What this driver does
A Trusted Platform Module is a small, isolated cryptographic processor with its own protected storage. It performs a fixed menu of security operations: generating and storing keys that never leave the chip, hashing boot measurements, and signing attestation statements that prove what code the machine booted. The TPM driver, tpm.sys in Windows, is the transport that carries commands and responses between the OS and that processor over the TPM's command interface. The module comes in three physical forms, and the driver abstracts all of them. A discrete TPM (dTPM) is a dedicated chip soldered to the board or on a header. Intel PTT and AMD fTPM are firmware TPMs, running the same TPM 2.0 command set inside a protected mode of the CPU rather than in separate silicon. To Windows they look alike, because the driver presents one standard interface regardless of the underlying implementation. The module's most-used feature is measured boot. As each stage of the boot chain runs, its hash is extended into a Platform Configuration Register, a PCR, producing a chain of values that uniquely reflects the code path taken. BitLocker seals its volume key to a chosen set of PCRs, so the key is released only when the machine boots the exact configuration it was sealed against, which is what ties disk encryption to boot integrity. The TPM also anchors identity and attestation. It holds an Endorsement Key burned in at manufacture, derives an attestation identity key, and can sign a quote of its PCR state for a remote verifier. Windows uses these for device health attestation and for anti-cheat and enterprise scenarios that demand proof the machine is in a known-good state, all mediated through the same driver.
Observable states associated with this device class
These states describe how hardware, firmware, operating-system services, and a driver can interact. They do not identify a cause on their own.
- BitLocker demands its 48-digit recovery key on every boot even though the disk and hardware are unchanged
- AMD fTPM causes brief, repeating stutters or audio dropouts during gaming or heavy I/O
- Windows 11 setup reports the PC is unsupported because no TPM 2.0 is detected
- The security processor shows a yellow triangle or 'device cannot start' in Device Manager
- An anti-cheat system refuses to launch a game, citing a missing or non-compliant TPM 2.0
- tpm.msc reports the TPM is not ready, or shows a 1.2 module where 2.0 is expected
How it works in a real system
Drivers operate in the background as translators. This setup shows the software, connection, and physical hardware that the TPM driver supports.
Compatibility model
Driver compatibility is defined by the device hardware identifier, the operating-system driver model, processor architecture, and the interfaces implemented by the hardware or firmware. A shared device class does not imply that packages from different manufacturers are interchangeable.