incremental update check reintroduced

git-svn-id: https://joinup.ec.europa.eu/svn/pdf-as/trunk@244 7b5415b0-85f9-ee4d-85bd-d5d0c3b42d1c

1 files changed, 168 insertions, 104 deletions

diff --git a/src/main/java/at/gv/egiz/pdfas/impl/vfilter/VerificationFilterImpl.java b/src/main/java/at/gv/egiz/pdfas/impl/vfilter/VerificationFilterImpl.java
index d192f7a..2aa5c28 100644
--- a/src/main/java/at/gv/egiz/pdfas/impl/vfilter/VerificationFilterImpl.java
+++ b/src/main/java/at/gv/egiz/pdfas/impl/vfilter/VerificationFilterImpl.java
@@ -55,6 +55,8 @@ public class VerificationFilterImpl implements VerificationFilter
 

   // tzefferer: added

   public static final String CHECK_DOCUMENT = "check_document";

+  public static final String BINARY_ONLY = "binary_only";

+  public static final String ASSUME_ONLY_SIGNATURE_BLOCKS = "assume_only_signature_blocks";

   

   /**

    * @see at.gv.egiz.pdfas.framework.vfilter.VerificationFilter#extractSignatureHolders(at.gv.egiz.pdfas.framework.input.PdfDataSource,

@@ -81,6 +83,26 @@ public class VerificationFilterImpl implements VerificationFilter
       debugIUBlocks(blocks);

     }

 

+    

+    SettingsReader settings;

+    try {

+      settings = SettingsReader.getInstance();

+    } catch (SettingsException e) {

+      throw new VerificationFilterException(e);

+    }

+    String check_doc = settings.getSetting(CHECK_DOCUMENT, "false");

+

+    // tzefferer: check document for textual sigs here here if binary_only is set    

+    if ("true".equalsIgnoreCase(check_doc) &&

+      parameters.extractBinarySignaturesOnly()) {

+

+      checkBinaryOnly(pdf, parameters.scanForOldSignatures());

+      log.debug("checkDocument: " + sw.getTime() + "ms.");

+    } else {

+      log.debug("Skipping checkDocument for textual sigs.");

+    }

+    // end add

+    

     List signatureHolderChain = null;

 

     if (parameters.extractBinarySignaturesOnly())

@@ -116,26 +138,7 @@ public class VerificationFilterImpl implements VerificationFilter
     sw.stop();

     log.debug("extractSignatureHolders: " + sw.getTime() + "ms.");

     

-    SettingsReader settings;

-    try {

-      settings = SettingsReader.getInstance();

-    } catch (SettingsException e) {

-      throw new VerificationFilterException(e);

-    }

-    String check_doc = settings.getSetting(CHECK_DOCUMENT, "false");

-

-    // tzefferer: check document here

-    // check doesn't make sense if we don't have any signatures

-    if (signatureHolderChain != null && !signatureHolderChain.isEmpty() && "true".equalsIgnoreCase(check_doc)) {

-   	 sw.reset();

-   	 sw.start();

-   	 checkDocument(pdf, blocks, parameters);

-   	 sw.stop();

-   	 log.debug("checkDocument: " + sw.getTime() + "ms.");

-    } else {

-   	 log.debug("Skipping checkDocument.");

-    }

-    // end add

+    

     

     return signatureHolderChain;

   }

@@ -268,10 +271,23 @@ public class VerificationFilterImpl implements VerificationFilter
     List flattedOutPartitions = flattenOutTextPartitions(partitions, blocks);

     partitions = flattedOutPartitions;

 

+    SettingsReader settings;

+    try {

+      settings = SettingsReader.getInstance();

+    } catch (SettingsException e) {

+      throw new VerificationFilterException(e);

+    }

+    String check_doc = settings.getSetting(CHECK_DOCUMENT, "false");

+    

+    // flags for determination of illegal incremental update

+    int sigs_found = 0; 

+    int sigs_found_prev = 0;

+    

     List partitionResults = new ArrayList(partitions.size());

     for (int i = 0; i < partitions.size(); i++)

     {

       Partition p = (Partition) partitions.get(i);

+      

 

       if (p instanceof TextPartition)

       {

@@ -290,9 +306,27 @@ public class VerificationFilterImpl implements VerificationFilter
         {

           partitionResult = extractSignaturesFromPartition(pdf, tp);

