Is renaming folders & files and changing file types an effective solution for file security of a PC? 

I am an application programmer and have an extensive background in it. I have written a robust program that renames folders and files and also changes file types. It does not compromise the integrity of the file, although I have been able to do that as well and change it back.

I am just wondering, how secure this is. I know that if for example I change: test.jpeg to test.txt, if someone were to simply change it back, my security is compromised. I've obviously made it more complex than this, but is there a loophole? Is there a way to check PC logs for file changes or some other way a pro would decipher this. As I said, my program that 'encrypts' these files is very robust, I highly doubt anyone but myself would be able to understand / compromise it.

Some of the security vulnerabilities I do know about:


A user could simply rename all of the files and thus have beaten the
security

To solve this I would add a header line to files so that even if the file was renamed it could no be read by the program.
For images a user could check the system thumbnails

To counter this I clear all temporary files upon encrypting files.
PC backups that contain the non-encrypted file

Know and control your backups.


Any other ways to crack this security?



A further note to this, this security solution was thought of after having CryptoVirus attack my server. Awfully impossible to reverse the changes that that virus made. I thought why not apply the same methodology to my file security.



Another note is that I am building upon Windows 7, with thoughts to expanding to other Windows platforms.

What you are doing is no kind of encryption, it is just obfuscation. It relies on security by obscurity. It may be enough to hide your files from an amateur/casual observer, but anyone analyzing the files in a hex editor is going to be able to rebuild and access them.

Effectively your method is about equal in complexity to attempting file undeletion, for which there are a host of tools available to anyone versed in digital forensics.

By contrast, the CryptoLocker malware you mentioned uses valid public-key cryptography, which is probably a method you should consider.
