WebAuthn Registration | Result

The goal is to verify the authenticity and integrity of the data returned by the client, ensure that the credential is bound to the expected user, and safely register a public key credential for future authentication.

 

The server must validate the client response following these steps:

 

• Parse the client response: The client sends a response like this to the server.

 

{
  "id": "base64url-encoded credential ID",
  "rawId": "base64url-encoded ID bytes",
  "response": {
    "clientDataJSON": "base64url",
    "attestationObject": "base64url"
  },
  "type": "public-key"
}

 

• The server validates the clientDataJSON and attestationObject
• Verifies the Attestation Statement (if defined)
• If everything is valid, it stores the credential and can trust the public key for future logins.

 

 

Registration Successful

If the response sent by the client is valid, the event OnWebAuthnRegistrationSuccessful is called and the Credential Record can be safely stored into a database for future logins validations.

 

void OnWebAuthnRegistrationSuccessful(
    object sender,
    WebAuthnRegistration registration,
    WebAuthnCredentialRecord credentialRecord,
    ref bool accept)
{
    // Store in a database
    using (var cmd = dbConnection.CreateCommand())
    {
        cmd.CommandText = "INSERT INTO Credentials (Credentials) VALUES (@json)";
        var param = cmd.CreateParameter();
        param.ParameterName = "@json";
        param.Value = credentialRecord.AsJson(); // or .AsJSON depending on naming
        cmd.Parameters.Add(param);
        cmd.ExecuteNonQuery();
    }
}

Registration Error

If there is any error while validating the client response, the event OnWebAuthnRegistrationError is called and you can access the reason for the error in the parameter aError.

 

void OnWebAuthnRegistrationError(
    object sender,
    WebAuthnRegistrationVerifyRequest request,
    WebAuthnRegistration registration,
    string error)
{
    Log("#webauthn_registration_error: " + error);
}