The International Organization for Standardization (ISO) has made a significant decision for the entire crypto industry: the Classic McEliece algorithm has been officially included in the asymmetric encryption standard ISO/IEC 18033-2. This is not just a bureaucratic step, but a signal to the market that protection against quantum computers is moving from experimental technology to a practical level.
Why Classic McEliece is not just "another algorithm"
Developed back in 1978 by Robert McEliece, this key encapsulation mechanism fundamentally differs from the familiar RSA and Diffie-Hellman protocol. Instead of factorization or discrete logarithms, it relies on error-correcting codes, specifically binary Goppa codes. Over nearly 50 years of existence, the system has not been broken, making it one of the most conservative and time-tested constructions in post-quantum cryptography.
Key features and application scenarios
The main trade-off of Classic McEliece is the public key size: from 255 KB to 1.3 MB. However, the ciphertext size remains minimal—up to 208 bytes. This makes the algorithm ideal for static scenarios, such as VPN connections or file encryption, where key size is not a critical factor. For example, the British company Post-Quantum has successfully tested the algorithm on combat drones under limited communication conditions, proving its practical viability.
Why ISO, not NIST?
Notably, the US National Institute of Standards and Technology (NIST) previously postponed the standardization of Classic McEliece, favoring the HQC algorithm. However, NIST acknowledged that it might consider adopting a standard based on the ISO version in the future. Meanwhile, the ISO decision has already opened doors for governments and private companies from 177 countries, allowing for more consistent and unified implementation of the method.
Current status and prospects
Classic McEliece is already mentioned in the recommendations of regulators in the Netherlands and Germany. Support for the algorithm has been implemented in projects such as Debian, Ubuntu, and the Bouncy Castle library. This means that the infrastructure for its adoption already exists and is actively developing.
From my perspective, the standardization of Classic McEliece is an important but only a first step. The industry will need to solve the scaling challenge: how to make post-quantum protection accessible to mass users without sacrificing performance. However, the fact that an algorithm developed in the 1970s is becoming an international standard today suggests that in cryptography, time-tested solutions often prove to be the most reliable.