Secure quantum string seal exists

TL;DR

This paper challenges previous claims by demonstrating that imperfect quantum string seals can be unconditionally secure because the measurement method previously thought to compromise security yields trivial information.

Contribution

It shows that imperfect quantum string seals are secure against certain measurements, countering prior assertions of universal insecurity.

Findings

Imperfect quantum string seals can be unconditionally secure.

The measurement proposed in prior work provides only trivial information.

Previous claims of insecurity do not hold for imperfect seals.

Abstract

It was claimed that all quantum string seals are insecure [H. F. Chau, quant-ph/0602099]. However, here it will be shown that for imperfect quantum string seals, the information obtained by the measurement proposed in that reference is trivial. Therefore imperfect quantum string seals can be unconditionally secure.