Tom Lookabaugh

Security analysis of selectively encrypted MPEG-2 streams

Selective encryption exploits the relationship between encryption and compression to reduce encryption requirements, saving in complexity and facilitating new system functionality. Selective encryption of MPEG video streams has been proposed in a number of variations, yet has seen little application to date. Here we focus on high encryption savings, targeting 10% of the bit stream or less encrypted, moderate security in the sense that the content is degraded to the point that purchase would be preferred over consuming free content, no impact on compression efficiency, and a cryptanalytic approach to validating security. We find that adequate security is plausible if the compressor is cooperative or at least neutral with respect to the selective encryption system, but implausible if the compressor is operated antagonistically. The unusually low encryption targeted makes application of this solution appealing.

VoIP Security: Not an Afterthought

Voice over IP (VoIP) promises to up-end a century-old model of voice telephony by breaking the traditional monolithic service model of the public switched telephone network (PSTN) and changing the point of control and provision from the central office switch to the end user’s device. Placing intelligence at the edge, in the Internet tradition, has a number of consequences: a wider community of developers - in particular the large community of Web service developers - can work on voice applications; open interfaces and decomposable functionality facilitate multi-vendor and homegrown solutions; and open source and nonproprietary software development can facilitate innovation and experimentation.

Selective encryption, information theory and compression

Selective encryption only encrypts a portion of a compressed bitstream, relying on the characteristics of the compression format to render the remaining in-the-clear content unusable. While the technique has been proposed in a number of practical applications, it is also motivated by concepts from the origins of Shannon theory on the links between source coding and encryption and benefits from an evaluation of its performance on compression primitives, such as quantization and Huffman coding, used in constructing many compression algorithms.

Selective encryption for consumer applications

Selective encryption is a technique to save computational complexity or enable new system functionality by encrypting only a portion of a compressed bitstream while achieving adequate security. Although suggested in a number of specific cases, selective encryption could be much more widely used in consumer electronic applications, ranging from mobile multimedia terminals to digital cameras, were it subjected to a more thorough security analysis. We describe selective encryption and develop a simple scalar quantizer example to demonstrate the power of the concept, list a number of potential consumer electronics applications, then describe an appropriate method for developing and analyzing selective encryption for particular compression algorithms. We summarize results from the application of this method to the MPEG-2 video compression algorithm.

A Model for Emergency Service of VoIP Through Certification and Labeling

Voice over Internet Protocol (VoIP) will transform many aspects of traditional telephony service including technology, the business models and the regulatory constructs that govern such service. This transformation is generating a host of technical, business, social and policy problems. The Federal Communications Commission (FCC) could attempt to mandate obligations or specific solutions to the policy issues around VoIP, but is instead looking first to industry initiatives focused on key functionality that users have come to expect of telecommunications services. High among these desired functionalities is access to emergency services that allow a user to summon fire, medical or law enforcement agencies. Such services were traditionally required (and subsequently implemented) through state and federal regulations. Reproducing emergency services in the VoIP space has proven to be a considerable task, if for no other reason then the wide and diverse variety of VoIP implementations and implementers. Regardless of this difficulty, emergency service capability is a critical social concern, making it is particularly important for the industry to propose viable solutions for promoting VoIP emergency services before regulators are compelled to mandate a solution, an outcome that often suffers compromises both through demands on expertise that may be better represented in industry and through the mechanisms of political influence and regulatory capture. While technical and business communities have, in fact, made considerable progress in this area, significant uncertainty and deployment problems still exist. The question we ask is: can an industry based certification and labeling process credibly address social and policy expectations regarding emergency services and VoIP, thus avoiding the need for government regulation at this critical time?1 We hypothesize that it can. To establish this, we developed just such a model for VoIP emergency service compliance through industry certification and device labeling. The intent of this model is to support a wide range of emergency service implementations while providing the user some validation that the service will operate as anticipated. To do this we first examine possible technical implementations for emergency services for VoIP.2 Next, we summarize the theory of certification as self-regulation and examine several relevant examples. Finally, we synthesize a specific model for certification of VoIP emergency services. We believe that the model we describe provides both short term and long-term opportunities. In the short term, an industry driven effort to solve the important current problem of emergency services in VoIP, if properly structured and overseen as we suggest, should be both effective and efficient. In the long term, such a process can serve as a model for the application of self-regulation to social policy goals in telecommunications, an attractive tool to have as telecommunications becomes increasingly diverse and heterogeneous.

Security and Lock-In

The cases of set-top boxes in the U. S. cable industry, video games and their cartridges, and printers and their cartridges all illustrate ways in which security technology can play an enhanced role in lock-in of customers by their suppliers through creation of substantial switching costs. Openness of technology, normally an inhibitor of lock-in, can be argued against in the case of security on the basis of a presumed increase in security by keeping details of the security system secret and proprietary. Whether open or not, security technology can be used to make permissible reverse engineering equivalent to an infeasible problem of breaking a cryptographically strong algorithm. And what might appear to be permissible reverse engineering may be conflated with an effort to enable illegitimate piracy and rendered illegal. The extra potential for security technology as a locus of lock-in raises its importance in the strategic considerations of both customers and vendors and for legislators and regulators. Customers will want to consider how to reduce the effect of lock-in, particularly on access to innovation; vendors will want to consider how to increase lock-in where possible, and policy makers will want to consider where the public interest motivates efforts to intervene to mitigate lock-in.

Information technology mediated education - revolution not evolution

Information technology, and in particular distance education technology, is becoming more prevalent across society and throughout higher education. But as information technology mediated education moves from trials towards educating non-trivial numbers of students, we can expect established universities to resist wholesale adoption; particularly when it threatens core perceptions of what students want and need and the culture and financial model of the institution. The resulting increasing tension creates the potential for sudden and dramatic shifts rather than gradual adoption. Applications and practices that can signal the maturation of information technology mediated education include course importation and remote laboratory experiences. For institutions, successful development of information technology mediated education may require autonomous units. For individuals, the decision revolves around whether to participate and, if so, in what manner, particularly given academic culture and the potential for institutional resistance.