Threema becomes quantum-safe: Partnership with IBM Research

The Swiss messenger Threema is to become quantum-safe. To this end, the company has entered into a partnership with IBM Research, as Threema announced. By securing chats early on, the aim is to ensure that they can only be decrypted to a limited extent retroactively once quantum computers have the necessary number of error-free qubits.

The concern that occupies security researchers is “Harvest Now, Decrypt Later.” Those who “harvest” communication encrypted with today's methods could unlock it later to profit from it. For this reason, messaging services such as Signal and Apple iMessage are among the first to already use post-quantum cryptography. Threema had been left out so far, even though the Swiss place high value on security promises. An analysis by the German Council on Foreign Relations (DGAP) in November 2024 concluded that the messenger is “quantum-unsafe,” similar to WhatsApp, Telegram, and others.

Threema relies on ML-KEM

In the future, the ML-KEM algorithm will be used – a new encryption method that can withstand quantum computers. It was largely developed by IBM researchers and officially certified by the US standardization institute NIST in the summer of 2024. The idea is not to replace the current encryption but to combine it with the new method – a so-called hybrid approach.

Signal relies on “PQXDH” (Post-Quantum Extended Diffie-Hellman) and protects the beginning of a conversation from quantum computers, but after that, encryption continues classically. Apple goes further with PQ3 and regularly renews quantum protection even during ongoing chats – so the connection automatically recovers, even if a key has been compromised. Threema has neither yet but is announcing exactly that with IBM – how profound the implementation will be is still open.

No concrete timetable yet

IBM Research is not a random partner here. The company's cryptographers co-developed two of the three new NIST standards themselves. IBM also operates the so-called “Quantum Safe” program, which supports companies in migrating to quantum-safe infrastructure.

There is no concrete timetable or finished implementation yet. The partnership is currently at the research level. Furthermore, Threema itself is under new management; the financial investor Comitis Capital took over the service only in January 2026.

(mki)