// GLOSSARY -- BLOCKCHAIN & CRYPTO FUNDAMENTALS

What is Digital Signature?

1 min read Updated

A digital signature is a cryptographic proof that a message or transaction was authorized by the holder of a specific private key — providing authentication, integrity, and non-repudiation on the blockchain.

WHY IT MATTERS

Digital signatures are how blockchain knows who authorized a transaction. When you sign a transaction with your private key, anyone with your public key can verify the signature is valid — mathematically proving you approved it.

Ethereum uses ECDSA (Elliptic Curve Digital Signature Algorithm) with the secp256k1 curve. Each signature produces (v, r, s) values that, combined with the message hash, allow recovery of the signer's public key.

For smart contracts, signatures enable off-chain authorization: signing permit messages for gasless token approvals (EIP-2612), signing orders for decentralized exchanges, and multi-sig verification.

FREQUENTLY ASKED QUESTIONS

How do digital signatures work?
The signer hashes the message, encrypts the hash with their private key to produce the signature. Verifiers decrypt with the public key and compare hashes. A match proves the signer authorized the message.
What is EIP-712?
A standard for signing structured data. Instead of signing raw bytes, EIP-712 defines typed, human-readable messages — so you can see exactly what you're signing in your wallet.
Can signatures be forged?
Not without the private key. The security of ECDSA on secp256k1 relies on the elliptic curve discrete logarithm problem, which is computationally infeasible to solve.

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