It seems the accusations of backdoors in encryption were taken out of context. Chaum describes a system that can provide many of the anonymity benefits of the Tor system in a faster and more efficient (more scalable) way while avoiding some of the abuses and vulnerabilities in Tor's system.
In the paper describing some of the technology in his new system, Chaum writes:
"PrivaTegrity addresses potential abuse of anonymity services by establishing a trust modelthat offers a balance of anonymity and accountability. On the one hand, PrivaTegrity aims to provide privacy at a technicallevel that is not penetrable by nation states.
On the otherhand, PrivaTegrity aims to provide integrity, both prior restraintand accountability after the fact, that is inescapably tied toindividuals. Only if all of the mixing nodes cooperate, can thesenders and receivers of messages be linked or identiﬁed."