Comment by PhantomGremlin | Hacker News Reader

Comment by PhantomGremlin | Hacker News Reader

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The findmyfriends feature on my iPhone has been 100% accurate in identifying where my friends are

My wife and I use Find My Friends quite often to keep track of our children. I've used it for years, so I'm quite familiar with it. Our experience is quite the opposite of "100% accurate".

I provided more detail in this other post: https://news.ycombinator.com/item?id=10950107

Edit: just looked up the USA version of "probable cause" here: https://en.wikipedia.org/wiki/Probable_cause#United_States

In my opinion Find My Friends does not meet the standard of probable cause as defined by that Wikipedia article. I'd characterize its behavior be somewhere in between "reasonable suspicion" and "probable cause". I've seen the location be wrong and stay wrong for 1/2 hour or more. And I don't mean it can't find a location, I mean that it is repeatedly reporting the wrong location ("now") for an extended period of time.

Oh, and BTW following that Wiki link for "reasonable suspicion" says that it is sufficient for obtaining a warrant. IMO Find My Friends does meet that standard, at least as I understand it by a quick reading of Wiki.

Why do parents track their children? Kids are tougher than parents credit them for. It's unfortunate that new technology will let parents hover forever.

Luckily, they're resourceful. I wonder if it's possible to hack the app to send false location data? There are ways to jailbreak a phone that make it appear unjailbroken (e.g. to put a keylogger on it). Maybe this technique could be used to acquire freedom, by MITMing whatever findmyfriends is sending to their servers and modifying it in transit. The phone's location is probably a JSON field in the request. TLS provides no protection against an attacker with sudo privileges on the same box, so it seems possible.

Wanting to sneak out to see someone at 1 AM is a pretty powerful force, so this would be an amusingly effective way to get teens interested in hacking.

>Why do parents track their children?

Two reasons come to mind:

- parents spend a ridiculous amount of time worrying over ever-yet-more unlikely ways that their children will be maimed or murdered that very day

- it's not unknown for kids to have relatively poor reasoning and decision-making skills

> - it's not unknown for kids to have relatively poor reasoning and decision-making skills

Agreed. And one way to get better at decision making (if you're a kid) is having the opportunity to try and fail at it. So this isn't a good reason to track your kids after all, IMHO.

Why do parents track their children? Kids are tougher than parents credit them for. It's unfortunate that new technology will let parents hover forever.

That's me. I "stalk" my children. Here's the long story of why.

I live in a relatively safe area, the suburbs of Portland Oregon. There's a fair amount of petty property crime, which tends to be tolerated if not quite condoned.

Fortunately the region has generally investigated violent crimes quite aggressively, and the violent crime rate is relatively low compared to many parts of the country.

But that doesn't mean there aren't bad guys, violent sociopaths who live in the area. People like that live everywhere. E.g. here's something horrible that happened just a few miles away to two girls, one age 12 the other age 13: https://en.wikipedia.org/wiki/Ward_Weaver_III#Murders_of_Ash...

My girls were just about that age when they got iPhones. So, I try to keep an eye on them. There's a slight chance they'll run into some serious danger and I might be able to help.

But, more realistically, it helps kids stay out of trouble, because they know there's an increased probability that they will get caught. It's not perfect. E.g. my older daughter was only supposed to drive my car from home to high school and back. But she chose to drive off campus at lunch. And, since she was a very inexperienced driver, she got into a car accident. So, even when she knew that dad might be stalking her, she chose to be a free spirit. That's just how some kids are.

Certainly some kids will be resourceful enough to hack their phones. More power to them! But there are simpler ways. My older one simply turns off location services and then blames it on "Low Power Mode".

But, more realistically, it helps kids stay out of trouble, because they know there's an increased probability that they will get caught.

If my father knew I'd stolen his car to go see a girlfriend at 1 AM on a school day, he would have completely flipped out.

He'd have stopped me. And in doing so, would have deprived me of one of the best nights of my life.

I won't question your parenting methods. No one should, unless they have children.

But what you've described sounds like a meager existence. I hope your children can escape their taskmaster.

More likely, they'll grow up shaped into whatever form you decided suits them. Hopefully you're a tasteful architect.

Just know that this kind of thing can have long-term trauma effects. I wish I could paste the conversation from a physicist friend. I asked her how she's been, and she said completely miserable. "What?" "Well... Don't worry, I'm less miserable now than I was before."

This was alarming. She's nearing the end of grad school, and by all accounts is a successful physicist at the start of her career. She's worked very hard for four years to get there. Miserable? Isn't this what she's worked so hard to attain?

