Summary: Some subjects are encrypted MD5 hashes of the real subject.

[The text below is a summary of posts by "Ahab", Saddle
<hung@plainmail.com> and Doc.Cypher from the thread "RANDOM STRINGS"
containing the "Message-ID:" above.]

On Mon, 9 Apr 2001, "Public <Anonymous_Account>" <remailer@xganon.com>
wrote:
> Most of the messages in <alt.anonymous.messages> are PGP encrypted
> but what are the random strings of numbers and letters which appear
> in the subject line?

Some people configure their nym accounts to have incoming email
messages delivered to newsgroup <alt.anonymous.messages> (AAM) instead
of to an email address.  To find their messages among the many in AAM
without disclosing their identity, the "Subject:" line contains
information encrypted to a key only they know.

This process is automated if you use Jack B Nymble (JBN).  A freeware
DLL (PSESUB32.DLL) called the Esub plugin adds encrypted subject
scanning support to JBN versions 2.1.d and later, and Esub support to
Reliable versions 1.0.1 and later:

	<http://www.skuz.net/potatoware/esubplug.html>

RProcess included the Esub plugin with JBN2.1.4.

An more detailed explanation is in the Reliable User's Manual:

<http://www.theinternet.cc/potatoware/jbn2/JBNR-en.htm#dirEncryptSubject>

According to the Reliable User's Manual, the "random" strings of
numbers and letters which appear in the "Subject:" line are encrypted
MD5 hashes of the final "Subject:" line.  That is, the remailer client
calculates an MD5 hash from the "Subject:" line(which might be, e.g.,
"ATTN: Dave") in the final or hash headers (below the "##").  This MD5
hash that results from this calculation is likely to be unique to that
particular "Subject:" line.  The remailer client then encrypts the MD5
hash using conventional (symmetric) encryption, specifically IDEA.
The encryption and decryption key is the passphrase given for the
"Encrypt-Subject:" directive.