how to encrypt initrd.img and decrypt in vmlinuz.
 

so that I can prevent sb. to mount the initrd.img and protect my application in it.

I need to know:
1.which source files in kernel should I rewrite.
2.where is the initrd.img put in without file system,so that I can read it and decrypt.
3.where should I put the decrypted initrd.img so that it can be unzip properly.

thanks a lot.

Any partition/file can be mounted manually only by root. So if someone wants to mount it - must get the account/password.

What you can do is to encrypt the file (or keep it on an encrypted filesystem). But...from what I have deen the decryption is used during the init stage, so long after using initrd. Maybe there's an easy way to have encrypted initrd, but I have not seen one.