It's actually quite simple. This signature was designed by Nokia to improve the security of mobile phones. Any software installed on the mobile phone must be signed. If the software is not signed, it cannot be installed. In fact, it is to prevent some messy software from being installed in mobile phones, so anyone who wants to install it in Nokia mobile phones must pass Nokia's audit. If the software is proved to be safe after examination, you will be given a certificate, and then you can install the software with this certificate.

However, this kind of signature technology can't be realized by ordinary software development companies, and it must be approved by Saipan before the software can be signed. It can be installed in a mobile phone.

As for the certificate, it is related to the signature mentioned above. The premise of signing is to have a certificate, which is applied from Saipan company, and then sign with this certificate after the application is obtained. Ordinary software development companies can't get a certificate, so they have to apply.

In a word, all the software to be installed in Nokia must get a certificate before you can sign it. These two links are indispensable.

However, most famous software development companies will sign your name. As for those messy software, you have to find a way to sign it yourself.