On web page http://www.gnupg.org/faq/why-not-idea.en.html, it shows a like to
idea.c.gz as ftp://ftp.gnupg.dk/pub/contrib-dk/idea.c.gz, when the link is
currently at ftp://ftp.gnupg.dk/contrib-dk/idea.c.gz.

The same problem exists for the signature, which is reported to be at
ftp://ftp.gnupg.dk/pub/contrib-dk/idea.c.gz.sig, but it's really at
ftp://ftp.gnupg.dk/contrib-dk/idea.c.gz.sig.

By the way, thanks for a great site and a great product.