Modified Six State Cryptographic Protocol with Entangled Ancilla States

Abstract

In a realistic situation, it is very difficult to communicate securely between two distant parties without introducing any disturbances. These disturbances might occur either due to external noise or may be due to the interference of an eavesdropper sitting in between the sender and the receiver. In this work, we probe here the existence of the possibility of the situation of generation of a secret key even if the eavesdropper is able to construct an entangled ancilla state in such a way that she can extract information from the intercepted qubit. To achieve this task, we consider and modify the six-state QKD protocol in which Eve can construct the unitary transformation that may make all ancilla components entangled at the output. Then, we calculate the mutual information between Alice and Bob and Alice and Eve, and identify the region where the secret key is generated even in the presence of Eve. We find that, in general, the mutual information of Alice and Eve depends not only on the disturbance D, but here we have shown that it also depends on the concurrence of the ancilla component states. We have further shown that it is possible to derive the disturbance-free mutual information of Alice and Eve, if Eve manipulates her entangled ancilla state in a particular manner. Thus, in this way, we are able to show that a secret key can be generated between Alice and Bob even if the disturbance is large enough. Moreover, we show that Bruss's six state QKD protocol failed to generate the secret key in the region where the modified six-state QKD protocol can generate the secret key.

10 pages, 2 figures, Accepted in EPJD (2024), Title modified

References in corpus (20)

• Quantum entanglement
• Quantum Cryptography
• The Security of Practical Quantum Key Distribution
• Quantum secret sharing
• Simple Proof of Security of the BB84 Quantum Key Distribution Protocol
• Advances in Quantum Cryptography
• Unconditional Security Of Quantum Key Distribution Over Arbitrarily Long Distances
• Optimal eavesdropping in quantum cryptography with six states
• Quantum cryptography with 3-state systems
• An information-theoretic security proof for QKD protocols
• Optimal eavesdropping in cryptography with three-dimensional quantum states
• Security in Quantum Cryptography
• Fast and simple one-way Quantum Key Distribution
• Lower and upper bounds on the secret key rate for QKD protocols using one--way classical communication
• Quantum-secured blockchain
• Optimal teleportation with a mixed state of two qubits
• Security of two-way quantum key distribution
• Quantum cryptography on noisy channels: quantum versus classical key-agreement protocols
• Optimal eavesdropping on noisy states in quantum key distribution
• Revisiting optimal eavesdropping in quantum cryptography: Optimal interaction is unique up to rotation of the underlying basis

Cited by in corpus (1)

• Condition for the generation of the secret key in a BB84 like quantum key distribution protocol