Private unique device identifier in iOS

Question

We're working on a project with my colleagues which involves using a lot of private and non official code. This is not intended for AppStore use.

The first and only requirement we have is to not use jailbreak.

First of all, UDID or OpenUDID or any other solutions don't work here and they're not expected to.

We've done a lot of background research and tests, starting with trying to get the IMEI, ICCID, IMSI and the Serial Number programatically. None of the above methods work with iOS 7 and above without jailbreak.

We've also spent a couple of months to play with IOKit framework using the famous IOKitBrowser and dumping the whole contents of iOS internals. Unfortunately, we discovered that with iOS 8.3 it stopped working.

We're talking here not about getting the UDID or any other "mainstream" thing, but generally speaking we need a way to get

any permanent hardware identifier unique enough to identify a device that would persist in spite of device wipes and amongst different iOS versions

This question is no duplicate to others (no solutions are found here, for example) and is targeting solely private APIs.

Any help would be highly appreciated.

Answer 1

I'm sorry to say that apparently from iOS 8.3, to get any unique identifier you need a higher access level than normal user.

Without exploiting anything, just with private frameworks, libraries and kernel requests, any request to unique identifiers returns null.

Illustrating:

Trying to use IOKit:

void *IOKit = dlopen("/System/Library/Frameworks/IOKit.framework/IOKit", RTLD_NOW);
if (IOKit)
{
    mach_port_t *kIOMasterPortDefault = dlsym(IOKit, "kIOMasterPortDefault");
    CFMutableDictionaryRef (*IOServiceMatching)(const char *name) = dlsym(IOKit, "IOServiceMatching");
    mach_port_t (*IOServiceGetMatchingService)(mach_port_t masterPort, CFDictionaryRef matching) = dlsym(IOKit, "IOServiceGetMatchingService");
    CFTypeRef (*IORegistryEntryCreateCFProperty)(mach_port_t entry, CFStringRef key, CFAllocatorRef allocator, uint32_t options) = dlsym(IOKit, "IORegistryEntryCreateCFProperty");
    kern_return_t (*IOObjectRelease)(mach_port_t object) = dlsym(IOKit, "IOObjectRelease");

    if (kIOMasterPortDefault && IOServiceGetMatchingService && IORegistryEntryCreateCFProperty && IOObjectRelease)
    {
        mach_port_t platformExpertDevice = IOServiceGetMatchingService(*kIOMasterPortDefault, IOServiceMatching("IOPlatformExpertDevice"));
        if (platformExpertDevice)
        {
            CFTypeRef platformSerialNumber = IORegistryEntryCreateCFProperty(platformExpertDevice, CFSTR("IOPlatformSerialNumber"), kCFAllocatorDefault, 0);
            if (platformSerialNumber && CFGetTypeID(platformSerialNumber) == CFStringGetTypeID())
            {
                serialNumber = [NSString stringWithString:(__bridge NSString *)platformSerialNumber];
                CFRelease(platformSerialNumber);
            }
            IOObjectRelease(platformExpertDevice);
        }
    }
    dlclose(IOKit);
}

Fails. Reason: IOPlatformSerialNumber is not accessible. Many other requests work fine.

Trying to use Mach calls to get network adapters HW IDs:

int         mib[6], len;
char            *buf;
unsigned char       *ptr;
struct if_msghdr    *ifm;
struct sockaddr_dl  *sdl;

mib[0] = CTL_NET;
mib[1] = AF_ROUTE;
mib[2] = 0;
mib[3] = AF_LINK;
mib[4] = NET_RT_IFLIST;
if ((mib[5] = if_nametoindex("en0")) == 0) {
    perror("if_nametoindex error");
    exit(2);
}

if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0) {
    perror("sysctl 1 error");
    exit(3);
}

if ((buf = malloc(len)) == NULL) {
    perror("malloc error");
    exit(4);
}

if (sysctl(mib, 6, buf, &len, NULL, 0) < 0) {
    perror("sysctl 2 error");
    exit(5);
}

ifm = (struct if_msghdr *)buf;
sdl = (struct sockaddr_dl *)(ifm + 1);
ptr = (unsigned char *)LLADDR(sdl);
printf("%02x:%02x:%02x:%02x:%02x:%02x\n", *ptr, *(ptr+1), *(ptr+2),
       *(ptr+3), *(ptr+4), *(ptr+5));

Fails. Reason: Returns 02:00:00:00:00:00 for any network adapter.

