Symbian still uses certificates to sign applications. In the case you want to roll out your own Symbian application, you need some way to sign your app. Turns out the certificates can easily be created on your own by use of the OpenSSL toolkit :

$ openssl genrsa 1024 >my.key

$ openssl req -new -x509 -nodes -sha1 -days 3650 -key my.key >my.cer

After entering the second command, you are prompted for various bits of information about yourself that is embedded into the certificate. This process only needs to be performed once, and the generated certificate can then be kept for future use with CreateSIS or SignSIS.