Evil Copy Protection vs. Good Crypto-Capable Objects

[Tom Vogt]

Bill Stewart wrote:
> Music Hoarders have a somewhat harder problem, in that they
> want to copy-protect information while providing near-identical
> copies to large numbers of people, while you're more likely
> to want to provide your personal transaction information or
> private messages only to a small number of recipients -
> but you may still want some kind of watermarking to identify
> who sold your "private" information to somebody you didn't authorize.

putting watermarking aside, this is the core. the normal use for
encryption is to make sure only a few people can access the information.
the movie/record/content "protection" purpose is not, you still want to
distribute your stuff high and wide, to as many people as possible. you
can say "authorized access" in both cases, but it has a different
meaning. both "root" and "ftp" ask for a password when you log into the
FTP server, but they're hardly on the same level.
therefore, software (and hardware) does and needs to work differently in
these cases. you don't use PGP for DVDs, you invent CSS.

I do think these things are farther apart than they appear. what it
boils down to is that the "protection" scheme doesn't seriously want to
stop anyone accessing the content. what it really wants is to make sure
he's following the rules (such as paying a fee). this is more an
authorization/permission system than an encryption one.