Germany's BSI advises against Classic McEliece for new systems
23 JANUARY 2026, BONN
Germany's Federal Office for Information Security, the BSI, advised against using Classic McEliece in new systems in the January 2026 update to its Technical Guideline TR-02102-1. The agency cited progress in cryptanalysis as the reason and framed the advice as precautionary. It does not declare the algorithm broken; it steers new systems toward other options as a matter of caution.
The distinction matters. A precautionary warning reflects the BSI's judgment that cryptanalytic progress warrants caution, not a demonstrated break of the scheme. For organizations, that means the guidance shapes forward-looking choices for new systems rather than forcing an emergency replacement of existing ones.
The episode illustrates why crypto agility matters. Guidance about specific algorithms changes as cryptanalysis advances, and an organization that hard-codes one algorithm into its systems must re-engineer them when advice shifts. A system built to swap algorithms can absorb a change like this with far less effort, which is the practical lesson behind the BSI's update.
Why it matters. The BSI's advice shows that even post-quantum candidates are subject to ongoing scrutiny, and that national agencies will update their recommendations as cryptanalysis progresses. Organizations should read it as a reminder to favour mainstream, well-supported algorithms for new systems and to build crypto agility so that future guidance changes cost less. The precautionary framing means existing Classic McEliece uses need review, not panic.