AuthorsP. Fauzi, M. N. Hovd and H. Raddum
EditorsT. J. P. C. J.H.
TitleA Practical Adaptive Key Recovery Attack on the LGM (GSW-like) Cryptosystem
Project(s)Simula UiB
Publication TypeProceedings, refereed
Year of Publication2021
Conference NameInternational Conference on Post-Quantum Cryptography
Date Published07/2021
Publisher Springer
ISBN Number978-3-030-81292-8
KeywordsGSW, Key recovery, Somewhat homomorphic encryption, Statistical attack

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.

Citation Key27900

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