Trying to connect to lockdownd:

void *libHandle = dlopen("/usr/lib/liblockdown.dylib", RTLD_LAZY);
if (libHandle)
{
    lockdown_connect = dlsym(libHandle, "lockdown_connect");
    lockdown_copy_value = dlsym(libHandle, "lockdown_copy_value");

    id connection = lockdown_connect();
    NSString *kLockdownDeviceColorKey
    NSString *color = lockdown_copy_value(connection, nil, kLockdownDeviceColorKey);
    NSLog(@"color = %@", color);
    lockdown_disconnect(connection);

    dlclose(libHandle);
}
else {
    printf("[%s] Unable to open liblockdown.dylib: %s\n",
           __FILE__, dlerror());
}

Fails. Reason: lockdown_connect() fails, returning null.

Trying to use libMobileGestalt:

void *libHandle = dlopen("/usr/lib/libMobileGestalt.dylib", RTLD_LAZY);
if (libHandle)
{
    MGCopyAnswer = dlsym(libHandle, "MGCopyAnswer");

    NSString* value = MGCopyAnswer(CFSTR("SerialNumber"));
    NSLog(@"Value: %@", value);
    CFRelease(value);
}

Fails. Reason: requests for unique identifiers return null. Any other request works fine.

My suggestion is to use some privilege escalation technique to get superuser access, then run any of the methods listed here to get the property.

Also, extend the study on liblockdown. If it's accessible at user-level (with something other than lockdown_connect), it might be possible to read these things.

Answer 2

After some digging, I've found that all private APIs use libMobileGestalt for getting any hardware identifiers, which in turn uses IOKit. MobileGestalt checks sandbox rules for current pid and looks for com.apple.private.MobileGestalt.AllowedProtectedKeys entitlement.

See the code below:

signed int __fastcall sub_2EB8803C(int a1, int a2, int a3, int a4)
{
  int v4; // r5@1
  int v5; // r4@1
  int v6; // r10@1
  int v7; // r2@1
  int v8; // r0@3
  int v9; // r6@3
  int v10; // r11@4
  int v11; // r4@4
  int v12; // r0@5
  signed int v13; // r6@6
  int v14; // r6@7
  char *v15; // r0@7
  int v16; // r1@7
  int v17; // r1@14
  int v18; // r3@16
  int v19; // r5@16
  signed int v20; // r1@17
  int v21; // r0@17
  __CFString *v22; // r2@19
  int v23; // r4@27
  __CFString *v24; // r2@27
  int v26; // [sp+8h] [bp-428h]@1
  char v27; // [sp+10h] [bp-420h]@1
  int v28; // [sp+414h] [bp-1Ch]@1

