Quantum Computing and the Future of Encryption

Widely used public-key schemes such as RSA, Elliptic Curve Cryptography (ECC), and Diffie-Hellman depend on mathematical assumptions that are computationally infeasible for classical computers to break. However, a sufficiently powerful quantum computer running Shor’s algorithm would be capable of solving these problems in practical timeframes, effectively undermining the security of these encryption methods. Shor’s algorithm is a complex program that uses quantum mechanics to find the periodicity of a function in relation to the number being factored, which allows it to operate much more quickly and efficiently than classical algorithms. A successful compromise of public-key encryption would allow attackers to read protected communications and create fraudulent digital signatures.

While symmetric algorithms such as AES aren’t immune to quantum attacks, they do perform better. Through the use of Grover’s algorithm, quantum computers could accelerate brute-force key searches, reducing the security margin provided by symmetric key lengths. Grover’s algorithm uses superposition to quadratically speedup the amount of time it takes to solve different problems. Instead of checking variables one by one to reach a solution it can process them all at once, leading to it being much more efficient. Although symmetric encryption remains viable, preserving its effectiveness over time will require increased key lengths and updated implementation strategies.

Encryption in transit safeguards data while it is being transmitted across networks, such as during web browsing or email communication. This security mainly uses asymmetric key exchanges, which quantum computing is able to take advantage of. Protocols such as TLS rely on asymmetric key exchanges to establish shared session keys, after which symmetric encryption is used for data transfer. If a quantum computer successfully breaks the initial key change, all of the session traffic could be exposed. Encryption at rest protects stored data (data on servers, laptops, the cloud, etc.). It often uses symmetric encryption for the bulk data and public-key methods to protect the keys. An additional concern is that attackers may collect encrypted data now with the intention of decrypting it in the future once quantum capabilities mature, posing a risk to things such as medical records, intellectual property, classified government documents, and more.

In response to these threats, researchers are developing post-quantum cryptographic algorithms designed to remain secure even in the presence of quantum threats. The National Institute of Standards and Technology (NIST) has begun standardizing quantum-resistant algorithms intended to replace existing vulnerable public-key schemes. Many companies are taking hybrid approaches that combine existing cryptography with quantum-safe alternatives. These defenses must be implemented proactively, before quantum computing capabilities reach a level that makes current vulnerabilities exploitable. Some actions to help improve security as the threat landscape changes are planning and testing migration paths to PQC standards, understanding where quantum-vulnerable algorithms are used, and using hybrid cryptographic solutions. Current solutions being implemented are PQC (post-quantum cryptography) and hybrid methods mixing traditional algorithms, such as X25519, with newer post-quantum algorithms such as ML-KEM, which protects data from both traditional attacks and quantum attacks by combining both types of security systems. Some challenges with implementing the hybrid algorithms are that they take up a lot more power and resources and they make room for more opportunity for bugs or flaws in code due to them being two algorithms in one instead of just one algorithm by itself. Additionally, a large amount of the hardware currently being used isn’t suitable for PQC integration.

While quantum computing can bring about a lot of positive change, it also threatens vulnerabilities in modern cryptography. By being educated on quantum threats and making proper adjustments to account for them, data can be kept protected and secure.