integrated into the key construction process. Furthermore, keys or files in transit should not reveal anything regarding their locations/times of applicability. After reviewing the objectives of location-based encryption, this paper introduces a specific approach called geo-encryption. The described geo-encryption approach builds on established cryptographic algorithms and protocols in a way that provides an additional layer of security beyond that provided by conventional cryptography. It allows data to be encrypted for a specific location(s) or for specific area(s), e.g. a corporation’s campus area. Constraints in time as well as location can also be enforced. Geo-encryption can be used with both fixed and mobile applications and supports a wide range of data sharing and distribution policies. We then discuss a process of applying successive geoencryptions at the originating node to enforce specific geographic routings for transmission to the final destination node. With each intervening node removing one layer of encryption, unless the file has gone through the proper sequence of nodes, decryption will fail. Using a similar process, messages can be location authenticated by applying one layer of encryption at each intervening node. Next, we discuss some specific applications. In the civilian sector, there has been a great deal of interest in providing location-based security for digital cinema distribution and forensic analysis in cases of piracy. In this application, the same, large (25 to 190 Gbyte), encrypted media file might be used at multiple theatre locations but with distinct GeoLocked keys specific to the intended recipient location and exhibition license. This provides a secure and efficient point to multipoint distribution model applicable to distributions via satellite or DVD. At the exhibition hall, robust watermarking/steganographic techniques can introduce location, time and exhibition license information into the exhibition for subsequent use in piracy investigations. For the military GPS user, we show how individual waypoints can be uniquely encrypted so as to be accessible only when the set is physically within the route parameters; both location and time wise. An intact, captured set would not reveal mission parameters.
Published in:	Proceedings of the 2003 National Technical Meeting of The Institute of Navigation January 22 - 24, 2003 Disneyland Paradise Pier Hotel Anaheim, CA
Pages:	734 - 740
Cite this article:	Scott, L., Denning, D.E., "A Location Based Encryption Technique and Some of Its Applications," Proceedings of the 2003 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2003, pp. 734-740.
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