From: an5877@anon.penet.fi (deadbeat)
Date: Mon, 22 Feb 93 23:12:55 PST
To: cypherpunks@toad.com
Subject: Re: Beware of anon.penet.fi message!
Message-ID: <9302230608.AA04870@anon.penet.fi>
MIME-Version: 1.0
Content-Type: text/plain


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David,

> As was said, the doubleblind system is a great idea, but incomplete
> if you want to correspond to someone without revealing your anon id.

Well, I don't agree that doubleblind is a great idea.

For example, if at any time, Alice sends pseudonymously to Bob, Bob can
not reply directly: this would expose his identity at anon.penet.fi.
Bob must reply through a remailer.

Note the irony -- Bob must take special steps to protect his pseudonym
because anon.penet.fi is acting affirmatively to conceal his actual
identity.  If Bob slips up and simply replies, he is exposed.

Hal,

> (It's interesting that he also sent his message via one of the Cypherpunks
> remailers.  Maybe he thought they worked like the Penet remailer and
> he could break anonymity on those as well.)

Actually, I don't know why my message went through a Cypherpunks
remailer -- I didn't ask it to.  I don't know of any weaknesses in
the Cypherpunks remailers (other than extreme vulnerability to social
engineering).

> Evidentally there is positive harm that can occur by automatically
> anonymizing all messages which pass through a remailer.  ... For
> anonymous posting and for mail to a non-anonymous address, it's more
> reasonable to assume that anonymization is desired.  ... But when
> sending a message to an anonymous address, it's not known whether the
> sender wants to be anonymized or not.

I think it's imperative that the sender use X-Anon-To to be
pseudonymous.  This is consistent with the principle of least
astonishment.

> It might seem that people should just be careful about what they
> send through Penet, but there are some problems with this.  What do
> you do if you get a message from an5877@anon.penet.fi asking for
> advice on cryptography mailing lists?  If you reply, your questioner
> can figure out who the reply is coming from, and sees your Penet
> alias.  There is no way to prevent this from happening currently.

A Cypherpunks remailer can be used to conceal the correspondent's
pseudonymous identity.

> Also, I have seen proposals that anonymous ID's should be made less
> recognizable, so that instead of an5877@anon.penet.fi we would have
> joe@serv.uba.edu.  In such a situation it might be tedious to
> scrutinize every email address we send to (via replies, for example)
> to make sure it isn't a remailer where you have an anonymous ID.

It would be a real boon to make pseudonyms less prominent -- this
seems to have kicked over a hornet's nest on USENET (even though
pseudonyms have been quietly in use for years).  But were this the
case, scrutiny would be an understatement.

> All in all, I think some changes need to be made in how anonymous
> addresses are used and implemented in order to provide reasonable
> amounts of security.

I agree that more discussion is in order.  I'm especially concerned 
about the broader issues regarding anonymity through remailers.

DEADBEAT

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