BibTeX
@MISC{Yamakami902pseudorandomgenerators,
author = {Tomoyuki Yamakami},
title = {Pseudorandom Generators against CFL/n},
year = {902}
}
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Abstract
Abstract. Pseudorandomness has played a central role in modern cryptography, finding theoretical and practical applications to various fields of computer science. A function that generates such pseudorandom strings from shorter but truly random seeds is known as a pseudorandom generator. Our generators are designed to fool languages, rather than probabilistic algorithms. In particular, our generators take context-free languages with advice as their adversaries. We present an explicit example of such a pseudorandom generator, which can be also computed by a single-tape deterministic Turing machine running in time O(n 2). In contrast, we show that there is no almost 1-1 pseudorandom generator against even context-free languages (without advice) if we demand it should be computed by a nondeterministic pushdown automaton equipped with a write-only output tape. Our proofs are all elementary, requiring no complicated proof techniques as in a polynomial-time setting, and utilize a specific feature of nondeterministic pushdown automata, which is interesting on its own light.
Keyphrases
pseudorandom generator context-free language nondeterministic pushdown automaton proof technique single-tape deterministic turing machine explicit example various field specific feature random seed write-only output tape 1-1 pseudorandom generator practical application computer science pseudorandom string central role polynomial-time setting probabilistic algorithm modern cryptography
