Author (of the code) here.

The context is the US mobile drivers licenses and the forthcoming digital identity documents in the EU. The government gives you an electronic document stored in your device, and now the problem is, why would you ever want to give a copy of your document to a third party. This code solves the problem via zero-knowledge presentations of the document. This is real stuff already integrated in Google Wallet, not vaporware. See also the paper linked from GitHub. Ignore the marketing in TFA.