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What is blind signing?
Blind signing is approving a transaction or message whose contents your wallet cannot show in readable form, often just a string of hexadecimal characters. You authorize it without being able to see what it does, which is how many harmful approvals and wallet drains get signed.
What it means for you
A signed transaction cannot be taken back once broadcast, and one unreadable approval can hand over every token of a kind. Before you confirm, check that your wallet shows the action in plain words: the contract, the spender, the amount. If the screen shows only hex or a hash, you are relying entirely on the website; you can reject it and check the request another way.
A common mistake: “A hardware wallet protects me no matter what I sign.”
In fact: A hardware wallet keeps the private key off your computer, but it signs whatever you approve. If you confirm a request you cannot read, the device produces a valid signature for the attacker's transaction.
How it works
A transaction that calls a smart contract carries a data field of raw hexadecimal bytes encoding which function to run and with what values. ethereum.org notes that because these bytes are opaque, it is very hard to verify what a transaction will do. Hardware wallets with small screens, and wallets that lack the contract's description, may show only this hex. EIP-712 tackles part of the problem for signed messages by giving them typed, readable fields, and ERC-7730 descriptors let wallets render contract calls in plain language. Research finds users still misread critical parameters even when shown them.
Sources: ethereum.org: Transactions (blind signing and clear signing), EIP-712: Typed structured data hashing and signing, Qin and Duan, "What I Sign Is Not What I See" (arXiv) · checked 4 October 2026
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