If you have a Nokia phone, any app that you run comes with a certificate from the phone manufacturer that allows it to run for a certain length of time. After this, if you want to continue using the app you will have to re-sign the certificate. The signed certificates are available on Nokia’s website, but they don't make the process easy. You will have to create an account and you can't use an email address like Yahoo or Hotmail. However, there is an easier way to update it.
Symbian is an operating system designed for Nokia mobile phones. Apps that run on this system need a Software Installation Script - or SIS - file to get permission to install on Nokia phones. A SIS file is a compressed archive containing all the files needed to install its application on a smartphone. The developer has to sign the SIS file by including a certificate. If this certificate expires, no one will be able to install the application. Here's how to update it.
Download Sign4ever from the MediaFire website (see Resources). You should download the program onto a PC, not onto your smartphone.
Copy any phone app installation files that need their certificates renewed into the same folder where you downloaded Sign4ever. These files all have either a .sis or .sisx file extension. You should only process one file at a time.
Run Sign4ever. A blue screen will appear giving you the status of its operation. When instructed, press any key to end the program and the blue window will close. In the directory where you copied Sign4ever you should now find a file called Signed.sis. Rename this file to the same name the application installation file you started with. This process updates the certificate on the SIS file to make it valid for 20 years.
Copy the .sis file back onto your phone. The application will now install without any certificate expiry errors.
Clean up the directory on your PC where you processed the .sis file. You will see that as well as the recently renamed file, there is also a Signed.BAK file. You can delete this.
The SIS certification system exists to block malware. Only use this certificate update procedure on files that you know are genuine applications for your phone.