  The Trusted Platform Module (TPM) version 2.0 provides a two-phase key
exchange primitive which can be used to implement three widely-standardized
authenticated key exchange protocols: the Full Unified Model, the Full MQV, and
the SM2 key exchange protocols. However, vulnerabilities have been found in all
of these protocols. Fortunately, it seems that the protections offered by TPM
chips can mitigate these vulnerabilities. In this paper, we present a security
model which captures TPM's protections on keys and protocols' computation
environments and in which multiple protocols can be analyzed in a unified way.
Based on the unified security model, we give the first formal security analysis
of the key exchange primitive of TPM 2.0, and the analysis results show that,
with the help of hardware protections of TPM chips, the key exchange primitive
indeed satisfies the well-defined security property of our security model, but
unfortunately under some impractical limiting conditions, which would prevent
the application of the key exchange primitive in real-world networks. To make
TPM 2.0 applicable to real-world networks, we present a revision of the key
exchange primitive of TPM 2.0, which can be secure without the limiting
conditions. We give a rigorous analysis of our revision, and the results show
that our revision achieves not only the basic security property of modern AKE
security models but also some further security properties.
