From ca954e8fc5832a7ff686e0b878951079d8f8fe12 Mon Sep 17 00:00:00 2001
From: Thomas <>
Date: Mon, 31 May 2021 18:20:57 +0200
Subject: possible fix of PDF-UA problem

---
 .../impl/signing/pdfbox2/PADESPDFBOXSigner.java    | 63 +++++++++++++++++++---
 1 file changed, 55 insertions(+), 8 deletions(-)

diff --git a/pdf-as-pdfbox-2/src/main/java/at/gv/egiz/pdfas/lib/impl/signing/pdfbox2/PADESPDFBOXSigner.java b/pdf-as-pdfbox-2/src/main/java/at/gv/egiz/pdfas/lib/impl/signing/pdfbox2/PADESPDFBOXSigner.java
index 6345a714..a33517cb 100644
--- a/pdf-as-pdfbox-2/src/main/java/at/gv/egiz/pdfas/lib/impl/signing/pdfbox2/PADESPDFBOXSigner.java
+++ b/pdf-as-pdfbox-2/src/main/java/at/gv/egiz/pdfas/lib/impl/signing/pdfbox2/PADESPDFBOXSigner.java
@@ -64,6 +64,7 @@ import org.apache.pdfbox.pdmodel.PDDocument;
 import org.apache.pdfbox.pdmodel.PDDocumentCatalog;
 import org.apache.pdfbox.pdmodel.PDPage;
 import org.apache.pdfbox.pdmodel.PDResources;
+import org.apache.pdfbox.pdmodel.common.COSObjectable;
 import org.apache.pdfbox.pdmodel.common.PDMetadata;
 import org.apache.pdfbox.pdmodel.common.PDNumberTreeNode;
 import org.apache.pdfbox.pdmodel.common.PDRectangle;
@@ -96,7 +97,10 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.util.ArrayList;
 import java.util.Calendar;
+import java.util.Collections;
+import java.util.LinkedHashMap;
 import java.util.List;
+import java.util.Map;
 
 public class PADESPDFBOXSigner implements IPdfSigner, IConfigurationConstants {
 
@@ -213,7 +217,8 @@ public class PADESPDFBOXSigner implements IPdfSigner, IConfigurationConstants {
 			}
 			SignatureProfileSettings signatureProfileSettings = TableFactory
 					.createProfile(requestedSignature.getSignatureProfileID(), pdfObject.getStatus().getSettings());
-            //Check if input document is PDF-A conform
+            			
+			//Check if input document is PDF-A conform
             if (signatureProfileSettings.isPDFA()) {
                 DataSource origDoc = pdfObject.getOriginalDocument();
                 InputStream stream = origDoc.getInputStream();
@@ -510,12 +515,13 @@ public class PADESPDFBOXSigner implements IPdfSigner, IConfigurationConstants {
 
 						}
 					}
-
+					
 					PDStructureElement sigBlock = new PDStructureElement("Form", docElement);
 
 					// create object dictionary and add as child element
 					COSDictionary objectDic = new COSDictionary();
 					objectDic.setName("Type", "OBJR");
+										
 					objectDic.setItem("Pg", signatureField.getWidget().getPage());
 					objectDic.setItem("Obj", signatureField.getWidget());
 
@@ -541,7 +547,6 @@ public class PADESPDFBOXSigner implements IPdfSigner, IConfigurationConstants {
 
 					// Modify number tree
 					PDNumberTreeNode ntn = structureTreeRoot.getParentTree();
-					int parentTreeNextKey = structureTreeRoot.getParentTreeNextKey();
 					if (ntn == null) {
 						ntn = new PDNumberTreeNode(objectDic, null);
 						logger.info("No number-tree-node found!");
@@ -549,9 +554,10 @@ public class PADESPDFBOXSigner implements IPdfSigner, IConfigurationConstants {
 
 					COSArray ntnKids = (COSArray) ntn.getCOSObject().getDictionaryObject(COSName.KIDS);
 					COSArray ntnNumbers = (COSArray) ntn.getCOSObject().getDictionaryObject(COSName.NUMS);
-
-					if(ntnNumbers == null && ntnKids != null){//no number array, so continue with the kids array
-
+					
+					int parentTreeNextKey = getParentTreeNextKey(structureTreeRoot);
+					
+					if(ntnNumbers == null && ntnKids != null){//no number array, so continue with the kids array																								
 						//create dictionary with limits and nums array
 						COSDictionary pTreeEntry = new COSDictionary();
 						COSArray limitsArray = new COSArray();
@@ -630,7 +636,7 @@ public class PADESPDFBOXSigner implements IPdfSigner, IConfigurationConstants {
                             byte[] outputDocument = bos.toByteArray();
                             pdfObject.setSignedDocument(outputDocument);
                 }
-                        /* Check if resulting pdf is PDF-A conform */
+                        /* Check if resulting pdf is PDF-A conform */                                                
                     if (signatureProfileSettings.isPDFA()) {
                         runPDFAPreflight(new ByteArrayDataSource(pdfObject.getSignedDocument()));
                     }
@@ -665,7 +671,23 @@ public class PADESPDFBOXSigner implements IPdfSigner, IConfigurationConstants {
 		}
 	}
 
-    /**
+    private int getParentTreeNextKey(PDStructureTreeRoot structureTreeRoot) throws IOException {
+    	int nextKey = structureTreeRoot.getParentTreeNextKey();
+    	if (nextKey < 0) {
+    		Map<Integer, COSObjectable> destNumberTreeAsMap = getNumberTreeAsMap(structureTreeRoot.getParentTree());
+    		if (destNumberTreeAsMap.isEmpty()) {
+    			nextKey = 0;
+                
+            } else {
+            	nextKey = Collections.max(destNumberTreeAsMap.keySet()) + 1;
+            	
+            }    		
+    	} 
+    	    	
+		return nextKey;
+	}
+
+	/**
      * Check via PreFlightParser if PDF-Document is a valid PDFA1
      * @param signedDocument: signed Document
      * @throws PdfAsException
@@ -950,4 +972,29 @@ public class PADESPDFBOXSigner implements IPdfSigner, IConfigurationConstants {
 		}
 		return result;
 	}
+	
+	static Map<Integer, COSObjectable> getNumberTreeAsMap(PDNumberTreeNode tree)
+            throws IOException
+    {
+        Map<Integer, COSObjectable> numbers = tree.getNumbers();
+        if (numbers == null)
+        {
+            numbers = new LinkedHashMap<>();
+        }
+        else
+        {
+            // must copy because the map is read only
+            numbers = new LinkedHashMap<>(numbers);
+        }
+        List<PDNumberTreeNode> kids = tree.getKids();
+        if (kids != null)
+        {
+            for (PDNumberTreeNode kid : kids)
+            {
+                numbers.putAll(getNumberTreeAsMap(kid));
+            }
+        }
+        return numbers;
+    }
+	
 }
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