Setting Up a Blockchain-Based Conflict of Interest Registry

A conflict of interest (COI) registry is a critical governance tool for organizations, tracking relationships that could influence decision-making. Traditional registries rely on centralized databases or manual forms, which are prone to human error, retroactive edits, and lack of verifiable audit trails. Blockchain technology offers a paradigm shift by providing an immutable ledger where each disclosure is a permanent, timestamped record. This creates a single source of truth that is transparent to authorized parties and cryptographically secured against unauthorized modification.

The core of a blockchain-based COI system is a smart contract deployed on a network like Ethereum, Polygon, or a private consortium chain. This contract defines the data structure for a disclosure—typically including the disclosing party's identifier, the nature of the conflict, related parties, dates, and a status flag. Key functions allow users to submitDisclosure(), updateStatus(), and queryDisclosures(). Because transactions require a cryptographic signature, each entry is non-repudiable and directly attributable to a specific individual's wallet address.

For developers, setting up the registry begins with writing the smart contract logic. A basic Solidity struct might define a Disclosure with fields like address discloser, string description, uint256 timestamp, and bool isActive. The contract's state—a mapping of IDs to Disclosure structs—is stored on-chain. Front-end applications, built with frameworks like React and libraries such as ethers.js or web3.js, interact with this contract. They enable users to connect their wallets (e.g., MetaMask) and submit transactions that call the contract functions, paying the necessary gas fees.

Automation is a key advantage. Smart contracts can enforce business rules programmatically. For example, a rule could automatically flag a procurement approval if the reviewing officer has a recent, active disclosure linked to the vendor. This logic executes deterministically based on the on-chain data, removing manual oversight delays. Furthermore, zero-knowledge proofs (ZKPs) or custom access controls can be integrated to manage confidentiality, allowing sensitive details to be verified without being fully exposed on the public ledger.

Implementing this system requires careful planning around key management (using hardware wallets or multi-sig for administrative keys), data privacy (using hashes or encryption for sensitive fields), and cost optimization (selecting a blockchain with low transaction fees for high-volume use). The result is a robust, automated registry that enhances compliance, reduces administrative burden, and builds institutional trust through technological transparency and integrity.

Before writing a single line of code, you need a solid foundation in core Web3 technologies. Proficiency in JavaScript or TypeScript is non-negotiable for interacting with smart contracts and building the frontend. You must understand Ethereum fundamentals, including accounts, gas, transactions, and the EVM. A working knowledge of smart contract development with Solidity (or Vyper) is essential for creating the registry's logic. Familiarity with decentralized storage solutions like IPFS or Arweave is also crucial for storing supporting documents off-chain while maintaining cryptographic integrity on-chain.

Your development environment requires specific tooling. Install Node.js (v18 or later) and a package manager like npm or yarn. You will use Hardhat or Foundry as your development framework for compiling, testing, and deploying smart contracts; these tools provide local blockchain networks for rapid iteration. For wallet interaction and frontend development, the MetaMask browser extension and the ethers.js or web3.js libraries are standard. Finally, set up an account on a blockchain explorer like Etherscan (for Ethereum) or its equivalent for your target chain to verify and interact with deployed contracts.

For the registry's backend logic, you'll write smart contracts in Solidity 0.8.x, leveraging OpenZeppelin's audited contracts for security-critical components like AccessControl. The frontend can be built with a modern framework like Next.js or Vite, using Wagmi and Viem for streamlined Ethereum interaction. You'll need access to a blockchain node provider (such as Alchemy, Infura, or a private node) for reading chain data and broadcasting transactions. For the final step, prepare a wallet with testnet ETH (e.g., from a Sepolia faucet) to pay for deployment gas costs before moving to mainnet.

A Conflict of Interest (COI) registry is fundamentally a structured database of relationships. Your smart contract must define the data schema for each entry. Essential fields include the declarant (an Ethereum address), the counterparty (another address or identifier), the relationshipType (e.g., "financial interest", "family member", "board position"), and a description string. Timestamps for declaration and last update are also critical for audit trails. This schema is implemented using Solidity structs.

