Exemple d'utilisation avancée de WebAuthn

4 septembre 2025 · Composants

Voici un exemple Delphi plus complet qui démontre des endpoints personnalisés, des politiques de challenge, le stockage d'identifiants en base de données, la validation des métadonnées FIDO, et la prise en charge des iframes cross-origin. Le code met en avant une gestion avancée des événements pour appliquer des politiques de sécurité.

sgcWebSockets serveur WebAuthn Exemple

procedure TForm1.ConfigureWebAuthn;
begin
  // Component setup
  FWebAuthn := TsgcWSServer_API_WebAuthn.Create(nil);
  FWebAuthn.Server := FHTTPServer;
  FWebAuthn.Enabled := True;
  // Endpoint remapping
  FWebAuthn.EndpointsOptions.AuthenticationOptions.Endpoint := '/auth/options';
  FWebAuthn.EndpointsOptions.AuthenticationVerify.Endpoint  := '/auth/verify';
  FWebAuthn.EndpointsOptions.RegistrationOptions.Endpoint   := '/reg/options';
  FWebAuthn.EndpointsOptions.RegistrationVerify.Endpoint    := '/reg/verify';
  // Relying-party definition
  with FWebAuthn.WebAuthnOptions do
  begin
    RelyingParty := 'secure.example.com';
    Origins.Origins.Text      := 'https://app.example.com'#13#10'https://login.example.net';
    Origins.TopOrigins.Text   := 'https://host.example.org';
    Origins.AllowCrossOrigins := True;
    // Cryptographic & UX policies
    Algorithms                                   := [waunalgES256, waunalgRS256];
    DefaultOptions.Registration.UserVerification := waunuvPreferred;
    DefaultOptions.Registration.Attestation      := waunaDirect;
    Timeout                                      := 60000;
    // Challenge: 32 CSPRNG-random bytes, hex-encoded, generated internally by
    // the server; not configurable. Override Response.Challenge instead, in
    // OnWebAuthnRegistrationOptionsResponse / OnWebAuthnAuthenticationOptionsResponse.
    // Metadata Service configuration
    MDS.Enabled            := True;
    MDS.MDS_FileName       := 'mds.json';
    MDS.RootCert_FileName  := 'root.pem';
  end;
  // Hook events
  FWebAuthn.OnWebAuthnRegistrationOptionsRequest := AuthnRegOptionsRequest;
  FWebAuthn.OnWebAuthnRegistrationOptionsResponse := AuthnRegOptionsResponse;
  FWebAuthn.OnWebAuthnRegistrationValidateCertificate := AuthnRegVerify;
  FWebAuthn.OnWebAuthnRegistrationSuccessful     := AuthnRegSuccess;
  FWebAuthn.OnWebAuthnAuthenticationOptionsRequest := AuthnOptionsRequest;
  FWebAuthn.OnWebAuthnAuthenticationSuccessful     := AuthnSuccess;
end;

Implémentations d'événements

procedure TForm1.AuthnRegOptionsRequest(Sender: TObject;
  const Request: TsgcWebAuthn_RegistrationOptions_Request; var Accept: Boolean);
begin
  // Verify user is eligible for registration
  Accept := not UserExists(Request.Username);
end;
procedure TForm1.AuthnRegOptionsResponse(Sender: TObject;
  const Request: TsgcWebAuthn_RegistrationOptions_Request;
  const Response: TsgcWebAuthn_RegistrationOptions_Response);
begin
  // Optionally assign a user handle (binary identifier)
  Response.User.Id := HexToBin(UserGUIDToHex(GenerateGUID));
  Response.AuthenticatorSelection.AuthenticatorAttachment := 'platform';
end;
procedure TForm1.AuthnRegVerify(Sender: TObject;
  const Request: TsgcWebAuthn_RegistrationVerify_Request;
  const Validate: TsgcWebAuthnValidateAttestationStatement; var Accept: Boolean);
begin
  // Perform extra attestation validation against MDS entries
  Accept := ValidateAttestationWithMDS(Validate);
end;
procedure TForm1.AuthnRegSuccess(Sender: TObject;
  const Registration: TsgcWebAuthn_Registration;
  const CredentialRecord: TsgcWebAuthn_CredentialRecord; var Accept: Boolean);
begin
  // Persist credential details in database
  SaveCredentialToDB(
    CredentialRecord.Username,
    CredentialRecord.CredentialId,
    CredentialRecord.PublicKey,
    CredentialRecord.SignCount,
    CredentialRecord.UserId
  );
  Accept := True;
end;
procedure TForm1.AuthnOptionsRequest(Sender: TObject;
  const Request: TsgcWebAuthn_AuthenticationOptions_Request;
  var CredentialRecords: TsgcWebAuthn_CredentialRecords; var Accept: Boolean);
begin
  // Retrieve all credential records for user
  CredentialRecords := LoadCredentialRecordsFromDB(Request.Username);
  Accept := True;
end;
procedure TForm1.AuthnSuccess(Sender: TObject;
  const Request: TsgcWebAuthn_AuthenticationVerify_Request;
  const Authentication: TsgcWebAuthn_Authentication; var Accept: Boolean);
var
  StoredCounter: Cardinal;
begin
  // Ensure sign counter increases
  StoredCounter := GetSignCounterFromDB(Authentication.Credential.CredentialRecord.CredentialId);
  Accept := Authentication.Credential.CredentialRecord.SignCount > StoredCounter;
  if Accept then
  begin
    UpdateSignCounterInDB(Authentication.Credential.CredentialRecord.CredentialId,
      Authentication.Credential.CredentialRecord.SignCount);
    IssueSessionToken(Authentication.Credential.CredentialRecord.Username);
  end;
end;

Points clés

Aléa du challenge – Chaque challenge est généré en interne par le serveur sous forme de 32 octets aléatoires cryptographiquement sûrs, encodés en hexadécimal, ce qui résiste déjà aux attaques par rejeu sans configuration supplémentaire.
Identifiants utilisateur personnalisés – Attribuer un identifiant utilisateur binaire unique permet à l'authenticator de store a privacy-preserving identifier independent de usernames.
Metadata-Based Attestation Validation – Le ValidateAttestationWithMDS routine cross-checks authenticator model, status reports, et revocation lists, ensuring seulement trusted devices are registered.
Sign Counter Enforcement – AuthnSuccess rejects responses que ne pas strictly increment le authenticator's counter, detecting cloned credentials.
Base de données Integration – Credential data, sign counters, et session tokens are stored et updated via external persistence functions, demonstrating comment integrate le composant avec un real-world backend.
Cross-Origin Iframe Support – Enabled through AllowCrossOrigins et configured TopOrigins, allowing WebAuthn flows initiated depuis embedded frames (par ex. login widget on different domain).
Attestation Policy – Direct attestation coupled avec MDS ensures seulement approved authenticators peut register, useful for enterprise compliance scenarios.
Transport Selection – Though not shown, événements peut constrain acceptable transports (par ex. USB,NFC,BLE) to tailor qui types de authenticators are permitted.