An Authentication Federation Proxy Which Conceals Attributes and Authorization Policies Each Other

A mechanism for privacy-enhanced authentication and authorization federation is proposed. The mechanism conceals attributes of a user provided by the IdP from the SP, and simultaneously conceals an authorization policy of a service presented by the SP from the IdP. The mechanism is implemented as an authentication federation proxy which works between an IdP and an SP. Attributes of a user is provided to the proxy by the IdP and an authorization policy is presented to the proxy by the SP, but both of the attributes and the authorization policy are scrambled. The proxy can determine whether the given attributes match the policy but it can neither know the detail of attributes nor the policy.

I. Introduction

Authentication infrastructures which have been developed for internal use within an organization like a university or a company are now expected to work together as a social platform for identity federation. Such attempts are actively done in academic organization. There are more than 30 countries where nation-wide academic federation among universities based on SAML (Security Assertion Markup Language) [1] has been established. In Japan, National Institute of Informatics is conducting an international academic federation called GakuNin [2].