[Nadya]

>Something like your proposal may work if it involves a one-way hash of biometric data (fingerprint scan) so that people can't "lose their cert", but that comes with its own problems too.

Such as biometrics make terrible passwords because they can't be changed. Once compromised (3d printed fingerprints anyone? [0]) then you are forever compromised. Just in case someone wanted an example of why biometrics are terrible.

[0] http://www.novetta.com/wp-content/uploads/2015/10/NovettaBio...