Bit commitment is an essential primitive in quantum cryptography. It is the basic building block of many cryptographic protocols in which it provides security over distrustful parties. This paper proposes a secured quantum two-bit commitment protocol for any two classical bits. The protocol contains two parties - a committer and a receiver - who share both quantum and classical communication channels. The main phases of this protocol are commitment and revealing phases where the concealing and binding conditions are proved in order to accept the commitment message. The proposed framework utilizes different security layers to hide specific quantum states in a superposition alongside trivial one qubit operations. The secured unitary transformations are applied by the two parties to meet the concealing and binding conditions. To verify the success of the proposed protocol, the measured output of the two parties are compared. The protocol operates under the assumption that the two parties might cheat and the possible existence of an eavesdropper.
Bit commitment is an essential primitive in quantum cryptography. It is the basic building block of many cryptographic protocols in which it provides security over distrustful parties. This paper proposes a secured quantum two-bit commitment protocol for any two classical bits. The protocol contains two parties - a committer and a receiver - who share both quantum and classical communication channels. The main phases of this protocol are commitment and revealing phases where the concealing and binding conditions are proved in order to accept the commitment message. The proposed framework utilizes different security layers to hide specific quantum states in a superposition alongside trivial one qubit operations. The secured unitary transformations are applied by the two parties to meet the concealing and binding conditions. To verify the success of the proposed protocol, the measured output of the two parties are compared. The protocol operates under the assumption that the two parties might cheat and the possible existence of an eavesdropper.
Bit commitment is a fundamental cryptographic primitive and a cornerstone for numerous two-party cryptographic protocols, including zero-knowledge proofs. However, it has been proven that unconditionally secure bit commitment, both classical and quantum, is impossible. In this work, we demonstrate that imposing a restriction on the committing party to perform only separable operations enables secure quantum bit-commitment schemes. Specifically, we prove that in any perfectly hiding bit-commitment protocol, an honestly committing party limited to separable operations will be detected with high probability if they attempt to alter their commitment. To illustrate our findings, we present an example protocol.
In quantum bit commitment(QBC),most existed proposals analyze little of communicating an innocent message over noisy quantum channels.These methods are not practical.Based on the information hiding characteristics of quantum steganography,a novel QBC protocal is proposed.An elegant scheme is presented for disguising secret information as quantum noise,and embedding it in stego qubits which encode into a codeword of quantum error-correcting code.The method is proved secure and effective in the presence of noisy quantum channel and it's a potential eavesdropper.The results of theoretical analysis and numerical simulation show that the proposed scheme has perfect concealing and binding properties. Theoretical analysis proved the validity.The method forms a theoretical basis for the promotion and application of quantum cryptographic protocols.
We propose an efficient quantum protocol performing quantum bit commitment, which is a simple cryptographic primitive involved with two parties, called a committer and a verifier. Our protocol is non-interactive, uses no supplemental shared information, and achieves computational concealing and statistical binding under a natural complexity-theoretical assumption. An earlier protocol in the literature relies on the existence of an efficient quantum one-way function. Our protocol, on the contrary, exploits a seemingly weaker assumption on computational difficulty of distinguishing two specific ensembles of reduced quantum states. This assumption is guaranteed by, for example, computational hardness of solving the graph automorphism problem efficiently on a quantum computer.
Abstract Commitment scheme is a fundamental cryptographic primitive that serve as building blocks for many other two-party protocols. In this paper, we propose a novel quantum bit commitment scheme, which is secure and does not require quantum memory. Our scheme processes the quantum information using coherent states and unambiguous state discrimination (USD) measurements, which can be experimentally realized by linear optics and photon detectors. We ensure the unconditionally hiding and binding property by preventing both Alice and Bob from obtaining complete information about the commitment in committing stage, and eliminate the requirement for quantum memory by performing USD measurements and phase shifts immediately after receiving the coherent states.
Quantum Bit Commitment (QBC) is a foundational primitive in quantum cryptography, intended to enable secure commitments with strong information-theoretic guarantees. The protocol described in ‘Unconditionally secure multi-party quantum commitment scheme’, [1] published in Quantum information processing, 2018 Springer, uses coherent-state encoding and claims statistical hiding and computational binding. In this work, we identify a fundamental vulnerability in the hiding property of the protocol. Specifically, we demonstrate that an adversarial receiver applies Hadamard transformation to the incoming states, effectively changing the basis to enhance distinguishability between the two received messages. This linear optical strategy enables partial extraction of message without the use of quantum storage or entangled resources. We formally analyze the structure of the protocol and quantify the information leakage by computing the distinguishability between quantum state ensembles associated with different commitments. Our findings indicate that the protocol fails to maintain statistical hiding under general quantum adversarial models, raising concerns about its applicability in settings requiring strong concealment guarantees.
Constructing oblivious transfer and bit commitment protocols based on chan-nel’s quantum nature to achieve statistical security has always been a basic aspect of quantum cryptography. Here we put forward a scheme to reach this goal. The idea is constructing first a random oblivious transfer (R-OT, an ex-tension of Rabin’s OT) protocol based on non-orthogonal states transmission over a quantum channel, then, as that usually do in modern cryptography, we construct a one-out-of-two oblivious transfer protocol on top of the R-OT protocol. Finally, we present a bit commitment protocol based on the one-out-of-two OT protocol, and show that it is statistically secure both in concealing and binding.