pub fn export(
threema_id: &[u8],
secret_key: &[u8],
password: &str
) -> Result<String, &'static str>
Exports a threema backup string with a given password.
This uses the process explained in this pdf
to export a threema backup. This can be used to safely store your secret key together with
your Threema identity.
let backup = export(&[0; 8], &[0; 32], "password").unwrap();