Anonymity and cost

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Wei Dai writes:

> Anonymous e-mail that goes through a chain of N remailers will cost at
> least N times as much bandwidth and have N times as much latency as normal
> e-mail.  But e-mail is hardly the state-of-the-art of network
> communication, while anonymous e-mail IS the state of the art for
> anonymous communication.  How long will it take for the technology of
> anonymous video conferencing to develope, for example?  By then, of
> course, those who are not concerned with anonymity will probably have
> things such as full sensory virtual interaction. 

At a very basic level, anonymous (not pseudonymous, like the remailers
are) messages are *cheaper*, because they carry less information; they
do not need to send the bits which identify the sender. 

This conversation seems to elide distinctions between low-level
anonymity (where source information is simply not transmitted) and
high-level anonymity, where source information is transmitted but is
not used for social or political reasons.

Anonymous remailers are considered "anonymous" because (some of us)
agree that we won't treat the "From:" line as indicating the real
author of the text below. We agree this because we know how
remailers work; we know that (probably) the person who wrote the
message isn't the same person as the owner of the "From:" address.

When we say a message is "anonymous" we mean that its real author
should not/cannot be connected with the text of the message. We could
just as easily agree on an "Identify-Author:" header field by which
authors could indicate whether or not they wished to be speaking
"on the record" when they wrote the message. 

A multi-hop message where the "From:" line changes with each hop
costs almost precisely what a multi-hop message would cost without
the "From:" line changes. Folks feeling detail-oriented can calculate
the cost of the CPU time to strip header information vs. the cost of
sending that header information to the next hop. I don't care about
the answer, so I'm not going to.

Anonymous video conferencing is available now; go to Kinko's, pay
cash for the use of their video conference room. Or, ask/convince
the recipient to consider the conversation "off the record". 

Current remailer operators experience a cost in that they 
receive some amount of hassle and exposure to liability by
running remailers; but this is merely a "cost" shifted from one
person (the author) to another, the surrogate author. This may
look like a cost of anonymity but it's more accurately 
described as the cost of being provocative or rude or illegal.


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Greg Broiles wrote:

> At a very basic level, anonymous (not pseudonymous, like the remailers
> are) messages are *cheaper*, because they carry less information; they
> do not need to send the bits which identify the sender. 

I think the meaning of "anonymous" here is clearly with respect to
_traffic analysis_. The "cost of anonymity" is with respect to the
costs and delays of using digital mixes (remailers)). The relatively
few bytes of header information don't affect the cost in any
substantive way.

> This conversation seems to elide distinctions between low-level
> anonymity (where source information is simply not transmitted) and
> high-level anonymity, where source information is transmitted but is
> not used for social or political reasons.

Again, traffic analysis is the issue. (And I don't necessarily mean
NSA-type traffic analysis...Net-savvy investigators can trace messages
back to origins even when a message is ostensibly anonymous. So far as
I know, some form of mix/remailer is needed to ensure anonymity.))0

> A multi-hop message where the "From:" line changes with each hop
> costs almost precisely what a multi-hop message would cost without
> the "From:" line changes. Folks feeling detail-oriented can calculate
> the cost of the CPU time to strip header information vs. the cost of
> sending that header information to the next hop. I don't care about
> the answer, so I'm not going to.

??? 

This is not the "cost" that is being discussed. Stripping or changing
headers is a trivial cost compared to the latency delays that may
result when mix reordering is done (how much latency is involved is a
function of several things, including reordering desired ("N"), amount
of other traffic).

> Anonymous video conferencing is available now; go to Kinko's, pay
> cash for the use of their video conference room. Or, ask/convince
> the recipient to consider the conversation "off the record". 

Neither of these kinds of "anonymity" are cryptographically
interesting, or strong.

--Tim May

-- 
..........................................................................
Timothy C. May         | Crypto Anarchy: encryption, digital money,  
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Tim May wrote:

> > At a very basic level, anonymous (not pseudonymous, like the remailers
> > are) messages are *cheaper*, because they carry less information; they
> > do not need to send the bits which identify the sender. 

> I think the meaning of "anonymous" here is clearly with respect to
> _traffic analysis_. The "cost of anonymity" is with respect to the
> costs and delays of using digital mixes (remailers)).

I don't think it's useful to redefine "anonymous" to include some 
messages which identify the author, and to exclude some messages which
do not identify the author. Then again, I'm not sure it's useful to
play Language Cop, either. But count mine as a voice in favor of
describing accurately what's being discussed. (Perhaps messages which
defy traffic analysis might be called "untraceable" but not 
"anonymous", unless they also do not identify an author.)

> > Anonymous video conferencing is available now; go to Kinko's, pay
> > cash for the use of their video conference room. Or, ask/convince
> > the recipient to consider the conversation "off the record". 

> Neither of these kinds of "anonymity" are cryptographically
> interesting, or strong.

I agree. I fear I've been influenced by some of the authors on that
Cypher[something] list who've recently argued persausively in favor
of applying technology appropriate to local conditions; e.g., not
wasting time on the techno-gadget-of-the-month when more pedestrian
but functional means are available.


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