Non-malleability for quantum public-key encryption

TL;DR

This paper extends the concept of non-malleability to quantum public-key encryption, overcoming key challenges and establishing definitions and relations for quantum and symmetric-key settings.

Contribution

It generalizes classical non-malleability notions to quantum encryption and explores one-time non-malleability for symmetric-key encryption.

Findings

Generalized classical non-malleability to quantum setting

Overcame the 'recording barrier' in quantum non-malleability

Characterized relations between plaintext and ciphertext variants

Abstract

Non-malleability is an important security property for public-key encryption (PKE). Its significance is due to the fundamental unachievability of integrity and authenticity guarantees in this setting, rendering it the strongest integrity-like property achievable using only PKE, without digital signatures. In this work, we generalize this notion to the setting of quantum public-key encryption. Overcoming the notorious "recording barrier" known from generalizing other integrity-like security notions to quantum encryption, we generalize one of the equivalent classical definitions, comparison-based non-malleability, and show how it can be fulfilled. In addition, we explore one-time non-malleability notions for symmetric-key encryption from the literature by defining plaintext and ciphertext variants and by characterizing their relation.