descriptorBase64OrNull  
  Produces the base 64 descriptor string for this AuthKey.Private in the form of {address-w/o-.onion}:descriptor:{algorithm}:{base-64}, or null if isDestroyed is true.
Produces the base 64 descriptor string for this AuthKey.Private in the form of {address-w/o-.onion}:descriptor:{algorithm}:{base-64}, or null if isDestroyed is true.