Efficient Adaptation of TFHE for High End-to-End Throughput

Kang Hoon Lee, Ji Won Yoon

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Homomorphic Encryption (HE) allows to process over user’s encrypted data. There are various HE schemes including TFHE, which offers homomorphic binary gate operation combined with bootstrapping. In most used case of TFHE’s gate operations, however, they encrypted a single bit of message in a single ciphertext, resulting in low throughput when sending ciphertexts. In this paper, we present a simple solution for the user to increase the throughput by packing multiple bits inside a single ciphertext using a ring based message space in TFHE. With the packing method, we propose a modified gate bootstrapping procedure to operate the same binary circuits on the server. Finally, without any additional public keys, we propose a new Keyswitching algorithm that we call PackKS, which enables even the server to pack multiple messages, thereby achieving high end-to-end throughput for TFHE.

Original languageEnglish
Title of host publicationInformation Security Applications - 22nd International Conference, WISA 2021, Revised Selected Papers
EditorsHyoungshick Kim
PublisherSpringer Science and Business Media Deutschland GmbH
Number of pages13
ISBN (Print)9783030894313
Publication statusPublished - 2021
Event22nd World Conference on Information Security Application, WISA 2021 - Jeju, Korea, Republic of
Duration: 2021 Aug 112021 Aug 13

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume13009 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference22nd World Conference on Information Security Application, WISA 2021
Country/TerritoryKorea, Republic of

Bibliographical note

Funding Information:
This work was supported by Institute of Information & communications Technology Planning & Evaluation (IITP) grant funded by the Korea government (MSIT) (No. 2021-0-00558, Development of national statistical analysis system using homomorphic encryption technology).

Publisher Copyright:
© 2021, Springer Nature Switzerland AG.


  • Homomorphic Encryption
  • Key switching
  • TFHE

ASJC Scopus subject areas

  • Theoretical Computer Science
  • General Computer Science


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