         }

-

+        

+        sigs_found_prev = sigs_found;

+        sigs_found = partitionResult.size();

         partitionResults.add(partitionResult);

+      } else {

+        // should be binary partition

+        if(p instanceof BinaryPartition) {

+          BinaryPartition binpart = (BinaryPartition)p;

+          // add number (n) of found binary signatures - if there is a subsequent textual partition, 

+          // at least n+1 sigs have to be found (note: sig-blocks of binary signatures are also extracted and detected) 

+          sigs_found = sigs_found + binpart.blocks.size();

+          

+        }

       }

+      

+      // throw an Exception if there were already signatures, but current block does not contain any signatures

+      if((check_doc.equalsIgnoreCase("true"))&& ((sigs_found_prev > 0) && !(sigs_found > sigs_found_prev)) ) {

+        log.error("Illegal document modification!");

+        throw new VerificationFilterException(ErrorCode.MODIFIED_AFTER_SIGNATION, "The document has been modified after being signed.");

+      }

+      

     }

 

     List extractedSignatures = new ArrayList();

@@ -493,6 +527,16 @@ public class VerificationFilterImpl implements VerificationFilter
    */

   protected List extractBinarySignaturesOnly(PdfDataSource pdf, List blocks) throws VerificationFilterException

   {

+    SettingsReader settings;

+    try {

+      settings = SettingsReader.getInstance();

+    } catch (SettingsException e) {

+      throw new VerificationFilterException(e);

+    }

+    String check_doc = settings.getSetting(CHECK_DOCUMENT, "false");

+    String binary_only = settings.getSetting(BINARY_ONLY, "false");

+    String assume_sigs_only = settings.getSetting(ASSUME_ONLY_SIGNATURE_BLOCKS, "false");

+    

     try

     {

       // PERF: extract binary signatures needs byte array

@@ -502,6 +546,7 @@ public class VerificationFilterImpl implements VerificationFilter
 

       Iterator it = blocks.iterator();

       int prev_end = 0;

+      boolean sig_detected = false;

       while (it.hasNext())

       {

         FooterParseResult fpr = (FooterParseResult) it.next();

@@ -515,6 +560,24 @@ public class VerificationFilterImpl implements VerificationFilter
           List binary_holders = verificator.parseBlock(pdf, data, fpr, prev_end);

 

           binarySignatures.addAll(binary_holders);

+          if(binary_holders.size() > 0) {

+            sig_detected = true;

+          }

+        } else {

+          // an Exception is thrown here if:

+          // 1) check_document is activated

+          // 2) assume_only_signature_blocks is false - otherwise we permit updates

+          // 3) binary_only is true - otherwise updates are handled in method performFullConservative(). 

+          //    when binary-only is true, we can be sure that a block that contains no egiz-dict is no textual 

+          //    signature either but an illegal update, otherwise an Exception (doc contains textual sig) would have been thrown before

+          // 4) a binary signature has been detected in a previous block

+          if(check_doc.equalsIgnoreCase("true") && 

+             binary_only.equalsIgnoreCase("true") &&

+             assume_sigs_only.equalsIgnoreCase("false") &&

+             sig_detected) {            

+            

+            throw new VerificationFilterException(ErrorCode.MODIFIED_AFTER_SIGNATION, "The document has been modified after being signed.");

+          }

         }

 

         prev_end = fpr.next_index;

@@ -595,6 +658,7 @@ public class VerificationFilterImpl implements VerificationFilter
        log.debug("Extracting text from 0 to " + endOfDocument + " (total document size = " + pdf.getLength() + "):");

       String extractedText = extractText(pdf, endOfDocument);

       log.debug("Extracting text finished.");

+      log.debug("extracted text: " + extractedText);

 

       SignaturesAndOld sao = extractSignaturesAndOld(extractedText);

 

@@ -606,90 +670,90 @@ public class VerificationFilterImpl implements VerificationFilter
     }

   }

 

+//  // tzefferer: added method

+//  protected void checkDocument(PdfDataSource pdf, List blocks, VerificationFilterParameters parameters) throws VerificationFilterException {

+//    

+//    boolean consider_old_sigs = parameters.scanForOldSignatures();

+//    boolean binary_only = parameters.extractBinarySignaturesOnly();

+//    boolean assume_sigs_only = parameters.assumeOnlySignatureUpdateBlocks();

