wolfTPM brings TPM Physical Presence and IO Support to Embedded Systems

We see a continuing adoption of wolfTPM and TPM 2.0 modules in IoT and Edge embedded systems. In addition, there is a new trend of adding wolfTPM to safety-critical systems, such as aerospace and medical products. For many years, there was no TPM 2.0 stack designed for baremetal and RTOS systems and wolfTPM changed this.

Today, we can announce that wolfTPM is also the first TPM 2.0 stack to support Physical Presence (PP). This feature allows the user to confirm TPM 2.0 operations by asserting physical input to the TPM chip and increase the level of security assurance for critical operations.

For example, TPM2_Clear is a command that returns the TPM to a factory state, destroying existing primary and storage keys, and can be safeguarded by a PP request. TPM2_Clear is typically used when onboarding a new owner of a system, e.g. second market or internal change of ownership equipment.

PP requests are satisfied by controlling a dedicated I/O pin on the TPM chip and now wolfTPM has the capability to extend the list of commands that require it. This could be used to restrict certain operations. It could also be used in existing designs to replace a mechanical switch previously used for Physical Presence.

Another new feature of wolfTPM is the ability to control extra I/O pins available on TPM modules, such as the STMicroelectronics ST33 TPM 2.0 module. The developer can use a single wolfTPM call to control additional I/O pins and pass physical signals, as sign of security or system events, to other subsystems.


For more information about TPM 2.0 Physical Presence and extra I/O support, please contact us at facts@wolfssl.com