Verifiable Quantum Encryption and its Practical Applications

Caifen Wang

As more and more electronic transactions are being conducted on the IN TERNET, fair exchange protocol is becoming more and more important. Verifiable e ncryption is introduced as a primitive that can be used to build extremely effic ient fair exchange protocols where the items exchanged represent digital signat ures. In this paper, new verifiable encryption schemes are presented, and based on this scheme, a blinded verifiable encryption is presented. They are advantage ous over previous schemes in that they are more efficient and practical.

Surasak Chiangga, Patrick Zarda, Thomas D. Jennewein +1 more

Baasansuren Bat-Erdene, Yuping Yan, Mohammed B. Alshawki +1 more

Attribute-based encryption (ABE) is an extension scheme of identity-based encryption and public-key encryption. It can achieve fine-grained access control and one-to-many encryption mode, suitable for practical applications. In addition to mathematical proofs, it is essential to verify its security properties using different protocols. This paper proposes two key exchange protocols to securely exchange the user secret keys in ABE. ProVerif is an automated cryptographic protocol verifier that we have used during protocol verification. We specifically aim to protect the confidentiality of the generated keys. The proposed protocols are formally analysed and their security property has been formally proved.

Gorjan Alagic, Anne Broadbent, Bill Fefferman +3 more

ARTUR K. EKERT

Aniket Kate, Pratyay Mukherjee, Hamza Saleem +2 more

We present a new framework for constructing practically efficient publicly verifiable secret sharing (PVSS) with non-interactive dealers , in that the dealer may go offline after sending a single message, and is not involved in the share verification process. We use identity-based encryption (IBE) and commitments as the main ingredients and avoid expensive zero-knowledge proofs. By instantiating them with post-quantum secure schemes, a lattice-based IBE and a hash-based commitment, we obtain our first construction: a post-quantum secure PVSS with non-interactive dealers that outperforms the prior lattice-based practical construction by Gentry et al. [Eurocrypt 2022]. However, to enable the aggregation of PVSS transcripts (which facilitates many additional applications such as secure voting), we propose our second construction by replacing hash-based commitments with Pedersen's homomorphic commitments. While this does not achieve full-fledged post-quantum security (as Pedersen's scheme is not quantum safe), it still provides privacy against a post-quantum adversary. We prove the security of this construction in a new model, which we call long-lasting security. This model guarantees that the protocol is secure in the present (pre-quantum era) while maintaining privacy in the long term (post-quantum era). This new model is of independent interest for constructing efficient schemes that are resilient to the harvest-now-decrypt-later line of attacks. In this model, we propose a blockchain-compatible secure voting scheme using our PVSS scheme. Our PVSS schemes demonstrate practical efficiency: our post-quantum PVSS shares a secret among 1024 receivers in 667 ms and verifies the dealing in < 5 ms, and communicates 4.4MB, overall whereas the state of the art [Gentry et al., Eurocrypt 2022] communicates 251MB and requires 2060s for dealing the secret.