Introducing Peer Copy - A fully Decentralized File Transfer Tool

About this talk

In this short conference presentation from IFIP Networking 2021, Dennis Trautwein introduces Peer Copy (pcp), a fully decentralized peer-to-peer file transfer tool built on libp2p and developed with co-authors Moritz Schubotz and Bela Gipp. The talk explains how pcp lets any two parties exchange a file using only a short, memorable sequence of words drawn from the BIP39 wordlist — no accounts, no relay servers, and no central rendezvous service. Trautwein walks through the two-stage protocol: peer discovery happens via multicast DNS when both endpoints sit on the same local network and via provider records in the InterPlanetary File System's distributed hash table when they are separated by the public internet, after which the shared word sequence is fed into a password-authenticated key exchange (PAKE) to derive a strong session key that authenticates the peers and encrypts the transfer. He contrasts this design with established tools like croc and magic-wormhole, which still depend on operator-run rendezvous infrastructure, and presents measurements showing that the fully decentralized approach can match the performance of these centralized alternatives while removing single points of failure and trust.