Hi all,

I would like to know if someone knows in SoC (OMAP2, Xscale, MSM...)
based approach, which technics can be applied and exist for securing
video shared memory. For example, imagine a DRM agent that processes
video contents. Is it possible to restrict read access to several
portions of the video memory (i.e. only the DRM agent can read/write
this video memory space) ?

Or/and if you have some links, it could be really nice.

Thanks.
Have a nice day.

David Icksss wrote:

If the memory is external, no. The normal way of doing this in "hard"
DRM is to have a crypto engine between RAM and processor. Everything in
RAM is encrypted and has to come through the crypto engine - which is
integrated with the MMU - so the only way of getting into the "secure"
areas is through whatever rules the DRM code set up.

If you're merely trying to protect against another process looking at
your memory, this is generally done with the MMU (assuming the OS is
safe and doesn't provide any hooks to get around these features). In
the case of video memory, you'd normally have an overlay window open,
and only the overlay buffer would be hidden this way.

PS: Working on DRM is much worse for the world than pouring napalm onto
babies.

Thank you for your answer,

but if there is no MMU, are there any others solutions ?

In these SoC with MMU (Xscale, Freescale, broadcom, qualcomm (MSM)), or
one of them. have you more details than we can know in their publics
specifications about how the security is integrated?

Thanks.

PS:

David Icksss wrote:
You know I was reading some while about the encryption method that
various arcade machines utilize and was fairly surprised at how hard
they worked and the cleverness of their solutions.

One was to XOR the data on the output with some function of the address
lines (but that can be figured out with some effort).

The Neo Geo MVS for example swizzled address bits on external ROM so
that it would be quite confusing for the person reverse engineering the
system to extract the games' program code.

If you are using external memory you can swizzle the address bits, say
the CPU's A0 will go to A7 or something of an SRAM, DRAM, SDRAM, etc.
You can also swizzle the data bits too. Though that will not deter
someone who is keeps a cool head though.


I'm not sure what you can do with only an MMU in the system.
-Isaac

Isaac Bosompem wrote:

This will provide no protection at all against code running in the same
micro. It's not clear from the OP's posting what he is attempting to
prevent, but it looked to me as if he's trying to keep video memory
secret from other processes.

All the platforms I saw mentioned have an MMU in them.

All the platforms that have special DRM bullshit hardware on-chip have
most of the info about that locked up behind NDAs.

I hate the RIAA and MPAA. Will never buy another movie or record that
pays money to them, in fact.

"larwe" <zwsdotcom@gmail.com> wrote in message
news:1147291830.399622.159860@i40g2000cwc.googlegr oups.com...
The principle (of protecting the rights of the copyright holder(s) and,
indeed, investors) is good. The practice (of how they go about it) is not.

I have many complaints about such bodies, both as a musician and a music
sales enabler, and as a businessman. My view re music (not necessarily
video) is that what they (and similar bodies in the UK etc) are primarily
trying to protect is a *business model*, and certainly not primarily the
artists and originators (who have been ripped off by the industry, with rare
exceptions, since the industry was born). It's understandable, but
misguided - and the tactics employed re enforcement are suspect.

My company is - hopefully - playing a part in providing alternatives.

(That's the very brief version - it's a complicated subject. The longer one
requires many beers.)

Steve
http://www.fivetrees.com

On Wed, 10 May 2006 22:37:10 +0100, "Steve at fivetrees"
<steve@NOSPAMTAfivetrees.com> wrote:

<OT> After browsing your website - I'm impressed. I wish there were
more companies with your philosophy and standards. </OT>
--
Al Balmer
Sun City, AZ

"Al Balmer" <albalmer@att.net> wrote in message
news:u6o462dv92cmnqabvo0782971jdnkl24db@4ax.com...
Thanks. (Although I'm aware that the website needs a bit more work to make
this clear - we recently revamped the shop, and it really needs to shout "WE
ARE NOT A RETAILER!" .)

Steve
http://www.fivetrees.com

um, than I guess you're going to be really behind the times, since
they're involved in almost every aspect of music and movies produced in
the U.S. Plus if you really like the artists and what they're
creating, wouldn't you want to support and protect it so the William
Hungs of the world won't record it? I don't see what the big deal is.

maskedkoalaprincess@gmail.com wrote:
If you really like the artist, you should show your appreciation to the
artist - not to some purulent boil on the buttocks of humanity, sitting
in an armchair taking 60-75% of the gross receipts. Worse, these
worthless excrescences use that unearned income to buy politicans and
get anti-innovation laws pushed through the legislative process.

"larwe" <zwsdotcom@gmail.com> wrote in message
news:1147983077.633502.273790@i40g2000cwc.googlegr oups.com...
Exactly right.

Years ago, I signed a recording and management contract. Like many
musicians, I had little choice - if I wanted to stay in the band I was in.
Nonetheless, I sat down and read it, researched it, eventually understood
it - unlike most musicians . Bottom line: they owned me, and everything I
did, for a certain period - with options (on their side) to extend that
period. Period!

Since then, I've read many, many more contracts. Terms have generally
improved over the years (too many high-profile court cases), but the fact is
that a musician (esp. a non-writing band member) sits at the end of a long
chain of slice-of-pie takers, and then gets a percentage of what's left over
at the end. There are any number of ways for the queue upstream to arrange
for nothing to be left at the end... and bands are rather good at wasting
record-company money, forgetting that it's effectively a loan...

That's basically why fivetrees operates on the art-gallery (commission on
sales) model. Idealism . I'm interested in exploring public *patronage*,
in one form or another, rather than the old model of corporate investment...
It's not a magic bullet; I'm not dumb enough to believe we can change the
system - or the public. But maybe we can provide an alternative.

Things *are* getting more democratic now - the Internet, PayPal, etc etc..
and companies like mine. But it's still a marketing-based business, and
marketing is expensive. Unless it's word-of-mouth - in which case, the best
way of "showing your appreciation" is by spreading the word. Many of our
artists actively encourage sharing the music with friends etc - they see it
as free promotion. This only works, of course, if you still have or can
produce more product to sell - and are out there earning money by performing
to (hopefully) ever-larger audiences.

I'm in danger of rambling. As I said earlier, I have way too much to say on
this subject .

Steve
http://www.fivetrees.com