CCA Secure Updatable Encryption from Non-Mappable Group Actions

ePrint Report: CCA Secure Updatable Encryption from Non-Mappable Group Actions

Jonas Meers, Doreen Riepel

Ciphertext-independent updatable encryption (UE) allows to rotate encryption keys and update ciphertexts via a token without the need to first download the ciphertexts. Although, syntactically, UE is a symmetric-key primitive, ciphertext-independent UE with forward secrecy and post-compromise security is known to imply public-key encryption (Alamati, Montgomery and Patranabis, CRYPTO 2019).


Constructing post-quantum secure UE turns out to be a difficult task. While lattices offer the necessary …

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