The transform at the heart of Pontifex has various asymmetries and special cases that make it difficult to express in a few clean, elegant lines of math. It almost has to be written down as pseudo-code. But why settle for pseudo when you can have the real thing? What follows is Pontifex written as a Perl script. The variable $D contains the 54-element permutation. The subroutine e generates the next keystream value whilst evolving $D.