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## Seminars given

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***July 05, 2018* - Minimizing Leakage with Garbled Circuits

by Aurélien Dupin

Abstract: | Secure two-party computation provides a way for two parties to compute a function, that depends on the two parties' inputs, while keeping them private. Known since the 1980s, Yao's garbled circuits appear to be a general solution to this problem, in the semi-honest model.
Decades of optimizations have made this tool a very practical solution. This presentation starts with an introduction to garbled circuits and some of its optimizations.
However, it is well known that a malicious adversary could modify a garbled circuit before submitting it.
Many protocols, mostly based on cut-&-choose, have been proposed to secure Yao's garbled circuits in the presence of malicious adversaries.
Nevertheless, how much an adversary can modify a circuit and make it still executable has not been studied yet.
We first prove that any modification made by an adversary is equivalent to adding/removing NOT gates arbitrarily in the original circuit, otherwise the adversary can get caught.
Thereafter, we study some evaluation functions for which, even without using cut-&-choose, no adversary can gain more information about the inputs by modifying the circuit. |