Turns out, she's never wanted to be a physicist. Her father coerced her into thinking she wanted to be. And now he's still pushing her to go into academia by pressuring her to get a PhD. She says that getting a real job is all she's dreamed about for years.

She's one of the smartest people I know. She's a brilliant mathematician, far better than I could ever hope to be. How could someone so smart end up with such a miserable life?

Because her parents decided that would be best, of course. I'm sure they meant well.

As you chip away with hammer and chisel, try to use a light touch. Therapists can't always reverse the damage.

> I won't question your parenting methods...

Ok, cool!

> But what you've described sounds like a meager existence. I hope your children can escape their taskmaster... More likely, they'll grow up shaped into whatever form you decided suits them... Therapists can't always reverse the damage.

Uhhhm...

It's not necessarily wrong to do any of that.

It had a profoundly bad outcome for me, but maybe that's a one-off. It's arguable whether it had a bad outcome for my physicist friend. After all, she is a successful physicist.

This was intended to highlight some things that may not be immediately obvious. Life is counterintuitive.

It is very easy to do terrible things by accident. Morals are subjective. Is it morally wrong to declaw a cat? Some are horrified and compare it to clipping off a finger. Others think it's good for the cat and perfectly normal.

If I sat here and said "What you're doing is wrong; stop this," what good would it do? Absolutely nothing.

Sharing data is a little different. No one has perfect information. They have to choose to do something, and I respect that. Highlighting unintended consequences of a decision isn't quite the same as judging it.

What percent of the time is the location totally wrong? Greater than 50% of the time? If not then it's totally justified.

Wait... you are saying you are willing to have a 49% chance that the police hold you in custody and search your house when you are totally innocent?!? Think about that.... there are LOTS of stolen phones and tablets, and if the police end up searching the wrong house nearly HALF the time that would be hundreds of innocent people. Fuck that I am SO not willing to live in a society where that happens.

It was a missing girl, not a random stolen phone. Yes I'd absolutely be willing to risk inconveniencing one person to save a kidnapped girl.

The 50% number was made up anyway, it's likely higher than that. GPS especially is pretty accurate, and these tracking systems probably use it when available.

For a single stolen phone, probably not. Though you can still go to their house and then call the phone right as they answer the door. If you hear ringing then that's probable cause.

Think of the children?

Either a location is enough for the police to search your place or it is not. Don't pull the kidnapped big eyed little girl card, please.

What are you talking about? The standards should definitely be lower for missing children. Finding your missing phone is a lot less important than finding a kidnapped girl. Are you really saying the police shouldn't have been allowed to do that search?

I'm saying that the same indicator ("location service claims this is the spot") should have the same result (probable cause?).

If crime1 w/ probable cause means you enter the building and crime2 w/ probable cause means you enter the building then there's no reason to bring up tiny girls or puppies.

Your argument works equally well against you. Most people agree the search is justified if it's a missing girl, therefore it should also be justified for any trivial crime as well.

But obviously there is a difference between trivial crimes and kidnappings. Inconveniencing a few people to save a life is acceptable. The expected utility is positive. It likely is not for more trivial crimes.

That it not how statistics work. Assume it is correct 90% of the time. There are 700 million iPhones worldwide. Assume 1% of them use the app, that is 7 million friends found, and 700k incorrect locations.

And only 1% of those users will have their phones stolen, and only 0.01% of those users will be suspected kidnapping victims. So only a handful of people would actually be actually be inconvenienced by such a policy.

The way this would work out in a proper world, is that the search would take place, they'd realize it was fruitless and that the location information provided was incorrect and then the phone manufacturer and the cell phone company would each cut a check for $1,000,000 to the person who was false accused. And this would happen each and every single time a person's civil rights were violated because some product developer did a shitty job. A 1% failure rate is pretty low quality.

You aren't owed a million dollars because your house was falsely searched. That's absurd. The police have a right to do searches if there is decent evidence or suspicion of a crime, and 99% is way more than enough for probable cause. A 1% failure rate is actually incredibly good and means it will be very very rare for innocent people to get searched at all.

What percent of the time is the location totally wrong?

As I discussed in my other post, I'd say that:

10% of the time, no location at all

60% of the time, highly accurate location

30% of the time, accurate to a general area, a few hundred feet up to a few miles

2% of the time, totally haywire. Location jumps around randomly, or stays wrong for an extended period of time.

(Statistics are my SWAG, and don't total to 100%).

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