Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

An information-theoretic security analysis of quantum string sealing

Masaki Nakanishi, Seiichiro Tani, Shigeru Yamashita

Published Dec 14, 2007• 1 citation
OpenAlex

Abstract

Abstract: A quantum sealing protocol is a quantum cryptographic protocol that can detect unsealing of a message. It is known that quantum bit sealing is insecure. However, this does not imply that quantum string sealing is also insecure. So the possibility of quantum string sealing has been studied. In this paper, we propose a quantum sealing protocol and give an information theoretic analysis. We also show that our protocol is almost optimal for uniformly distributed inputs in the sense that the upper bound of information leaks almost matches the trivial lower bound.

Related papers

Quantum string seal is insecure

H. F. Chau

A quantum string seal encodes the value of a (bit) string as a quantum state in such a way that everyone can extract a non-negligible amount of available information on the string by a suitable measurement. Moreover, such measurement must disturb the quantum state and is likely to be detected by an authorized verifier. In this way, the intactness of the encoded quantum state plays the role of a wax seal in the digital world. Here we analyze the security of quantum string seal by studying the information disturbance trade-off of a measurement. This information disturbance trade-off analysis extends the earlier results of Bechamann-Pasquinucci, D'Ariano, and Macchiavello [Int. J. Quant. Inform. 3, 435 (2005)] and Chau [Phys. Lett. A 354, 31 (2006)] by concluding that all quantum string seals are insecure. Specifically, we find a way to obtain nontrivial available information on the string that escapes the verifier's detection with at least 50% chance.

arXiv:quant-ph/0602099•Physical Review A•Jan 24, 2007•8 citations

QUANTUM BIT STRING SEALING

Guang Ping He

Though it was proven that secure quantum sealing of a single classical bit is impossible in principle, here we propose an unconditionally secure quantum sealing protocol which seals a classical bit string. Any reader can obtain each bit of the sealed string with an arbitrarily small error rate, while reading the string is detectable. The protocol is simple and easy to implement. The possibility of using this protocol to seal a single bit in practice is also briefly discussed.

arXiv:quant-ph/0502091•International Journal of Quantum Information•Aug 1, 2006•9 citations

Secure quantum string seal exists

Guang Ping He

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.

arXiv:quant-ph/0602159•Feb 18, 2006•3 citations

Comment on “Quantum string seal is insecure”

Guang Ping He

An attack strategy was recently proposed by Chau [Phys. Rev. A 75, 012327 (2007)], which was claimed to be able to break all quantum string seal protocols. Here it will be shown that the attack cannot obtain nontrivial information and escape the detection simultaneously in a class of quantum string seal, including the one proposed by He [Int. J. Quantum Inf. 4, 677 (2006)]. Thus it is insufficient to conclude that all quantum string seals are insecure.

arXiv:quant-ph/0612071•Physical Review A•Nov 16, 2007•5 citations

Upper bounds of a class of imperfect quantum sealing protocols

Guang-Ping He

The model of the quantum protocols sealing a classical bit is studied. It is shown that there exist upper bounds on its security. For any protocol where the bit can be read correctly with the probability $\ensuremath{\alpha}$, and reading the bit can be detected with the probability $\ensuremath{\beta}$, the upper bounds are $\ensuremath{\beta}\ensuremath{\leqslant}1∕2$ and $\ensuremath{\alpha}+\ensuremath{\beta}\ensuremath{\leqslant}9∕8$.

arXiv:quant-ph/0502179•Physical Review A•May 31, 2005•10 citations

Security of quantum bit-string generation

Jonathan Barrett, Serge Massar

We consider the cryptographic task of bit-string generation. This is a generalization of coin tossing in which two mistrustful parties wish to generate a string of random bits such that an honest party can be sure that the other cannot have biased the string too much. We consider a quantum protocol for this task, originally introduced in Phys. Rev. A 69, 022322 (2004), that is feasible with present day technology. We introduce security conditions based on the average bias of the bits and the Shannon entropy of the string. For each, we prove rigorous security bounds for this protocol in both noiseless and noisy conditions under the most general attacks allowed by quantum mechanics. Roughly speaking, in the absence of noise, a cheater can only bias significantly a vanishing fraction of the bits, whereas in the presence of noise, a cheater can bias a constant fraction, with this fraction depending quantitatively on the level of noise. We also discuss classical protocols for the same task, deriving upper bounds on how well a classical protocol can perform. This enables the determination of how much noise the quantum protocol can tolerate while still outperforming classical protocols. We raise several conjectures concerning both quantum and classical possibilities for large $n$ cryptography. An experiment corresponding to the scheme analyzed in this paper has been performed and is reported elsewhere.

arXiv:quant-ph/0408120•Physical Review A•Nov 11, 2004•16 citations
Abstract: A quantum sealing protocol is a quantum cryptographic protocol that can detect unsealing of a message. It is known that quantum bit sealing is insecure. However, this does not imply that quantum string sealing is also insecure. So the possibility of quantum string sealing has been studied. In this paper, we propose a quantum sealing protocol and give an information theoretic analysis. We also show that our protocol is almost optimal for uniformly distributed inputs in the sense that the upper bound of information leaks almost matches the trivial lower bound.
A quantum string seal encodes the value of a (bit) string as a quantum state in such a way that everyone can extract a non-negligible amount of available information on the string by a suitable measurement. Moreover, such measurement must disturb the quantum state and is likely to be detected by an authorized verifier. In this way, the intactness of the encoded quantum state plays the role of a wax seal in the digital world. Here we analyze the security of quantum string seal by studying the information disturbance trade-off of a measurement. This information disturbance trade-off analysis extends the earlier results of Bechamann-Pasquinucci, D'Ariano, and Macchiavello [Int. J. Quant. Inform. 3, 435 (2005)] and Chau [Phys. Lett. A 354, 31 (2006)] by concluding that all quantum string seals are insecure. Specifically, we find a way to obtain nontrivial available information on the string that escapes the verifier's detection with at least 50% chance.
The model of the quantum protocols sealing a classical bit is studied. It is shown that there exist upper bounds on its security. For any protocol where the bit can be read correctly with the probability $\ensuremath{\alpha}$, and reading the bit can be detected with the probability $\ensuremath{\beta}$, the upper bounds are $\ensuremath{\beta}\ensuremath{\leqslant}1∕2$ and $\ensuremath{\alpha}+\ensuremath{\beta}\ensuremath{\leqslant}9∕8$.
We consider the cryptographic task of bit-string generation. This is a generalization of coin tossing in which two mistrustful parties wish to generate a string of random bits such that an honest party can be sure that the other cannot have biased the string too much. We consider a quantum protocol for this task, originally introduced in Phys. Rev. A 69, 022322 (2004), that is feasible with present day technology. We introduce security conditions based on the average bias of the bits and the Shannon entropy of the string. For each, we prove rigorous security bounds for this protocol in both noiseless and noisy conditions under the most general attacks allowed by quantum mechanics. Roughly speaking, in the absence of noise, a cheater can only bias significantly a vanishing fraction of the bits, whereas in the presence of noise, a cheater can bias a constant fraction, with this fraction depending quantitatively on the level of noise. We also discuss classical protocols for the same task, deriving upper bounds on how well a classical protocol can perform. This enables the determination of how much noise the quantum protocol can tolerate while still outperforming classical protocols. We raise several conjectures concerning both quantum and classical possibilities for large nnn cryptography. An experiment corresponding to the scheme analyzed in this paper has been performed and is reported elsewhere.