Module::Signature adds cryptographic authentications to CPAN distributions, via the special SIGNATURE file. If you are a module user, all you have to do is to remember running "cpansign -v" (or just "cpansign") before issuing "perl Makefile.PL" or "perl Build.PL"; that will ensure the distribution has not been tampered with. For module authors, you'd want to add the SIGNATURE file to your MANIFEST, then type "cpansign -s" before making a distribution. WWW: http://search.cpan.org/dist/Module-Signature/