ssimpson writes "Everyone has probably forgotten the SDMI challenge to hackers to try to break a handful of proposed watermarking and "other" protection mechanisms? Well, it was recognised that a group of researchers at Princeton University broke all of the protection mechanisms and were due to publish a paper on at the 4th International Information Hiding Workshop (25-29 April) but have been threatened with the DMCA if they publish the results. So much for academic freedom, eh? SDMI seem particularly upset because one of the protection mechanims broken in the paper, The Verance Watermark, is currently used for DVD-Audio and SDMI Phase I products. Oops. Somehow, a copy of the threatening letter and the full paper entitled "Reading Between the Lines: Lessons from the SDMI Challenge" has appeared on John Young's excellent Cryptome site. SMDI's urge to "withdraw the paper submitted for the upcoming Information Hiding Workshop, assure that it is removed from the Workshop distribution materials and destroyed, and avoid a public discussion of confidential information." seems a little weak now...."