This repo defines a smart contract, EthPublish which allows the publishing of data associated to an Ethereum address. An Ethereum address is the Keccak-256 hash of a secp256k1 elliptic curve public key, truncated to 20 bytes.
The functionality is very similar to the IPNS functionality of IPFS whereby data is published and associated with the hash of a public key defining the node ID of an IPFS node.
The contract accepts a signature, a publisher in the form of an Ethereum address and data in bytes form. If the signature validates the contract will store the mapping from Ethereum address to data.
The signature is taken over the hash of the following:
<0x19> <0x00> <EthPublish contract address> <string "eth-publish"> <nonce of publisher address> <publisher address>, <data>
An incrementing nonce is used to prevent replay attacks where an adversary uses a past signature to republish old data.