-----BEGIN PGP SIGNED MESSAGE----- It seems like there are several problems that arise from this "automatic" anonymization of messages sent through the Penet remailer. You have these security threats which involve people being tricked into sending messages through the remailer in such a way that the recipient knows the true email address from where the messages are coming. (I think that is what happened here with "deadbeat", because otherwise why would he have asked people to send their email addresses? He wouldn't need email addresses since he could reply to people without knowing them, by just using a "reply" command in his mailer.) (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.) Another problem that people have complained about is when they respond to an anonymous posting, they get a message from Penet saying that they now have an anonymous ID assigned. This confuses and bothers some people. We had some debate about this issue here several months ago (before Penet was operating, I think). One question is, if I send mail to anonymous person A, does that mean or imply that I should be made anonymous to A? This is to some extent a matter of expectations. Some people argued that should be no expectation of anonymity in this case; A is the one who wants to be anonymous, not the people who are sending to him/her. Others replied that since some anonymous remailers already worked this way, there would be an expectation of anonymity, and so the safest assumption was to anonymize all messages since people can always override the anonymity by revealing their true addresses. I think these attacks on Penet re-open these questions. Evidentally there is positive harm that can occur by automatically anonymizing all messages which pass through a remailer. (BTW, I certainly don't mean here to be presuming to tell Julf what he should or should not do with Penet. I'm just taking that as an example. We have discussed adding similar functionality to our Cypher- punks remailers. The main problem occurs when sending a message to an anonymous Penet address. For the other uses of the Penet remailer, for anonymous posting and for mail to a non-anonymous address, it's more reasonable to assume that anonymization is desired. (Otherwise, why would they be using the service?) But when sending a message to an anonymous address, it's not known whether the sender wants to be anonymized or not. One possibility (which might not be that easy technically) would be to assign a new anonymous ID for each such message through the Penet server. This means that you would get a _different_ anonymous ID for each of these messages, preventing an attacker from pairing up your "usual" posting ID with your email address. (Perhaps this anonymous ID creation could be suppressed with another X- command, as proposed earlier, but this could be the default behavior.) It might be hard to keep track of that many anonymous ID's, but perhaps they could be kept active for only a limited period of time (several weeks or months) and retired after that. 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. 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. 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. Hal Finney -----BEGIN PGP SIGNATURE----- Version: 2.1 iQCVAgUBK4lfIagTA69YIUw3AQGzQAQApOduiD7P2C26f7ml5tcOJf6xQff7bdV0 qw+zjOevW6hSBunOY59Qstkk5uQ2CoEALDAyUfKRsy7dionBAtCJYlwfX7uclHKL Sonor8bg0NPHMP8SV/antacq00fK3b5wtiFFMn3WsjCvSEjhGoB9SIE/TB/zL9Et Ow8JEodP488= =cXHd -----END PGP SIGNATURE-----