Sivaramakrishnan Rajagopalan

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We consider the problem of sending messages \into the future ." Previous constructions for this task were either based on heuristic assumptions or did not provide anonymity to the sender of the message. In the public-key setting, we present an eecient and secure timed-release encryption scheme using a \time server" which inputs the current time into the(More)
This paper explores the problem of protecting a site on the Internet against hostile external Java applets while allowing trusted internal applets to run. With careful implementation , a site can be made resistant to current Java security weaknesses as well as those yet to be discovered. In addition, we describe a new attack on certain sophisticated(More)
We present applications of splay trees to two topics in data compression. First is a variant of the move-to-front (mtf) data compression (of Bentley,Sleator Tar'an and Wei) algorithm, where we introduce secondary list(s , ". This seems to capture higher-order correlations. An implementation of this algorithm with Sleator-Tarjan splay trees runs in time(More)
We present a scheme for general purpose pseudo-random generators useful for randomized algorithms, simulations and cryptography. We begin with a slow but high quality generator e.g. bits from a cryptographically strong [Blum-Micali, Yao 821 generator or those extracted from weakly random sources [Vazirani Vazi-rani, Zuckerman]. Using the bits of the slow(More)
1 Introduction The theory of average case completeness initiated by Leonid Levin and further developed by othersvich 91] proposes a robust notion of hard-on-average problems. It considers NP problems with their instances generated under sam-plable (generatable in polynomial time) distributions. Such a complete problem can not have a fast on average(More)
This paper describes our initial steps towards self-connguring mechanisms for automating high-level security and service policies in dynamic networks. We build on the NESTOR system developed at Columbia University for instrumenting and monitoring constraints on network elements and services such as DHCP, DNS zones, host-based access controls, rewalls, and(More)
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