We propose a four-qubit quantum key distribution protocol via two Bell states which constitute a transmitted unit from the sender to the receiver in each communication. An encryption here is designed by randomly grouping four qubits of a unit into two new couples, which is a way to increase the possibility of detecting the eavesdropper. Ultimately, the receiver randomly measures this grouped unit with two Bell state measurements. From the comparison of grouping information of these four qubits, we find that the two sides in a valid communication can discover the illegal party in the channel. In the proposed protocol, the receiver measures the unit when he receives it instantly, which is an efficient way to overcome the ultrashort storage time of quantum state.
We propose a four-qubit quantum key distribution protocol via two Bell states which constitute a transmitted unit from the sender to the receiver in each communication. An encryption here is designed by randomly grouping four qubits of a unit into two new couples, which is a way to increase the possibility of detecting the eavesdropper. Ultimately, the receiver randomly measures this grouped unit with two Bell state measurements. From the comparison of grouping information of these four qubits, we find that the two sides in a valid communication can discover the illegal party in the channel. In the proposed protocol, the receiver measures the unit when he receives it instantly, which is an efficient way to overcome the ultrashort storage time of quantum state.
The traditional security system, which depends on asymmetric and symmetric key exchange protocol, is now under threat due to recent developments in quantum computing. In order to generate the safe key without storing the qubit by the sender or recipient trustworthy parties, a unique Quantum Key Distribution (QKD) protocol was presented. Four random classical bits coupled to generate a pair of bell states in any of the places {(1,2,3,4), (1,3,2,4) and (1,4,2,3)}. "n/2" groups were used to generate the raw key while the remaining groups were used to check for Eve. The flying bell states scatter into four separate bell states as a result of Eve's involvement in choosing the incorrect measurement basis, which causes entanglement swapping and its identification during communication. The sender will alter the key in accordance with the receiver's position preference because, in traditional communication, key receiving parties must announce the position information. Under the intercept-measure-resend attack, the trade-off between the key generating rate and disturbance is computed and security is examined. Circuit simulation is demonstrated graphically in IBM Quantum Lab and the proposed protocol is implemented.
A quantum key distribution (QKD) protocol based on constructed nonorthogonal states is proposed. By transmitting the photons from Bell states in random order the sender constructs nonorthogonal states, which can prevent an eavesdropper from extracting the key information. At the destination, the receiver performs Bell measurements and then obtains secure key. Different from previous nonorthogonal-states-based QKD protocols, our protocol exhibits a new feature, that is, the users can also obtain some key bits even when they choose different "bases"! Thus it can reach a higher efficiency in theory. Besides, we present a trade-off between the information that an eavesdropper can elicit and the corresponding error rate he/she would introduce, which shows that our protocol is secure.
Considering the security and efficiency of quantum communication system, one step quantum key distribution protocol based on hyperentangled Bell state is proposed. Every 6 classical bits are divided into a group, which are encoded by single particle and hyperentangled Bell state, the sender Alice sends them to receiver Bob, Bob randomly selects the position of hyperentangled Bell state to measure and detects the existence of eavesdropper Eve by comparing measurement results in his hand and transmitted by Alice. Quantum key distribution protocol based on grouping is proposed to solve the storage problem of quantum information and improve the maneuverability, a security analysis is calculated under the intercept-measure-resend attack which introduce at least an error rate of 46.875%, if Eve wants to get all the information, the probability of detection eavesdropping under the entanglement-measure attack is 93.75%, so it proves that proposed protocol does not need to store the quantum state and asymptotically secure under intercept-measure-resend attack and entanglement-measure attack.
Quantum Key Distribution (QKD) allows two legitimate parties to establish a secret key with informationtheoretic security. However, existing protocols have a very low noise tolerance, limiting their deployment in practical quantum channels with finite resources. We propose a novel QKD protocol based on entanglement swapping that achieves higher noise tolerance and improved key rates. In the proposed protocol, a six-bit symbol is encoded in a six-qubit state formed by randomly grouping the state into three pairs to form three Bell states. The proposed protocol maintains a positive secrecy rate for eavesdropper interception probabilities approaching 100 % under the intercept-and-resend attack model, significantly outperforming existing protocols in the literature.
Quantum cryptography is based on quantum mechanics to guarantee secure communication.It allows two parties to produce a shared random bit string known only to them.These random bits can be used as a key to encrypt and decrypt messages.The most important and unique property of quantum cryptography is the ability of the two communicating users to detect the presence of any third party trying to gain knowledge of the key.It is based on fundamental aspects of quantum mechanics.By using quantum entanglement or quantum super positions and transmitting information in quantum states, a communication system can be implemented which detects eavesdropping.Quantum cryptography is used to produce and distribute a key, not to transmit any message data.This key along with certain encryption algorithm, is used to encrypt (and decrypt) a message, which can then be transmitted over a standard communication channel.This paper concentrates on comparison between classical and quantum cryptography as well as survey on various quantum key distribution protocols used to generate and distribute the key among communicating parties.
An efficient two-step quantum key distribution (QKD) protocol with orthogonal product states in the n ⊗ n ( n ⩾3) Hilbert space is presented. In this protocol, the particles in the orthogonal product states form two particle sequences. The sender, Alice, first sends one sequence to the receiver, Bob. After Bob receives the first particle sequence, Alice and Bob check eavesdropping by measuring a fraction of particles randomly chosen. After ensuring the security of the quantum channel, Alice sends the other particle sequence to Bob. By making an orthogonal measurement on the two particle sequences, Bob can obtain the information of the orthogonal product states sent by Alice. This protocol has many distinct features such as great capacity, high efficiency in that it uses all orthogonal product states in distributing the key except those chosen for checking eavesdroppers.