¹ Repudiation in SimpleX Chat will include client-server protocol from v5.7 or v5.8. Currently it is implemented but not enabled yet, as its support requires releasing the relay protocol that breaks backward compatibility.
² Post-quantum cryptography is available in beta version, as opt-in only for direct conversations. See below how it will be rolled-out further.
Some columns are marked with a yellow checkmark:
when messages are padded, but not to a fixed size.
when repudiation does not include client-server connection. In case of Cwtch it appears that the presence of cryptographic signatures compromises repudiation (deniability), but it needs to be clarified.
when 2-factor key exchange is optional (via security code verification).
when post-quantum cryptography is only added to the initial key agreement and does not protect break-in recovery.