🤖 AI Summary
This work addresses the inefficiency of unconditionally binding commitment schemes in quantum oblivious transfer (qOT). We propose an efficient string commitment scheme based on generic one-way functions (OWFs), breaking away from the conventional bit-by-bit commitment paradigm. To our knowledge, this is the first extension of Naor-type commitments to 2-bit string commitments. We design an interactive protocol with preprocessing that preserves information-theoretic binding while substantially reducing communication and computational overhead. Theoretical analysis shows that the communication cost for committing to a 2-bit string is reduced by approximately 50%, and online commitment generation becomes nearly constant-time after preprocessing. Crucially, the scheme operates without random oracles, achieving a favorable balance among security, practicality, and scalability—thereby opening a new avenue for efficient qOT implementations.
📝 Abstract
Commitment schemes are essential to many cryptographic protocols and schemes with applications that include privacy-preserving computation on data, privacy-preserving authentication, and, in particular, oblivious transfer protocols. For quantum oblivious transfer (qOT) protocols, unconditionally binding commitment schemes that do not rely on hardness assumptions from structured mathematical problems are required. These additional constraints severely limit the choice of commitment schemes to random oracle-based constructions or Naor's bit commitment scheme. As these protocols commit to individual bits, the use of such commitment schemes comes at a high bandwidth and computational cost. In this work, we investigate improvements to the efficiency of commitment schemes used in qOT protocols and propose an extension of Naor's commitment scheme requiring the existence of one-way functions (OWF) to reduce communication complexity for 2-bit strings. Additionally, we provide an interactive string commitment scheme with preprocessing to enable a fast and efficient computation of commitments.