Permenant unique device identifier

Question

Is there a way to identify a device even after having uninstalled an app and reinstalling again? I found topics where it's possible to get a UUID but it seems that after uninstalling the app the value of the UUID changes

The value in this property remains the same while the app (or another app from the same vendor) is installed on the iOS device. The value changes when the user deletes all of that vendor’s apps from the device and subsequently reinstalls one or more of them.

I installed an App called Jodel, you don't have to create an Account to use the app and After uninstalling it, delete iCloud data, logging out from iCloud... an reinstalling it I was still logged in in the App. I assume they use a unique device identifier? Do you have an idea how such mechanism could be implemented?

Also take a look at my question - https://stackoverflow.com/questions/29760472/private-unique-device-identifier-in-ios — Sergey Grischyov, Jan 22 '18 at 13:49

score 1 · Answer 1 · answered Jan 22 '18 at 08:58

1

You can use Keychain Service to store data still after uninstalling app from device.

for more reference about keychain service check this

https://developer.apple.com/documentation/security/keychain_services

answered Jan 22 '18 at 08:58

Jaydeep Vora

6,085
1
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score 1 · Answer 2 · edited Jan 22 '18 at 12:19

Yes, It's Possible

#import "UICKeyChainStore.h"

AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{
    [self getDeviceIdFromKeychain];
}

- (void)getDeviceIdFromKeychain 
{
    NSString *deviceID = [UICKeyChainStore stringForKey:@"KEY TO SAVE TO Keychain" service:nil];

    // if vandorid from keychain is not nil
    if (deviceID)
    {
        [[NSUserDefaults standardUserDefaults] setObject:deviceID forKey:@"deviceID"];
        [[NSUserDefaults standardUserDefaults] synchronize];
    }
    // else it goes for new vendorid and then stored it to keychan
    else if (deviceID == (id)[NSNull null] || deviceID.length == 0 )
    {
        deviceID = [[[UIDevice currentDevice] identifierForVendor] UUIDString];

        [UICKeyChainStore setString:deviceID forKey:@"KEY TO SAVE TO Keychain"  service:nil];

        [[NSUserDefaults standardUserDefaults] setObject:deviceID forKey:@"deviceID"];
        [[NSUserDefaults standardUserDefaults] synchronize];
        // NSLog(@"VendorID Local - %@",deviceID);
    }
}

ViewContoller.m

- (void)viewDidLoad 
{
    NSString *strDeviceId = [[NSUserDefaults standardUserDefaults]objectForKey:@"deviceID"];
}

Thanks, would the user be able to bypass this by deleting manually the keychain data? — j.doe, Jan 22 '18 at 09:09
Actually you can delete keychain data by erasing your device and setting it up as new ;-) You still have the same device in your hands but to all 3rd party apps and services it is now an entirely new device. — Sergey Grischyov, Jan 22 '18 at 13:51

Permenant unique device identifier

2 Answers2