Client-Side Signing

What is Client-Side Signing?

Client-side signing is a security practice where a blockchain transaction is signed on the user's local device rather than on a remote server. It ensures that private keys never leave the user's control.

How does Client-Side Signing work?

1. A dApp or website prepares a transaction and sends the request to the user's wallet.
2. The wallet (e.g., a browser extension or mobile app) receives the request and displays the details.
3. The user reviews the transaction and clicks "Sign" or "Confirm."
4. The wallet uses the private key stored on the device to create a cryptographic signature.
5. Only the signed transactionnever the private keyis sent to the network to be broadcast.

Why does Client-Side Signing matter?

It is the foundation of self-custody. By keeping the signing process local, users are protected from server-side hacks or malicious service providers who might otherwise steal their keys or change their transactions.

Key features of Client-Side Signing

• Private keys stay on the user's device
• No trust required in a central server for signing
• Protection against remote key theft
• Enables true "non-custodial" wallet behavior
• Requires users to carefully review what they are signing

Examples of Client-Side Signing

• Using a Ledger hardware wallet to sign a transaction that was initiated in a browser.
• MetaMask signing a token swap locally before sending it to an RPC provider.
• A mobile wallet using a phone's "Secure Enclave" to sign a message.