Benjamin McLemore writes:

All I was trying to point out with my post is what I saw as a flaw in my previous understanding of the depth of the security provided by anonymous remailers. There is a difference between relying on the mathematics of strong crypto to protect you from government spooks and prying bureacrats-- and relying on one's belief that- although one's security has been compromised, it will be too expensive or otherwise difficult for the government to use this information against you.

Cypherpunks remailers are far from "ideal digital mixes," as described in David Chaum's February 1981 "Communications of the ACM" paper. This is well known, and the issues of traffic analysis Benjamin raises are also valid and known issues. A while back we had many debates about what to do about message size padding (e.g., quantizing all outgoing packet sizes to a standard size, or perhaps to one of several (small, medium, large. etc.) packet sizes. And we debated adding latency, so that a message waits until N total messages have been received before remailing. And so on. In any case, Chaum's ideal digital mix is hard to implement now for several reasons, largely economic. Ideal mixes also need physical security against tampering, against interception of internal operations (perhaps via RF monitoring), etc. Perhaps most critical, and least studied to date, remailers are only as good as the human policies at the sites are. (My conception of ideal remailers involves remailer hardware, perhaps on boards containing enough RAM and/or disk drive space to hold the batch of messages, that is "untouched" by human hands. Tamper-resistant modules, sealed hardware, etc. Lots of issues here. I think "Mom and Pop remailers" could be sold on boards similar to SoundBlaster boards.) Chaum's original hardware-based mix also has some weaknesses, as noted in a EuroCrypt '89 paper by Pfitzmann and others. The software-based "DC-Net," which comes up so often on this list, is generally better. Several Cypherpunks are interested in implementing DC-nets. So far, no progress to report.

It seems to me that anonymous remailers, despite my initial assumptions that they were cryptographically strong, are probably compromised by the ability of the NSA to monitor Internet backbone traffic, a hypothesis I would love to see disproved. Additionally, my

No, they are very far from being even cryptographically strong (although parts of the process, involving sending encrypted messages to the next node, are of course as secure as, say, PGP is).

I want unbreakable security, untraceable communication and unforgeable digital cash--ALL of it mathematically guaranteed and none of it compromisable by some underpaid bureacrat who might decide to make a little money off of ME in his spare time.

Well, wanting something is not the same thing as getting it. Read the 1981 paper, the 1988 DC-Net paper (available at the soda.berkeley.edu ftp site), and follow the Cypherpunks activities on DC-Nets. Then look at the various Cypherpunks remailers...some _require_ encryption (most don't, and most of us don't even use encryption, which means anyone reading the packets can see what's going on! A fatal flaw or just laziness?), some add hours of latency (though not N latency, as too few messages are flowing), and so on. The market will push development in possibly more secure directions. Right now, you can see that Cyperpunks remailers, and also Julf's penet site, have significant flaws. You get what you pay for (this is a serious point: the lack of real commerce, the volunteer nature of all of this, and the generally "hobby-like" nature of these systems explains why these weaknesses are not getting fixed. These are largely "toy" systems to provide some experience. They'll get better with time. --Tim May -- .......................................................................... Timothy C. May | Crypto Anarchy: encryption, digital money, tcmay@netcom.com | anonymous networks, digital pseudonyms, zero 408-688-5409 | knowledge, reputations, information markets, W.A.S.T.E.: Aptos, CA | black markets, collapse of governments. Higher Power: 2^756839 | Public Key: PGP and MailSafe available. Note: I put time and money into writing this posting. I hope you enjoy it.