From: tcmay@netcom.com (Timothy C. May)
Date: Sat, 7 Jan 95 16:18:40 PST
To: greg@ideath.goldenbear.com (Greg Broiles)
Subject: Re: Anonymity and cost
In-Reply-To: <199501072330.AA30350@ideath.goldenbear.com>
Message-ID: <199501080018.QAA11241@netcom4.netcom.com>
MIME-Version: 1.0
Content-Type: text/plain


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

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