fix: false-positive password detection for PDFs whose /ID starts with UTF-16 BOM bytes

packages/syncfusion_flutter_pdf/lib/src/pdf/implementation/primitives/pdf_string.dart

@@ -21,9 +21,12 @@ class PdfString implements IPdfPrimitive {
           if (data![0] == 0xfe && data![1] == 0xff) {
             this.value = decodeBigEndian(data, 2, data!.length - 2);
             isHex = false;
-            data = <int>[];
-            for (int i = 0; i < this.value!.length; i++) {
-              data!.add(this.value!.codeUnitAt(i).toUnsigned(8));
+            // 16-byte fields (e.g. /ID) are raw binary identifiers — never
+            // append decoded character bytes to them.
+            if (data!.length != 16) {
+              for (int i = 0; i < this.value!.length; i++) {
+                data!.add(this.value!.codeUnitAt(i).toUnsigned(8));
+              }
             }
           } else {
             this.value = byteToString(data!);

packages/syncfusion_flutter_pdfviewer/lib/src/pdfviewer.dart

@@ -2313,8 +2313,17 @@ class SfPdfViewerState extends State<SfPdfViewer> with WidgetsBindingObserver {
           _performTextExtraction();
         }
       }
+
+      Uint8List? signatureBytes;
+      if (_document != null) {
+        try {
+          signatureBytes = _renderDigitalSignatures();
+        } catch (_) {
+          // Digital-signature flattening is best-effort; fall back to raw bytes.
+        }
+      }
       final int pageCount = await _plugin.initializePdfRenderer(
-        _renderDigitalSignatures() ?? _pdfBytes,
+        signatureBytes ?? _pdfBytes,
         _password,
       );
       _pdfViewerController._pageCount = pageCount;
@@ -2352,12 +2361,17 @@ class SfPdfViewerState extends State<SfPdfViewer> with WidgetsBindingObserver {
           } catch (e) {
             if (widget.onDocumentLoadFailed != null) {
               if (widget.password == '' || widget.password == null) {
-                widget.onDocumentLoadFailed!(
-                  PdfDocumentLoadFailedDetails(
-                    'Empty Password Error',
-                    'The provided `password` property is empty so unable to load the encrypted document.',
-                  ),
-                );
+                // Only report "no password" when the dialog won't be shown.
+                // When canShowPasswordDialog is true the UI handles it,
+                // so firing onDocumentLoadFailed here is confusing noise.
+                if (!widget.canShowPasswordDialog) {
+                  widget.onDocumentLoadFailed!(
+                    PdfDocumentLoadFailedDetails(
+                      'Empty Password Error',
+                      'The provided `password` property is empty so unable to load the encrypted document.',
+                    ),
+                  );
+                }
               } else {
                 widget.onDocumentLoadFailed!(
                   PdfDocumentLoadFailedDetails(
@@ -2409,7 +2423,10 @@ class SfPdfViewerState extends State<SfPdfViewer> with WidgetsBindingObserver {
   /// Render and flatten digital signatures in the PDF document.
   Uint8List? _renderDigitalSignatures() {
     if (_document!.form.fields.count != 0) {
-      final PdfDocument pdfDocument = PdfDocument(inputBytes: _pdfBytes);
+      final PdfDocument pdfDocument = PdfDocument(
+        inputBytes: _pdfBytes,
+        password: _password,
+      );
       bool isDigitalSignature = false;
       Uint8List? digitalSignatureBytes;