Normalize backend API token

README.md

@@ -163,9 +163,12 @@ Bei HTTP-Fehlern wie `401 Unauthorized` protokolliert der Agent:
 - ob ein Authorization-Header gesetzt wurde
 - Authorization-Scheme, z. B. `Bearer`
 - Token-Länge, aber niemals den Token selbst
+- kurzer SHA-256-Fingerprint des Tokens zum Abgleich mit dem Backend
 - `WWW-Authenticate`-Header des Backends
 - gekürzten Response-Body des Backends
 
+Beim Speichern wird der API-Token normalisiert. Falls versehentlich `Bearer ...` oder `Authorization: Bearer ...` eingefügt wurde, speichert der Agent nur den eigentlichen Tokenwert.
+
 ## Nicht mehr im Agent
 
 - keine Layout-JSON-Verwaltung

src/LabelPrintAgent/App/SettingsForm.cs

@@ -168,7 +168,9 @@ internal sealed class SettingsForm : Form
         var settings = _settingsStore.Load();
         settings.Backend.BaseUrl = _backendBaseUrl.Text.Trim();
         settings.Backend.AgentId = _agentId.Text.Trim();
-        settings.Backend.EncryptedApiToken = _settingsStore.EncryptPassword(_apiToken.Text);
+        var normalizedToken = SettingsStore.NormalizeBackendApiToken(_apiToken.Text);
+        settings.Backend.EncryptedApiToken = _settingsStore.EncryptPassword(normalizedToken);
+        _apiToken.Text = normalizedToken;
         settings.Backend.NextJobPath = _nextJobPath.Text.Trim();
         settings.Backend.ImagePath = _imagePath.Text.Trim();
         settings.Backend.ReportSuccessPath = _reportSuccessPath.Text.Trim();

src/LabelPrintAgent/Backend/BackendClient.cs

@@ -1,6 +1,8 @@
 using System.Drawing;
 using System.Net.Http.Headers;
 using System.Net.Http.Json;
+using System.Security.Cryptography;
+using System.Text;
 using System.Text.Json;
 using LabelPrintAgent.Configuration;
 using Serilog;
@@ -117,7 +119,7 @@ public sealed class BackendClient
     private HttpRequestMessage CreateRequest(HttpMethod method, string url, AppSettings settings)
     {
         var request = new HttpRequestMessage(method, url);
-        var token = _settingsStore.DecryptBackendApiToken(settings);
+        var token = SettingsStore.NormalizeBackendApiToken(_settingsStore.DecryptBackendApiToken(settings));
         if (!string.IsNullOrWhiteSpace(token))
         {
             request.Headers.Authorization = new AuthenticationHeaderValue("Bearer", token);
@@ -154,7 +156,7 @@ public sealed class BackendClient
         Log.Warning(
             "Backend request failed: {Method} {Url} -> {StatusCode} {ReasonPhrase}. " +
             "AuthorizationHeaderPresent={AuthorizationHeaderPresent}, AuthorizationScheme={AuthorizationScheme}, " +
-            "TokenLength={TokenLength}, WwwAuthenticate={WwwAuthenticate}, ResponseBody={ResponseBody}",
+            "TokenLength={TokenLength}, TokenSha256Prefix={TokenSha256Prefix}, WwwAuthenticate={WwwAuthenticate}, ResponseBody={ResponseBody}",
             request.Method.Method,
             request.RequestUri,
             (int)response.StatusCode,
@@ -162,6 +164,7 @@ public sealed class BackendClient
             authorization is not null,
             authorization?.Scheme ?? string.Empty,
             authorization?.Parameter?.Length ?? 0,
+            GetTokenSha256Prefix(authorization?.Parameter),
             wwwAuthenticate,
             Truncate(responseBody, 2000));
 
@@ -197,6 +200,17 @@ public sealed class BackendClient
         return value[..maxLength] + "...";
     }
 
+    private static string GetTokenSha256Prefix(string? token)
+    {
+        if (string.IsNullOrEmpty(token))
+        {
+            return string.Empty;
+        }
+
+        var hash = SHA256.HashData(Encoding.UTF8.GetBytes(token));
+        return Convert.ToHexString(hash)[..12];
+    }
+
     private static Bitmap CreateBitmap(byte[] bytes)
     {
         using var stream = new MemoryStream(bytes);

src/LabelPrintAgent/Configuration/SettingsStore.cs

@@ -57,4 +57,25 @@ public sealed class SettingsStore
     public string EncryptPassword(string password) => _protectedStringService.Protect(password);
 
     public string DecryptBackendApiToken(AppSettings settings) => _protectedStringService.Unprotect(settings.Backend.EncryptedApiToken);
+
+    public static string NormalizeBackendApiToken(string token)
+    {
+        if (string.IsNullOrWhiteSpace(token))
+        {
+            return string.Empty;
+        }
+
+        var normalized = token.Trim().Trim('"', '\'').Trim();
+        if (normalized.StartsWith("Authorization:", StringComparison.OrdinalIgnoreCase))
+        {
+            normalized = normalized["Authorization:".Length..].Trim();
+        }
+
+        if (normalized.StartsWith("Bearer ", StringComparison.OrdinalIgnoreCase))
+        {
+            normalized = normalized["Bearer ".Length..].Trim();
+        }
+
+        return normalized.Trim().Trim('"', '\'').Trim();
+    }
 }