Efficiently Obfuscating Re-Encryption Program Under DDH Assumption

  • Akshayaram Srinivasan
  • Chandrasekaran Pandu Rangan
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 10355)

Abstract

The re-encryption functionality transforms a ciphertext encrypted under a public key \(pk_1\) to a ciphertext of the same message encrypted under a different public key \(pk_2\). Hohenberger et al. (TCC 2007) proposed a pairing-based obfuscator for the family of circuits implementing the re-encryption functionality under a new notion of obfuscation called as average-case secure obfuscation. Chandran et al. (PKC 2014) proposed a lattice-based construction for the same.

The construction given by Hohenberger et al. could only support polynomial sized message space and the proof of security relies on strong assumptions on bilinear groups. Chandran et al.’s construction could only satisfy a relaxed notion of correctness.

In this work, we propose a simple and efficient obfuscator for the re-encryption functionality that satisfies the strongest notion of correctness, supports encryption of messages from an exponential sized domain and relies on the standard DDH-assumption. This is the first construction that does not rely on pairings or lattices. All our proofs are in the standard model.

Keywords

Re-encryption functionality Average-case secure obfuscation DDH assumption Standard model 

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  • Akshayaram Srinivasan
    • 1
  • Chandrasekaran Pandu Rangan
    • 2
  1. 1.University of CaliforniaBerkeleyUSA
  2. 2.Indian Institute of TechnologyMadrasIndia

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