Access control is paramount for data integrity and compliance. The contract should implement a role-based system, typically using OpenZeppelin's AccessControl library. Core roles include:

• REGISTRAR: A trusted address (or multisig) permitted to submit or update declarations on behalf of users.
• AUDITOR: A read-only role with permission to view all records for compliance checks.
• DEFAULT_ADMIN_ROLE: Manages the other roles. This ensures that only authorized entities can modify the registry, while designated auditors can verify entries without alteration rights.

The contract's state-changing functions will center on CRUD operations—Create, Read, Update. However, to preserve a non-repudiable history, we design for immutability. Instead of allowing deletions, we implement a state flag like isActive. Declarations can be superseded by new entries and marked inactive, but the historical record remains permanently on-chain. This is a key compliance feature, as it creates an auditable, tamper-proof ledger of all submissions.

Consider gas optimization and future-proofing during design. Storing large description text on-chain is expensive. A common pattern is to store a reference hash (like a CID if using IPFS) on-chain while keeping the full document off-chain. Also, design events meticulously. Emitting detailed DeclarationSubmitted and DeclarationUpdated events allows off-chain indexers (like The Graph) to efficiently track the registry's history, which is essential for building a frontend or compliance dashboard.

Finally, map out the initial deployment and upgrade strategy. For a production registry, you will likely use a proxy pattern (e.g., Transparent Proxy or UUPS) from OpenZeppelin to allow for future bug fixes and improvements without losing the accumulated data. The initial design should separate logic from data storage to facilitate this. This step, done before writing a line of code, prevents costly architectural changes later.

A blockchain wallet address is a pseudonymous identifier, insufficient for a formal registry requiring real-world accountability. Decentralized Identifiers (DIDs) solve this by creating a persistent, cryptographically verifiable identifier controlled by the user, independent of any centralized registry. For a conflict of interest registry, each participant—be it an employee, board member, or external contractor—would generate their own DID. This DID becomes their primary identity anchor in the system, to which all subsequent verifiable credentials (VCs) about their affiliations and holdings are linked.

The core standard for implementing DIDs is the W3C's Decentralized Identifiers (DIDs) v1.0. You must choose a DID method that defines how the DID is created, resolved, updated, and deactivated on a specific blockchain or network. For Ethereum-based systems, did:ethr (used by the uPort/Veramo ecosystem) and did:pkh (used by Ceramic/IDX) are common. For a Polygon or other EVM chain registry, did:polygonid offers a full suite of tools. The method dictates the format; for example, a did:ethr DID looks like did:ethr:0x5B38Da6a701c568545dCfcB03FcB875f56beddC4.

Implementation requires a DID resolver, a software component that takes a DID string and returns its associated DID Document (DIDDoc). This JSON-LD document contains the public keys, service endpoints, and verification methods that allow others to interact with and verify proofs from that identity. You can run your own resolver or use a public one. In code, using the did-resolver library and the ethr-did-resolver for Ethereum, you can resolve a DID to inspect its keys:

javascriptCopy
import { Resolver } from 'did-resolver';
import { getResolver } from 'ethr-did-resolver';
const providerConfig = { networks: [{ name: 'mainnet', rpcUrl: 'https://mainnet.infura.io/v3/YOUR_KEY' }] };
const ethrResolver = getResolver(providerConfig);
const resolver = new Resolver(ethrResolver);
const didDoc = await resolver.resolve('did:ethr:0x5B38Da6a701c568545dCfcB03FcB875f56beddC4');

The user's private key, stored securely in their wallet, allows them to prove control of their DID. This is used to sign Verifiable Credentials issued to them (e.g., an "Employee Credential" from HR) and to create Verifiable Presentations when they need to disclose certain credentials to the registry smart contract. The registry contract doesn't store personal data; it stores cryptographic commitments (like hashes) of the credentials and verifies the signatures against the public keys in the resolved DIDDoc. This pattern ensures data minimization and user sovereignty.

For a production registry, consider using an identity wallet SDK like Veramo or SpruceID's Kepler to handle the complexity of DID management, credential signing, and storage. These frameworks provide APIs for creating DIDs, issuing VCs, and generating presentations. The final architecture sees the registry smart contract acting as a verifier, checking the validity of a DID-based presentation that discloses a conflict, while the actual credential data can be stored off-chain in the user's own encrypted storage (e.g., Ceramic, IPFS, or a private cloud), referenced via a content identifier (CID).

