The Perl 5 module Crypt::RC4 provides a simple implementation of
the RC4 algorithm, developed by RSA Security, Inc.

Disclaimer: Strictly speaking, this module uses the "alleged" RC4
algorithm. The Algorithm known as "RC4" is a trademark of RSA
Security Inc., and this document [the module documentation] makes
no claims one way or another that this is the correct algorithm,
and further, make no claims about the quality of the source code
nor any licensing requirements for commercial use