  v26 = a2;
  v4 = a1;
  v5 = a3;
  v6 = a4;
  v28 = __stack_chk_guard;
  memset(&v27, 0, 0x401u);
  v7 = *(_DWORD *)(dword_32260254 + 260);
  if ( !v7 )
    v7 = sub_2EB8047C(65, 2);
  v8 = ((int (__fastcall *)(int, _DWORD))v7)(v4, "com.apple.private.MobileGestalt.AllowedProtectedKeys");
  v9 = v8;
  if ( !v8 )
    goto LABEL_12;
  v10 = v5;
  v11 = CFGetTypeID(v8);
  if ( v11 != CFArrayGetTypeID() )
  {
    v14 = (int)"/SourceCache/MobileGestalt/MobileGestalt-297.1.14/MobileGestalt.c";
    v15 = rindex("/SourceCache/MobileGestalt/MobileGestalt-297.1.14/MobileGestalt.c", 47);
    v16 = *(_DWORD *)(dword_32260254 + 288);
    if ( v15 )
      v14 = (int)(v15 + 1);
    if ( !v16 )
      v16 = sub_2EB8047C(72, 2);
    ((void (__fastcall *)(int))v16)(v4);
    _MGLog(3, v14);
LABEL_12:
    v13 = 0;
    goto LABEL_13;
  }
  v12 = CFArrayGetCount(v9);
  if ( CFArrayContainsValue(v9, 0, v12, v26) )
    v13 = 1;
  else
    v13 = sub_2EB7F948(v9, v26, v10, "MGCopyAnswer");
LABEL_13:
  if ( !v6 )
    goto LABEL_30;
  v17 = *(_DWORD *)(dword_32260254 + 288);
  if ( !v17 )
    v17 = sub_2EB8047C(72, 2);
  v19 = ((int (__fastcall *)(int))v17)(v4);
  if ( v13 != 1 )
  {
    v21 = *(_DWORD *)v6;
    if ( *(_DWORD *)v6 )
    {
      v22 = CFSTR(" and IS NOT appropriately entitled");
      goto LABEL_22;
    }
    v23 = CFStringCreateMutable(0, 0);
    *(_DWORD *)v6 = v23;
    sub_2EB7F644(v19, &v27);
    v24 = CFSTR("pid %d (%s) IS NOT appropriately entitled to fetch %@");
    goto LABEL_29;
  }
  v20 = MGGetBoolAnswer((int)CFSTR("LBJfwOEzExRxzlAnSuI7eg"));
  v21 = *(_DWORD *)v6;
  if ( v20 == 1 )
  {
    if ( v21 )
    {
      v22 = CFSTR(" but IS appropriately entitled; all is good in the world");
LABEL_22:
      CFStringAppendFormat(v21, 0, v22, v18);
      goto LABEL_30;
    }
    v23 = CFStringCreateMutable(0, 0);
    *(_DWORD *)v6 = v23;
    sub_2EB7F644(v19, &v27);
    v24 = CFSTR("pid %d (%s) IS appropriately entitled to fetch %@; all is good in the world");
LABEL_29:
    CFStringAppendFormat(v23, 0, v24, v19);
    goto LABEL_30;
  }
  if ( v21 )
  {
    CFRelease(v21);
    *(_DWORD *)v6 = 0;
  }
  *(_DWORD *)v6 = 0;
LABEL_30:
  if ( __stack_chk_guard != v28 )
    __stack_chk_fail(__stack_chk_guard - v28);
  return v13;
}

signed int __fastcall sub_2EB88228(int a1, int a2, int a3)
{
  int v3; // r4@1
  int v4; // r10@1
  int v5; // r0@1
  int v6; // r6@1
  int v7; // r5@5
  signed int result; // r0@6
  char v9; // [sp+8h] [bp-420h]@5
  int v10; // [sp+40Ch] [bp-1Ch]@1

  v3 = a1;
  v4 = a3;
  v10 = __stack_chk_guard;
  v5 = sandbox_check();
  v6 = v5;
  if ( v5 )
    v5 = 1;
  if ( v4 && v5 == 1 )
  {
    memset(&v9, 0, 0x401u);
    v7 = CFStringCreateMutable(0, 0);
    *(_DWORD *)v4 = v7;
    sub_2EB7F644(v3, &v9);
    CFStringAppendFormat(v7, 0, CFSTR("pid %d (%s) does not have sandbox access for %@"), v3);
  }
  result = 0;
  if ( !v6 )
    result = 1;
  if ( __stack_chk_guard != v10 )
    __stack_chk_fail(result);
  return result;
}

As described here, UDID is calculated like this:

UDID = SHA1(serial + ECID + wifiMac + bluetoothMac)

MobileGestalt gets these values via IOKit like this:

CFMutableDictionaryRef service = IOServiceMatching("IOPlatformExpertDevice");
    io_service_t ioservice = IOServiceGetMatchingService(kIOMasterPortDefault, service);
    CFTypeRef entry = IORegistryEntryCreateCFProperty(ioservice, CFSTR("IOPlatformSerialNumber"), kCFAllocatorDefault, 0);

    const UInt8 * data = CFDataGetBytePtr(entry);
    CFStringRef string = CFStringCreateWithCString(kCFAllocatorDefault, data, kCFStringEncodingUTF8);

If you try to do it yourself, it will fail because new sandbox rules in iOS 8.3 are very strict and deny access to all hardware identifiers like this:

deny iokit-get-properties IOPlatformSerialNumber

Possible Solution

It looks like the only way you can get UDID is the following:

1. Launch a web server inside the app with two pages: one should return specially crafted MobileConfiguration profile and another should collect UDID. More info here, here and here.
2. You open the first page in Mobile Safari from inside the app and it redirects you to Settings.app asking to install configuration profile. After you install the profile, UDID is sent to the second web page and you can access it from inside the app. (Settings.app has all necessary entitlements and different sandbox rules).

