A libp2p protocol for handing a signed dataset to another peer that can serve it as a verifiable replica of the original publisher.
Protocol id /zzzync/push/1.0.0.
sequenceDiagram
autonumber
participant D as Dialer
participant H as Handler
D->>H: open /zzzync/push/1.0.0
D->>H: IPNS key
D->>H: auth frame (optional)
H->>D: challenge nonce
D->>H: dialer nonce + signature
Note over H: signature proves the dialer holds the IPNS key
Note over H: key and auth frame checked by allow.multihash callback
D->>H: IPNS record
Note over H: record checked by allow.record callback
H->>D: record accepted
D->>H: CAR file (root matches the record)
Note over H: every block verified to descend from the root
Note over H: verified record handed to onReceive callback
H->>D: close
A publisher proves it holds an IPNS key, sends a signed IPNS record, and waits for the handler to accept it before streaming a CAR of its content. The handler verifies the signature and the content, then hands the record to your application to pin and serve. The acceptance step matters: the handler is not reading the stream while it runs its checks, so a dialer that sent the CAR straight after the record would pile the whole transfer into a buffer nobody is draining.
The dialer can pass an optional auth frame (a delegation-chain CAR, for example) via dialZzzync's auth option, a function returning the frame's bytes. The handler byte-caps it (default 16KiB, override via CreateHandlerOptions.maxAuthFrameBytes) and hands it to allow.multihash, which runs only after the challenge, so an application callback never sees a key the dialer has not proven it holds.
The result is a durable, verifiable copy that stays available even while the publisher is offline.
npm install @tabcat/zzzyncAPI reference and examples: https://tabcat.github.io/zzzync
Won a gold medal at HACKFS 2022. Additional work was funded by a Protocol Labs grant. Current work is independent.