Verulink x Predicate: Faster, safer cross-chain transfers

Cross-chain bridges are essential to blockchain interoperability, but they’re also prime targets for exploits. Verulink, a trusted bridge between Ethereum and Aleo, was designed with strong security in mind, using a multi-attestor model to validate transfers. Initially, this was accomplished through a 24-hour delay to ensure money laundering risk mitigation.

With the integration of Predicate, pre-transaction policy infrastructure, Verulink reduced that delay to just 15 minutes—without sacrificing safety or ARC-100 compliance.

Verulink's multi-attestor security model

Verulink facilitates asset transfers between Ethereum and Aleo using a multi-attestor architecture, with five independent attestors monitoring bridge activity. When a user initiates a transfer, these attestors validate the transaction and sign off before tokens are released on the destination chain

Verulink’s architecture relies on a network of five independent attestors that monitor and validate bridge activity. When a user initiates a transfer, attestors review and approve it before tokens are released on the destination chain.

To minimize exposure to malicious actors, Verulink implemented:

A 24-hour delay in attestation for manual blacklist checks
Static blocklists for high-risk tokens (e.g., USDC, USDT)
A 10% TVL daily withdrawal cap

These mechanisms ensure that every bridge transaction remains secure while reducing exposure to malicious actors.

Real-time compliance with Predicate

The integration of Predicate significantly improved the transaction screening process. By leveraging a comprehensive social graph built on Predicate to assess a wallet address's legitimacy, Verulink detects and prevents transactions from malicious actors.

Here’s how it works.

1. User-Initiated Transfer

The user starts a transfer on the Verulink front end by entering the token, amount, and destination chain address.

2. Predicate Screening API Call

Verulink sends the transfer request to the Predicate Network for address screening.

API Endpoint

POST https://api.predicate.io/v1

Headers

Authorization: Bearer <API_KEY> Content-Type: application/json

Request Body

{ "from": "0xSenderAddress", "to": "0xVerulinkPredicateServiceAddress", "data": "0xEncodedArgs", "value": "1000000000000000000 }

Encoded Function Arguments

packFunctionArgs('_transfer(address,uint256,string)', [ "0xTokenAddress", // Token being bridged "1000000000000000000", // Amount in wei "aleo1recipientaddress..." // Destination Aleo address ])

3. Predicate Response

If the sender is compliant, Predicate responds with:

{ "is_compliant": true, "task_id": "task_abc123", "expiry_block": 23456789, "signers": [ "0xPredicateSigner1", "0xPredicateSigner2", "0xPredicateSigner3" ], "signature": "0xPredicateSignature }

If the address is flagged, a 400 error is returned and the transfer process stops.

4. Transaction Creation and Signing

Verulink creates a transaction using the Predicate-approved message. The user signs and broadcasts this transaction on the source chain.

5. On-Chain Verification

The Verulink smart contract verifies the Predicate signature, checks token blacklists (e.g., USDC/USDT), and enforces withdrawal limits (10% of bridge TVL per day). If everything passes, a transfer event is emitted.

6. Attestor Validation

Attestors detect the transfer event and validate it based on the Predicate response and onchain data. They then sign the transaction within 15 minutes. These signatures are used to release wrapped assets on the destination chain.

Benefits of building policies on Predicate

By integrating Predicate, Verulink has enhanced security and compliance without sacrificing speed. Key benefits include:

Reduced Attestation Delay: From 24 hours to just 15 minutes
Real-Time Compliance: Predicate Network screens each wallet using graph-based analysis
ARC-100 Compliance: Ensuring regulatory adherence at the smart contract level
Layered Security: Predicate complements existing blacklists and withdrawal caps

With Predicate’s automated screening, Verulink has accelerated attestor validation while maintaining strict security controls. This integration strengthens our bridge’s resilience and scalability, positioning Verulink as the most secure gateway between Ethereum and Aleo.