The Hardy-Littlewood comparison cuts the other way. Two collaborators in the same subfield sharing terminology is the baseline, not evidence of anything. What makes the Back case interesting is convergence on things that have nothing to do with cryptography: the same Napster vs Gnutella analogy, the same celebrity email filtering idea, the same obscure FDR gold ban interest, the same weird hyphenation errors. Pick any two cypherpunks at random and you won't find that kind of overlap on non-technical quirks.

Then add the negative space. Back was one of the most prolific voices on these lists for a decade, especially on digital cash. Satoshi shows up, Back goes quiet. Satoshi leaves, Back comes back. Hardy and Littlewood never had that problem.

>the same Napster vs Gnutella analogy, the same celebrity email filtering idea, the same obscure FDR gold ban interest, the same weird hyphenation errors

Dunno it assumes their cypherpunk group must always discuss strictly cryptography and never discuss anything else. It could be just some off-topic ideas floating around in their community.

For me, the only solid, damning evidence would be statistical methods of text analysis like they do to prove authenticity of a literary work.