2. You can brush the official firmware, but generally do not brush the official firmware. After you brush the official firmware, you have to sign your mobile phone. If you want to brush, brush the firmware of the player's own DIY.
The third and fifth editions of S60 have greatly improved the security, and have stricter regulations on the installation and operation of third-party software in the system. Special restrictions are imposed on the operation of some software related to mobile phone hardware and software/personal information security (for example, automatic startup of mobile phone startup is one of the restricted functions). Mainly to prevent malicious software. In order to realize these "specially restricted" functions, the application must obtain a "signature". In other words, someone should be responsible for the safety of this operation! A program without any signature cannot be installed and run.
In short, signature is a measure to solve security problems, and its functions are mainly two points: 1. Prove the legitimacy of the software. 2。 Allow the software to start itself.
Let me give you an example: in a big city, the city manager gives all citizens a city gate key (13 certificate of authority-the software maker's), and we can use it to get in and out of the city, while our own door, of course, needs our own key (17 certificate of authority-our own signature). Can you ask the city management to give everyone a key to their home?