Hi friends, i am new to linux. My final year project is related to linux OS.My question is can we modify the kernel and use the modified version.If yes, how can we modify it?

In detail:
The aim of my project is to enhance the file data security in linux OS by integrating Secure File System into the kernel.During the write operation if the name of the directory(where the file to be stored) has "encrypt" as prefix , the kernel's VFS(virtual File System) should pass the control flow to Secure File System(SFS).SFS will encrypt the file and then store it.Similarly during read operation VFS should check the name of the directory and decrypt the file if neccessary. Encryption and Decryption should be done on the fly.To implement this, i need to add some code in kernel's VFS part.Please give some suggestions to implement this. I am using mandriva OS

thanks in advance