Systems and methods are disclosed for privacy-preserving flexible user-selected anonymous and pseudonymous access at a relying party, mediated by an identity provider. The stem has a proximal stem portion and a distal stem portion. The outputs of the transformers are rectified in two rectifiers, respectively, and smoothed in two reactors. The first relay apparatus selects, as a transfer destination of the message, the second information processing apparatus or a second relay apparatus upon receiving the message.