The iOS 4.3 GM build was released earlier today (March 3) and a few hours after its release, the iOS 4.3 GM firmware has been jailbroken on the iPhone 4! Thanks to @jcf_dev(bundles), and @msft_guy (TetheredBoot, tools, etc) and @besweeet, the pre-jailbroken iOS 4.3 GM IPSW files are available so that you could restore to it.

Jailbreak iPhone 4 4.3 iOS GM

NOTE : This is a tethered jailbreak. Also, it is advised to backup all your data before doing it. It is also told that you should do this only if you know what you are doing. Be careful!

  1. Download the jailbroken iOS 4.3 GM IPSW for iPhone 4 from here.
  2. If you’re on Mac OS X, download PwnageTool 4.2. If you’re on Windows, download iREB RC3.
  3. If you’re on Mac OS X, open your downloaded copy of PwnageTool 4.2 and use its “DFU” mode button to put your device into pwned DFU mode (it’s slightly different from regular DFU mode, and won’t work unless you do it this way). If you’re on Windows, open your downloaded copy of iREB RC2 and click on your device to put it into pwned DFU mode (it’s slightly different from regular DFU mode, and won’t work unless you do it this way).
  4. Once you’re finished,open up iTunes.
  5. If you’re on Mac OS X, hold alt/option while clicking on the restore button, and find the custom IPSW. If you’re on Windows, hold shift while clicking on the restore button, and find the custom IPSW.

TetheredBoot instructions

  1. If you’re on Mac OS X, download THIS. If you’re on Windows, download THIS.
  2. Put your device into DFU mode (turn your device on; hold power+home for 10 seconds; while continuing to hold home, let go of power; you should now be in DFU mode (iTunes should detect your device in recovery mode, and your screen should be completely off).
  3. Follow this video.

To get the iBSS and kernel cache (which is required for TetheredBoot), you’ll have to rename your custom IPSW to a .ZIP file. After extracting the contents of the .ZIP (IPSWs are just ZIPped up files), you’ll be presented with the kernel cache. K48 is for the iPad, N90 is for the iPhone, and N81 is for the iPT4G. To get the iBSS, you’ll have to go to the /Firmware/dfu/ folder. Make sure you grab the iBSS, not the iBEC! Use this files in conjunction with the video above to boot your iDevice up. It may seem like a lot at first, but it’s very straightforward after you try it once.)

That’s it guys!

via Jailbreak Zone

Stay tuned to Tips Needed as we come with more updates on iOS 4.3 jailbreak!