View the demo running on the Ropsten network
This is a proof-of-concept "Dapp" running on the test network. The javascript front-end code is also open-source.
This service provides a way to publicly verify signatures on a digital document without the need for a trusted outside party.
Using the Ethereum blockchain, we can store a hash of a private document (a contract, for example) along with an Ethereum Address. This proves in a public and secure way that the owner of the Ethereum Address has signed the document. Other parties to the contract can sign it as well. All they need is a copy of the original digital document.
The contents of the document remain a secret only known by those who possess the original digital document. This is possible because only the hash of the document is stored and not the document itself.
The original document always generates the same hash. If there is ever a dispute over the details of the document, anybody who possesses the original digital document can generate the hash and show that people have signed it by searching the blockchain for that hash and the accompanying Addresses.
The hash is a cryptographic string that cannot be reverse-engineered. The hash can only be generated by providing the original digital document as a seed.
This project was bootstrapped with Truffle.