Before revision:  To address many of the underlying issues involved in certification, and as a proof of concept for future pandemics, we have developed a prototype mobile phone app  that facilitates instant verification of tamper-proof test results.
After revision:  To address many of the underlying issues involved in providing tamper-proof and privacy-preserving certification, both for COVID-19 immunity and in general. Methods: We developed a prototype mobile phone app that facilitates instant verification of tamper-proof test results.