In JEE and .NET applications we often store data access configuration parameters such as username, password, datasource URL in properties files. But how to protect this sensitive information? The obvious answer is to encrypt the file or the 'string' properties. But then the question is - where do U store the key? If U encrypt the key, then U would require another key to decrypt this key...a classic chicken-and-egg problem.
Browsing thru OWASP site pages, I came across this page that contained some interesting ideas for this problem. Snippet from the site:
"Some environments have protected locations, such as the WebSphere configuration files, or the system registry. You can use a file in a protected location, that uses OS access control to limit access to only the application. You could put the key in the code, but that makes it difficult to change and deploy securely. You can also force the master key to be entered when the system boots up so it's only in memory, but that means you lose automatic reboot. You can even split the key and put parts in more than one of these locations."
The page also contains a sample implementation in Java for encrypting properties file.