The heart of the registry is the function for submitting a new declaration. This function must record the essential details of a potential conflict, such as the declarant (the person making the declaration), the counterparty (the entity with whom the conflict exists), the relationshipType (e.g., financial, familial, advisory), and a description. A critical best practice is to emit an event, such as DeclarationSubmitted, containing all these details. Events provide a gas-efficient, queryable log for off-chain applications to track submissions. The function should also include a check, like onlyRegisteredUser, to ensure only authorized addresses can submit declarations.

For updating declarations, you need a separate function that allows a declarant to modify an existing record, typically by its unique declarationId. This function must enforce that only the original declarant (using msg.sender) can update their own entry. It should accept the same parameters as the submission function and overwrite the stored data in the contract's mapping. Crucially, it must also emit an DeclarationUpdated event. This creates a transparent, immutable audit trail. Without this event, external systems would have no efficient way to detect changes to the on-chain state.

Robust input validation is non-negotiable for trust and data integrity. Your functions should revert transactions if critical validations fail. Key checks include: verifying the declarant and counterparty addresses are not zero, ensuring the declarationId exists before allowing an update, and confirming the relationshipType matches a predefined set of allowed values (e.g., stored in an enum). Using Solidity's require() statements for these conditions prevents invalid or malicious data from being written to the blockchain, protecting the registry's reliability.

Consider the state variable structure that underpins these functions. A typical pattern uses a mapping(uint256 => DeclarationStruct) to store declarations by ID, and a mapping(address => uint256[]) to track all declaration IDs submitted by a given address. The DeclarationStruct itself would contain the declarant's address, timestamp, and the declaration details. This design allows efficient lookup both by the declaration's unique ID and by the declarant's address, which is essential for building user-facing interfaces that display a person's submission history.

Finally, integrate these functions with the access control mechanism established in Step 2. Decorate your submitDeclaration and updateDeclaration functions with the appropriate modifier, such as onlyRole(DECLARANT_ROLE). This ensures the contract's permission rules are centrally managed and consistently applied. The complete logic flow is: 1) Check role-based permissions, 2) Validate all input parameters, 3) Update the contract's storage mappings, and 4) Emit a corresponding event. This pattern ensures a secure, auditable, and functional core for your Conflict of Interest Registry.

The checkForConflict function is the automated engine of your registry. It must be called every time a new relationship is proposed for registration. Its primary job is to query the on-chain storage—typically a mapping or array—to see if the involved entities (e.g., entityA and entityB) already have a declared relationship. In Solidity, this involves comparing the new proposal's hashed identifier against a stored data structure. A basic check might look for an exact match, but more sophisticated logic can be implemented.

For a robust system, consider implementing multi-faceted checks. Beyond a simple direct match, your function should also check for indirect conflicts. For example, if EntityA is registering a relationship with EntityB, you should also verify that EntityA isn't already linked to a parent company or subsidiary of EntityB. This requires storing and traversing a graph-like structure on-chain, which can be gas-intensive, or utilizing an off-chain oracle for complex corporate hierarchies.

The function's return value is critical for workflow integration. It should return a clear status, such as a bool for conflictFound and a string or enum detailing the conflictType (e.g., "DIRECT_CONFLICT", "INDIRECT_AFFILIATION"). This output will determine the next step: either allowing automatic registration for clean entries or routing the proposal to a manual review process managed by a multisig or DAO vote.

Optimizing this function for gas efficiency is essential, as it may be called frequently. Use view or pure function modifiers where possible, as they don't require gas when called externally. Store data using efficient patterns like mapping bytes32 identifiers to structs. For complex relationship graphs, consider storing only the minimal data on-chain (like a merkle root of the relationship tree) and deferring detailed analysis to an off-chain indexer or oracle like Chainlink.

Finally, ensure the conflict logic is upgradeable to adapt to new regulations or entity structures. Using a proxy pattern (like the Transparent Proxy or UUPS) allows you to deploy a new implementation of the conflict-checking logic without migrating the stored registry data. Emit a clear ConflictCheckPerformed event with all relevant parameters (proposer, entities, result) for full transparency and off-chain monitoring.

