Internet applications are mostly secured by a combination of symmetric and asymmetric encryption. Asymmetric protocols such as RSA, DSA DHEC, etc. are normally used for key establishment and authentication.
How secure are the existing encryption protocols?
Security of existing protocols can be easily broken when an adequately large and reliable quantum computer is designed and run Shor’s algorithm in it. All traffic can be decrypted without needing its keys by the quantum computer. Even though expert predictions of the timeline of such computers vary perilously; hardware vendors predict such computers to come online within 10 years.
Networks can be secured against quantum computers by using Quantum Key Distribution (QKD) approach. This is one among several methods to secure networks.
What is Quantum Key Distribution (QKD) ?
QKD is a quantum encryption method. It relies on photons to comply on a secret key and protects the key exchange by the laws of physics. QKD is implemented on special purpose networks, QKD networks, specifically built for it. QKD networks normally use reliable intermediate nodes to prolong beyond single hops as quantum states are fragile.
How QKD solves the issue?
QKD relies on the laws of quantum physics to distribute keys for encryption. During communication, two parties use QKD to agree upon a secret key that can be used for standard encryption algorithms like AES. Quantum states are generated from secret key bits and encoded into individual photons. These photons are transmitted over optical fibers or across spaces.
Many different QKD protocols are available, and they rely on a quantum phenomenon called collapse of the wave function. If an intrusion happens to steal the key by monitoring the photons, laws of quantum physics dictate it and the photons will change. Hence the attack will be detected. When an attack is detected, the key won’t be used anymore as it is assumed unsafe.
Classical and quantum computers cannot break QKD protocols, and it is proven mathematically.
Data transmitted over internet today are vulnerable to attacks in future when large-scale quantum computers are developed. However, if we can protect the same data using quantum safe methods, which will make solution secure even after the arrival of more powerful quantum computing.