Token Approvals & Permit2

Bungee Auto uses Permit2 to enable efficient token transfers, while Bungee Manual uses traditional approvals. This page explains how token approvals work, your options, and important security considerations.

Comparison of Token Approvals

Aspect	Traditional Approvals (Bungee Manual)	Permit2 Approvals (Bungee Auto)
Gas Cost	Two transactions needed (approve + transfer)	One-time approval, then gasless signatures
Control	Basic approve amount and revoke onchain	Fine-grained with expiration times
Security	Unlimited approvals can be used to transfer any amount	Unlimited approvals to permit2 contract cannot transfer without your signature

See Uniswap Permit2 for technical details.

How Signatures Work

Each signature for a Permit2 transfer includes:

• Token Details: Address and amount
• Expiration Time: When the signature becomes invalid
• Nonce: Ensures signatures can't be reused
• Chain ID: Prevents cross-chain replay attacks

How Bungee Uses Permit2

Bungee Auto integrates Permit2 to create a better user experience:

1. Initial Setup:

   • Approve Permit2 for your tokens
   • Choose between limited or unlimited approval amounts

2. For Each Transfer:

   • Sign a message specifying exact amount and expiration
   • No gas needed for approval
   • Transfer only happens with your signature

3. Security Features:

   • Each signature has an expiration time
   • Signatures specify exact amounts
   • Transfers require explicit approval

Approval Options

Choose Your Approval Type

Permit2 supports two approval methods:

1. Limited: Approve specific amounts. Requires new on-chain approval for each request, using more gas.
2. Unlimited: One-time approval. Future requests only need signatures, saving gas.