About Signature Verifier

Verify RSA/EC cryptographic signatures with public key validation. Part of the DevTools Surf developer suite. Browse more tools in the Security / Crypto collection.

Use Cases

• Verify that a software release artifact matches the developer's published signature.
• Validate webhook signatures (e.g., Stripe HMAC-SHA256) to confirm requests originate from the expected sender.
• Check code signing certificates on executables before running them in a sandbox.
• Verify JWT signatures to confirm a token was issued by a trusted authority.

Tips

• Always verify the signature against the correct message — a common implementation bug is hashing the message before signing but verifying against the unhashed message (or vice versa).
• Check the algorithm in the signature metadata matches what you expect — algorithm confusion attacks work by replacing a strong algorithm (RS256) with a weaker one (HS256) that the verifier accepts.
• Verify the certificate chain, not just the signature — a valid signature from an untrusted key is not a valid signature.

Fun Facts

• The RSA digital signature algorithm was published by Rivest, Shamir, and Adleman in 1978 — the same paper that introduced RSA encryption. Digital signatures were conceived as a practical implementation of public-key cryptography.
• ECDSA (Elliptic Curve Digital Signature Algorithm) produces signatures 6x shorter than RSA-2048 at equivalent security, which is why it replaced RSA for TLS certificates in most modern deployments.
• The PlayStation 3's ECDSA implementation was broken in 2010 because Sony used a static random number in the signing algorithm instead of a cryptographically random nonce — allowing private key extraction from just two signatures.

FAQ

What's the difference between RSA and ECDSA signatures?

Both are asymmetric signing algorithms. ECDSA uses elliptic curve math producing shorter signatures (64 bytes vs. 256 bytes for RSA-2048) with equivalent security. ECDSA signing is faster; RSA verification is faster.

How do I verify a signature without the private key?

Signature verification uses only the public key — that is the point of asymmetric cryptography. You need: the original message, the signature, and the signer's public key or certificate.