Ultimately a one-way hash is a good choice. Store your password as a hashed string. Hash the password the user inputs and compare it with the hash of your required password. You can use Digest::MD5 or something else if you'd like. Either way your password isn't visable in the source and is not reversable.

However, as pointed out above, if everyone else has advanced privileges on the system they can just copy your program and change the hash, or change any part of the program to allow them access. So it is seemingly futile.