Functionalities of the TPM. The TPM has various functionalities from which a distinction can be made. These are Secure storage, Platform measurement and reporting and Platform authentication [30]. Secure storage. One can store data securely by using keys generated by the TPM [10]. The TPM consists of a Hashing engine, RSA key generation, RSA signing and encryption and also a Random number generator which can be used in the generation of keys [30, 2]. Platform measurement and reporting. Platform Configuration Registers (PCR) play a vital role. These are registers in the TPM that can compute hashes or also known as measurements of a component and store it [2]. These measurements can be extended which means that the current PCR value is the accumulation of all the measurements it has stored. The PCR value can be used as an authentication signal by for example assuring the state of a platform to a third party or ensuring data is only accessible to authorised software [30].
