Quantum secure communication is a powerful solution to the growing real-world vulnerabilities in today's encryption systems. As quantum computing hardware and algorithms advance, classical cryptographic methods like RSA and ECC are more and more prone to insecurity. In this post, we address some of the most common and critical questions we’re asked about Quantum Secure Communication, particularly through protocols like BBM92.
Can quantum hackers spoof entangled photons?
In a word: no.
Quantum hackers cannot spoof entangled photons because:
- Spoofing would require replicating the exact quantum correlations that only genuine entangled pairs exhibit. These correlations are unique because they violate classical assumptions about reality—something that can be statistically tested through violations of Bell’s inequality—and cannot be reproduced using classical systems or pre-programmed.
- Any attempt to intercept, replicate, or tamper with entangled photons would inevitably disturb their quantum state, making such interference detectable.
In practice, there are potential loopholes in the implementation of these tests that, if not carefully closed, can be exploited to simulate entanglement-like correlations. However, modern quantum communication systems are increasingly designed to close these loopholes, making practical spoofing infeasible.
So while quantum hackers may try to intercept and duplicate quantum states, they cannot truly mimic the unique quantum relationship that defines entangled photons. The laws of quantum physics inherently prevent such spoofing.
Is BBM92 guaranteed to be secure in all circumstances?
Like any protocol, the BBM92 protocol can not be guaranteed secure under any and all circumstances; its security depends also on the quality of its implementation.
BBM92 is secure based on the principles of quantum mechanics. However, practical deployment can sometimes introduce vulnerabilities due to hardware imperfections. For example, detectors with dead time and limited efficiency, calibration errors, or unintended information leakage through side channels can open the door to potential attacks. If the measurement devices are not properly shielded or calibrated, side-channel attacks or detector blinding attacks could be exploited by a sophisticated adversary.
BBM92 offers a high level of theoretical security, but achieving that level of security in practice requires system validation, calibration, and defense against implementation-specific vulnerabilities. When you’re aware of what these vulnerabilities are, you can ensure that the network is protected against them.
What attacks can BBM92 prevent?
BBM92 is designed to prevent a class of attacks targeting classical cryptographic systems that rely on computational hardness to protect communications. Here’s what it defends against effectively:
- Eavesdropping. In BBM92, any attempt by an eavesdropper to measure the photons in transit will disturb their quantum state. This disturbance is detectable through increased error rates in the key verification phase, alerting users to the presence of a problem before sensitive information has been put at risk.
- Man-in-the-Middle attacks. If authentication of classical channels is ensured, BBM92 protects against these attacks by providing tamper-evident channels: any interception or modification of entangled photons is detected almost immediately.
- Attacks that rely on computational assumptions. BBM92 provides information-theoretic security, meaning it doesn’t rely on mathematical problems like factoring or discrete logarithms, which are vulnerable to quantum computers. It prevents attacks such as brute-force key guessing and other quantum-assisted factoring techniques. It also prevents Harvest Now Decrypt Later attacks, where adversaries collect encrypted data to decrypt later when the computational resources to do so are available.
BBM92 offers resilience against computationally-driven vulnerabilities, making it especially valuable in a post-quantum world where those classical assumptions will no longer hold.
How do quantum and classical links work together?
The quantum and classical links work in tandem, with quantum links generating truly random keys and classical links managing their secure transmission and application.
Quantum links are responsible for delivering the entangled quantum states that make up the raw key material. The classical link acts as the control, coordination, and key management channel in a quantum communication system.
How are quantum keys translated into usable outputs?
Quantum key generation protocols like BBM92 generate truly random keys and also alert users when those keys have been compromised before any sensitive information is transmitted. How does this process translate into secure communication in practice?
Once the key bits are verified, they are processed into usable forms: typically segmented into fixed-length blocks (like 256-bit keys) and assigned unique identifiers. These keys can then be integrated into existing encryption infrastructure through protocols like Cisco’s SKIP or ETSI QKD 014, supporting secure applications such as VPN tunnels, IPsec encryption, and dynamic key rotation. While the randomness of quantum-generated keys is important, the real strength of BBM92 lies in its ability to make key theft detectable, and therefore preventable.
Ultimately, the goal of this process is to make Quantum Secure Communication as straightforward and practical as classical key management, empowering network operators and end-users with advanced protection without added complexity.
As quantum technologies mature, securing information against quantum threats is no longer a theoretical exercise, it is a strategic imperative. Protocols such as BBM92 provide a way to use quantum mechanics for stronger communication security to meet this imperative. Effective deployment comes down to thoughtful implementation, robust hardware, and integration with existing systems. Organizations that leverage the expertise of hardware and software partners will be poised for success in building their Quantum Secure Communications networks.
