As per Geohot's blog:
On the iPhone: usbdump huh? how?

Get the free usbview here:
http://www.ftdichip.com/Resources/Utilities/usbview.zip
For mac, use system profiler

1. Power off your phone
2. Holding the home button, plug your phone into your computer until you get into recovery mode.
3. Open usbview.
4. In "options", check off "config descriptors"
5. Hit F5 on your keyboard to refresh
6. Scroll down til you see "Apple Recovery (iBoot) USB drive, and click on it.
7. Look for ECID.
8. Copy the 16 digits that follow the ECID
9. Go to http://purplera1n.com/
10. Paste your ECID in the field just under the picture of geohot and hit "enter"
11. Save your iBSS certificate.
12. To get out of recovery mode, press and hold the power and home til your phone reboots.

Edit: I was unclear about some details of why exactly this is important for jailbreaking, and now that I understand it a little better, I thought I'd share.

The exploit that currently allows for a tethered jailbreak in 3GS phones is in iBoot, which is not a persistent jailbreak, meaning you need to re-jailbreak every time you power cycle the phone.
Having a tethered jailbreak allows us to use the bootrom 24kPwn exploit (which is at the hardware level and can not be patched by Apple), giving us an untethered jailbreak, which is persistent, and only undone when you do a restore.
The current iBoot will likely be patched by Apple in future firmware updates, closing the hole for tethered jailbreaking, meaning no more untethered jailbreaks either, even though the exploit still exists for untethered jailbreaking.
With the 3GS (unlike the 3G), there is additional security where code being uploaded to the phone must be signed by Apple using your EDID, or that code will be rejected by the phone. Apple will probably close the hole in iBoot with an updated version of iBoot in the next firmware update. Then since there is that extra security, Apple can then disallow use of older (exploitable) versions of iBoot. This means that jailbreaking with future firmware versions is not possible, unless you have the iBSS certificate which contains your EDID and a valid Apple signature (or unless a new exploit is found in the new iBoot). If you have the file generated by the above process, you should be able to continue jailbreaking future firmware versions, since the iBSS certificate will allow you to use the exploitable iBoot.

If someone figures a way around the EDID security, then none of this will be necessary. I'm not clear whether you need the certificate to jailbreak 3.0 or not, but you will certainly need it to jailbreak future firmware versions.

If I'm wrong on anything, feel free to correct me

Thanks man for the guide! Going to try right now
I want a jailbreak for iPhone 3GS.

EDIT: In step 4. In "options", check off "config descriptors" Means ENABLE the option so u can view your ECID 16 digit.

Works great! Saved the file.

OMG I cant wait for the jailbreak for this thing come on baby JB

Thanks for the guide!

I'm on a Mac...3GS in recovery mode...System Profiler is showing me my Mac's details but not my 3GS details or ECID#. Can anyone tell me what to do at this point please?

All help is appreciated. Obviously, I'm not a techno-pro and this is a learning-by-doing situation for me.

copy the 16 hex number after the ECID then go to http://purplera1n.com/

Under geohot picture, there is an invisible box, paste your hex numbers in there and hit ENTER. It will generate a file, download it and save it and guard it. It's your personal dump for your specific iphone 3GS

Edit:
NEVERMIND Found it...I can be so stupid. *faceplant*


dtube:

How do I find my ECID# while using System Profiler on a Mac?

When I put my 3GS in recovery mode and open System Profiler, it only shows my mac book pro's details. I don't see any info from the 3GS. Do you have any ideas on how I can find that ECID# using a mac please?

Once I can find it, I can plug into purplera1n.

Thanks for your help. I realize I probably look really n00b, but I'm trying to learn this. :p

FYI -

I googled ECID. Definition I found? Equine Combined Immunodeficiency. -LOL

Originally Posted by decagon

Edit:
NEVERMIND Found it...I can be so stupid. *faceplant*


dtube:

How do I find my ECID# while using System Profiler on a Mac?

When I put my 3GS in recovery mode and open System Profiler, it only shows my mac book pro's details. I don't see any info from the 3GS. Do you have any ideas on how I can find that ECID# using a mac please?

Once I can find it, I can plug into purplera1n.

Thanks for your help. I realize I probably look really n00b, but I'm trying to learn this. :p

Here's my Mac guide: Hack that Phone - Finding the ECID for the iPhone 3G S

Apple - thanks to Geohot and the rest of the devteam, I will now upgrade to the 3Gs - another one sold ;-)

However I will not be able to do so until I get back to the States next week - will I still be able to "purplera1n" the 3Gs ?

I do not plan to upgrade iTunes/MAC between now and next week. Anything else I should not do - like sync perhaps ?

Anyone ?

Originally Posted by decagon

Edit:
NEVERMIND Found it...I can be so stupid. *faceplant*


dtube:

How do I find my ECID# while using System Profiler on a Mac?

When I put my 3GS in recovery mode and open System Profiler, it only shows my mac book pro's details. I don't see any info from the 3GS. Do you have any ideas on how I can find that ECID# using a mac please?

Once I can find it, I can plug into purplera1n.

Thanks for your help. I realize I probably look really n00b, but I'm trying to learn this. :p

Run System profiler.
Look for USB
On the right hand pane, you will see Apple mobile device, under that you will see the iphone in recovery mode. Voila ...

Don't worry about being n00b. We're here to help & learn. We all have much to learn.

Enjoy