In a recent paper, Lo and Chau explain how to break a family of quantum bit commitment schemes, and they claim that their attack applies to the 1993 protocol of Brassard, Crépeau, Jozsa and Langlois (BCJL). The intuition behind their attack is correct, and indeed they expose a weakness common to all proposals of a certain kind, but the BCJL protocol does not fall in this category. Nevertheless, it is true that the BCJL protocol is insecure, but the required attack and proof are more subtle. Here we provide the first complete proof that the BCJL protocol is insecure.
We propose a framework of bit commitment protocol using a comparison scheme and present a compound comparison scheme based on counterfactual cryptography. Finally, we propose a counterfactual quantum bit commitment protocol. In security analysis, we give the proper security parameters for counterfactual quantum bit commitment and prove that intercept attack and intercept/resend attack are ineffective attack for our protocol. In addition, we explain that counterfactual quantum bit commitment protocol cannot be attacked with no-go theorem attack by current technology.
We propose here a two-round relativistic bit commitment scheme where committer commits in the first round and then confirms his/her commitment in the second round. The scheme offers indefinite commitment time where both committer and receiver extract non-locally correlated measurement outcomes during the scheme that can be stored and revealed after arbitrarily long time. We show that the proposed scheme turns out to be a multiparty bit commitment scheme where both parties commit and reveal simultaneously. The multiparty generalization would have applications in business and secure multiparty c…
We propose a practical quantum oblivious transfer and a bit commitment protocols which replace the single-photon source with weak coherent pulses and allow error and loss in channel and detectors. These protocols can be realized with available optoelectronic apparatus.
The aim of this thesis project is to investigate the bit commitment protocol in the framework of operational probabilistic theories. In particular a careful study is carried on the feasibility of bit commitment in the non-local boxes theory. New aspects of the theory are also presented.
Non-Interactive Statistically-Hiding Quantum Bit Commitment from Any Quantum One-Way Function
本文提出了一种非交互式的量子比特承诺方案，该方案对任何量子单向函数都具有隐藏性和计算绑定性。我们的协议基本上是以前的非交互式量子比特承诺计划（基于量子单向排列，由于Dumais，Mayer和Salvail（EUROWALPT 2000））与成对独立的散列函数的并行组合。为了从任意量子单向函数构造非交互量子比特承诺方案，我们遵循以下步骤：（i）从Dumais-Mayer-Salvail方案到弱隐藏和二选一绑定承诺（ii）从弱隐藏和2选1绑定承诺到强隐藏和2选1绑定承诺;（iii）从强隐藏和二选一约束承诺到正常隐藏承诺。在经典的情况下，可以使用自动隐藏比特承诺方案（Haitner，Nguyen，Ong，Reingold和Vadhan（SIAM J. Comput.，Vol.39，2009））也可以从任何单向函数构造。虽然经典的隐藏比特承诺具有较大的轮复杂度，但我们的量子方案是非交互的，这比经典方案更有优势。一个主要的技术贡献是提供了一个量子模拟的新的互动哈希定理，由于海特纳和Reingold（CCC 2007）。此外，并行组合使我们能够大大简化安全分析。
We proposed a new quantum bit commitment scheme in which secret key need not to be provided by other quantum key distribution system. We can get the bit commitment with probability p by adding a waiting time in a frame during operating the BB84 protocol. Then the measurement outcomes can be encrypted by one-time pad with the key generated by BB84 protocol. We can also obtain the redundant secret keys to encrypt other information in this quantum key distribution system.
We introduce a new setting for two-party cryptography with temporarily trusted third parties. In addition to Alice and Bob in this setting, there are additional third parties, which Alice and Bob both trust to be honest during the protocol. However, once the protocol concludes, there is no guarantee over the behaviour of these third parties. It is possible that they collaborate and act adversarially. Our goal is to use these third parties to facilitate protocols which are impossible in two-party cryptography. We implement a variant of bit commitment in this setting, which we call erasable bit …
Bit-commitment is a fundamental cryptographic task, in which Alice commits a bit to Bob such that she cannot later change the value of the bit, while, simultaneously, the bit is hidden from Bob. It is known that ideal bit-commitment is impossible within quantum theory. In this work, we show that it is also impossible in generalised probabilistic theories (under a small set of assumptions) by presenting a quantitative trade-off between Alice's and Bob's cheating probabilities. Our proof relies crucially on a formulation of cheating strategies as cone programs, a natural generalisation of semide…
Bit commitment is a fundamental cryptographic primitive in which Alice wishes to commit a secret bit to Bob. Perfectly secure bit commitment between two mistrustful parties is impossible through asynchronous exchange of quantum information. Perfect security is however possible when Alice and Bob each split into several agents exchanging classical information at times and locations suitably chosen to satisfy specific relativistic constraints. In this Letter we first revisit a previously proposed scheme that realizes bit commitment using only classical communication. We prove that the protocol i…
