2 Accepted Papers at PKC 2023
The paper "GLUE: Generalizing Unbounded Attribute-Based Encryption for Flexible Efficiency Trade-Offs" by Greg Alpár (Open Universiteit, Heerlen and Radboud University, Nijmegen) and Marloes Venema (Bergische Universität Wuppertal) was also accepted to PKC 2023, the 26th IACR International Conference on Practice and Theory of Public-Key Cryptography. This paper introduces GLUE: a family of attribute-based encryption schemes that can support desirable properties such as non-monotonicity -- i.e., the support of negations in the policies -- and provides a flexible efficiency trade-off. In particular, GLUE can be configured to have a much more efficient decryption algorithm than was previously possible for schemes with the same properties.
Furthermore, the paper "Simple, Fast, Efficient, and Tightly-Secure Non-Malleable Non-Interactive Timed Commitments" by Peter Chvojka (IMDEA Software Institute, Madrid) and Tibor Jager (Bergische Universität Wuppertal) was accepted to PKC 2023, the 26th IACR International Conference on Practice and Theory of Public-Key Cryptography.
Abstract:
Timed commitment schemes, introduced by Boneh and Naor (CRYPTO 2000), can be used to achieve fairness in secure computation protocols in a simple and elegant way. The only known non-malleable construction in the standard model is due to Katz, Loss, and Xu (TCC 2020). This construction requires general-purpose zero knowledge proofs with specific properties, and it suffers from an inefficient commitment protocol, which requires the committing party to solve a computationally expensive puzzle.
We propose new constructions of non-malleable non-interactive timed commitments, which combine (an extension of) the Naor-Yung paradigm used to construct IND-CCA secure encryption with a non-interactive ZK proof for a simple algebraic language. This yields much simpler and more efficient non-malleable timed commitments in the standard model.
Furthermore, our constructions also compare favourably to known constructions of timed commitments in the random oracle model, as they achieve several further interesting properties that make the schemes very practical. This includes the possibility of using a homomorphism for the forced opening of multiple commitments in the sense of Malavolta and Thyagarajan (CRYPTO 2019), and they are the first constructions to achieve public verifiability, which seems particularly useful to apply the homomorphism in practical applications.
