Is it suffice to self sign my app if SDCARD access required?

[xuxiang]

I am a newbie in deploying my apps and confused about signing.

I've wrote a Qt application and tested to run from Qt 4.6.3 or above. It works on my 5530 and N900. It uses media player function to play music and need to read / write text or binary files from user's SDCARD. It won't access user's personal data on the phone.

I plan to place it on my site for public download. Is it suffice to self sign the app (packaged as smart installer) and runs on the users' phone?

As an additional question, if I added some tcp/ip socket programming to connect to my server to read /write some member data, is it also OK to just self sign ?

Thanks for any advice!