[MPlayer-users] [OT] AC3 vs. DTS

Giacomo Comes comes at naic.edu
Wed Aug 3 16:25:26 CEST 2005

On Mon, Aug 01, 2005 at 08:01:35PM -0400, Rich Felker wrote:
> On Mon, Aug 01, 2005 at 05:46:23PM -0400, Giacomo Comes wrote:
> > > > In your statement you say that knowing a key "will make the cryptography
> > > > be cracked in no time"
> > > > That's only valid if the encryption algorithm is weak.
> > > 
> > > No, this statement is blatently false. Assuming you know the key (or
> > > have it somewhere and just haven't found it), the only factors making
> > > it difficult to crack the 'protection' are the level of obfuscation of
> > > the key and the level of obfuscation of the encryption (i.e. using an
> > > encryption method that's not well-known). Both of these are matters of
> > > security through obscurity. The weakness or strength of the encryption
> > > itself is always irrelevant when the only security comes from
> > > obscurity.
> > 
> > Looks like you were thinking about circumventing a protection,
> > but you were talking about breaking cryptography.
> No, I was never talking about breaking cryptography. That's totally
> unnecessary if you have the key. All I was talking about was getting a
> way to read protected discs.

Well, my understanding of english is far from perfect, but when I read:

  > Heavily protected? Any cryptography where the attacker has the key is
  > not heavily protected, it's just basic obscuring/obfuscation and will
  > be cracked in no time, just like CSS.

I undertand that you are talking about cryptography. But it is true
that I should have guessed what you were talking about.

> > Circumventing a 'protection' is one thing, it can be easy.
> > Breaking a cryptograph algorithm is another thing.
> > libdvdcss does not circumvent CSS, it breaks the weak algorithm.
> I agree totally, but it's not necessary to break the weak algorithm.
> That was just done to avoid distributing the salvaged key since some
> people hypothesized the DVD people could claim copyright on the key.
> FYI, the original DeCSS _DID_ use the salvaged key. Only modern
> libdvdcss does the cracking.

Did you read samewhere me mentioning DeCSS in order to crack CSS?

I suggest you to go through the mails again and read what I says
about breaking cryptography. 
That's what I was talking about all the time.


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