Wallet approvals and signing: what you are really saying yes to

Two kinds of “yes”: transactions and signatures

Every time a DeFi app asks your wallet for something, you are being asked one of two things.

• Sign and send a transaction. This changes the blockchain: sending tokens, swapping, depositing into a pool or granting an approval. It costs a network fee (gas) and, once confirmed, cannot be undone.
• Sign a message. This produces a signature without sending anything on-chain, so there is no fee. Some messages are harmless, like proving you own an address to log in. Others are instructions that someone else can later submit on-chain on your behalf.

The danger is that both can look similar in a wallet pop-up, and a free, no-gas message can carry as much power as a transaction. Understanding what each request does is the core skill of staying safe in DeFi.

Token approvals and allowances

On Ethereum and similar networks, most tokens follow a standard that separates permission from movement. Before a decentralized exchange or lending protocol can take your tokens, you must approve its smart contract to spend them. That approval sets an allowance: the maximum amount the contract may move on your behalf.

Once the allowance exists, the contract can pull tokens up to that limit whenever its code allows, without asking you again. That is what makes a two-step “approve, then swap” flow work.

Unlimited approvals save a little time and a fee on later trades. The cost is a standing permission that lasts until you revoke it. Many wallets now let you edit the approval amount before confirming. Use that option and set it to what you need.

Permit-style signatures: approvals without gas

Some tokens and protocols support permit signatures. Instead of sending an on-chain approval transaction, you sign an off-chain message saying “this spender may move this amount of my tokens until this deadline.” Anyone holding that signature can then submit it to the blockchain to activate the approval.

This is genuinely useful: it saves a transaction and a fee. It is also a favourite tool of phishing sites, because a permit request looks like a harmless message signature rather than a transaction. People who would never send tokens to a stranger will sign a “free” message that does the same thing.

Blind signing and how to read what you sign

Blind signing happens when your wallet or hardware device shows you a request it cannot decode, often as a long string of letters and numbers. You are asked to approve data you cannot read. Some hardware wallets require you to switch on a setting before they will allow it at all, which is a hint about the risk.

A clear signing request should tell you, in readable terms, at least:

• Which network you are on.
• Which contract or address you are interacting with, and whether it is the one you expected.
• What the action is: transfer, approval, swap, permit or something else.
• Which token and how much, including whether an approval is unlimited.
• For signatures, any spender address and deadline.

If any of that is missing or does not match what you meant to do, reject the request. A legitimate app will still be there after you check its address from a trusted bookmark.

Simulation previews

Many wallets and some security tools now offer a transaction simulation: before you sign, they run the transaction against a copy of the current blockchain state and show the expected result, such as “you send 100 units, you receive 0.03 units of another token” or “this grants unlimited spending to an unknown address.”

Simulations are a strong second opinion, especially for spotting approvals hidden inside a swap or a signature that would hand over assets. Treat them as a warning system, not a guarantee. The real outcome can differ if conditions change between preview and confirmation, and a cleverly built contract may behave differently from what a simulation shows. If a simulation says something surprising, believe the warning and walk away.

Reviewing and revoking approvals

Old approvals pile up quietly. Every app you have tried may still hold permission to move some of your tokens. Reviewing them every few months, and after any scare, is good hygiene.

1. Open the official block explorer for the network you use, reached through a bookmark, and find its token approval checker (often listed under tools).
2. Connect your wallet or paste your address to see a list of contracts with active allowances and their limits.
3. Look for unlimited approvals, contracts you do not recognise and apps you no longer use.
4. Revoke the ones you do not need. Revoking is an on-chain transaction, so it costs a small network fee.
5. Repeat on each network you use; approvals are separate per network.

Revoking stops future pulls. It does not recover anything already taken. If tokens have already left, move remaining assets to a fresh wallet and follow the scam response checklist.

Your checklist

• Read every request: network, contract, action, token, amount and spender.
• Edit approval amounts down to what you need instead of accepting unlimited.
• Treat gasless signature requests that name a spender as approvals.
• Avoid blind signing unless you fully trust the source and understand the action.
• Use a simulation preview where available and heed its warnings.
• Review and revoke unused approvals on each network every few months.

Sources and dates

• Ethereum security and scam prevention — ethereum.orgreference
  No date shown on page · checked 2026-10-31. Wallet security habits and common scams.
• Introduction to smart contracts — ethereum.orgreference
  No date shown on page · checked 2026-10-31. What a smart contract is and how it executes.
• Ethereum wallets — ethereum.orgreference
  No date shown on page · checked 2026-10-31. What wallets are and how they hold keys.
• Gas and fees — ethereum.orgreference
  No date shown on page · checked 2026-10-31. How transaction fees (gas) work on Ethereum.