Today’s PCs are locked up with Trusted Platform Module (TPM) devices so much so that modern Windows versions insist on having a recent TPM to even install. These have become so prevalent that even larger embedded boards now have TPM and, of course, if you are repurposing consumer hardware, you’ll have to deal with it, too. [Sigma Star] has just the primer for you. It explains what TPM does, how it applies to embedded devices, and where the pitfalls are.
The TPM is sometimes a chip or sometimes secure firmware that is difficult to tamper with. They provide secret storage and can store boot signatures to detect if something has changed how a computer starts up. The TPM can also “sign off” that the system configuration is the same to a remote entity. This allows, for example, a network to prevent a hacked or rogue computer from communicating with other computers.
Embedded systems, usually, aren’t like PCs. A weather station at a remote location may have strangers poking at it without anyone noticing. Also, that remote computer might be expected to be working for many more years than a typical laptop or desktop computer.
This leads to a variety of security concerns that TPM 2.0 attempts to mitigate. For example, it is unreasonable to think a typical attacker might connect a logic analyzer to your PC, but for an embedded system, it is easier to imagine. There is a session-based encryption to protect against someone simply snooping traffic off the communication bus. According to the post, not all implementations use this encryption, however.
Motherboard has a slot for TPM, but no board? We’ve seen people build their own TPM boards.
Title image by [Raimond Spekking] CC BY-SA-4.0