Information Security and Cryptography Research Group

New Perspectives on Weak Oblivious Transfer

Ueli Maurer and João Ribeiro

2016 IEEE International Symposium on Information Theory (ISIT), pp. 790–794, Jul 2016.

Most cryptographic security proofs require showing that two systems are indistinguishable. A central tool in such proofs is that of a game, where winning the game means provoking a certain condition, and it is shown that the two systems considered cannot be distinguished unless this condition is provoked. Upper bounding the probability of winning such a game, i.e., provoking this condition, for an arbitrary strategy is usually hard, except in the special case where the best strategy for winning such a game is known to be non-adaptive.

A sufficient criterion for ensuring the optimality of non-adaptive strategies is that of conditional equivalence to a system, a notion introduced in [Mau02]. In this paper, we show that this criterion is not necessary to ensure the optimality of non-adaptive strategies by giving two results of independent interest: 1) the optimality of non-adaptive strategies is not preserved under parallel composition; 2) in contrast, conditional equivalence is preserved under parallel composition.

BibTeX Citation

@inproceedings{MauRib16,
    author       = {Ueli Maurer and João Ribeiro},
    title        = {New Perspectives on Weak Oblivious Transfer},
    booktitle    = {2016 IEEE International Symposium on Information Theory (ISIT)},
    pages        = {790--794},
    year         = {2016},
    month        = {7},
}

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