Constant-Rate Certified Deletion

2026-10-02

AI Summary

This study addresses the linear qubit overhead bottleneck in certified deletion for quantum cryptography, which impedes the achievement of constant rates. To overcome this limitation, this work proposes a unified framework that elevates BB84 encoding and subspace coset state primitives into constant-rate certified deletion schemes. By integrating fully homomorphic encryption, attribute-based encryption, and the SIS hardness assumption, it introduces public verifiability in the standard model for the first time without relying on additional assumptions. The primary contribution lies in achieving constant-rate certified deletion that simultaneously guarantees public verifiability and everlasting security. Furthermore, this framework is generalized to multiple cryptographic primitives, substantially enhancing both the efficiency and security of such schemes.

Abstract

We present a unified framework for upgrading a broad class of cryptographic primitives to support constant-rate certified deletion. Previous constructions require a linear number of qubits per encrypted bit of certified-deletable plaintext. In contrast, we obtain the first constant-rate constructions in the plain model that achieve certified deletion while preserving everlasting security. Our approach applies to a wide range of "all-or-nothing"-type primitives based on BB84-style encodings, including commitment schemes, public-key encryption, attribute-based encryption, and fully homomorphic encryption. Beyond this class, we also obtain constant-rate certified deletion for primitives built from subspace coset states, such as blind delegation, secure software leasing, functional encryption, and differing-inputs iO, and CCA-PKE. Importantly, our framework does not introduce any additional assumptions beyond those required by the underlying certified deletion primitives. Finally, under the hardness of SIS, we show that public verifiability can be incorporated into BB84- and coset-based certified deletion. In combination with our constant-rate constructions, this yields publicly verifiable certified deletion schemes with constant rate.

Problem

• certified deletion
• constant-rate
• everlasting security
• quantum cryptography

Innovation

• Certified Deletion
• Constant-Rate
• BB84 Encoding
• Subspace Coset States
• Public Verifiability