S60 certificate is limited by level and authority. The minimum certificate can only be used to install ordinary games, themes and general application software. This certificate can be installed by turning off the setting options of certificate checking (operation steps: menu key-application management-options-settings, select "All" for software installation, and "Off" for online certificate checking). Because the default setting is that the certificate with slightly higher authority can let the software information enter the system folder of the C drive of the mobile phone, so that the software has high authority, such as automatically starting and modifying system parameters. At present, all the certificates that we need to sign by ourselves are such certificates. The highest authority certificate can modify the system, but it needs to be paid to Nokia. The certificate corresponds to the unique serial number of your mobile phone, so the certificate cannot be used universally. Your own certificate can only be used by your mobile phone, that is, you can use your certificate to sign countless software you want to put into your mobile phone. But you can't sign someone with your certificate and then install the signed software on someone else's mobile phone.

At present, you can't get a mobile phone certificate directly through official website for free, but you can go to the Avatar Signature Center to help you get a mobile phone certificate for free. And there are detailed tutorials. Yes, all new certificates applied from June 5438+February 2007 are valid for three years, and all previous certificates are valid for half a year. After the expiration, the installed software still works normally. The only impact is that you re-sign the software with this certificate. Therefore, when installing the software, the third or fifth version of S60 system will prompt that the certificate time is wrong and installation is not allowed.

Solution: Either you apply for another certificate, or you adjust the mobile phone time to any time within the validity period after the time you originally applied for the certificate, then sign with the original certificate, and then adjust the mobile phone time back to normal after installing the software. At present, the validity period of the certificate is enough for us to use, but some software that cracked the signature has passed the validity period, and this software can also be used to clear the old signature and re-sign.