Phase 3 PR 19 — LDAP user identity + Basic256Sha256 security profile. Replaces the anonymous-only endpoint with a configurable security profile and an LDAP-backed UserName token validator. New IUserAuthenticator abstraction in Backend/Security/: LdapUserAuthenticator binds to the configured directory (reuses the pattern from Admin.Security.LdapAuthService without the cross-app dependency — Novell.Directory.Ldap.NETStandard 3.6.0 package ref added to Server alongside the existing OPCFoundation packages) and maps group membership to OPC UA roles via LdapOptions.GroupToRole (case-insensitive). DenyAllUserAuthenticator is the default when Ldap.Enabled=false so UserName token attempts return a clean BadUserAccessDenied rather than hanging on a localhost:3893 bind attempt. OpcUaSecurityProfile enum + LdapOptions nested record on OpcUaServerOptions. Profile=None keeps the PR 17 shape (SecurityPolicies.None + Anonymous token only) so existing integration tests stay green; Profile=Basic256Sha256SignAndEncrypt adds a second ServerSecurityPolicy (Basic256Sha256 + SignAndEncrypt) to the collection and, when Ldap.Enabled=true, adds a UserName token policy scoped to SecurityPolicies.Basic256Sha256 only — passwords must ride an encrypted channel, the stack rejects UserName over None. OtOpcUaServer.OnServerStarted hooks SessionManager.ImpersonateUser: AnonymousIdentityToken passes through; UserNameIdentityToken delegates to IUserAuthenticator.AuthenticateAsync — rejected identities throw ServiceResultException(BadUserAccessDenied); accepted identities get a RoleBasedIdentity that carries the resolved roles through session.Identity so future PRs can gate writes by role. OpcUaApplicationHost + OtOpcUaServer constructors take IUserAuthenticator as a dependency. Program.cs binds the new OpcUaServer:Ldap section from appsettings (Enabled defaults false, GroupToRole parsed as Dictionary<string,string>), registers IUserAuthenticator as LdapUserAuthenticator when enabled or DenyAllUserAuthenticator otherwise. PR 17 integration test updated to pass DenyAllUserAuthenticator so it keeps exercising the anonymous-only path unchanged. Tests — SecurityConfigurationTests (new, 13 cases): DenyAllAuthenticator rejects every credential; LdapAuthenticator rejects blank creds without hitting the server; rejects when Enabled=false; rejects plaintext when both UseTls=false AND AllowInsecureLdap=false (safety guard matching the Admin service); EscapeLdapFilter theory (4 rows: plain passthrough, parens/asterisk/backslash → hex escape) — regression guard against LDAP injection; ExtractOuSegment theory (3 rows: finds ou=, returns null when absent, handles multiple ou segments by returning first); ExtractFirstRdnValue theory (3 rows: strips cn= prefix, handles single-segment DN, returns plain string unchanged when no =). OpcUaServerOptions_default_is_anonymous_only asserts the default posture preserves PR 17 behavior. InternalsVisibleTo('ZB.MOM.WW.OtOpcUa.Server.Tests') added to Server csproj so ExtractOuSegment and siblings are reachable from the tests. Full solution: 0 errors, 180 tests pass (8 Core + 14 Proxy + 24 Configuration + 6 Shared + 91 Galaxy.Host + 19 Server (17 unit + 2 integration) + 18 Admin). Live-LDAP integration test (connect via Basic256Sha256 endpoint with a real user from GLAuth, assert the session.Identity carries the mapped role) is deferred to a follow-up — it requires the GLAuth dev instance to be running at localhost:3893 which is dev-machine-specific, and the test harness for that also needs a fresh client-side certificate provisioned by the live server's trusted store.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/ZB.MOM.WW.OtOpcUa.Server/OpcUa/OpcUaServerOptions.cs

@@ -1,5 +1,23 @@
+using ZB.MOM.WW.OtOpcUa.Server.Security;
+
 namespace ZB.MOM.WW.OtOpcUa.Server.OpcUa;
 
+/// <summary>
+///     OPC UA transport security profile selector. Controls which <c>ServerSecurityPolicy</c>
+///     entries the endpoint advertises + which token types the <c>UserTokenPolicies</c> permits.
+/// </summary>
+public enum OpcUaSecurityProfile
+{
+    /// <summary>Anonymous only on <c>SecurityPolicies.None</c> — dev-only, no signing or encryption.</summary>
+    None,
+
+    /// <summary>
+    ///     <c>Basic256Sha256 SignAndEncrypt</c> with <c>UserName</c> and <c>Anonymous</c> token
+    ///     policies. Clients must present a valid application certificate + user credentials.
+    /// </summary>
+    Basic256Sha256SignAndEncrypt,
+}
+
 /// <summary>
 ///     OPC UA server endpoint + application-identity configuration. Bound from the
 ///     <c>OpcUaServer</c> section of <c>appsettings.json</c>. PR 17 minimum-viable scope: no LDAP,
@@ -39,4 +57,18 @@ public sealed class OpcUaServerOptions
     ///     Admin UI.
     /// </summary>
     public bool AutoAcceptUntrustedClientCertificates { get; init; } = true;
+
+    /// <summary>
+    ///     Security profile advertised on the endpoint. Default <see cref="OpcUaSecurityProfile.None"/>
+    ///     preserves the PR 17 endpoint shape; set to <see cref="OpcUaSecurityProfile.Basic256Sha256SignAndEncrypt"/>
+    ///     for production deployments with LDAP-backed UserName auth.
+    /// </summary>
+    public OpcUaSecurityProfile SecurityProfile { get; init; } = OpcUaSecurityProfile.None;
+
+    /// <summary>
+    ///     LDAP binding for UserName token validation. Only consulted when the active
+    ///     <see cref="SecurityProfile"/> advertises a UserName token policy. When
+    ///     <c>LdapOptions.Enabled = false</c>, UserName token attempts are rejected.
+    /// </summary>
+    public LdapOptions Ldap { get; init; } = new();
 }