  With the COVID-19 pandemic entering a second phase and vaccination strategies
being applied by countries and governments worldwide, there is an increasing
expectation by people to return to normal life. There is currently a debate
about immunity passports, privacy, and the enablement of individuals to safely
enter everyday social life, workplace, and travel. Such digital immunity
passports and vaccination certificates should meet people's expectations for
privacy while enabling them to present to 3rd party verifiers tamper-evident
credentials. This paper provides a comprehensive answer to the technological,
ethical and security challenges, by proposing an architecture that provides to
individuals, employers, and government agencies, a digital, decentralized,
portable, immutable, and non-refutable health status cryptographic proof. It
can be used to evaluate the risk of allowing individuals to return to work,
travel, and public life activities.
