Trusted Computing Platforms: TCPA Technology in Context

Platform Configuration Register (PCR)

A platform configuration register is a storage register that is the same length as an SHA-1 digest. It is used to hold a value that summarizes all the measurement results that were presented to it and the order in which those values were presented to it. This storage register has two advantages: an indefinite number of results can be stored in a single register, and no measurement results need to be discarded to make room for new measurement results. This property is important because, otherwise, there would be an upper limit on the number of measurement results that could be stored. Results cannot just be discarded because this allows an unauthenticated rogue to replace proper results with bogus results, ...