To prevent a key from being checked out, then copied, the key is fingerprinted with various pieces of system information. These fingerprint values are later checked to make sure that the system currently running is largely the same as it was before. Some changes are allowed, in case the user needs to update parts of their hardware (memory, disk, etc). Some of the parameters (listed in the next section) are not appropriate for all platforms. The selection of platform parameters is dependent upon the actual tamper resistance detection implementation.