Quantum Key Distribution (QKD) is a method of securely distributing encryption keys between two parties (typically called Alice and Bob) by leveraging the principles of quantum mechanics, such as the no-cloning theorem and the disturbance caused by measurement. The most well-known QKD protocol is BB84, which ensures that any eavesdropping attempt (e.g., by an attacker named Eve) can be detected due to the inherent properties of quantum states.
Key Generation:
Alice sends a series of quantum bits (qubits) to Bob over a quantum channel (e.g., fiber optics or free space). Each qubit is prepared in one of two bases (rectilinear or diagonal) with random polarization states. Bob measures the qubits using a randomly chosen basis.
Key Sifting:
Alice and Bob publicly compare their chosen bases (but not the actual bit values). They keep only the bits where their bases matched, forming a raw key.
Error Checking:
They compare a subset of the raw key to estimate the error rate. If the error rate is too high (indicating possible eavesdropping), they abort the process.
Privacy Amplification:
If the error rate is acceptable, they apply classical algorithms to distill a shorter, secure final key with reduced information leakage.
Encryption:
The final shared key is used for symmetric encryption (e.g., AES) to protect terminal communications.
Suppose Alice wants to send a confidential message to Bob. They use QKD to generate a shared secret key. Alice encrypts her message with this key (e.g., using AES-256) and sends it over a public channel. Only Bob, who has the same key, can decrypt it. Any attempt by Eve to intercept the qubits during QKD will introduce detectable errors.
For enterprises or critical infrastructure, integrating QKD with existing networks requires specialized hardware (e.g., quantum light sources and detectors). Cloud providers like Tencent Cloud offer quantum-safe solutions, including hybrid encryption services that combine QKD with post-quantum cryptography to future-proof communications. Tencent Cloud’s infrastructure also supports secure key management and quantum-resistant algorithms for terminals.
By using QKD, terminal communications achieve unconditional security based on physical laws, ensuring confidentiality even against quantum computing threats.