The Quantum Computing Threat (2024)

Quantum computers (QCs) are essentially the next generation of supercomputing platforms. QCs use the laws of quantum mechanics to vastly decrease the amount of time it takes to process data and run algorithms, including algorithms that can break classical decryption. Operations that would take a classical computer hundreds or thousands of years to process take seconds or even microseconds for a QC. Instead of being based on classical bits (zeros and ones) that increase a supercomputer's power linearly, QCs use qubits, which are based on polarized photons (light) and increase a QC's processing power exponentially.

There are several ways to create qubits and the method affects qubit quality—the efficiency of the qubits. The higher the quality of the qubits, the faster and more effective the QC. Because of their quantum nature, a qubit represents two states at one time and those states can be replicated across great distances. This is due to the quantum effects of superpositioning and entanglement:

There are three types of QCs:

QCs create a multi-dimensional space comprised of many entangled qubits in which to solve complex problems. For example, classical computers take each element of a database, process it, and then combine it with other elements after processing all the elements. QCs create an algorithm that solves for every state and outcome you're looking for. They pass the entire database through the algorithm simultaneously, analyzing the data for every outcome simultaneously. This makes QCs potentially millions of times faster than classical computers and is one reason they are excellent at solving complex mathematical problems such as breaking encryption.

The vastly increased processing power and speed of QCs threaten to break classical methods for encrypting data, which could compromise your public key infrastructure (PKI).

The most immediate threat is Harvest Now, Decrypt Later attacks that steal your encrypted data with the intention of using a CRQC to decrypt it in the future. Once attackers steal your data and classical key material, there's no way to stop them from decrypting the data in the future using a CRQC. If the stolen data is still valid at that time, it is compromised.

Classical asymmetric encryption is based on prime numbers and relies on the difficulty of factoring complex numbers to derive those prime numbers. A quantum algorithm called Shor's algorithm can factor complex numbers and solve discrete logarithm problems. Shor's algorithm threatens PKI security, which is based on two very large prime numbers to produce the key. However, Shor's algorithm can't break PKI security in less than millions of years using a classical computer. Without CRQCs, Shor's algorithm wasn't a threat. However, given the processing power of a CRQC, Shor's algorithm can factor complex numbers and crack classical asymmetrical encryption (such as the key exchange material needed to decrypt data) in seconds or less. This is why Harvest Now, Decrypt Later attacks are an immediate threat.

The consequences of breaking classical encryption include compromising the security of classical PKI cryptographies that were thought to be secure, such as Diffie-Hellman (DH), Elliptic Curve Cryptography (ECC), and Elliptic Curve Diffie-Hellman (ECDH). The key exchange is at greatest risk and is why you need to configure post-quantum IKEv2 VPNs to secure the key exchange.

Certificates have been the foundation of how two endpoints establish trust. However, CRQCs can also compromise RSA, which is used to create and secure digital certificates. This means that attackers can steal or impersonate digital signatures with a CRQC, so the server you think you're connecting to might actually be an attacker's server. The ability to do this might come as soon as the next decade.

In addition, the sheer brute force processing power of QCs means that symmetric encryption isn't safe either. Grover's algorithm is a quantum, quadratically accelerated unstructured search algorithm that finds the unique input that produces a particular output value. Grover's algorithm targets symmetric cryptography and hash functions. It essentially halves the crypto strength of AES algorithms, so if you use AES-128 bit encryption, Grover's algorithm drops it to the crypto strength of 64-bit encryption. Because classical computers don't have anywhere near enough processing power, they can't use Grover's algorithm to break symmetric encryption. However, using a QC, Grover's algorithm can break AES-128 bit encryption.

Post-quantum cryptographies (PQCs) are available today and most security-savvy people can download and set up PQCs, which can't be decrypted. If you allow unauthorized PQCs on your network, an internal bad actor could introduce PQCs into your network. If that happens, you have no visibility into traffic that uses a PQC and no visibility into threats in that traffic. Use Decryption features to detect unauthorized PQCs on your network and automatically block traffic that uses PQCs.

Take these actions now to resist post-quantum Harvest Now, Decrypt Later attacks. Review your VPN connections and harden them:

In addition, review your SSL/TLS connections and harden them: