Vaccine passports are not only meant to annoy the unvaccinated, they'll be used for contact tracing too.

The vaccine passports that I've seen have ECDSA signatures but no public key in them. That means a central authority has to verify the signature.

In other words, every time someone scans your passport, the central authority knows where you were at that time.

@verretor You can recover the pubkey from an ECDSA signature. If you already know one signature for that pubkey passed when you sent the signature to the central authority, you can verify every additional signature for the same pubkey independently.

(But, yeah, nobody is actually going to go through that effort to protect your privacy.)

@harding @verretor I remember telling to some cryptography types a year ago that trying to implement vaccine passports and track and trace with privacy protecting crypto was counterproductive because you'd just end up legitimizing the invasive tech that would inevitably get implemented anyway.

@pete @verretor I mean, what's the chance the government doesn't already know where everyone is by just using their cell phones?

Sure, there's no law that says you need to carry your phone or keep it in broadcast mode, while checking vaccine passports is a law, but I wonder if it's a real difference.

@harding @verretor It's a _huge_ difference if there is no way to turn it off. Absolutely massive.

Also, passive phone surveillance based on cell towers is pretty low accuracy. It can't tell what buildings you're actually in in most cases, and is often off by kilometers. Vaccine passports are much more precise.

@pete @verretor I guess, but phone surveillance tells them when you're at places that don't have vaccine checkins, e.g. home or other people's houses. Most of the places they want to do vaccine passports for already have credit card readers and most people are probably using those, leaving a travel trail already.

I completely agree that not being able to opt-out is bad, but I wonder if it's a difference for most normal people.

@harding @verretor Again, this gets back to the fact that mandatory surveillance with no way to avoid it is much worse.

And I don't think you realize how bad this gets... Singapore among other places has trace and trace readers at entrances to even outdoor public parks.

@pete @verretor I guess my point is that I agree it's worse from a civil liberties perspective but it doesn't seem worse to me from a practical perspective for 99% of the population.

@harding @verretor Well that's a very silly way to look at it. The 1% of the time when you really need the privacy matters.

I leave GPS tracking _on_ in my phone. But the fact I can turn it off is so important.