Scalable Policy Based Cryptography using ROBDD

Abstract

Policy-based cryptography is a cryptographic method which makes possible to perform policy enforcement in large-scale open environments. Policy based cryptosystems have data minimization principle that strictly ensures that only the necessary information is encrypted. In open computing environments, many interactions occur between the entities from different domains without pre-existing trust relationships which may require the exchange of sensitive resources and hence they need to be carefully protected through clear and concise policies.

The policy-based cryptography uses a digital credential which is basically a digitally signed assertion by a trusted authority of a specific user. The policy-based crypto-systems suffer from the problems like scalability and are not suitable in a multilevel hierarchal structure.

In the present policy based crypto-system the policies are strictly defined using the monotone binary expressions. The min-terms and the max-terms defined in such expressions always produce multiple and redundant optimized policy, which need to change dynamically upon adding or removing the users. This task has been simplified in the present work with the use of Reduced Ordered Binary Decision Diagrams (ROBDD). The policies defined using the ROBDD can ensure that the system is flexible and scalable. ROBDD has another advantage of reducing the decision of resolving the policies amongst the communicating parties.






References:


1. S.S. Al-Riyami, J. Malone-Lee, and N.P. Smart. Escrow-free encryption supporting 
    cryptographic workflow. Cryptology ePrint Archive, Report 2004/258, 2004.
    http://eprint.iacr.org/


2. Establishment of Ad-Hoc Communities through Policy-Based Cryptography-Walid Bagga
    http://www.argreenhouse.com/society/wcan06/wcan06s4p2.pdf


3. http://en.wikipedia.org/wiki/Binary_decision_diagram

Firesay adds simple voice navigation to Firefox

Voice navigation is now commonplace on modern-day Android devices, but on the desktop, many of the accessibility tools that would bring voice commands to the end user still require special system level software or customized hardware.

That's not the case with a new Firefox add-on called Firesay, which brings hands-free voice controls to just the browser. Once installed as an add-on, it can pick up voice commands to do Web searches, open and close sites, and even pull up TV shows on Hulu.

The number of commands, and sites users can visit is extremely limited for the time being. You can, for instance, only open up a handful of Web sites and TV shows, as long as they're in the list of those that have been programmed in. Though the add-on is able to recognize and transcribe voice commands for its Web search feature. The add-on also requires that the user is on Windows 7, leaving XP, Vista, and Mac OS users behind.

One very cool feature is the option to open up a new site in the background of another tab, which normally requires: the link be coded that way, a special mouse click, or the use of a contextual menu within the browser. Firesay's solution is to have the user say "multitask" in front of a site's name, which opens it up and lets it load in an adjacent tab. The same behavior is used to do Web searches, which for now, are all done through Google.

Firesay's creators say future versions will bring voice recognition that is more easily able to pull out words from a noisy room. To some degree, Google has gotten around this problem on the mobile side by making use of noise cancellation hardware on the phone and software algorithms within the Android OS. On the desktop side of things, Firesay is simply suggesting that users invest in a microphone with noise cancellation built-in.