iphone SHSH Certificate

Literacy: SHSH is short, the full name should be ECID SHSH or Shsh blob or ECID shsh blob.

Before we say SHSH, let's say what is Ecid, Ecid's English full name is Exclusive Chip ID, that is, every iphone, Ipod, ipad has a unique identifier based on its own chip. This can be achieved by looking at the phone, viewing the registry, using software to read and so on.

Then we say why Apple to do Shsh, the previous smartphone, we brush the new version, not easy to use, and then brush back to the lower version. It didn't matter, but after Apple's iphone, the problem was serious. Apple's new version will generally block the old version of the jailbreak, Apple does not want to let everyone escape, of course, Apple does not want everyone to brush back, so with a new verification technology, this is SHSH. SHSH is a signed file based on a complex operation of each machine's ecid and current version, SHSH not on your computer, but on Apple's servers. When you brush the machine, Apple will be connected to the server to verify that the current version of your brush and ecid generated by the SHSH and the server match, if it does not match, you can not brush the machine.

Now that you understand how SHSH came in, it's easy to understand the following questions:

Why the new version of the program can not back up the old version of the SHSH, because once the new version, all the SHSH have been updated, and the purpose of the update is to prevent you to brush back to the lower version. If you don't want to brush back the old version, then SHSH is of no use to you. Whether you are using 4.0 or 4.0.1, when you back up your SHSH, you can only back up to the current version of the Shsh file.

In fact, no matter how clever the verification technology, we understand the verification mechanism, we can do whatever we want, using a server instead of Apple (by modifying the Hosts file easily implemented), the previous backup of their SHSH files on the server, so you can brush back to the old version of the previous. (This section is from Baidu)

Step into the business
Make sure the computer is under the itunes client, Windows system.
Please make sure your iPhone4 has escaped from prison successfully.
Need to use the software, Umbrella-4.01.03.exe, Baidu Search bar.

1, after the jailbreak into the Cydia, please click Make my life easier,thanks!, in fact this step has been done, but for the sake of insurance, it is recommended to continue the following operations.
2, download Umbrella-4.01.03.exe extract to their own any folder, is generally the following two files

3, open your iPhone4, connect the computer, strongly recommend the use of the original data cable, and then open Umbrella-4.01.03.exe, check advanced options,device/version Select IPhone4 4.0.1,request From:cydia

4, save my Shsh, about 10 seconds to complete, save the path is generally C:DOCUMENTSANDSETTINGSADMINISTRATOR.SHSH format, backup size of 59.5K

5, as for the subsequent demotion method, need to further operation, relatively complex, first to establish their own servers, stat TSS server, depending on the speed of the situation, may be a few minutes to continue. Specific tutorials to be released later, theoretically backup over 4.0.1SHSH of iPhone4 can be demoted to 4.0.1.

Aurora suggested that before the next jailbreak software release, do not rashly upgrade your iphone, even if the upgrade, please back up your own shsh. I wish you all a happy play.