Wrapped HBAR (WHBAR)

WHBAR (ERC) in the Hedera Ecosystem

Core Functionalities

• Deposit & Mint: When you call the deposit() function and send HBAR, the contract mints an equivalent amount of WHBAR. Each unit of HBAR (represented in tinybars with 8 decimals) is matched with one unit of WHBAR. This ensures that the wrapped token maintains parity with the native token.
• Withdraw & Burn: To redeem your underlying HBAR, you call the withdraw(amount) function. The contract burns the specified WHBAR tokens and releases the corresponding HBAR back to your wallet. This burn mechanism is crucial for maintaining the correct token supply and preserving the peg between HBAR and WHBAR.
• ERC20 Standard Compliance: WHBAR implements all standard ERC20 functions (e.g., transfer, approve, transferFrom), ensuring seamless interaction with wallets, exchanges, and various DeFi protocols that support ERC20 tokens.

Implementation Guide

Wrapping HBAR

• Native HBAR: 8 decimal places (tinybars).
• WHBAR (ERC20): 8 decimal places (decimals = 8), 1:1 with tinybars.

• From Solidity (another contract calls WHBAR): msg.value is in tinybars, so 10 HBAR is 10 * 10**8.
• From a client through the JSON-RPC relay (ethers, viem, a wallet): the transaction value is in 18-decimal weibars, so 10 HBAR is parseEther("10"). The network converts it to tinybars before deposit() runs.

/**
 * @notice Wraps the 10 HBAR sent with this call and gives the WHBAR to the caller
 */
function wrapTenHbar() public payable {
    // msg.value is in tinybars inside the EVM: 10 HBAR = 10 * 10**8 tinybars.
    require(msg.value == 10 * 10**8, "Send exactly 10 HBAR");
    // deposit() credits msg.sender, which is this contract.
    whbarContract.deposit{value: msg.value}();
    // Pass the WHBAR on to the user who sent the HBAR.
    require(whbarContract.transfer(msg.sender, msg.value), "WHBAR transfer failed");
}

// From a client through the JSON-RPC relay: value is in weibars.
await whbar.deposit({ value: ethers.parseEther("10") }); // wraps 10 HBAR

Unwrapping WHBAR

// The WHBAR holder calls withdraw() directly: 5 WHBAR = 5 * 10^8 tinybars.
await whbar.withdraw(5n * 10n ** 8n);

Standard ERC20 Functions

Contract Deployments

Security Considerations:Audit and Testing

• Audit and Review:
  Although the WHBAR contract has been independently reviewed, developers and users should conduct their own security assessments. Even small oversights in smart contracts may lead to vulnerabilities.
• Test in a Sandbox:
  Always test interactions in a testnet environment before deploying or integrating with mainnet contracts. This helps ensure the behavior matches expectations.
• Follow Best Practices:
  Double-check function inputs and transaction amounts. Always use the designated functions (deposit() and withdraw()) to prevent unintended fund loss.

Integration Best Practices

• Check allowances: Before attempting transferFrom operations, verify that sufficient allowance has been granted.
• Verify contract addresses: Always double-check you’re interacting with the official WHBAR contract addresses listed in the documentation.
• Handle decimals properly: HBAR and WHBAR both use 8 decimals, so on-chain calculations are straightforward. Use 18-decimal weibars only for the value of a deposit sent from a client through the JSON-RPC relay.