EOS Amsterdam Launches Blockchain Signing Tool

EOS Amsterdam
2 min readAug 20, 2020


EOS Amsterdam is constantly working on contributing to the EOSIO ecosystem, and we have recently released a new EOSIO smart contract, “filehashfact”, which allows content creators to sign their work on the blockchain.

The workflow is pretty simple: the author of the content takes a SHA256 checksum from their file, and submits an “addfile” action to the smart contract. The contract then memorizes the the author’s account name, date and transaction ID of the submission, as well as the supplied file name and description.

Any third party can co-sign (endorse) the file, with an optional memo text, confirming the authenticity and correctness of the file. The contract also memorizes the co-signer’s account name, date, and the transaction ID.

The data is stored in blockchain RAM for 1 year, and is available for quick queries. After 1 year, the data is still available in blockchain history, and is available for retrieval. In addition, a small command-line utility for looking up the data on a blockchain is available.

Use cases

There’s a number of use cases for this smart contract:

  • An EOSIO block producer publishes a snapshot of a blockchain, or archival data, and signs the files with “filehashfact”. Other block producers may verify the validity of these files and co-sign, adding more trust to the original data.
  • A software company can sign its software releases. For example, EOS Sweden is publishing its own Debian packages of EOSIO software and its modifications (such as BOS and WAX versions). Users who verified and used these packages can endorse them with their signatures.
  • An artist can claim their authorship of the artwork before it’s used for NFT images. Third party experts can verify and confirm that the artwork is original.

This smart contract is a part of Europechain FACT software suite, and it can also be used as a standalone application, or integrated in other blockchain dApps. It is currently deployed on Europechain, EOS, WAX, Telos, and BOS.

About us

Founding block producer for the EOS mainnet. Telos, Lynx, BOS, and FIO Block Producer. Active top WAX Guild. Partner in the Europechain sister chain. Investor in blockchain projects. Governance, intercultural cooperation, and security specialist. You can find us here:
EOS, Europechain, and Lynx Block Producer name: eosamsterdam
BOS Block Producer name: amsterdambos
Telos Block Producer name: amsterdam
FIO Block Producer name: bp@eosamsterdam
WAX Guild name: amsterdamwax



EOS Amsterdam

Founding block producer for the EOS Mainnet. WAX Guild. Partner in Europechain. Investor in blockchain projects.