Patent attributes
Disclosed systems and methods implement a tracking system that tracks accesses to a TPM-secured key. In embodiments, the key may be encrypted using an encryption key, which is sealed using the TPM. A first value indicating an initial access state of the key is stored in a PCR of the TPM, and the encryption key is sealed against the PCR, so that it can be unsealed when contents of PCR match a next value derived from the first value. When the key is accessed, contents of the PCR is verified against an expected access state. If successfully verified, the PCR is extended hold the next value, the encryption key is unsealed, and the key decrypted. With each access, the encryption key is repeatedly resealed against the successive states stored in PCR. In this manner, the PCR may be used to track accesses and detect unauthorized accesses to the key.
