I probably should have included in the post that this is but one step in a defense-in-depth strategy. If one explicitly encodes a password in a Perl program, one must assume that password is fairly visible. There are more sophisticated ways of hiding that information (e.g., password daemon) but ultimately any proof-of-identity is imperfect. Cost of hurdles must be considered relative to value of information. But simply moving the unencrypted file to a path still accessible to the web server userid leaves the DB still vulnerable.

Thank you for describing so thoroughly the risks here. Detailed examples are very helpful in educating newer programmers, and I'm reading this as a rhetorical trick directed toward the GP.