My guess would be that My::Crypt is a local sub-class of something like Crypt::Lite with which seems to share its interface to the extent your code reveals. So you likely need to find My::Crypt on your system and check what it's base classing off of.
perl -e 'split//,q{john hurl, pest caretaker}and(map{print @_[$_]}(joi
+n(q{},map{sprintf(qq{%010u},$_)}(2**2*307*4993,5*101*641*5261,7*59*79
+*36997,13*17*71*45131,3**2*67*89*167*181))=~/\d{2}/g));'