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Withdraw Offer Signature Structure

Centralized Verification

NameService signatures are verified by Core.sol using validateAndConsumeNonce(). Uses NameServiceHashUtils.hashDataForWithdrawOffer() for hash generation.

To authorize the withdrawOffer operation within the Name Service, the user (the original offeror) must generate a cryptographic signature compliant with the EIP-191 standard using the Ethereum Signed Message format.

Signature Format​

{evvmId},{senderExecutor},{hashPayload},{originExecutor},{nonce},{isAsyncExec}

Hash Payload Generation​

The hashPayload is generated using NameServiceHashUtils.hashDataForWithdrawOffer():

import {NameServiceHashUtils} from "@evvm/testnet-contracts/library/signature/NameServiceHashUtils.sol";

bytes32 hashPayload = NameServiceHashUtils.hashDataForWithdrawOffer(
    username,  // Username associated with the offer
    offerID    // ID of the offer to withdraw
);

// Internal implementation
// keccak256(abi.encode("withdrawOffer", username, offerID))

Example​

Scenario: User wants to withdraw their offer on username "alice"

string memory username = "alice";
uint256 offerID = 42;

bytes32 hashPayload = NameServiceHashUtils.hashDataForWithdrawOffer(username, offerID);

Message: 1,0x0000000000000000000000000000000000000000,0x[hashPayload],0x0000000000000000000000000000000000000000,7,true

Technical Details
  • Hash Independence: The hash payload does NOT include executors (only username, offerID)
  • Operation Name: "withdrawOffer" is included in hash via NameServiceHashUtils
  • Ownership Check: Only the original offeror can withdraw their offer
  • EIP-191 Compliance: Uses "\x19Ethereum Signed Message:\n" prefix with message length
  • Offer ID Validation: _offerId must correspond to an existing offer made by the same user
  • Authorization: Only the original offeror can withdraw their own offers
  • Replay Protection: _nameServiceNonce prevents replay attacks
  • EVVM ID: Identifies the specific EVVM instance for signature verification

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