Two Schemes of PrivacyCA with Higher Untraceability

Because the PrivacyCA defined in TCG specification may leak user´s privacy and trace his transactions, two PrivacyCA schemes with higher untraceability are proposed. The agents-based one provides higher untraceability by introducing agents and VK certificates to eliminate the linkage between EK and AIK. By adopting Partially Blind Signature algorithm in the generation of AIK triples, PBS-based one provides absolute untraceability to user´s transactions because the public AIK is blinded while being signed by the PrivacyCA. New schemes keep good compatibility to TCG specification and provide different levels of untraceability to satisfy particular applications.