  Authentication proxies, which store users' secret credentials and submit them
to servers on their behalf, offer benefits with respect to security of the
authentication and usability of credential management. However, as being a
service that is not in control of users, one important problem they suffer is
the trust problem; how users trust that their secrets are handled securely in
the proxy and not revealed to third parties. In this paper, we present a
solution called Trust-in-the-Middle, a TPM based proxy system which ensures
that user credentials are securely stored and submitted without disclosing them
even if the proxy is compromised. We build our architecture on a trust chain
bootstrapped by TPM DRTM and prevent access to credentials if any entity in the
chain is maliciously modified. We use remote attestation to guarantee that all
critical operations on the proxy are performed securely and credentials are
cryptographically protected when they are not in DRTM-supported isolation.
