Is This the End of Asymmetric Cryptography?

Asymmetric cryptography, also known as public key cryptography, is an essential tool for secure communication in the digital world. It allows two parties to create a shared symmetric key by using a pair of complementary keys (an openly shared public key and a secret key) without having to pass it over an insecure channel.

Let’s examine how this paradigm is likely to shift due to the latest developments from an applied physics direction.

Though quantum entanglement caught the spotlight when it won the Nobel Prize in Physics 2022, this phenomenon has long been researched and is now starting to realize its practical applications.

Quantum entanglement networks is a new technology that promises to revolutionize secure communication. Two parties can generate a shared secret key — a mechanism known as quantum key distribution — by exploiting the phenomenon of quantum entanglement. It occurs when two or more particles correlate in such a way that their properties become inseparable, even if the particles are separated by large distances.

Enter Quantum Key Distribution

One practical way of generating entangled particles is by encoding quantum bits into photons of light and shooting these photons through a nonlinear crystal. Fiber links transmit these entangled photons to two distant recipients who read the same values, essentially making it a shared key. Or, in more technical terms, quantum correlations between these qubits can generate cryptographic keys that are secure against eavesdropping based on the laws of physics: the qubits remain entangled if their state isn’t observed.

In other words, eavesdropping isn’t possible because the eavesdropper would have to observe the state of the qubits, thus breaking the entanglement and causing error rates in the application to spike. This is also why it is not possible to have regular fiber amplifiers, which would observe the state of the qubits.

Handling photon loss because of fiber link length still poses a challenge to nodes situated at a long distance, but the industry is actively working to mitigate this challenge. You can find some details on this here.

This new alternative to classical key exchange has several advantages over traditional asymmetric cryptography:

• It is not vulnerable to the same mathematical attacks or simply poor implementation that threaten classical algorithms.
• One can generate the shared key faster, allowing for more efficient communication while having a guarantee it was not eavesdropped.
• In situations that require a long-lived encrypted tunnel (e.g., VPN), key exchanges typically occur at predefined time periods — or based on the amount of data exchanged. For such situations, one can potentially use shared keys for smaller chunks of data rather than slow and compute-intensive classic asymmetric key exchange.

How Quantum Entanglement Will Revolutionize Key Exchange

Overall, the emergence of quantum entanglement networks is likely to lead to the gradual demise of traditional asymmetric cryptography. It will start with backend-to-backend communication between remote sites and eventually make it to desktops and phones. It may even replace the key exchange of TLS because quantum computers are likely to break all existing asymmetric ciphers.

While this may require some adjustments in the way we approach secure communication, the benefits of this new technology are undeniable. It is exciting to see how this is going to play out.