About Certificate: Meaning: Mobile phone certificate can be understood as: Passport of software English name: Phone certificate S60 Third Edition has greatly improved the security, and has stricter regulations on the third-party software installed and operated 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). Some installed software will have functional restrictions, such as incoming calls, fonts, input methods and other 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. Where do you put the certificate? How to use it? The certificate is not used for installation, nor is it simply put in any folder, nor is it imported into the mobile phone (the import root certificate mentioned in XX mobile phone system permissions is still different from this). Certificates are used to sign software that needs to be "signed". Certificates are not used directly, but packaged into sis software through a special program. The role of a certificate is only to give the program certain permissions. Don't lose the certificate, put it in a storage medium that can be found at any time. What is a signature? The so-called "signature" is the process of packaging a certificate into a program that needs to be signed. This operation requires a special signature tool (software). What is self-signed program software? As the name implies, self-signature means that you need to sign yourself. This self-signed program software can only be used for mobile phone serial numbers, and other mobile phones cannot be used. (Now the forum is doing the same batch of 1000 serial number * * * one certificate. ) certificate expiration: the certificate mentioned here is not that the mobile phone prompts the certificate to expire when installing the program, but that the CER certificate file you applied for has expired. Actually, it doesn't matter if it expires. The expired certificate can also successfully sign the program, but when installing this signed program, you need to adjust your manual time to the validity period of the CER certificate file to install it. Certificates can be reused indefinitely. Usually downloaded mobile phone software has a signed version and an unsigned version. For unsigned software, we can apply for a certificate to make software for our machine, make the key file of our mobile phone through the sign tool provided by Saipan, and then write the software to be installed, and then the software can only be installed in your mobile phone. In short, the certificate mechanism 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.