Why is an iPhone Device ID 40 characters?

iphone ipod-touch uuid udid
Paul Prescod picture Paul Prescod · May 28, 2009 · Viewed 14.2k times · Source

UUIDs are usually 36 characters.

Answer

cdespinosa picture cdespinosa · May 28, 2009

Because UDID ≠ UUID. The iPhone Unique Device Identifier (UDID) is a hash of several different hardware identifiers pulled from the chips on the phone. It's not a software-generated identifier for a software object.

It's 160 bits, not 128 bits, so it takes 40 hex characters to represent, not 32 + 4 hyphens.

Related questions

Determine device (iPhone, iPod Touch) with iOS

Is there a way to determine the device running an application. I want to distinguish between iPhone and iPod Touch, if possible.

Read More
What are the sizes used for the iOS application splash screen?

I am developing an application using the iOS SDK. I need to know what Default splash screen sizes I need.

Read More
Can js/jQuery determine the orientation of the iPhone?

Out of curiosity I've been playing with jQuery to determine the browser's screen size, and it occurred to me that screen size could be used to determine whether or not a visitor was using an iPhone/iTouch to view the …

Read More