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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 o

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 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 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.

Houshalter 11y ago
What percent of the time is the location totally wrong? Greater than 50% of the time? If not then it's totally justified.
- cortesoft 11y ago
  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.
  - Houshalter 11y ago
    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.
    - darklajid 11y ago
      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.
      - Houshalter 11y ago
        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?
        darklajid 11y ago
        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.
        Houshalter 11y ago
        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.
- gnopgnip 11y ago
  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.
  - Houshalter 11y ago
    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.
    - wang_li 11y ago
      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.
      - Houshalter 11y ago
        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.
- PhantomGremlin 11y ago
  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%).
sillysaurus3 11y ago
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.
- mootothemax 11y ago
  >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
  - stkni 11y ago
    > - 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.
- PhantomGremlin 11y ago
  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_Ashley_Pond_and_Miranda_Gaddis 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".

Houshalter 11y ago

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

cortesoft 11y ago
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.
- Houshalter 11y ago
  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.
  - darklajid 11y ago
    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.
    - Houshalter 11y ago
      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?
      - darklajid 11y ago
        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.
        Houshalter 11y ago
        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.
gnopgnip 11y ago
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.
- Houshalter 11y ago
  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.
  - wang_li 11y ago
    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.
    - Houshalter 11y ago
      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.
PhantomGremlin 11y ago
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%).

sillysaurus3 11y ago

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.

mootothemax 11y ago
>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
- stkni 11y ago
  > - 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.
PhantomGremlin 11y ago
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_Ashley_Pond_and_Miranda_Gaddis 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".