In a secure bit commitment protocol involving only classical physics, A commits either a $0$ or a $1$ to B. If quantum information is used in the protocol, A may be able to commit a state of the form $\ensuremath{\alpha}|0〉+\ensuremath{\beta}|1〉.$ If so, she can also commit mixed states in which the committed bit is entangled with other quantum states under her control. We introduce here a quantum cryptographic primitive, bit commitment with a certificate of classicality (BCCC), which differs from standard bit commitment in that it guarantees that the committed state has a fixed classical value. We show that no unconditionally secure BCCC protocol based on special relativity and quantum theory exists. We also propose complete definitions of security for quantum and relativistic bit commitment.In a secure bit commitment protocol involving only classical physics, A commits either a $0$ or a $1$ to B. If quantum information is used in the protocol, A may be able to commit a state of the form $\ensuremath{\alpha}|0〉+\ensuremath{\beta}|1〉.$ If so, she can also commit mixed states in which the committed bit is entangled with other quantum states under her control. We introduce here a quantum cryptographic primitive, bit commitment with a certificate of classicality (BCCC), which differs from standard bit commitment in that it guarantees that the committed state has a fixed classical value. We show that no unconditionally secure BCCC protocol based on special relativity and quantum theory exists. We also propose complete definitions of security for quantum and relativistic bit commitment.

arXiv:quant-ph/9910087Physical Review AMar 2, 200023 citations

Semi-Counterfactual Quantum Bit Commitment Protocol

Yaqi Song, Li Yang

A semi-counterfactual quantum bit commitment (SCQBC) protocol is presented here for the first time, which makes use of counterfactual property. Similar to a counterfactual quantum key distribution scheme, half-photons are not transmitted through the quantum channel in our proposed protocol. In the SCQBC protocol, Bob, the verification party of the quantum bit commitment (QBC), sends the states while Alice, the commitment party, receives. Since Alice cannot receive all the states and entangle the commit bits with the verifier's registers, it is not subject to Mayers' and Lo-Chau's no-go theorem. In addition, a general bit commitment framework can be extracted from the SCQBC scheme, which opens up a new class of cryptographic protocols in counterfactual cryptography.A semi-counterfactual quantum bit commitment (SCQBC) protocol is presented here for the first time, which makes use of counterfactual property. Similar to a counterfactual quantum key distribution scheme, half-photons are not transmitted through the quantum channel in our proposed protocol. In the SCQBC protocol, Bob, the verification party of the quantum bit commitment (QBC), sends the states while Alice, the commitment party, receives. Since Alice cannot receive all the states and entangle the commit bits with the verifier's registers, it is not subject to Mayers' and Lo-Chau's no-go theorem. In addition, a general bit commitment framework can be extracted from the SCQBC scheme, which opens up a new class of cryptographic protocols in counterfactual cryptography.

Scientific ReportsApr 16, 20201 citation

Quantum Bit Commitment From a Physical Assumption

Louis Salvail

Jan 1, 19988 citations

A brief review on quantum bit commitment

Álvaro J. Almeida, Ricardo Loura, Nikola Paunković +5 more

In classical cryptography, the bit commitment scheme is one of the most important primitives. We review the state of the art of bit commitment protocols, emphasizing its main achievements and applications. Next, we present a practical quantum bit commitment scheme, whose security relies on current technological limitations, such as the lack of long-term stable quantum memories. We demonstrate the feasibility of our practical quantum bit commitment protocol and that it can be securely implemented with nowadays technology.In classical cryptography, the bit commitment scheme is one of the most important primitives. We review the state of the art of bit commitment protocols, emphasizing its main achievements and applications. Next, we present a practical quantum bit commitment scheme, whose security relies on current technological limitations, such as the lack of long-term stable quantum memories. We demonstrate the feasibility of our practical quantum bit commitment protocol and that it can be securely implemented with nowadays technology.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIEAug 22, 20148 citations

In a secure bit commitment protocol involving only classical physics, A commits either a

0

or a

1

to B. If quantum information is used in the protocol, A may be able to commit a state of the form $\ensuremath{\alpha}|0〉+\ensuremath{\beta}|1〉.$ If so, she can also commit mixed states in which the committed bit is entangled with other quantum states under her control. We introduce here a quantum cryptographic primitive, bit commitment with a certificate of classicality (BCCC), which differs from standard bit commitment in that it guarantees that the committed state has a fixed classical value. We show that no unconditionally secure BCCC protocol based on special relativity and quantum theory exists. We also propose complete definitions of security for quantum and relativistic bit commitment.