Re: Latency, bandwidth, and anonymity

My initial reaction to "Anonymous video conferencing" was
"That's when you wear black ski masks and use voice scramblers
and call from video payphones", i.e. not very useful.
("Subcomandata Marcos here...")

On the other hand, Wei Dai's followup message about
> In the longer term, anonymous communication is in danger of being used
> only by fringe groups if it falls too much behind the non-anonymous kind
> in terms of latency and bandwidth (and cost, I guess).  Maybe ONLY drug
> dealers, nuclear terrorists, etc., will use anonymous remailers when full
> sensory virtual interaction is the must popular way for most people to
> communicate and remailers are still the only choice for the
> anonymity-conscious.
puts a different spin on it.  It's a real problem, if not now, then
maybe in 5-10 years.  I realize that those of us in the Phone Company
who have predicted universal Picturephone in the past have been 
over-optimistic :-), but the video compression people and the faster-chip
people keep bringing us closer to having good-quality low-bandwidth video,
and ISDN and fast modems are bringing available loop-end bandwidth up
to the point that reasonably-priced circuits can carry it.  (Long-haul
raw bits have been cheap enough for a while; it's the distribution
and switching technology that have a lot of the cost, and providing
cheap high-bandwidth circuits makes it hard to make money on voice calls.)

The approaches to anonymous video conferencing will depend a bit
on whether the technology takes off on the nets or the phone system,
if those two are still different by then.  It's easier to obscure
the origins of a call on the nets, where users own large parts,
than it is on the phone system, where the Phone Companies own
and operate most of it; the latter environment would require
Phone Remailers, such as PBXs you call into on T1 lines and get
shuffled out on other circuits - it's hard to get adequate mixing
except in rather large environments....  Recircuiting on the nets
will be left as an excercise to the reader.

I suspect the harder parts of the job may be doing the faces and 
voices right - anonymous voice conference bridges are ok if the
participants mostly don't know each other, but they're less useful
if people know each other and cops with computerized voiceprint equipment
may be eavesdropping (not common now, though computers and models of
the human voice are improving; I suppose voice disguisers may improve
from the kid's-toy quality to something better if there's a market,
or if computers with full-duplex soundcards become more common.)

Faces are harder, and they're not really a crypto problem -
how do you fake them well?  It's not too hard to do a "quayletool"
quality solution that generates moving lips in front of a static
picture, even timed with an audio feed, but that won't play too well
in the business world, and having the camera pointing at your calendar
or home page is only semi-useful.  If video-calling evolves on the nets,
there'll be a lot more need for speed-matching services, and it may
be that computer-enhanced video receiving for high-bandwidth users
will fund the technology development for face-simulation?
If so, maybe you can use it to start with fake stills instead of 
real ones?

				Bill

On Sun, 8 Jan 1995 wcs@anchor.ho.att.com wrote:

> My initial reaction to "Anonymous video conferencing" was
> "That's when you wear black ski masks and use voice scramblers
> and call from video payphones", i.e. not very useful.
> ("Subcomandata Marcos here...")

Video conferencing was just ONE of the applications of high-bandwidth, 
low-latency anonymous communication.  Maybe it was a bad example.  Here's 
a couple more:

1.  anonymous distributed computing: suppose Alice wants to help Bob 
crack a secret key by using both of their computers, but the algorithm 
entails some heavy exchange of data between them

2.  anonymous remote consulting: Alice is building a nuclear bomb and 
needs help, so she sends a live video feed of her workshop to Bob (and 
have the computer blot out her face in real time).  Bob sends Alice an audio 
only commentary of what Alice is doing wrong.

We tend to focus on the more exotic applications of these tools, but as
mjk pointed out they will have perfectly ordinary uses by people who
simply don't want everyone in the world to be able to know everything
about them. Maybe Alice just wants to call AT&T to ask about their Clipper
phone, and not have everybody realize that and send her a bunch of
propaganda about Voice PGP.  :-) Even now, this may not be as implausible
as it sounds.  What if Alice is using MCI as the long distance carrier,
and MCI happens to be selling Voice PGP? 

Wei Dai

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In article <9501090353.AA13655@anchor.ho.att.com>,
wcs@anchor.ho.att.com (bill.stewart@pleasantonca.ncr.com +1-510-484-6204) wrote:

> My initial reaction to "Anonymous video conferencing" was
> "That's when you wear black ski masks and use voice scramblers
> and call from video payphones", i.e. not very useful.
> ("Subcomandata Marcos here...")

I thought so too, at first; but then I thought of this obvious application:

The scene is a bare room, with a single chair in the middle.  Seated on the
chair is THE VICTIM, whose head covered in a hood.  The victim's hands
are bound to the armrests, and the legs to those of the chair.

A KIDNAPPER enters the scene and walks over to the victim.  The
kidnapper's face is obscured, either by a hood or ski mask, or by
digital scrambling of the image.  The kidnapper's voice is scrambled
digitally.  The kidnapper pulls the hood off of the victim's head, and
speaks. 

KIDNAPPER:		Okay, you're on!  Talk!

The camera slowly zooms in on the victim's face.

VICTIM (tentatively):	Mom?  Dad?  It's me.

DAD (voice over):	Is that really you, son?  Are you all right?

VICTIM:			It's me.  I'm okay.  This is no picnic, but 
			they're treating me okay, considering.  Listen,
			have a message they want you to pass on to the 
			President.

DAD:			I don't know if I can get it to him.  It's not 
			like we play golf together.  

VICTIM (nervously):	You have to.  You'll find away.  Tell the President
			that he has to pull the troops out of Belgrade.
			If the U.S. forces aren't pulled completely out
			by the end of this month, they say they're going
			to cut me into pieces and send them to you piece
			piece. . . .

etc.

Whether technology is going to be developed for the convenience of 
kidnappers and terrorists is an open question.  But there is clearly 
at least this one clear use for anonymous video conferencing.  There are
probably more.



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