UDID

Not to be confused with IMEI.

UDID is an acronym for Unique Device ID. This UDID is actually a feature of Apple iDevices. It is basically a unique id for a single device that is being fetched by Apple servers every time a user tries to activate the device using iCloud or Setup app. This ID is also used by iTunes to detect the phone or to communicate with it while restoring the iPSW firmware. This unique ID cannot be changed by the user nor Apple, but changing the motherboard will also change this ID.

Presentation Form

This Unique ID is created from 40 letters and numbers. It is not written on the iDevice cover as the IMEI is, but it can be retrieved by iTunes in normal mode.

Usage

Apple usually uses this ID to assign Apple ID and iCloud ID to the device. This also holds the Find My iPhone activation status.

Calculation

The UDID is being calculated like this:

For the Verizon iPhone 4 and newer ones use:

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

All other devices use:

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

References

This article is issued from Wikipedia - version of the Thursday, April 07, 2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.