Confirmed working solution

Here is an example based on RoutingHTTPServer:

import UIKit
import RoutingHTTPServer

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    var bgTask = UIBackgroundTaskInvalid
    let server = HTTPServer()

    func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
        application.openURL(NSURL(string: "http://localhost:55555")!)
        return true
    }

    func applicationDidEnterBackground(application: UIApplication) {
        bgTask = application.beginBackgroundTaskWithExpirationHandler() {
            dispatch_async(dispatch_get_main_queue()) {[unowned self] in
                application.endBackgroundTask(self.bgTask)
                self.bgTask = UIBackgroundTaskInvalid
            }
        }
    }
}

class HTTPServer: RoutingHTTPServer {
    override init() {
        super.init()
        setPort(55555)
        handleMethod("GET", withPath: "/") {
            $1.setHeader("Content-Type", value: "application/x-apple-aspen-config")
            $1.respondWithData(NSData(contentsOfFile: NSBundle.mainBundle().pathForResource("udid", ofType: "mobileconfig")!)!)
        }
        handleMethod("POST", withPath: "/") {
            let raw = NSString(data:$0.body(), encoding:NSISOLatin1StringEncoding) as! String
            let plistString = raw.substringWithRange(Range(start: raw.rangeOfString("<?xml")!.startIndex,end: raw.rangeOfString("</plist>")!.endIndex))
            let plist = NSPropertyListSerialization.propertyListWithData(plistString.dataUsingEncoding(NSISOLatin1StringEncoding)!, options: .allZeros, format: nil, error: nil) as! [String:String]

            let udid = plist["UDID"]! 
            println(udid) // Here is your UDID!

            $1.statusCode = 200
            $1.respondWithString("see https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/iPhoneOTAConfiguration/ConfigurationProfileExamples/ConfigurationProfileExamples.html")
        }
        start(nil)
    }
}

Here are the contents of udid.mobileconfig:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
    <dict>
        <key>PayloadContent</key>
        <dict>
            <key>URL</key>
            <string>http://localhost:55555</string>
            <key>DeviceAttributes</key>
            <array>
                <string>IMEI</string>
                <string>UDID</string>
                <string>PRODUCT</string>
                <string>VERSION</string>
                <string>SERIAL</string>
            </array>
        </dict>
        <key>PayloadOrganization</key>
        <string>udid</string>
        <key>PayloadDisplayName</key>
        <string>Get Your UDID</string>
        <key>PayloadVersion</key>
        <integer>1</integer>
        <key>PayloadUUID</key>
        <string>9CF421B3-9853-9999-BC8A-982CBD3C907C</string>
        <key>PayloadIdentifier</key>
        <string>udid</string>
        <key>PayloadDescription</key>
        <string>Install this temporary profile to find and display your current device's UDID. It is automatically removed from device right after you get your UDID.</string>
        <key>PayloadType</key>
        <string>Profile Service</string>
    </dict>
</plist>

The profile installation will fail (I didn't bother to implement an expected response, see documentation), but the app will get a correct UDID. And you should also sign the mobileconfig.

Answer 3

You could try accessing lockdownd API directly, via libMobileGestalt.dylib.

Header here. The basic code to access the UDID should be: (you still need to load the dylib)

CFStringRef udid = (CFStringRef)MGCopyAnswer(kMGUniqueDeviceID);

taken (&slightly modified) from here.

For further information on libMobileGestalt , look here.

If this fails you could still try communicating with lockdownd via an SSL Socket( see here ), no idea how that works though, but you might figure it out.

As you may have noticed though, all stuff on this is years old. Still worth a try i guess.