The frontend acts as the primary user interface for the registry, translating user actions into blockchain transactions. We'll use a React application with Ethers.js v6 for wallet connection and contract interaction, and Vite for a fast development setup. The core flow involves: - Connecting a user's wallet (like MetaMask) via window.ethereum. - Instantiating a contract object using the ABI and deployed address. - Calling the submitDisclosure and getDisclosuresFor functions. A minimal UI will include a connection button, a form for new submissions, and a display area for existing records.

Start by initializing a new Vite React project: npm create vite@latest conflict-registry-frontend -- --template react. Then, install the essential dependencies: npm install ethers@6. In your main application component, you must first detect the Ethereum provider. Use window.ethereum to request account access, which triggers the wallet's connection prompt. Upon successful connection, you can create a Web3Provider and a Signer object, which are necessary for sending transactions that require the user's signature, such as submitting a new disclosure.

With the signer, instantiate the contract. You'll need the Contract ABI (Application Binary Interface), which is the JSON representation of your smart contract's functions, and the deployed contract address from Step 4. The code to create the contract instance looks like: const contract = new ethers.Contract(contractAddress, contractABI, signer);. This object now exposes all your contract's methods. Calling the read-only getDisclosuresFor function is straightforward: const disclosures = await contract.getDisclosuresFor(address);. For submitting a transaction, you call submitDisclosure with the required parameters, which returns a transaction response you can await.

When building the submission form, you must handle the disclosureText and relatedParties fields as defined in your Solidity struct. Before sending, consider implementing client-side validation and informing the user about gas fees. After the transaction is broadcast, use the returned transaction receipt to confirm on-chain inclusion. It's good practice to display a pending state and then update the UI with the new data by re-fetching the disclosures for the user's address. This provides immediate feedback and reinforces the permanence of the on-chain record.

For a production-ready application, integrate state management (like React Context or Zustand) to globally manage the connection state, user address, and contract instance. Implement robust error handling for rejected transactions, network switches, and contract reverts. The frontend should also be able to read disclosures for any Ethereum address, not just the connected one, by using a read-only provider (e.g., ethers.JsonRpcProvider) with a public RPC endpoint from services like Alchemy or Infura. Finally, consider adding event listeners using contract.on to update the UI in real-time when new disclosures are submitted, creating a dynamic experience.

A successful deployment is just the beginning. The true test of a blockchain-based conflict of interest registry is its operational resilience and trustworthiness over time. This requires establishing a robust auditing and monitoring framework. You should implement automated scripts using tools like Hardhat or Foundry to run regular security checks against your live contract. Monitor for unusual transaction patterns on-chain using services like Tenderly or OpenZeppelin Defender, which can alert you to potential governance attacks or unauthorized access attempts. Regular code reviews and dependency updates are non-negotiable for maintaining security.

For public, permissionless registries, consider submitting your smart contracts for a professional audit from firms like Trail of Bits, OpenZeppelin, or CertiK. An audit report provides third-party validation of your system's security, which is critical for institutional adoption. If your registry is private or consortium-based, establish an internal audit schedule and a bug bounty program on platforms like Immunefi to incentivize responsible disclosure of vulnerabilities. Document all audit findings and remediation steps transparently for stakeholders.

Governance is the next critical phase. Define clear processes for how registry parameters can be updated. Will you use a multisig wallet controlled by key stakeholders, a more complex DAO structure using Snapshot and a governance token, or off-chain legal agreements? For example, a TimelockController contract can be added to introduce a mandatory delay between a governance proposal and its execution, giving participants time to react to potentially harmful changes. Document this governance model clearly for all users.

Finally, plan for the future. Smart contracts are immutable, but requirements evolve. Design your system with upgradeability in mind using transparent proxy patterns (like the OpenZeppelin Upgrades plugin) or a robust data migration strategy. However, use upgrades sparingly, as each one can impact trust. Prepare documentation for integrating with external compliance tools and consider how your registry's on-chain data could be leveraged by DeFi protocols, KYC providers, or enterprise risk management systems to create a broader ecosystem of trust.