Non-malleability for quantum public-key encryption
This work addresses security challenges in quantum cryptography for researchers and practitioners, representing a foundational extension of classical concepts rather than an incremental improvement.
The authors tackled the problem of extending non-malleability, a key security property for public-key encryption, to quantum settings by overcoming the 'recording barrier' and generalizing comparison-based non-malleability, showing it can be fulfilled. They also explored one-time non-malleability for symmetric-key encryption by defining and relating plaintext and ciphertext variants.
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.