Messenger Apps starting to provide Quantum Secure Communication
The ongoing development of quantum computers endangers currently used cryptographic protocols and makes it necessary to deploy quantum secure encryption. An important step is the integration of quantum secure encryption in widely used messenger apps. As explained in a press release from 21.02.2024, soon also iMessage of Apple will apply quantum secure encryption.
The PQ3 protocol will be used in iMessage for encrypted communication starting with iOS 17.4, iPadOS 17.4, macOS 14.4 and watchOS 10.4. The protocol is based on a hybrid encryption scheme that uses the classical Elliptic Curve Diffie-Hellman (ECDH) protocol in combination with CRYSTALS-Kyber, which is a quantum secure cryptographic primitive based on lattice-based cryptography.
Similarly also the PQXDH protocol which is part of the Signal protocol since end of 2023 and used in the messengers Signal and and WhatsApp is a hybrid encryption scheme based on ECDH and CRYSTALS-Kyber. More details can be found in the blog of Signal about this topic.
These encryption schemes belong to the so-called Post Quantum Cryptography (PQC) and can prevent that messages send today are stored and decoded in the future once suitable quantum computers are available (Harvest Now – Decrypt Later attack). Therefore PQ3 and PQXDH still use classical authentication schemes and only the encryption is quantum secure. An alternative approach for quantum secure communication is Quantum Key Distribution (QKD). Additional information about PQC, QKD and the problems with current cryptographic approaches can be found in the document WiN-Lab Research: PQC versus QKD.