© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

arXiv:quant-ph/0602099 · Physical Review A

Quantum string seal is insecure

H. F. Chau

Published Jan 24, 2007• 8 citations

Abstract

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.

DOI: 10.1103/physreva.75.012327

Related papers

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

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

An information-theoretic security analysis of quantum string sealing

Masaki Nakanishi, Seiichiro Tani, Shigeru Yamashita

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.

•Dec 14, 2007•1 citation

Reply to “Comment on ‘Quantum string seal is insecure’ ”

H. F. Chau

In Phys. Rev. A 76, 056301 (2007), He claimed that the proof in my earlier paper [Phys. Rev. A 75, 012327 (2007)] is insufficient to conclude the insecurity of all quantum string seals because my measurement strategy cannot obtain nontrivial information on the sealed string and escape detection at the same time. Here, I clarify that our disagreement comes from our adoption of two different criteria on the minimum amount of information a quantum string seal can reveal to members of the public. I also point out that He did not follow my measurement strategy correctly.

arXiv:0711.2768•Physical Review A•Nov 16, 2007•4 citations

Quantum Seals

Sudhir Kumar Singh, R. Srikanth

A quantum seal is a way of encoding a message into quantum states, so that anybody may read the message with little error, while authorized verifiers can detect that the seal has been broken. We present a simple extension to the Bechmann–Pasquinucci majority-voting scheme that is impervious to coherent attacks, and further, encompasses sealing quantum messages by means of quantum encryption. The scheme is relatively easy to implement, requiring neither entanglement nor controlled operations during the state preparation, reading or verification stages.

arXiv:quant-ph/0410017•Physica Scripta•Jan 1, 2005•12 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

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.

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.

In Phys. Rev. A 76, 056301 (2007), He claimed that the proof in my earlier paper [Phys. Rev. A 75, 012327 (2007)] is insufficient to conclude the insecurity of all quantum string seals because my measurement strategy cannot obtain nontrivial information on the sealed string and escape detection at the same time. Here, I clarify that our disagreement comes from our adoption of two different criteria on the minimum amount of information a quantum string seal can reveal to members of the public. I also point out that He did not follow my measurement strategy correctly.

A quantum seal is a way of encoding a message into quantum states, so that anybody may read the message with little error, while authorized verifiers can detect that the seal has been broken. We present a simple extension to the Bechmann–Pasquinucci majority-voting scheme that is impervious to coherent attacks, and further, encompasses sealing quantum messages by means of quantum encryption. The scheme is relatively easy to implement, requiring neither entanglement nor controlled operations during the state preparation, reading or verification stages.