Subject: RE: Summary of RE: [Sip] Comment, SIP Privacy draft

From: "Christian Huitema" <[email-masked]>
Date: Mon, 15 Apr 2002 09:10:14 -0700

I have heard many contributors assert that to get real anonymity, one
will have to use a relay, e.g. an "anonymizing B2BUA". I would like to
point out a failure in this line of reasoning: anonymizing relays have
been tried before, for e-mail, and the experience was absolutely not
conclusive. In fact, two different kind of anonymizers have been tried:
free ones, that kept absolutely no record, and subscriber-based, which
kept some records. Both have failed, for different reason.

The failure mode of a completely free relay is basically spam, and
similar sort of abuse. There is documentation available on the fate for
example of the cypherpunk experiment: this set of relays was set up to
provide true anonymity on the Internet, using a sophisticated mix of
random redirection and cryptography. In theory, the design was
excellent. In practice, the system was quickly overwhelmed by porn
traffic, and the relays dropped one by one out of the system because
they could not bear the resulting congestion.

Subscriber based relays are relays that keep some state: they actually
identify the sender, before washing out the identity in the outgoing
message. They are more robust to congestion, since they can get some
funding in the process, but they have a different failure mode: lawsuit.
Since they keep some records, the records can be subpoenaed, and the
provider can be forced to disclose the identity of the sending party. In
fact, in many codes, if the providers refuse to do so, they may be
deemed an accomplice of whatever action was carried out in the anonymous
exchange. Many providers have chosen to close their doors rather than
have to defend more lawsuit -- often after a brush with the Church of
Scientology.

If we really want practical anonymity, it has to be based on the UA, and
it should not rely on the help of a third party. We should use a
combination of encryption, pre-paid subscriptions, and anonymous IP
addresses (e.g. IPv6 privacy addresses.)

-- Christian Huitema

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---

From: Chris Martin <[email-masked]>
Date: Wed, 17 Apr 2002 19:58:14 -0500

> have to defend more lawsuit -- often after a brush with the Church of

Privacy, I think, in relation to a service provider is not the same as
anonimity to an Internet based user. Privacy is used to mask the
original user to the called party, and does not prevent law enforcement
from getting the originator of such calls if a law is broken. B2BUA's
implemented by an SP need not contain any user account information to
provide the level of privacy afforded by the B2BUA (topology hiding) as
opposed to the function of privacy which may be implemented by an SP
which may alias the users true identity to <PRIVATE> before sending the
packet on to the B2BUA which can then scrub the IP address. You can
still track the communication to the SP, but then you must use the
proper vehicle to request the proprietary information located in the SP
databases to identify the caller.

How do SP's of PSTN networks cope with lawsuits today when law
enforcement must get this information? I am seriously asking this
question not being sarcastic, anyone know the answer? It seems to me
that the questions have been answered by the the SPs' of the dinosaurs
that we are replacing, we must take some of the lessons learned as a
model for answering these questions dont you think?

> addresses (e.g. IPv6 privacy addresses.)

I can see this for publicly non-service provider hosted UA's as a
possibility, but for those enterprises, SOHO's serviced by SP's
regulations will be developed that require SP's of these types of
communications to have more stringent rules and processes. The
telecommunications industry today must comply with such regualtions for
call traces, wiretaps etc. Every country has some set of regulations
that place these requirements on SP's of our particular flavor of
communications, which though different from the PSTN world will no doubt
adopt many of those same restrictions and regulations for many similar
aspects. I am not versed in the regulations or telecommunications but I
do know that they exist. Many parties in this list have brought many
such examples to the list, which were of great interest to me. 

I think that implementing it on the UA will be a great idea, and
probably will be implemented by many vendors just as NAT and firewall
traversal solutions are today, but in the SP realm many of these
features will not be required to be active and in many cases will be
restricted by policies other than the SP due to the fact that the SP
will most likely provide a centralized functin for this service in order
to meet regulation as well as to meet security policies implemented by
customers of the SP which would look upon such mechanisms as a bypass of
such policies, not to mention not very scalable in larger environments.

Just my 2 cents
Chris