Jack Brassil

Copyright protection for the electronic distribution of text documents

Each copy of a text document can be made different in a nearly invisible way by repositioning or modifying the appearance of different elements of text, i.e., lines, words, or characters. A unique copy can be registered with its recipient, so that subsequent unauthorized copies that are retrieved can be traced back to the original owner. In this paper we describe and compare several mechanisms for marking documents and several other mechanisms for decoding the marks after documents have been subjected to common types of distortion. The marks are intended to protect documents of limited value that are owned by individuals who would rather possess a legal than an illegal copy if they can be distinguished. We describe attacks that remove the marks and countermeasures to those attacks. An architecture is described for distributing a large number of copies without burdening the publisher with creating and transmitting the unique documents. The architecture also allows the publisher to determine the identity of a recipient who has illegally redistributed the document, without compromising the privacy of individuals who are not operating illegally. Two experimental systems are described. One was used to distribute an issue of the IEEE Journal on Selected Areas in Communications, and the second was used to mark copies of company private memoranda.

Electronic marking and identification techniques to discourage document copying

Modern computer networks make it possible to distribute documents quickly and economically by electronic means rather than by conventional paper means. However, the widespread adoption of electronic distribution of copyrighted material is currently impeded by the ease of unauthorized copying and dissemination. In this paper we propose techniques that discourage unauthorized distribution by embedding each document with a unique codeword. Our encoding techniques are indiscernible by readers, yet enable us to identify the sanctioned recipient of a document by examination of a recovered document. We propose three coding methods, describe one in detail, and present experimental results showing that our identification techniques are highly reliable, even after documents have been photocopied. >

Document marking and identification using both line and word shifting

Continues a study of document marking to deter illicit dissemination. An experiment performed reveals that the distortion on the photocopy of a document is very different in the vertical and horizontal directions. This leads to the strategy that marks a text line both vertically using line shifting and horizontally using word shifting. A line that is marked is always accompanied by two unmarked control lines one above and one below. They are used to measure distortions in the vertical and horizontal directions in order to decide whether line or word shift should be detected. Line shifts are detected using a centroid method that bases its decision on the relative distance of line centroids. Word shifts are detected using a correlation method that treats a profile as a waveform and decides whether it originated from a waveform whose middle block has been shifted left or right. The maximum likelihood detectors for both methods are given.

Bounds on maximum delay in networks with deflection routing

We consider the problem of finding the worst case packet transit delay in networks using deflection routing. Several classes of networks are studied, including many topologies for which deflection routing has been proposed or implemented (e.g., hypercube, Manhattan Street Network, shuffle-exchange network). We derive new upper bounds on the evacuation time of batch admissions, and present simple proofs for several existing bounds. Also derived are bounds on worst case transit delay for certain networks admitting packets continuously. To demonstrate the practical utility of our results, we compare a new delay bound to the maximum delay observed in simulations. The results have application in both protocol design and the determination of the required capacity of packet resequencing buffers. >

Enhancing Internet streaming media with cueing protocols

We propose a new, media-independent protocol for including program timing, structure and identity information in Internet media streams. The protocol uses signaling messages called cues to indicate events whose timing is significant to receivers, such as the start or stop time of a media program. We describe the implementation and operation of a prototype Internet radio station which transmits program cues in audio broadcasts using the Real-Time Transport Protocol. A collection of simple yet powerful stream processing applications we implemented demonstrate how application creation is greatly eased when media streams are enriched with program cues.

Handheld routers: intelligent bandwidth aggregation for mobile collaborative communities

Multi-homed, mobile wireless computing and communication devices can spontaneously form communities to logically combine and share the bandwidth of each others wide-area communication links using inverse multiplexing. But membership in such a community can be highly dynamic, as devices and their associated WAN links randomly join and leave the community. We identify the issues and tradeoffs faced in designing a decentralized inverse multiplexing system in this challenging setting, and determine precisely how heterogeneous WAN links should be characterized, and when they should be added to, or deleted from, the shared pool. We then propose methods of choosing the appropriate channels on which to assign newly-arriving application flows. Using video traffic as a motivating example, we demonstrate how significant performance gains can be realized by adapting allocation of the shared WAN channels to specific application requirements. Our simulation and experimentation results show that collaborative bandwidth aggregation systems are, indeed, a practical and compelling means of achieving high-speed Internet access for groups of wireless computing devices beyond the reach of public or private access points.

Watermarking Document Images with Bounding Box Expansion

Imperceptible displacements of text objects has been shown to be a successful technique for hiding data in document images. In this paper we extend our earlier work to show how the height of a bounding box enclosing a group of text words can be used to increase the density of information hidden on a page. We present experimental results which show that bounding box expansions as small as 1/300 inch can be reliably detected, even after the distortions introduced by noisy image reproduction devices such as plain paper copiers. Digital watermarks based on this technique can be used with electronically disseminated documents for applications including copyright protection, authentication, and tagging.

Structuring Internet media streams with cueing protocols

We propose a new, media-independent protocol for including program timing, structure, and identity information in Internet media streams. The protocol uses signaling messages called cues to indicate events whose timing is significant to receivers, such as the start or stop time of a media program. We describe the implementation and operation of a prototype Internet radio station which transmits program cues in audio broadcasts using the Real-Time Transport Protocol (RTP). A collection of simple yet powerful stream processing applications we implemented demonstrate how application creation is greatly eased when media streams are enriched with program cues.

Marking text features of document images to deter illicit dissemination

A major impediment to the widespread adoption of services for electronic distribution of copyrighted material is the ease with which illicit copies can be made and disseminated. In this paper, we describe feature coding techniques to mark document images with codes that are indiscernible by readers but can be decoded by document feature analysis techniques. These codes can be used to trace the source of errant documents. We propose three coding methods: line-shift coding, word-shift coding, and character coding. We describe how the coding features are found, inserted, and decoded. Finally, we show preliminary experimental results indicating robustness of the line-shift coding method where decoding can be performed even from images of up to ten generations of photocopying.

Aggregating Bandwidth for Multihomed Mobile Collaborative Communities

Multihomed, mobile wireless computing and communication devices can spontaneously form communities to logically combine and share the bandwidth of each others wide-area communication links using inverse multiplexing. But, membership in such a community can be highly dynamic, as devices and their associated WWAN links randomly join and leave the community. We identify the issues and trade-offs faced in designing a decentralized inverse multiplexing system in this challenging setting and determine precisely how heterogeneous WWAN links should be characterized and when they should be added to, or deleted from, the shared pool. We then propose methods of choosing the appropriate channels on which to assign newly arriving application flows. Using video traffic as a motivating example, we demonstrate how significant performance gains can be realized by adapting allocation of the shared WWAN channels to specific application requirements. Our simulation and experimentation results show that collaborative bandwidth aggregation systems are, indeed, a practical and compelling means of achieving high-speed Internet access for groups of wireless computing devices beyond the reach of public or private access points