Since a lot of readers seem either unwilling or unable to use the search function I will cross link the relevant posts.
My original post from October 24, 2011, 11:27:48 PM fingering Robert Hettinga as Satoishi based on forum posts:
https://bitcointalk.org/index.php?topic=49751.0A followup post in 2013 dealing with the Szabo issue:
https://bitcointalk.org/index.php?topic=358790.0In 2013, an analysis of the Bitcoin paper suggested it was written by Nick Szabo. I too had noticed that the forum posts and bitcoin paper seem to have been written by different people, but possibly been a collaboration. Since Nick Szabo and Robert Hettinga knew each other very well and were good friends, this introduces the possibility that Bitcoin was a collaboration between the two, with David Chaum doing the coding.
However, my recent thinking is that Szabo cannot have written the paper, despite the Slashdot analysis. The reason for this is that the paper uses Latex, but in a highly non-standard way that appears converted from MS Word, whereas the few times Szabo has published a paper, it uses standard Latex formatting. Also, Szabo's papers feature high-quality, academically informed references. The references in the 2008 Bitcoin paper are the work of an amateur. The overall layout and style of the graphics and objects differ from Szabo's style and tendencies. Therefore, I think my original conclusion still stands: Hettinga wrote both the forum posts and the paper.