- The app encrypts the message using Signal Protocol, as usual.
- Include the sender certificate and encrypted message in an envelope.
- Encrypt the envelope using the sender and recipient identity keys.
- Without authenticating, send the encrypted envelope to the Signal server along with the recipient's delivery token.
- The message recipient can then decrypt the envelope by validating the identity key to know the sender of the message.
Is Signal able to give out the sender to a data requester, for example the FBI, with the mentioned process of sealing the sender?