Intro

This smart contract is meant to:

Create proofs of the existence of a Hash (representing some document or text), thus verify their existence

• Owner (and whitelisted others) can create new proofs, like verified time-based document watermarks on the blockchain

• Contract creates proofs as NFT/ERC721, which can be sent to a recipient address

• Whitelisted others can add confirmations for proofs

• Roles:

  • default_admin: contract deployer set as default, can be transferred; is allowed to grant/revoke all roles (admins + whitelists)

  • proof_whitelisted: add/delete proofs; admins are not automatically whitelisted, so that needs to be added if desired

  • confirm_whitelisted: add/delete confirmations of proofs

• Note: Recipient wallets need to be able to handle ER721. For safety reasons, it is not possible to send a token to a contract that does not explicitly support it.

tl/dr instructions

• Tools:

  • Deploy contract via Remix​

  • Use contract interaction via Etherscan​

  • Create doc/string hashes using Hash Calculator​

• proofs

  • whitelist deployment address plus any group of addresses with grantRole() as Proof_Whitelisted using 0xf555e1ec80c58c7664dc73d872d3ef6e07bdd9c5ba6b3bf7a91ffaa413b8dac5

  • create new proof with addProof() using proofHash (hash of a document, file, string, etc.), string (any description of the hash) and the address where the proofHash shall be sent to

  • (If you hold the proof in your address) you can delete it by using deleteProof()

• confirmation of proofs

  • whitelist any group of addresses with grantRole() as Confirm_Whitelisted with 0x53eebd7fe83ace838d6b0a9d4f111237deb02359c62b25f1025613d537b2379b

  • create new confirmation of a proof with addConfirmation() using tokenId

• Review proof data

  • Query either using getProofData() and/or getProofIdByHash() to getproofHash, timestamp, description`

Notable Functions

Read Functions

Write Functions

Swarm - Example Use Cases

Core initial use case

The Swarm Council can publish protocols of decisions taken on GitHub and verify the Hash via VerifiedExistence:

• ​Dedicated contract for VerifiedExistence for Swarm Network

• Contract owner and proof_whitelisted is multisig with council members (tbd)

• Council published documents with hashes;

• Create Proof (Hash + meta data) and proof NFT / ERC721 is sent to dedicated wallet (e.g. Gnosis Safe, which allows ERC721 to be kept as “Collectibles”)

• Example: Swarm Council Votes (SCVs)

  • listed in this repo; text between </hash-start> and </hash-end> tags is hashed

  • create proofs using hash and title; send it to a Swarm Council wallet; e.g proof (SCV_1587031154_Decision regarding_April_Voting_Period.md)

Other potential use cases:

Proof of Masternode

• Smart contract, which tracks verified Masternodes, could be added to proof_whitelisted of a contract put in place by council

• A smart contract / person / process could keep track of active masternodes and create/delete corresponding proofs and send proof NFTs to masternode wallets

• Masternode distributions could be using NFTs held as basis for reward distribution

• Masternodes could be confirming various actions of the Council contract

Masternodes could be added as confirm_whitelisted

• Can then add supporting votes (confirmations) to certain actions