pub fn sign_message(
identity: &IdentityKeys,
msg: &RoomMessage,
) -> Result<SignedRoomMessage>Expand description
Wrap a RoomMessage into a SignedRoomMessage using the given identity’s
signing key. Mirror of verify_signed; symmetric helper so phase B/F/G/etc.
don’t each open-code the base64 dance.
huddle 0.7.11: also populates signed_at_ms with the current epoch in
milliseconds, and signs over (payload || signed_at_ms) so the receiver’s
replay-window check is signature-bound.