Nicholas Tollervey/Holger Krekel - The Return of "The Return of Peer to Peer Computing". At last year's Europython Holger Krekel gave a keynote called "The Return of Peer to Peer Computing". He described how developers, in light of the Snowden surveillance revelations, ought to learn about and build decentralized peer-to-peer systems with strong cryptography. This talk introduces, describes and demonstrates ideas, concepts and code that a group of Pythonistas have been working on since Holger's keynote. We asked ourselves two questions: what are the fundamental elements / abstractions of a peer-to-peer application and, given a reasonable answer to the first question, what can we build? We will present work done so far, discuss the sorts of application that might be written and explore how peer-to-peer technology could be both attractive and viable from an economic point of view. ----- This talk introduces, describes and demonstrates concepts and code created during sprints and via online collaboration by a distributed group of Pythonistas under the working title p4p2p. We asked ourselves, as frameworks such as Zope/Plone, Django, Pyramid or Flask are to web development what would the equivalent sort of framework look like for peer-to-peer application development? We've tackled several different technical issues: remote execution of code among peers, distributed hash tables as a mechanism for peer discovery and data storage, various cryptographic requirements and the nuts and bolts of punching holes in firewalls. Work is ongoing (we have another sprint at the end of March) and the final content of the talk will depend on progress made. However, we expect to touch upon the following (subject to the caveat above): * What is the problem we're trying to solve? * Why P2P? * The story of how we ended up asking the questions outlined in the abstract. * What we've done to address these questions. * An exploration of the sorts of application that could be built using P2P. * A call for helpers and collaboration.