Signatures
Verify a signature, convert its encoding, find out why it does not verify, generate test vectors, see the elliptic-curve arithmetic underneath and split a secret into Shamir shares — every tool runs in your browser.
7 tools
ECDSA Signature Verifier
Verify any ECDSA signature
Paste a public key, message and signature — auto-detects curve (P-256, P-384, P-521, secp256k1), signature format (DER or raw) and encoding, then verifies locally in your browser.
Open toolDER ⇄ Raw Converter
Convert signature formats
Convert ECDSA signatures between ASN.1 DER and raw r‖s (IEEE P1363) formats, inspect r and s values, and detect non-canonical high-S signatures.
Open toolSignature Error Explainer
Diagnose why verification fails
Your signature looks valid but verification fails? Paste key, message and signature — the explainer tests common mismatch causes: wrong hash, wrong curve, encoding confusion, high-S, double hashing.
Open toolTest Vector Generator
Generate keys & signatures for your tests
Generate reproducible ECDSA test vectors: key pairs, messages and signatures for any curve and hash, exported as JSON, JWK and PEM — including deliberately invalid vectors for negative tests.
Open toolLibrary Interop Cheatsheet
Why library A's signature fails in library B
An interactive matrix of how OpenSSL, Node.js, WebCrypto, Go, Python and Java handle ECDSA: default signature formats, high-S policy, deterministic nonces — pick a signer and a verifier to get a compatibility checklist.
Open toolElliptic Curve Playground
See the math behind the signatures
An interactive visualization of an elliptic curve over a small prime field: point addition, scalar multiplication and why reversing it is hard — the intuition behind every ECDSA key.
Open toolShamir Secret Sharing
Split a secret into K-of-N shares
Split a secret — a key, a recovery phrase, a password — into shares so that any K of N recover it and fewer reveal nothing, then combine shares back. Everything runs in your browser.
Open tool