downgrading
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iFaith v1.4 allows downgrade to iOS 5.0, jailbreaker's dream come true
In the game of Apple versus the jailbreakers, Cupertino threw the community a curveball with iOS 5's newly restricted downgrade system which blocks devices from restoring to old 5.x firmware. With the help of his noble steed iFaith (a custom Windows tool), hacker iH8sn0w has found a way around the firmware block, making it possible for dumped iOS 5 signature hash blobs (SHSH blobs) to permit unsigned restores. Why all the fuss about downgrading to prohibited firmware? Prominent iOS hackers MuscleNerd and pod2g have stated that the first untethered jailbreak will arrive on iOS 5.0 and, as such, may require iFaith's downgrade process to facilitate user restores. While the jailbreak is still under construction, iFaith should assure disheartened users in the community that all is not lost. Want to learn about blobs, blobs, and more blobs? Continue past the break to view iH8sn0w's informative video.
TUAW How To: Downgrading your 3.1.3 iPhone to 3.1.2
Last week I downloaded (but did not install) the iPhone OS 3.1.3 firmware for my 3GS. I wanted to have a copy of the firmware on hand, but didn't want to upgrade right away. I checked "Do not ask me again" and clicked Download Only. I thought that was the end of the matter. Unfortunately, this Sunday, I plugged in my iPhone and left the room to grab some tea. When I returned, the iPhone was 50% of the way through the 3.1.3 firmware upgrade procedure. It did something I had no idea that it would do: it upgraded me without asking. How frustrating! What's more, I didn't have a copy of 3.1.2 on-hand to downgrade to because iTunes automatically deleted the old firmware files and I was using default Time Machine settings; Time Machine does not normally back up ~/Library, the folder that contains the iTunes ipsw files. Fortunately, I had several resources. First, because I had jailbroken my phone and registered my device signature with Jay Freeman's caching service, I knew I could downgrade my phone. As Jay and I discussed in this LiveChat from a few months back, Apple no longer allows you to freely downgrade your iPhone software. All firmware installations must be verified with Apple's signature servers. By jailbreaking your phone and registering your device signature with Jay's system, you'll be able to bypass Apple's verification system and return to the firmware you prefer -- or at least to the earliest firmware whose signature you have stored on the caching site. To make this happen, you must both register your device and update your /etc/hosts file. Jay's site has complete instructions on how to comply. Second, I could grab a copy of old firmware from sites like Felix Bruns' http://www.felixbruns.de/iPod/firmware/ and iClarified's http://www.iclarified.com/entry/index.php?enid=750. These sites provide Apple download links for old firmware releases. I downloaded a fresh copy of the 3.1.2 ipsw (iPhone software archive) and installed it onto my system. Using a standard option-restore trick, I was able to put that firmware onto my iPhone. iTunes verified the upgrade with Jay's server and installed it onto the device. Note: If you receive the "The iPhone could not be restored. An unknown error occurred (3004)." error, make sure to quit iTunes and flush caches at the command line: sudo dscacheutil -flushcache. If your device updates properly, you will receive a 1015 error and your unit will now enter a semi-permanent recovery mode, the mode in which your device shows an iTunes logo and will not boot further. To proceed, you'll need to use iRecovery. Download a copy from this site. (It requires libusb, so read the entire post before running.) Run iRecovery from the command line and supply the -s flag. Wait for the "]" prompt, and do not type anything until you see that prompt appear. Enter the following commands: ] setenv auto-boot true ] saveenv ] /exit After, you will return to the command line. Reboot your phone by pressing the home and sleep buttons for 10 seconds, per the instructions on the site, and your iPhone should boot back to standard 3.1.2. Note: Be aware that this method does not downgrade your baseband. It remains at the 3.1.3 setting. Thanks Jay Freeman, Sjoerd (aka WiFone), and Paul "PhoenixDev" Griffin
TA-082 users now able to use homebrew
Some modern PSPs are manufactured with hardware that prevented downgrading to older firmware. They can be identified by opening the UMD drive and looking inside: if numbers appear inside (pictured right), then the system was unable to downgrade... that is, until now. Programmer 0okm has developed SoftDown" for TA-082 users, and is willing to work with you one-on-one via e-mail to get your system downgraded. Of course, like he says, you'll have to trust him with your e-mail address, PSP serial number and your firmware data. If you're ready to start taking the first steps towards a very homebrew-friendly system, check out 0okm's website for more info.[Via PSP Hacks]
Downgrading gets an easy upgrade
A lot of you seem confused about the whole 2.71 downgrading process. Thankfully, Xtrusion has made a super-simple way for the less technically inclined to downgrade their PSPs. Simply visit his website, and get the "Full" installer for 2.71 PSPs. Once again, make sure you don't have a TA-82 PSP or this will not work. Also, remember that there is always the chance of bricking your system, so please USE AT YOUR OWN RISK. REMINDER: If you successfully downgrade your system, you'll have to follow some steps to get homebrew running on your handheld.Truth be told, if this is still too difficult for you to understand, I highly recommend not jumping into homebrew. You can seriously mess up your system if you don't know what you're doing, so please: make sure you're mindful of what you're doing. Bricking a PSP won't be too much fun. If you can stomach these fairly simple instructions, then kudos to you: have fun!(P.S. Thanks to all the people that have left helpful comments over the past few days! Your help is much appreciated!)[Via PSP Hacks]
