We propose a device-independent prepare-and-measure quantum key distribution (DIPQKD) that the transmitter prepares and sends the qubits to the receiver who de-codes by measuring the qubits. Through characterizing the used channel and ruling out any classical strategies of mimicry, one can identify the security of DIPQKD against collective attacks.
We propose a device-independent prepare-and-measure quantum key distribution (DIPQKD) that the transmitter prepares and sends the qubits to the receiver who de-codes by measuring the qubits. Through characterizing the used channel and ruling out any classical strategies of mimicry, one can identify the security of DIPQKD against collective attacks.
Device-independent quantum key distribution (DIQKD) is a key distribution scheme whose security is based on the laws of quantum physics but does not require any assumptions about the devices used in the protocol. The security of the existing entanglement-based DIQKD protocol relies on the Bell test. Here, we propose an efficient device-independent quantum key distribution (EDIQKD) protocol in which one participant prepares states and transmits them to another participant through a quantum channel to measure. In this prepare-and-measure protocol, the transmission process between participants is characterized according to the process tomography for security, ruling out any mimicry using the classical initial, transmission, and final state. Comparing the minimal number of bits of the raw key to guarantee security against collective attacks, the efficiency of the EDIQKD protocol is two orders of magnitude more than that of the DIQKD protocol for the reliable key of which quantum bit error rate is allowed up to 6.5\%. This advantage will enable participants to substantially conserve the entangled pair's demanded resources and the measurement. According to the highest detection efficiency in the recent most advanced photonic experiment, our protocol can be realized with a non-zero key rate and remains more efficient than usual DIQKD. Our protocol and its security analysis may offer helpful insight into identifying the typical prepare-and-measure quantum information tasks with the device-independent scenario.
Similar to device-independent quantum key distribution (DI-QKD), semi-device-independent quantum key distribution (SDI-QKD) provides secure key distribution without any assumptions about the internal workings of the QKD devices. The only assumption is that the dimension of the Hilbert space is bounded. But SDI-QKD can be implemented in a one-way prepare-and-measure configuration without entanglement compared with DI-QKD. We propose a practical SDI-QKD protocol with four preparation states and three measurement bases by considering the maximal violation of dimension witnesses and specific processes of a QKD protocol. Moreover, we prove the security of the SDI-QKD protocol against collective attacks based on the min-entropy and dimension witnesses. We also show a comparison of the secret key rate between the SDI-QKD protocol and the standard QKD.
We propose a measurement-device-independent Quantum Key Distribution (MDI-QKD) protocol using weak coherent states and entanglement from weak coherent pulses. To overcome the side channel attacks, the sender and the receiver use decoy states to verify the security of the quantum channel. Then, they use uncorrelated entangled pairs to establish a correlated entanglement between them. The protocol establishes entangled communication channel between the sender and the receiver without performing the quantum distillation protocol. The protocol provides protection against side channel attacks such as photon-number-splitting (PNS). During the communication process, each party chooses to prepare a decoy state or a signal state. Then, they send their signals to a third party who performs Bell state measurement and then announces the measurement result. Using the information from the third party, who also could be an attacker, the sender and the receiver analyze the communication channel for any abnormalities. After verifying the security of the communication channel, the sender and the receiver establish the entanglement together for sharing secret keys.
We study a class of receiver-device-independent quantum key distribution protocols based on a prepare-and-measure setup which aims to simplify their implementation. The security of the presented protocols relies on the assumption that the sender, Alice, prepares states that have limited inner-products. Hence, Alice’s device is partially characterized. There is no explicit bound on the Hilbert space dimension required. The receiver’s, Bob’s, device demands no characterization and can be represented as a black-box. The protocols are therefore immune to attacks on Bob’s device, such as blinding attacks. The users can generate a secret key while monitoring the correct functioning of their devices through observed statistics. We report a proof-of-principle demonstration, involving mostly off-the-shelf equipment, as well as a high-efficiency superconducting nanowire detector. A positive key rate is demonstrated over a 4.8 km low-loss optical fiber with finite-key analysis.
While fully device-independent security in (BB84-like) prepare-and-measure quantum key distribution (QKD) is impossible, it can be guaranteed against individual attacks in a semi-device-independent (SDI) scenario, wherein no assumptions are made on the characteristics of the hardware used except for an upper bound on the dimension of the communicated system. Studying security under such minimal assumptions is especially relevant in the context of the recent quantum hacking attacks wherein the eavesdroppers can not only construct the devices used by the communicating parties but are also able to remotely alter their behavior. In this work, we study the security of a SDIQKD protocol based on the prepare-and-measure quantum implementation of a well-known cryptographic primitive, the random access code (RAC). We consider imperfect detectors and establish the critical values of the security parameters (the observed success probability of the RAC and the detection efficiency) required for guaranteeing security against eavesdroppers with and without quantum memory. Furthermore, we suggest a minimal characterization of the preparation device in order to lower the requirements for establishing a secure key.
Every quantum key distribution (QKD) protocol must limit the information available outside the users' laboratories. In device-independent QKD this is essentially the only assumption made on the devices. In a prepare-and-measure setting it cannot be imposed strictly, since the sender's device must emit a signal that depends on her private input. The natural replacement, and a minimal one, is a leakage bound: a bound on how much information about the input leaves the sender's laboratory, through the intended signal or through any side channel. We ask how far this unavoidable requirement can replace a detailed model of the source. We show that this single bound, quantified by the probability of guessing the input from everything the source emits, suffices to prove security against collective attacks. In our analysis, nothing is assumed about the precise form of the emitted states, their dimension, energy or purity, nor about the receiver's measurement device, beyond the standard requirement that it does not leak Bob's data. The standard B92 and BB84 protocols do not certify any key under this minimal leakage bound assumption. But closely related protocols can and, in the ideal limit, achieve one secret bit per key round. For noisy implementations, we compute key rates using semidefinite programming relaxations. Our best protocols tolerate visibilities down to 0.84, corresponding to an 8% quantum bit error rate, compared with the 11% threshold of standard device-dependent BB84.