I know that in linux and osx it's easy to create a disk image that is encrypted and (given you know the key) can be mounted and you can read/write its content.
Under windows there are plenty of tools to encrypt single files, I also know how to create encrypted read-only iso but I need a way to create an image (let's say 10GB iso file) that once mounted behaves like a normal folder and applications can read/write in it without knowing that it's encrypted. Encryption must be transparent to the applications.
PS: I've mentioned "iso" but it's not really important what format the disk image will be.
TrueCrypt
container is the best method.TrueCrypt
project has been discontinued, on their page it says "WARNING: Using TrueCrypt is not secure as it may contain unfixed security issues. This page exists only to help migrate existing data encrypted by TrueCrypt."