How to Bypass Two Anonymity Revocation Schemes

In recent years, there have been several proposals for anonymous communication systems that provide intentional weaknesses to allow anonymity to be circumvented in special cases. These anonymity revocation schemes attempt to retain the properties of strong anonymity systems while granting a special class of people the ability to selectively break through their protections. We evaluate the two dominant classes of anonymity revocation systems, and identify fundamental flaws in their architecture, leading to a failure to ensure proper anonymity revocation, as well as introducing additional weaknesses for users not targeted for anonymity revocation.