Fear of the controversial Digital Millennium Copyright Act (DMCA) is spreading as two well-known industry security experts, nervous about being sent to prison along with Dmitri Sklyarov, pulled their products from the net.

The last few months have seen growing concern among the security community since Sklyarov's arrest for cracking Adobe's eBook encryption, and professor Edward Felten's struggle to publish the techniques which cracked the Digital Music Initiative.

Even the Russian government has warned resident programmers not to travel to the US.

Fred Cohen, a professor of digital forensics, pulled his evidence-gathering tool, ForensiX, off his website, all.net, earlier this week.

But due to the media interest in this area, Cohen was quick to point out that he did not pull it "as a protest of any kind. I pulled it because I assessed that the business risk of law suits and prosecutions related to the DMCA was not worth the amount of money it generates, and because, as a matter of policy, we do not knowingly violate any law unless there is a compelling reason to do so."

Dug Song, a security programmer who works for arbornetworks.com, pulled his personal site, monkey.org/~dugsong, down.

This move appears to be in protest, however, as the only text on the site reads: "Censored by the Digital Millennium Copyright Act" and links to the DMCA protest site, Anti-DMCA.org.

These latest moves highlight the growing concern among cryptographers and coders in the industry since the DMCA was passed in 1998.

The Act is designed to prevent the circumvention of copy protection and the distribution of devices used to prevent copyright circumvention.

Its first test came in last year's court case over DeCSS, the program capable of decrypting DVD protection.

Since then, Hollywood, the music industry and a number of software giants have thrown their weight behind the DMCA, while the security industry has expressed fear and outrage at the legislation.

Recently Carnegie Mellon University aired a gallery of DVD decryption tools; a programmer claimed to have broken Microsoft's Reader ebook format, but declined to come forward; the Russian government advised programmers against going to the US; and Princeton University professor Edward Felten sued to prevent the publication of his research on the secure digital music initiative.