Signal messaging boosts Quantum resistance with new encryption protocol

Signal, the secure and privacy-focused messaging application, has announced the initial phase of quantum resistance enhancement for the Signal Protocol. This includes the modification of the X3DH specification, now termed PQXDH.

The upgrade is a preventive measure against potential future quantum computers, which could potentially be powerful enough to crack existing encryption standards. The Signal Protocol, which is also utilized by WhatsApp, Skype, and Google Messages, currently relies on public-key cryptography; a system not yet threatened by existing quantum computers due to their limited qubit capacity.

However, the potential future development of a quantum computer with sufficient power could enable the computation of a private key from a public key, compromising encrypted messages. To counteract this possibility, new post-quantum cryptosystems have been developed, incorporating one-way functions that cannot be advantageously reversed by a quantum computer.

The latest versions of Signal’s client applications already support the new protocol, which is active for chats initiated after both chat participants have updated to the latest Signal update. In the upcoming months, Signal will disable X3DH for new chats, mandating PQXDH instead. Concurrently, software updates will be released to upgrade existing chats to the new protocol.