A quantum scheme is proposed which seals a classical string. Each bit of the string can be read out with an arbitrarily small error rate, while reading the string can be detected except with an exponentially small probability.
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 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.