If you're against DRM's (Digital Restrictions Management), there is a way to show it. Check the Readers Bill of Rights for digital books and gather the logo's from their website. I have to say I'm extremely tired of restrictions that are forced upon digital books. One recent example of misusing the digital medium to apply absolutely ridiculous restrictions - that aren't even relevant for the print version of a book! - is the 26 check-out policy on digital books HarperCollins has suggested to libraries. Cory Doctorow makes a very good criticism of this in his Guardian article Ebooks: durability is a feature not a bug.
A French version of the logo's and the Reader's Bill of Rights exist on the e-bouquin website. Thanks to Clément Monjou for spreading the news on twitter.
Logo's in English on readersbillofrights.info
Logo's in French on ebouquin.fr