The Filter-Crypto distribution provides the means to convert your Perl files into an encrypted, yet still runnable, format to hide the source code from casual prying eyes. This is achieved using a Perl source code filter. The encrypted files, produced using the Filter::Crypto::CryptFile module automatically have one (unencrypted) line added to the start of them which loads the Filter::Crypto::Decrypt module. The latter is a Perl source code filter which decrypts the remaining (encrypted) part of the Perl file on-the-fly when it is run. See perlfilter if you want to know more about how Perl source code filters work. Encrypted files can also be produced more conveniently using the crypt_file script, or (if you also have the PAR module available) using the PAR::Filter::Crypto module. The latter can be utilised by the standard PAR tools to produce PAR archives in which your Perl files are encrypted. WWW: https://metacpan.org/release/Filter-Crypto