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Glossary

Permit (EIP-2612)

Definition

Permit is an EIP-2612 function that sets a token allowance from a signed message, so approval needs no separate on-chain transaction.

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CamoCrypt EditorialPublished Sep 8, 2026 · 1 min read · Human-edited, sources cited

EIP-2612 extends the ERC-20 standard with a permit function. Instead of sending a separate approval transaction, the owner signs an EIP-712 typed message off-chain, and any party can submit that signature to set the allowance. The abstract describes it as letting users “modify the allowance mapping using a signed message, instead of through msg.sender.” The signed message includes the owner, spender, value, a nonce, and a deadline after which it is invalid.

Why it matters

Permit improves user experience: it collapses approve-then-transfer into effectively one step and can let someone approve spending without first holding ETH for gas, since another party can submit the signature. The nonce increments after each use to prevent replay, and the deadline limits how long a signature stays valid.

Common misunderstanding

Because a permit is “just a signature” and not an obvious transaction, users sometimes assume it is harmless and sign without reading it. That is exactly what attackers exploit. A permit signature is a real, binding approval: signing a malicious permit can hand a spender the right to move your tokens. Wallets display permit requests as structured EIP-712 data precisely so you can check the spender and value before signing. Treat an unexpected permit request with the same caution as an approval, especially on a site you did not navigate to deliberately. Checking the spender address and the value in the signature request, every time, is the practical safeguard. If a permit request appears unexpectedly, decline it and leave the site.

Frequently asked questions

Is signing a permit safer than an on-chain approval?
Not inherently. A permit is a binding approval created by a signature. A malicious permit is as dangerous as a malicious approval, so read the spender and value first.

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