What is Transaction Signing?

Transaction signing is the process of cryptographically authorizing an on-chain action using your private key. The signature proves you intentionally authorized the transaction without revealing the private key itself.

How does Transaction Signing work?

Your wallet creates a transaction with recipient, amount, and optional contract data.
The transaction data is hashed.
Your private key signs the hash using ECDSA, producing a unique signature.
The signed transaction is broadcast; nodes verify the signature using your public key.
Invalid or mismatched signatures are rejected by the network.

Why does Transaction Signing matter?

It is the foundation of self-custody. No bank or intermediary confirms your transactions your private key signature is the sole proof of authorization.

Key features of Transaction Signing

Only the private key holder can produce a valid signature
Signature is unique per transaction cannot be reused
Network verifies without ever seeing the private key
Cannot be forged without the private key

Examples of Transaction Signing

When you send ETH from MetaMask, it silently signs the transaction with your private key before broadcasting. A hardware wallet signs offline and passes only the signature to the connected device the key never touches the internet.