✍️ Sign & Verify

Sign and verify with ECDSA, EdDSA, Schnorr (BIP340) and RSA-PSS.

Algorithm

Private key (hex, PEM or JWK)

Message Encoding

Message is already a hash (sign the digest as-is) Low-S

Notes

ECDSA hashes the message with the listed hash first (tick “already a hash” to sign a 32/48-byte digest directly, as Bitcoin and Ethereum do). Signatures are deterministic (RFC 6979) except Schnorr, which mixes in fresh randomness, and RSA-PSS, which uses a random salt (32 bytes here). Low-S: for every ECDSA signature (r, s) the pair (r, n − s) is also valid; Bitcoin and Ethereum only accept the low one. Schnorr BIP340 uses 32-byte x-only public keys. RSA keys must be PEM or JWK; use Key Generator to make one.