Blind Signing
Blind signing means approving a transaction or signature request without being able to see or understand what it actually does. Your wallet shows only a cryptic hash or raw data, and you confirm anyway.
Why blind signing happens
A simple transfer is easy to display: amount, recipient, fee. A smart-contract interaction is not. It may call a function with encoded parameters, and some message signatures are just long strings of hexadecimal characters. If the wallet or hardware device cannot decode the request into readable terms, it either refuses or, with a setting enabled, shows a hash and asks you to trust it.
Some hardware wallets require you to switch on blind signing manually for certain DeFi apps. Many software wallets show raw data by default for unknown contracts.
What can go wrong
If you cannot read the request, you cannot tell a normal swap from an unlimited token approval to an attacker, a permit signature that lets someone else spend your tokens, or a transfer of all your NFTs. Wallet drainer kits are designed around this: they present a harmless-looking site and a request most users will approve without decoding.
Blind signing is not only a retail problem. In February 2025, attackers stole roughly 1.5 billion dollars in ether-based assets from the exchange Bybit after signers approved a transaction whose real content differed from what their signing interface displayed.
Clear signing as the alternative
The industry is moving toward clear signing: the wallet decodes the request and shows what it means in plain terms, such as approving a specific contract to spend 100 USDC. Standards for structured messages, like EIP-712 on Ethereum, and transaction simulation features that preview balance changes help make this possible.
Habits that reduce the risk
Keep blind signing switched off on hardware wallets unless you need it for a specific trusted action, and switch it off afterwards. Prefer wallets that decode and simulate transactions. Approve only the token amount you need instead of unlimited allowances. If a request is unreadable and you arrived through a link, an ad or a message, reject it. Use a separate wallet with small funds for experimenting, and revoke old approvals.
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Frequently asked questions
Is blind signing ever necessary?
Sometimes, for complex contract interactions a device cannot yet decode. It should be limited to well-known apps reached directly, never to links from messages or ads.
Does a hardware wallet protect me from blind signing?
Only if it shows you what you are signing. If you approve a hash you cannot verify, the hardware wallet will sign whatever it is.
What is clear signing?
The opposite of blind signing: the wallet translates a request into readable details, such as which contract may spend how many of which token, before you approve.
Related terms
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