However, moving from classic contract deployments to per-EOA execution contexts introduces severe architectural blind spots—most notably, the complete breakdown of standard EIP-712 signature domain caching.

In this technical deep dive, we explore why standard implementation patterns (like OpenZeppelin’s EIP712 base) fail catastrophically under EIP-7702, and introduce VaultGuard7702—an institutional-grade execution guard and gas-sponsorship gateway engineered specifically for persistent delegation context.

The Broken Assumption: Static EIP-712 Domain Caching

In standard smart contract development, efficiency dictates caching the EIP-712 domain separator during construction or initialization to save gas on verification paths. The standard OpenZeppelin pattern looks like this:

// Standard OpenZeppelin Pattern — Catastrophic for EIP-7702

constructor(string memory name, string memory version) {

    bytes32 hashedName = keccak256(bytes(name));

    bytes32 hashedVersion = keccak256(bytes(version));

    _cachedDomainSeparator = keccak256(

        abi.encode(TYPE_HASH, hashedName, hashedVersion, block.chainid, address(this))

    );

}

At deployment time, address(this) evaluates to the implementation contract address (e.g., 0xImpl...).

The Execution Context Flip

Under EIP-7702 persistent delegation, the EOA's code pointer points directly to 0xImpl.... When a relayer or bundler interacts with the user's account, the bytecode executes entirely within the context of the user's EOA (e.g., 0xAlice...).

Every storage access, balance mutation, and invocation of address(this) operates under Alice's identity.

Because the cached domain separator is stubbornly frozen to 0xImpl..., every valid signature signed by Alice or Bob targeting their own EOA will fail cryptographically.

Worse, if a developer attempts to bypass this by completely decoupling the verifying contract check from address(this), they open the door to cross-user replay attacks, where a signature generated for Alice could be replayed across Bob’s account if they share the same implementation gateway.

The Solution: Stateless, On-the-Fly Domain Resolution

To bridge the gap between singleton implementation architecture and per-EOA execution context, VaultGuard7702enforces a completely stateless EIP-712 domain recomputation on every dynamic verification path.

function _deriveDomainSeparator() internal view returns (bytes32) {
    return keccak256(
        abi.encode(
            DOMAINS_TYPEHASH,
            HASHED_NAME,
            HASHED_VERSION,
            block.chainid,
            address(this) // Resolves dynamically to 0xAlice... or 0xBob... at call-time
        )
    );
}

By guaranteeing that address(this) is evaluated at runtime, the verifyingContract field dynamically mirrors the exact EOA executing the transaction.

Cryptographic and Architectural Safeguards Enabled:

0. Cross-User Replay Protection: Since verifyingContract is structurally tied to the executing EOA, identical intents (target, data, nonce, value, deadline) signed by two different users yield completely different EIP-712 digests. Alice can never replay Bob's payload.

1. Chain Isolation: Dynamic injection of block.chainid guarantees that signatures are structurally non-replayable across network hardforks or L2 rollups executing the same EIP-7702 framework.

2. Intent Expiry & Native Value Binding: The signed payload forces an explicit value parameter and a strict deadline. Relayers cannot attach unauthorized native ETH to guarded calls or hold intents hostage to execute them during adversarial market conditions.

Hardening Storage and Context Boundaries

Writing an execution guard for EIP-7702 requires rethinking state management entirely. An EOA does not natively expect contract state layout, creating massive risks of storage collision if the EOA is later upgraded or multi-delegated.

0. ERC-7201 Namespaced Storage for Replay Protection

VaultGuard7702 completely isolates replay protection states (executed[nonce]) into a deterministic storage slot defined by the vaultguard7702.storage.NonceStorage.v1 namespace.

Using inline assembly, the contract bypasses standard Solidity slot layout entirely:

// Bypassing slot 0 to protect EOA storage layout
bytes32 constant STORAGE_LOCATION = 0x8c5b... // keccak256(abi.encode(uint256(keccak256("vaultguard7702.storage.NonceStorage.v1")) - 1)) & ~bytes32(uint256(0xff));

function _getStorage() internal pure returns (NonceStorage storage ptr) {
    assembly {
        ptr.slot := STORAGE_LOCATION
    }
}

This prevents any collision with future protocol upgrades, account state fields, or other namespaced libraries executing inside the same EOA proxy boundary.

1. Transient Reentrancy Protection (EIP-1153)

Using persistent storage for reentrancy guards on an EIP-7702 account alters the permanent storage footprint of a user’s EOA unnecessarily. VaultGuard7702 integrates OpenZeppelin's ReentrancyGuardTransient, anchoring lock status inside Transient Storage via TSTORE and TLOAD. The guard is scoped strictly to the lifecycle of the atomic transaction and is completely wiped afterward.

2. Low-Level Revert Bubbling for Relayer Simulation

When an institutional relayer broadcasts a guarded transaction, downstream simulation infrastructure needs absolute transparency. If the target execution fails, VaultGuard7702 avoids concealing the execution context and bubbles up the callee's returndata verbatim:

assembly {
    let size := returndatasize()
    returndatacopy(0, 0, size)
    revert(0, size)
}

Production-Ready and Deterministic Deployment

To eliminate fragmentation, VaultGuard7702 utilizes CREATE2 deployment routing via the canonical factory (0x4e59b44847b379578588920cA78FbF26c0B4956C), making the core implementation address completely deterministic across all EVM networks.

• Mainnet Deployment: Live and verified at 0x00000000484FB1DF9c6682ac252c103b23707c26

• Licensing: MIT open-source infrastructure

The full ecosystem-grade suite—featuring 100% branch test coverage, fuzzing matrices simulating EIP-7702 attachments via Foundry cheatcodes (vm.signAndAttachDelegation), and an optimized Golang SDK wrapper for enterprise relayers—is entirely open-source.

Explore the repository, review the test vectors, or audit the integration architecture directly on GitHub:

👉 GitHub: harpy-wings/vault-guard-7702
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