http://developer.apple.com/library/ios/#documentation/uikit/reference/UIDevice_Class/Reference/UIDevice.html identifierForVendor

This is currently a container feature, but should be included in ICEmobile-SX. Since it can be implemented using offline communication and shared between multiple web applications, there are potential privacy implications.

An equivalent android mechanism needs to be investigated.

The iOS container now sets a cookie (with a unique device ID) as follows:

com.icesoft.device-id=CAFEBABE-2222-3333-4444-DEADBEEFCAFE

This value should be considered to be an opaque string to allow for different device formatting.

Sample android code:

http://stackoverflow.com/questions/2785485/is-there-a-unique-android-device-id

final TelephonyManager tm = (TelephonyManager) getBaseContext().getSystemService(Context.TELEPHONY_SERVICE);

final String tmDevice, tmSerial, androidId;
tmDevice = "" + tm.getDeviceId();
tmSerial = "" + tm.getSimSerialNumber();
androidId = "" + android.provider.Settings.Secure.getString(getContentResolver(), android.provider.Settings.Secure.ANDROID_ID);

UUID deviceUuid = new UUID(androidId.hashCode(), ((long)tmDevice.hashCode() << 32) | tmSerial.hashCode());
String deviceId = deviceUuid.toString();

If added to ICEmobile-SX with offline capability, it seems possible for the current Safari application to spoof the current domain and allow the unique ID to be used to identify the user across many different web sites. However, if the domain is spoofed, the ICEmobile-SX return URL will be different, resulting in the ID being transferred to a different web page. (In other words, the privacy implications may be accurately exposed to the user.)