The Certificate functions as follows:
The specifications have all been published on github
Given that the check also works offline (just tested it myself with the CovPass Check app), there cannot be any requests to any server. However, what the QR code includes, is data about the person (name and date of birth), as well as the information if the vaccination is complete (at least for the digital certificate issued in Germany). That data is most likely signed with a private key from the issuer, and this signature can then be validated with a public key, that’s part of the check app. This process doesn’t require any internet connection (the process of creating the QR code requires it, since it has to be generated by the holder of the private key).
Credit:stackoverflow.com‘
4 Mar, 2024
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