There’s many reasons to password-protect — or encrypt — one’s digital data. Foremost among them is to protect it during a security breach.
Another top reason is to keep the government out of your hard drive.
The issue is front and center as a federal magistrate is refusing to order a Wisconsin computer scientist to decrypt his data that the authorities seized from kiddie-porn suspect Jeffrey Feldman. The reason is simple: The Fifth Amendment right against compelled self-incrimination protects even those suspected of unsavory crimes, according to U.S. Magistrate William Callahan Jr. of Wisconsin, who wrote: "This is a close call, but I conclude that Feldman’s act of production, which would necessarily require his using a password of some type to decrypt the storage device, would be tantamount to telling the government something it does not already know with ‘reasonably particularity’—namely, that Feldman has personal access to and control over the encrypted storage devices."
Source: Wired. Read full article. (link)