Rafail Ostrovsky - Publications

Maliciously Circuit-Private FHE

Rafail Ostrovskt, Anat Paskin-Cherniavsky, Beni Paskin-Cherniavsky


We Present framework for transforming FHE ( fully homomorphic encryption) schemes with no circuit privacy requirements into maliciously circuit-private FHE. That is even if both maliciously formed public key and ciphertext are used, encrypted outputs only reveal the evaluation of the circuit on some well-formed iinput X. Previous literature on the FHE only considered semi-honest circuit privacy. Circuit-private FHE schemes have direct application to computing on encrypted data. In that setting one party ( a riceiver&$41 holding an input X wishes to learn the evaluation of a circuit C held by another party ( a sender).The goal is to make receiver's work sublinear (and ideally independent) of |C|, using a 2-message protocol. Thetransformation technique may be independent interest, and have various additional applications. The framework uses techniques akin to Gentry's bootstrapping and conditional disclosure of secrets )CDS [AUIR01]) combining a non circuit private FHE scheme. with a homomorphic encryption (HE) sceme for a smaller class of circuits which is maliciously circuit-private. We devise the first known circuit private FHE, by instantiating our framework by various (standard) FHE schemes from literature.

comment: EUROCRYPT 2014 PP: 536-553

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