alt Hacker News> the "decoy notes" may be considered an "effective technical measure" from the "Digital Millennium Copyright Act".
I really hope not. My understanding is that to be "effective" it needs to at least be a form of encryption with a secret key. At least, I'm not aware of any case law that allowed anything less than that.
IMO, "dummy notes" are nothing more than a form of obfuscation. If it's obvious how to filter them out, then I don't think it comes close to meeting the bare minimum of what might count as an "effective technical measure".
Of course, who knows what way the courts will rule if it ever reached that far.
shitty CAPTCHA’s and simple checksums have been ruled to be “effective measures”, so this would probably be too.
However, Section 1201(f) is designed to allow developers leeway in reverse engineering to make "independently created computer programs" talk to other "computer programs". But this usually distinguishes between talking to a binary (good) and reading a media file (bad).
My guess is the encoder is probably legal under 1201(f) because it’s reverse engineering a DMCA covered application to create new media files for it to use. But the decoder would be illegal because it reverse engineers a DMCA covered application to extract copyrighted media.