Forwarded message:
Subject: Re: Remailers and ecash (fwd) Date: Wed, 1 Oct 97 23:56:19 -0400 From: "Brian B. Riley" <brianbr@together.net>
And why does this by any security when it's the header info and contents that Mallet looks at, not the frequency. The only thing such approaches do is impliment security by obscurity, and that ain't security.
What header info?, its all messages to the remailer with nondescript info .. from that point the latency and mix takes over. The meaningful message looks no different from the 'cover' traffic.
Mallet will be following the cover traffic, since it is cover there will be no correllation uncovered between input and output traffic because the output traffic header info will either be a small class of destinations used over and over or else it will be chosen randomly using something like a spider on webpages or a usenet newsgroup crawler. Just send the bogus packets to random addresses, talk about spam with a bite... <hint: the LEA's would then instigate an investigation of the randomly selected target, depleting their resources, this might buy you 2-3 days if you got two halves of a clue to rub together> <speculation: anything short of several thousand entries in the bogus destinations will be trivial to track> <obvious: once a bogus address is used and known by the LEA's it will be worthless to send any further packets there> <obvious: all this traffic analysis will be done by computers with very nice databases so it might take one or two agents to review the full traffic set for just about any time frame under review> <speculation: given a determined and well equiped Mallet it should take no more than a week to 10 days to resolve the analysis if the destination party is a small set, say <= dozen, using todays remailers and traffic levels. Previously it was mentioned that one remailer handled about 4300 pieces a day, something Oracle or Sybase wouldn't have a problem with> <speculation: currently remailers are not seriously bothered by the BIG Big Brother's because it is not worth validating the paranoids out there that they are being watched> For the sender to chain from remailer to remailer to destination the destination has to be in the header info somewhere. Now in the most secure system each packet header will only contain the address of the next hop. When the next site gets it the packet contents are de-crypted (otherwise reading the chaining info is trivial) and the contents are uncovered to reveal another packet with the next hop header and another encrypted block. And on and on we go. <Question: Are there any remailer sets that impliment the encrypted nested packet system?> <speculation: an encrypted chain could be made stronger if the next hop header depended on which key was used to decode it. In other words, remailer A's key will produce one next hop address while remailer B's key will send it elsewhere. This is a subset of the different plaintext - same cyphertext problem - a hard problem as I understand it. Find two distinct texts that encrypt with different keys to the same cyphertext> Now if I were tasked with traffic analysis of this sort I would look at each incoming header and each outgoing header. I would look for some sort of correlation (ie some percentage of the time when I see this source address I see this destination address within some period) over time between the steps in the chain. Realisticaly it would take at least a dozen or so transmissions using the same remailer chain before a clear pattern would emerge. In general there are two types of classes in traffic analysis. The first is monitoring of a specific entity involved in the transfer, usualy source or destination. The second is passive traffic monitoring where I simply go from remailer to remailer and find statistical correlation between the various packets in the hope that somewhere somewhen I would come across something of use. <observation: without latency being added simply shuffling the messages will not significantly hamper the analysis. To be most effective the latencies should be randomly chosen. This implies that for best security the content of the traffic should not be greatly time sensitive. It furher implies that such traffic should be over a significant range, at least an order of magnitude say> <suggestion: I learned of the basics of traffic analysis from following the study of dinosaur teeth and trying to determine which type they were. Different dinosaurs leave distinctive but different types of scratches on their teeth. By applying statistics to the measurements it becomes possible to assign them to specific types> The first type is the most commen currently but with the various requests by the FBI and other LEA's it is becoming clear they want to get into the second class of traffic analysis in a big way. Guess they are finding it harder and harder to get the big-wigs like the drug cartels because they use a higher degree of technology than the LEA's do, they're simply out-classed. With the second class they could catch a email (for example) from some end user buying a couple of quarters of pot and then chase that chain in reverse. Without the passive second class monitoring they would have never gotten that lead in the first place. Now consider the LEA's think nothing of monitoring a suspect for years if required. I know of one case where the DEA spent 2 years tracking a 'kingpin' for 45 tons of herb. They even brought in specialist from the NSA and military to do covert monitoring for the over-seas participants, including traffic analysis of their communications. <observation: Blackhawks have a pretty nifty electronics system, watching downtown Bagdad via a sat link while flying along playing with Internet email and using your FLIR to not hit the cables between the poles> If they ain't LEA's then a whole new set of options become available. Also consider, if they aren't LEA's then they are probably doing a class one traffic analysis which is only a matter of time to resolve. Considering the current number of anonymous remailers it would not surprise me if the CIA/NSA/Massad/MI5/etc. are not currently monitoring them all. It is a given that countries like Iraq, Singapore, China, etc. are currently doing about all they can to monitor the remailers because they are known to be used by 'terrorist' organizations. It seems to me that many people have an inherent (and unrecognized) assumption that Mallet will have access only to a single remailer and won't bother actualy tracing the traffic. A bad assumption. It is also worth remembering, the government as a whole is quite slow but there are some quite capable individuals. ____________________________________________________________________ | | | The financial policy of the welfare state requires that there | | be no way for the owners of wealth to protect themselves. | | | | -Alan Greenspan- | | | | _____ The Armadillo Group | | ,::////;::-. Austin, Tx. USA | | /:'///// ``::>/|/ http:// www.ssz.com/ | | .', |||| `/( e\ | | -====~~mm-'`-```-mm --'- Jim Choate | | ravage@ssz.com | | 512-451-7087 | |____________________________________________________________________|