Pseudonymous Mixmaster

I’ve been thinking a bit over the last few days about why a Mixmaster user cannot receive replies to messages. Obviously the repies cannot be delivered to an email address as Mixmaster contains no Reply-Block functionality, but there’s no reason I can think of why replies can’t be encrypted and dropped into a global message pool such as a Usenet group.

In order for this concept to work, replies would have to be delivered to a form of Nymserver with the functionality to perform the encryption and post the message to Usenet. The big hiccup is that the Nymserver must have knowledge of the final user. Not their identity, but a password used to conventionaly encrypt each message. Without this conventional encryption, (over the top of PGP), the PGP key would provide linkability between messages destined for a single user.

My initial thoughts are that the Mixmaster user would create a payload that included all the headers required for delivery, these being:-
To, Subject, References and In-Reply-To
The message would then be PGP encrypted using a private key and delivered via Mixmaster to the Nymserver. The Nymserver would then extract the headers from the payload and assemble an outgoing message to the recipient. The From address would be extracted from the PGP key.

When replied to, a message would arrive at the Nymserver where it would be PGP encrypted to the Nym user and then conventionally encrypted using the user-supplied passphrase. The subject would be prepended by the nym address and conventionally encrypted. This provides the recipient with an easy means to identify postings for himself when attempting to decrypt all the Subject headers in the Newsgroup.

That’s it for the preliminary design thoughts. My nagging doubt is whether it’s worth the effort. To be worth the effort, it must be at least as good as current Type-I Nym’s. Then there’s Mixminion. Is there any point me spending much of my time trying to come up with a weak system like this when Mixminion has the potential to be so much better?

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