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Bootstrapping for HElib

  • Shai HaleviEmail author
  • Victor Shoup
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 9056)

Abstract

Gentry’s bootstrapping technique is still the only known method of obtaining fully homomorphic encryption where the system’s parameters do not depend on the complexity of the evaluated functions. Bootstrapping involves a recryption procedure where the scheme’s decryption algorithm is evaluated homomorphically. So far, there have been precious few implementations of recryption, and fewer still that can handle “packed ciphertexts” that encrypt vectors of elements.

In the current work, we report on an implementation of recryption of fully-packed ciphertexts using the HElib library for somewhat-homomorphic encryption. This implementation required extending the recryption algorithms from the literature, as well as many aspects of the HElib library. Our implementation supports bootstrapping of packed ciphertexts over many extension fields/rings. One example that we tested involves ciphertexts that encrypt vectors of 1024 elements from \({\text {GF}}(2^{16})\). In that setting, the recryption procedure takes under 5.5 minutes (at security-level \(\approx 76\)) on a single core, and allows a depth-9 computation before the next recryption is needed.

Keywords

Linear Transformation Security Level Homomorphic Encryption Tensor Decomposition Decryption Procedure 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© International Association for Cryptologic Research 2015

Authors and Affiliations

  1. 1.IBM ResearchYorktown HeightsUSA
  2. 2.New York UniversityNew YorkUSA

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