Permission Scope

Unlike all-or-nothing wallet connections, permission scopes enable fine-grained control. A user can grant a dApp the right to spend a specific token up to a set limit, without exposing their entire wallet balance. This is implemented via standards like EIP-712 for typed structured data signing, allowing users to review the exact parameters of the transaction they are authorizing.

Scopes can be bound to session keys—temporary private keys with limited authority—and include explicit expiry timestamps. This allows for seamless user experiences (e.g., playing a blockchain game) without repeated pop-ups, while automatically revoking permissions after a set time. The scope defines the session's lifespan and capabilities, mitigating the risk of indefinite access.

A critical feature is the ability to delegate calls to other contracts. A scope can authorize a relayer or smart contract wallet to execute a complex, multi-step transaction on the user's behalf. This enables gasless transactions (meta-transactions), batched operations, and advanced DeFi strategies, all within the pre-approved security boundaries of the scope.

Permissions are revocable at any time by the granting authority (typically the user). Since scopes are enforced on-chain by smart contract logic, not off-chain promises, revocation is immediate and trustless. This maintains the non-custodial principle; the dApp never holds user assets, only a temporary, revocable right to interact with them under strict rules.

Interoperability is driven by standards. ERC-7579 (Minimal Modular Smart Accounts) and related proposals define how scopes are structured, validated, and revoked across different smart account implementations. Standardized scope formats ensure that wallets can uniformly display permission requests, and auditors can verify security models consistently.

Scopes can encode conditional logic beyond simple allowances. Examples include:

• Rate limits: Max spend per day/week.
• Allowlists: Can only interact with pre-approved contract addresses.
• Asset restrictions: Limited to specific ERC-20 tokens or NFT collections.
• State-dependent rules: Permission only if a certain on-chain condition is met.

The most common scope, authorizing a smart contract to spend a specific amount of a user's ERC-20 tokens. This is a core primitive for DeFi protocols like Uniswap or Aave.

• Key Parameter: spender (contract address) and amount (max allowance).
• Example: Granting 100 USDC allowance to a DEX to facilitate a swap.

Grants permission for a contract to transfer a specific NFT (ERC-721/ERC-1155) from the user's wallet. Essential for NFT marketplaces like OpenSea or Blur.

• Key Parameter: operator (marketplace contract) and tokenId.
• Security Note: Can be set for a single token or for all tokens in a collection (dangerous).

A read-only scope that allows a dApp's backend or wallet to simulate a transaction's outcome before the user signs. This enables gas estimation and safety checks.

• Key Parameter: from, to, data, value.
• Purpose: Prevents failed transactions and reveals potential reverts or state changes.

Requests a user's cryptographic signature for a message, often used for off-chain authentication or proving wallet ownership without a gas fee.

• Key Parameter: The message hash to be signed.
• Use Cases: Login with Ethereum (SIWE), vote delegation in DAOs, or signing a permit for gasless token transfers.

A highly powerful and dangerous scope that allows a contract to execute code in the context of the user's wallet. It can modify the wallet's storage and drain assets.

• Key Parameter: The target contract address and calldata.
• Critical Warning: Should only be granted to immutable, audited contracts like smart account factories.

Authorizes a single transaction that bundles multiple actions (e.g., approve and swap). This scope improves UX and efficiency but combines multiple risks.

• Key Parameter: An array of individual calls (to, value, data).
• Benefit: Reduces gas costs and simplifies complex multi-step interactions.

The core security best practice for permission scopes. A dApp should request only the minimum permissions necessary for its function. For example, a DeFi swap dApp needs access to a user's token balance for the specific asset being traded, not blanket access to their entire wallet. Overly broad scopes increase the attack surface and potential loss if the dApp is compromised.

A secure permission system allows users to revoke access at any time. Modern standards like EIP-2255 (Wallet Permissions) and session keys enable time-limited or transaction-capped scopes. This contrasts with the historical risk of signing a transaction granting indefinite approval, which required manual revocation and was a common source of funds theft.

A major threat is a malicious dApp frontend tricking a user into signing a transaction with a broader scope than displayed. This is a signature phishing attack. Defenses include:

• Wallet security warnings that clearly decode the requested permissions.
• User education to verify transaction details in their wallet pop-up, not the website.
• Using established, audited dApp interfaces.

When a dApp uses an upgradable proxy contract, the permission scope granted to its address applies to all future logic implementations. If the proxy admin is malicious or compromised, a previously safe contract can be upgraded to one that exploits its existing broad user approvals. Users should be wary of granting unlimited approvals to proxy contracts.

Permission scopes become more complex in multi-chain and institutional settings. A multi-signature wallet may require defining which signers can approve specific types of transactions (e.g., swaps vs. transfers). Cross-chain messaging protocols (like IBC or CCIP) must also define clear scopes for what actions a message from another chain can trigger.

Session keys are temporary, limited-authority cryptographic keys derived from a user's main wallet. They are a practical implementation of permission scopes, allowing a dApp to perform specific actions (e.g., trade on a DEX, play a game) for a set period without requiring a signature for every transaction. This enhances user experience while maintaining security boundaries defined by the scope.

The classic token approval mechanism is a foundational form of permission scope. The approve(spender, amount) function grants a spender (e.g., a DEX router) the right to transfer up to a specified amount of the caller's tokens. The allowance(owner, spender) function queries the remaining permitted amount. This is a single-asset, amount-limited scope.

A low-level EVM opcode, DELEGATECALL, is a powerful but dangerous capability that can be part of a permission scope. It allows a contract to execute code from another contract in the context of the caller. If a user grants a scope that includes delegate call permissions, the dApp can potentially upgrade or modify the user's contract state, representing the highest level of trust.

This core cybersecurity principle directly applies to defining permission scopes. It states that a user or process should be granted the minimum levels of access (or permissions) necessary to complete its function. When connecting a wallet, users should seek the most restrictive scope possible (e.g., token-specific approval vs. full wallet access) to minimize attack surface and potential loss.