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Paper 2021/658

A Practical Adaptive Key Recovery Attack on the LGM (GSW-like) Cryptosystem

Prastudy Fauzi and Martha Norberg Hovd and Håvard Raddum

Abstract

We present an adaptive key recovery attack on the leveled homomorphic encryption scheme suggested by Li, Galbraith and Ma (Provsec 2016), which itself is a modification of the GSW cryptosystem designed to resist key recovery attacks by using a different linear combination of secret keys for each decryption. We were able to efficiently recover the secret key for a realistic choice of parameters using a statistical attack. In particular, this means that the Li, Galbraith and Ma strategy does not prevent adaptive key recovery attacks.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Published elsewhere. PQCrypto 2021
Keywords
Key recoverysomewhat homomorphic encryptionGSWstatistical attack
Contact author(s)
prastudy fauzi @ gmail com,martha @ simula no,haavardr @ simula no
History
2021-11-16: last of 2 revisions
2021-05-20: received
See all versions
Short URL
https://ia.cr/2021/658
License
Creative Commons Attribution
CC BY
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