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Passkey Address Deriver

Derive EVM addresses from P-256 passkey public keys — 100% client-side

P-256 public key

About the Passkey Address

Passkey wallets use P-256 (secp256r1) keys — the same elliptic curve used by WebAuthn, Face ID, Touch ID, and security keys. Unlike Ethereum secp256k1 keys, P-256 keys can be stored in hardware secure enclaves and used without seed phrases. Ritual Chain supports passkey transactions natively (type 0x77).

This deriver converts a P-256 public key into an EVM-compatible address using the standard derivation: keccak256 of the X and Y coordinates, take the last 20 bytes. Paste a key in any common format — uncompressed hex, compressed hex, or WebAuthn JSON.

  • Accepts uncompressed hex (04 + X + Y), compressed hex (02/03 + X), and WebAuthn JSON
  • Handles base64 and base64url encodings from WebAuthn responses
  • Decompresses compressed points using P-256 curve math
  • Derives using keccak256 — same as Ethereum address derivation
  • All computation happens locally — keys never transmitted

How to use

  1. Get your P-256 public key from WebAuthn registration, a hardware key, or generate one.
  2. Paste it above in any supported format.
  3. Click derive to see the EVM address.
  4. Use this address with Ritual Chain passkey transactions (type 0x77).

Frequently Asked Questions

Why do passkeys use P-256 instead of secp256k1? ▾

P-256 (secp256r1) is the NIST curve supported natively by WebAuthn, Apple Secure Enclave, Windows Hello, and hardware security keys. It enables biometric authentication without seed phrases. Ethereum uses secp256k1 for historical reasons — passkey wallets bridge the two.

Can I use this address on Ethereum mainnet? ▾

The derivation (keccak256 of X‖Y, last 20 bytes) is the standard convention for P-256 passkey wallets. However, Ethereum mainnet does not natively verify P-256 signatures — you need a smart contract wallet (like a passkey account abstraction wallet) or a chain like Ritual that enshrines P-256 verification (precompile 0x0100).

How do I get my passkey public key? ▾

Register a WebAuthn credential in your browser or app, then export the public key from the registration response. It contains the X and Y coordinates in base64url format. Some hardware keys also display the public key directly.

Is this tool free to use? ▾

Yes! This tool is 100% free. No signup, no credit card, no limits. It's part of Formatho's privacy-first developer toolkit.

Is my data safe? Does this tool send data to a server? ▾

Absolutely. This tool runs entirely in your browser. Your data never leaves your device. Zero server-side processing, zero tracking.