是否有可能从iphone GPS获取原子钟时间戳？ [英] Is it possible to get the atomic clock timestamp from the iphone GPS?

问题描述

我正在寻找一种可靠的方式来获得时间。它不能被篡改，它需要脱机工作。所以没有上网时间，没有设置用户时间，没有自上次重启后的BSD正常运行时间。我想知道，因为GPS使用原子钟工作，我是否可以访问这些信息。

谢谢

解决方案

这可以获得GPS时间：

  #import< CoreLocation / CoreLocation.h> ; 
 
 CLLocation * gps = [[CLLocation alloc] 
 initWithLatitude：（CLLocationDegrees）0.0 
 longitude：（CLLocationDegrees）0.0]; 
 NSDate * now = gps.timestamp; 
  

虽然它似乎不是防篡改的。

我在飞行模式（iOS 6.1）上的iPhone 4上试过这段代码，即便如此，它也给了一些时间。但不幸的是，这一次似乎随着系统时钟而改变。呃。

我发现有趣的事情（仍然处于飞行模式）是，如果您篡改系统时钟（转向关闭 Time& Date's 自动设置），然后将自动设置返回到在上，机器会顺利恢复真实（原始）时间。即使在关闭手机的电源之后，这种方式仍然有效因此，看起来 就像设备内部维护的防篡改时间。但如何访问这个？





2010年的一次讨论。倒数第二个评论的作者在一个放射性庇护所中试了一下：所以很明显，手机并没有从任何外部来源获得原始的时间。

附录，2013年7月

发现更多帖子（此处，这里和这里）关于另一种时间测量：系统内核启动时间。它通过这样的调用来访问： sysctlbyname（kern.boottime，& boottime，& size，NULL，0）; 。不幸的是，它也随着用户调整的数据和时间而改变，即使没有重新启动。另一个函数 gettimeofday（）同样依赖于用户定义的时间。

I'm looking for a reliable way to get the time. It can't be tampered with and it needs to work offline. So no internet time , no user time setup in settings and no BSD uptime time since last reboot. I was wondering since GPS works using atomic clock, whether I could access that information.

Thank you

解决方案

This works to get the GPS time:

#import <CoreLocation/CoreLocation.h>

CLLocation* gps = [[CLLocation alloc]
                       initWithLatitude:(CLLocationDegrees) 0.0
                       longitude:(CLLocationDegrees) 0.0];
NSDate* now = gps.timestamp;

It doesn't seem to be tamper-proof though.

I tried this code on an iPhone 4 in airplane mode (iOS 6.1), and even then it gives a time all right. But unfortunately this time seems to change with the system clock. Ugh.

Funny thing that I found (still in airplane mode) is that if you tamper with the system clock (after turning to off Time & Date's Set Automatically), and then turn Set Automatically back to on, the machine restores the real (original) time without a hitch. this works even after cycling the phone's power. So it seems that there is something like a tamper-proof time the device maintains internally. But how to access this?

P.S. A discussion of this from 2010. The author of the penultimate comment tried this in a fallout shelter: so it's clear the phone is not getting the pristine time from any external source.

Addendum, July 2013

Found a few more posts (here, here and here) about another kind of time measure: system kernel boot time. It's accessed through a call something like this: sysctlbyname("kern.boottime", &boottime, &size, NULL, 0);. Unfortunately it too changes with the user-adjusted data and time, even without reboot. Another function gettimeofday() is similarly dependent on user-defined time.

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