The Components of a Trusted Computing Platform
Architecturally, Trusted Computing Platforms are typically platforms modified by the addition of a small amount of extra hardware (roughly equivalent to a smart card chip), extra firmware and extra software, and an enhanced operating system. The fundamental functional alteration is the insertion of a root-of-trust into a platform. (A root-of-trust is a set of unconditionally trusted functions.) But a root-of-trust is not the whole story; commercial factors, political factors, and other requirements must all be addressed.
The Trusted Computing Platform Alliance's version of a Trusted Computing Platform uses the following (to first approximation):
Trusted functions that are typically implemented in a security chip
Symmetric encryption functions and support functions implemented in firmware and software
Modifications to the operating system
The remainder of this tutorial introduces the particular set of critical functions that are present in a TCPA-style Trusted Computing Platform.