[derefr]

I believe there is a Usenet newsgroup, somewhere under alt.binaries, that's effectively a numbers station: it's just GPG-encrypted (but not signed) blobs with no titles. Anyone can post, anyone can listen, everyone has to download everything to figure out which things they can personally decrypt.

Sadly, googling related keywords doesn't seem to pull up the name of the newsgroup. I believe I read about it during a discussion on a Tor onion-site forum, on "why people keep getting caught doing illegal things on Tor, and what real OPSEC looks like."

[kstrauser]

I think you're thinking of Mixmaster: http://mixmaster.sourceforge.net/faq.shtml

[schoen]

More likely alt.anonymous.messages, as a Usenet newsgroup.

[schoen]

Historically the newsgroup meant for this purpose was alt.anonymous.messages. I'm not sure how much use it sees nowadays.

[cgb223]

If someone could find a link to this that would be incredible