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Permissionless blockchain environments necessitate the use of a fast and attack-resilient message propagation protocol for Block and Transaction messages to keep nodes synchronised and avoid forks. We present GossipSub, a gossip-based pubsub protocol, which, in contrast to past pubsub protocols, incorporates resilience against a wide spectrum of attacks. Firstly, GossipSub's mesh construction implements an eager push model keeps the fan-out of the pubsub delivery low and balances excessive bandwidth consumption and fast message propagation throughout the mesh. Secondly, through gossip dissemination, GossipSub realises a lazy-pull model to reach nodes far-away or outside the mesh. Thirdly, through constant observation, nodes maintain a score profile for the peers they are connected to, allowing them to choose the most well-behaved nodes to include in the mesh. Finally, and most importantly, a number of tailor-made mitigation strategies designed specifically for these three components make GossipSub resilient against the most challenging Sybilbased attacks. We test GossipSub in a testbed environment involving more than 5000 VM nodes deployed on AWS and show that it stays immune to all considered attacks. Gos-sipSub is currently being integrated as the main messaging layer protocol in the Filecoin and the Ethereum 2.0 (ETH2.0) blockchains.

Recent data ownership initiatives such as GAIA-X attempt to shift from currently common centralised cloud storage solutions to decentralised alternatives, which gives users more control over their data. The InterPlanetary File System (IPFS) is a storage architecture which attempts to provide decentralised cloud storage by building on founding principles of P2P networking and content addressing. It combines approaches from previous research, such as Kademliabased Distributed Hash Tables (DHTs), git's versioning model with cryptographic hashing, Merkle Trees, and content-based addressing in order to compose a protocol stack that supports both forward and backward compatibility of components. IPFS is used by more than 250k peers per month and serves tens of millions of requests per day, which makes it an interesting large-scale operational network to study. In this editorial, we provide an overview of the IPFS design and its core features, along with the opportunities that it opens as well as the challenges that it faces because of its properties. IPFS provides persistence of names, censorship circumvention, built-in file deduplication with integrity verification, and file delivery to external users via an HTTP gateway, among other properties.

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