An explanation of quantum key distribution
In this video, Informa TechTarget managing editor Kate Murray explains how quantum key distribution uses physics principles to create more secure cryptographic keys that classic computing can't hack.
Keep your secret keys secret, with quantum key distribution.
Modern encryption is a critical part of cybersecurity. It relies on powerful mathematical algorithms to scramble the data before it's sent out on a network, or to keep precious data secured while it's at rest on a storage system.
These mathematical algorithms perform their calculations based on a unique code or sequence of characters called a cryptographic key. Not only is data scrambled in accordance with the key, but the key is also needed to reverse the encryption process and unscramble data back into a readable form.
But key distribution and management can pose real problems for encryption. The emergence of quantum computing has opened a vital new field of quantum encryption, which requires the use of quantum key distribution (QKD) technology.
Here, we're going to talk about how quantum key distribution fits in with modern cryptographic and cybersecurity concerns.
The ideas behind quantum key distribution are the same as traditional cryptography: Cryptographic keys are produced and shared between participating parties, allowing encrypted data to be decrypted into a readable form.
But quantum key distribution employs the laws of quantum physics, such as quantum entanglement and the Heisenberg uncertainty principle, instead of classical computations on a traditional computer.
Quantum key distribution is based on several important concepts:
- The first is a shared secret key, which parties can generate, and it is known only to the participants.
- Second, quantum signals are incredibly sensitive and prone to quantum decoherence. This means any attempt to intercept or eavesdrop on quantum signals will cause disruptions that immediately alert participants to intrusion.
- And third, quantum key distribution can use the laws of quantum physics to validate or prove secure communication.
So, what does it take to make a quantum key distribution system?
There are four major parts of a quantum key distribution system.
- A quantum signal source, such as a laser that generates photons.
- A communication medium to carry quantum signals, such as a fiber optic cable.
- Quantum detectors to see and measure the quantum signals arriving through the medium.
- A traditional communication channel -- such as a computing system and network -- and computing devices, for non-quantum tasks such as error correction, key management and reporting.
Here's how the QKD system works.
First, quantum signals are exchanged over a quantum communication channel. For example, single photons might be exchanged over a fiber optic cable.
Second, the quantum states of the quantum signals are encoded, adding random elements into the qubits. For this example, the photons might be polarized a particular way.
Third, the encoded quantum signals are received and measured. These measurements are processed by traditional computers to extract the encrypted data and a raw (or imperfect) key.
Fourth, a key distillation process uses traditional computing to apply error correction and other techniques to refine the raw key into a usable secret key and protect its secrecy.
And finally, any detectable errors in the communication (that indicate potential eavesdropping) alert the recipients and security team of a possible intrusion.
QKD offers a secure and verifiable means of exchanging cryptographic keys over quantum communication channels. But it's worth noting that quantum key distribution systems are considerably more complex to implement and maintain than systems that only use traditional computers and networks.
Distance can also be a factor since QKD can only send keys as far as other quantum signals can be transmitted. This means multiple nodes or repeaters may be needed to carry quantum keys over long distances -- which can introduce security and maintenance problems.
Do you think quantum physics can revolutionize communication security? Why or why not? Share your thoughts in the comments, and remember to like and subscribe, too.
Stephen J. Bigelow, senior technology editor at Informa TechTarget, has more than 30 years of technical writing experience in the PC and technology industry.
Sabrina Polin is a managing editor of video content for the Learning Content team. She plans and develops video content for Informa TechTarget's editorial YouTube channel, Eye on Tech. Previously, Sabrina was a reporter for the Products Content team.