Cryptology ePrint Archive: Report 2020/264

Plaintext Recovery Attacks against Linearly Decryptable Fully Homomorphic Encryption Schemes

Nicholas Mainardi and Alessandro Barenghi and Gerardo Pelosi

Abstract: Homomorphic encryption primitives have the potential to be the main enabler of privacy preserving computation delegation to cloud environments. One of the avenues which has been explored to reduce their significant computational overhead with respect to cleartext computation is the one of the so-called noise-free homomorphic encryption schemes. In this work, we present an attack against fully homomorphic encryption primitives where a distinguisher for a single plaintext value exists. We employ two noise-free homomorphic encryption schemes where such a property holds as our case studies, providing detailed attack procedure against them. We validate the effectiveness and performance of our attacks on prototype implementations of the said schemes, and suggest two countermeasures to our attack tailored to the schemes at hand.

Category / Keywords: public-key cryptography / cryptanalysis, fully homomorphic encryption, plaintext-recovery attack

Original Publication (with minor differences): International Journal of Computers & Security, Volume 87

Date: received 26 Feb 2020, last revised 26 Feb 2020

Contact author: nicholas mainardi at polimi it

Available format(s): PDF | BibTeX Citation

Note: The final version of this work is published in the International Journal of Computers & Security, Volume 87, November 2019. DOI:

Version: 20200304:080548 (All versions of this report)

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