WebAuthn Bitcoin Playground

Learn how WebAuthn PRF generates deterministic Bitcoin keys

₿ What is WebAuthn PRF?

WebAuthn (Web Authentication) is a web standard that lets you use your device's biometric sensor (fingerprint, Face ID) or security keys for authentication.

PRF (Pseudo-Random Function) is an extension that generates a deterministic secret based on your passkey and an input value. This secret is:

  • Deterministic: Same input always produces the same output
  • Secure: Protected by your device's secure enclave
  • Private: Never leaves your device
  • Biometric-protected: Requires your fingerprint/Face ID to access

This makes it perfect for generating Bitcoin keys that are both secure and recoverable!

� Step 1: Register Passkey
Create a passkey for this website. This generates a unique cryptographic credential stored securely in your device's hardware.
⚡ How It Works

1️⃣ Registration Phase:

  • Browser requests your device to create a new passkey
  • Your device generates a unique key pair in its secure enclave
  • PRF extension is enabled for this credential
  • Your biometric confirms the registration

2️⃣ Secret Generation Phase:

  • A deterministic input (PRF salt) is sent to the authenticator
  • Your biometric authentication unlocks the passkey
  • Authenticator computes: PRF-Output = HMAC(PasskeySecret, Input)
  • Same input always produces the same output (deterministic!)

3️⃣ Bitcoin Key Derivation:

  • PRF output becomes your Bitcoin private key (32 bytes)
  • secp256k1 generates the corresponding public key
  • Keys are formatted for Bitcoin wallets (WIF, BIP32)

⚡ Key Benefits: No passwords to remember • Hardware-secured • Phishing-resistant • Deterministic & recoverable

⚠️ Educational Purposes Only

This is a developer playground for learning WebAuthn PRF. Never use generated keys for real funds.

Made with ₿ to demonstrate WebAuthn PRF + Bitcoin key generation