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A Time-and-Times-Limited Strong Direct Anonymous Attestation Scheme

Direct Anonymous Attestation (DAA) has been adopted in Trusted Platform Module v 1.2 (TPM v1.2) Specification, described by Trusted Computing Group (TCG). It intends to solve the trusted platform attestation and the platform privacy protection. In DAA, the certificate can be used repeatedly and this will provide the opportunities for rogue TPMs to initiate the replay attacks. For identifying the rogue platform, DAA cannot but use a relatively fixed pseudonym rather than a random pseudonym, which would badly weaken the anonymity of the platform. To tackle this problem, a time-and-times-limited strong DAA (TTLS-DAA) scheme, which extends DAA by adding valid period of time and restriction of times into the certificate, is put forward. Since the pseudonym of the user platform is different for each attestation, TTLS-DAA provides stronger anonymity. Being able to control the use of the certificate, it can be widely used in practice especially in commercial fields.