Distributing IoTHub credentials using TPM

I bet, most of the time you have seen Azure IoT demos or most of the time you have programmed an IoT Uwp app yourself, you hard coded device credentials for the IoT hub. Yes, I’m guilty too 🙂

And this is, of course, a bad practice.

Not only, there is a risk these credentials are shared by checking them in into your version control system (like public Git). But it’s also inconvenient because, for each device running that production code, you will have to alter the credentials in the code and deploy again.

We could use configuration files. But this is still worthless in perspective of distribution.

We would like to pass the credentials to known devices separately, apart from the applications. We want to use a second channel. And this is possible with the current Windows IoT Core infrastructure.

All we need is a TPM. This is a Trusted Platform Module:

Trusted Platform Module (TPM) is an international standard for a secure cryptoprocessor, which is a dedicated microcontroller designed to secure hardware by integrating cryptographic keys into devices. TPM’s technical specification was written by a computer industry consortium called Trusted Computing Group (TCG). International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC) standardized the specification as ISO/IEC 11889 in 2009.[1]

Why do we need it? Microsoft provides a separate mechanism to write credentials into the module which acts like a vault.

In this example, we will look at Windows 10 Core running on a Raspberry Pi. And we will use IoT Hub device credentials stored in a TPM.

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