S stands for safety lock, safety lock and protection lock. S-OFF is the protection level. Safety lock is a kind of safety lock. It is a security lock designed by hardware designers to protect their firmware from being written. If this security lock is closed, then the write protection of the flash memory chip in the mobile phone is closed. The implication is that you can brush ROM at will.
S-ON is an open security lock. The mobile phone is write-protected. When the HTC machine is brushed with RUU, RUU will temporarily close the security lock. Then you can brush HTC's own ROM. HTC HBOOT also has signature verification. Therefore, the ROM without HTC signature can't pass the verification when it is swiped.
How can I get S-Off?
S-Off is a valid value in the HBO part of ROM, so if you want to turn on S-Off, you need to brush a specially modulated HBO file in the ROM area of the mobile phone.
Is there any danger in the process of obtaining S-OFF?
Yes, because hboot is responsible for starting the mobile phone. If there is something wrong with hboot, the machine will turn bricks. Therefore, in the process of obtaining S-Off, if there is a problem with the bin file that is swiped in, or there is an error in the process of swiping in, it will cause the phenomenon of brick turning after the phone is restarted.
What is the standard operating procedure for obtaining S-Off safely?
Because it is dangerous to brush Bhoot, we use backup verification to improve security. The standard operating procedure is as follows: firstly, back up HBoot twice in ROM, and then compare the MD5 values of the two files to ensure the correct backup (Android system natively supports MD5 verification, but only files can be detected. So when we check HBoot, we can only export it to a file and compare it with the file. Then we brush in the modulated version of the HBoot file, and then export it to a file for comparison. If they are the same, there is no problem. You can restart your phone. If they are not the same, there is a problem with the refresh. Backup needs to be restored. Do not restart the phone until the backup is successfully restored.