Post-quantum electronic signatures: why get ahead of a threat that doesn't exist yet

Electronic signatures today rely on public-key cryptography schemes such as RSA or elliptic curves, whose security depends on how hard it is for a classical computer to solve certain mathematical problems — factoring very large numbers, for instance. A sufficiently powerful quantum computer could solve those same problems in a dramatically shorter time, breaking those schemes.

Post-quantum cryptography refers to a set of algorithms built on different mathematical problems, chosen precisely because, based on current knowledge, they resist both quantum and classical computers. International standardization bodies have already selected and published several of these algorithms, which makes the transition technically possible today.

The urgency doesn't come from quantum computers capable of breaking today's cryptography already existing — they don't, yet. It comes from a quieter risk: data or signatures encrypted today can be intercepted and stored now, to be decrypted later once quantum computing capacity becomes available. For a document meant to remain legally binding for many years, that window of retroactive vulnerability matters starting now, not once the threat becomes tangible.

Organizations that base long-term commitments — contracts, deeds, notarized documents — on electronic signatures have good reason to plan this transition before it becomes a regulatory requirement or a technical emergency, rather than waiting until the threat is concrete to act.