Answer 4

I am unsure of your full intentions but would it be enough to have the app generate and store your own unique ID within the app on installation? Then perhaps have the app send that ID to a server and store the IP it came from. Perhaps also have some logic to have the app phone home every so often so you can store additional IP's if they change. Obviously this is not foolproof but it may be the beginnings of a workaround.

Answer 5

What about this: https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIDevice_Class/#//apple_ref/occ/instp/UIDevice/identifierForVendor

An alphanumeric string that uniquely identifies a device to the app’s vendor. (read-only)

The value of this property is the same for apps that come from the same vendor running on the same device. A different value is returned for apps on the same device that come from different vendors, and for apps on different devices regardless of vendor.

Since iOS 6 and current in iOS 8

This meets your requirement of:

any permanent hardware identifier unique enough to identify a device that would persist in spite of device wipes and amongst different iOS versions

This is documented to be unique per device and persistent whether from app store or enterprise delivered.

Normally, the vendor is determined by data provided by the App Store. If the app was not installed from the app store (such as enterprise apps and apps still in development), then a vendor identifier is calculated based on the app’s bundle ID. The bundle ID is assumed to be in reverse-DNS format.

Answer 6

I don't know if commercial solutions are of interest to you but check out http://www.appsflyer.com

I'm not affiliated with them but we used their SDK at my previous employer. They have a device fingerprint technology which does work.

Note: If the user resets the IDFA then AppsFlyer will see this as a new device. However, and its been awhile so I can't remember, I think you can use their SDK, not use AdSupport.framework, and then they won't have the IDFA available to them. So I'm guessing that their device fingerprinting may work.

They also have competitors, search for device fingerprinting. Check out Yozio and branch.io, they both claim to do this. I've not used their product, just seen their websites.

Answer 7

Actually i don't know this solution is helpful or not. but after removed support of UDID. i have manage Unique device identity following way. with help of Vendor ID. Here what we did that.

As initial while application will run, i will check out that weather vendor ID for specific app is stored in key chain or not. if it not stored then i will store that vendor ID in key chain. so second time once my app is going to check again that weather vendor ID for specific app it stored of not in key chain. if stored then bring it from key chain and doing action on same according to requirement. so here alway vendor ID is unique for device.

Here are the steps that we keep uniqueness of device with help of vendor ID.

Step 1 : Integrate Lockbox in your project. that will help you to stored/retrived vendor ID in/from key chain.

Step 2 : Here are the code that perform action of checking vendor ID and retrieving vendor ID from key chain.

-(NSString*)getidentifierForVendor{
    NSString *aStrExisting = [Lockbox stringForKey:[[[NSBundle mainBundle] infoDictionary] objectForKey:(NSString*)kCFBundleIdentifierKey]];

    if (aStrExisting == Nil) {
        NSString *aVendorID = [[[UIDevice currentDevice]identifierForVendor]UUIDString];
        aStrExisting=aVendorID;
        [Lockbox setString:aVendorID forKey:[[[NSBundle mainBundle] infoDictionary] objectForKey:(NSString*)kCFBundleIdentifierKey]];
        return aVendorID;
    }else{
        return aStrExisting;
    }

With help of above steps, you always get uniqueness of device. because key chain is never deleted. it always updated.

Hope this help you...

Answer 8

Are you allowed to ask the user for their MSISDN's? (international phone numbers) Like what whatsApp is doing when you first login with them by confirming with a SMS code sent to the user msisdn. If you know the MSISDN's of your users, you can keep them in your servers DB and only allow a white-listed msisdn to register and use your services. If you want to be more secure you can send the SMS's more often however there is a way to understand SIM-card change (this is for t-mobile and europe use i guess) from within the APP so that the user cant fool you by enetering SMS for a different MSISDN and then change to his/her real MSISDN sim card.

MSISDNs are unique worldwide and they are secured by the telecom operators so i guess this solution is strictly secure. What do you say? good luck

update: actually upon reading your question carefully again, I think you dont want the user to login any info right? if thats the case sorry for the wrong answer:/

note: why cant you use

[[[ASIdentifierManager sharedManager] advertisingIdentifier] UUIDString]

the advertising identifier is unique to the device and permanent i guess. I dont know if you can use it privately though..