Track 2 · Keys & identity · lesson 5
Signing is not sending
8 min
If you remember one thing from this track, make it this.
Signing and sending are different actions, and only one of them costs you anything.
Signing produces a signature. It happens entirely inside your wallet, costs no gas, touches no network, and changes nothing on-chain. You can sign a thousand messages and your balance will not move.
Sending broadcasts a signed transaction to the network, where it is executed and settles. This costs gas and changes state.
Every wallet popup is one or the other. Learning to tell them apart at a glance is the single most useful defensive habit in crypto.
How to tell which you are looking at
A signature request shows you text or structured data. There is no gas estimate, because none is needed.
A transaction request shows a recipient, a value, and a gas cost. Your wallet will tell you what it expects to pay.
Predict
A site asks you to sign a message. No gas fee is shown. How risky is that?
The dangerous signatures
Most signature requests are harmless — proving you control an address to log in, for example. Two are not:
permit(EIP-2612) — a gasless token approval. Signing it lets the holder of that signature move your tokens.- Seaport / marketplace orders — signing one is agreeing to a trade. Sign the wrong one and your NFT sells for nothing.
Both look like ordinary text prompts with no fee attached.
The defence is not sophistication, it is a habit: read what the wallet is showing you, and be suspicious precisely when there is no gas fee. Absence of a fee is not evidence of safety — it often means the cost has been moved to someone else, and the benefit with it.
Check
You sign a message. What has definitely happened on-chain?
Worth remembering
- Signing is offline, free, and changes nothing on-chain. Sending broadcasts and costs gas.
- A signature is an authorisation — someone else can submit it later and pay the gas.
- No gas fee shown means it is a signature request, not that it is safe.
- `permit` signatures and marketplace orders are the dangerous ones; both look like plain text.
- The habit that protects you is reading what the wallet displays.