+//   

+//    if(binary_only) {

+//      // check if document contains textual signatures

+//      checkBinaryOnly(pdf, consider_old_sigs);

+//    }    

+//    if(!assume_sigs_only) {

+//      // check if document contains post-sign modifications

+//      checkUpdateBlocks(pdf, blocks, consider_old_sigs);

+//    }     

+//  }  

   // tzefferer: added method

-  protected void checkDocument(PdfDataSource pdf, List blocks, VerificationFilterParameters parameters) throws VerificationFilterException {

-    

-    boolean consider_old_sigs = parameters.scanForOldSignatures();

-    boolean binary_only = parameters.extractBinarySignaturesOnly();

-    boolean assume_sigs_only = parameters.assumeOnlySignatureUpdateBlocks();

-   

-    if(binary_only) {

-      // check if document contains textual signatures

-      checkBinaryOnly(pdf, consider_old_sigs);

-    }    

-    if(!assume_sigs_only) {

-      // check if document contains post-sign modifications

-      checkUpdateBlocks(pdf, blocks, consider_old_sigs);

-    }     

-  }  

-  // tzefferer: added method

-  protected void checkUpdateBlocks(PdfDataSource pdf, List blocks, boolean considerOldSigs) throws VerificationFilterException {

-    

-    boolean sig_detected = false;

-    

-    if (considerOldSigs) {

-      

-      DelimitedPdfDataSource dds = new DelimitedPdfDataSource(pdf, pdf.getLength());

-      String text = null;

-      try {

-        text = PdfAS.extractNormalizedTextTextual(dds);

-      } catch (PresentableException e) {

-        throw new VerificationFilterException(e);

-      }

-      

-      SignaturesAndOld sao = extractSignaturesAndOld(text);

-      

-      if ((sao != null) && (sao.oldSignature != null)) {

-        sig_detected = true;

-      }      

-    }

-    

-    

-    Iterator it = blocks.iterator();

-    String prev_text = null;

-

-    while (it.hasNext())

-    {

-      boolean sig_in_current_block = false;

-      

-      FooterParseResult fpr = (FooterParseResult) it.next();

-             

-      DelimitedPdfDataSource dds = new DelimitedPdfDataSource(pdf, fpr.next_index);

-     

-      String text;

-      try {

-        text = PdfAS.extractNormalizedTextTextual(dds);

-      } catch (PresentableException e) {

-        throw new VerificationFilterException(e);

-      }

-

-      if (prev_text == null) {

-        prev_text = text;

-      } else {

-        String texttmp = text.substring(prev_text.length());

-        prev_text = text;

-        text = texttmp;

-      }

-

-      List sig_holders = null;

-      try {

-        sig_holders = AbsoluteTextSignature.extractSignatureHoldersFromText(text);

-      } catch (SignatureException e) {

-        throw new VerificationFilterException(e);

-      } catch (SignatureTypesException e) {

-        throw new VerificationFilterException(e);

-      }

-      

-      if((sig_holders != null) && (sig_holders.size() > 0)) {

-        sig_detected = true;

-        sig_in_current_block = true;

-      }

-

-      if((sig_detected) && (!sig_in_current_block)) {

-        throw new VerificationFilterException(ErrorCode.MODIFIED_AFTER_SIGNATION, "The document has been modified after being signed.");

-      }       

-    }            

-  }

+//  protected void checkUpdateBlocks(PdfDataSource pdf, List blocks, boolean considerOldSigs) throws VerificationFilterException {

+//    

+//    boolean sig_detected = false;

+//    

+//    if (considerOldSigs) {

+//      

+//      DelimitedPdfDataSource dds = new DelimitedPdfDataSource(pdf, pdf.getLength());

+//      String text = null;

+//      try {

+//        text = PdfAS.extractNormalizedTextTextual(dds);

+//      } catch (PresentableException e) {

+//        throw new VerificationFilterException(e);

+//      }

+//      

+//      SignaturesAndOld sao = extractSignaturesAndOld(text);

+//      

+//      if ((sao != null) && (sao.oldSignature != null)) {

+//        sig_detected = true;

+//      }      

+//    }

+//    

+//    

+//    Iterator it = blocks.iterator();

+//    String prev_text = null;

+//

+//    while (it.hasNext())

+//    {

+//      boolean sig_in_current_block = false;

+//      

+//      FooterParseResult fpr = (FooterParseResult) it.next();

+//             

+//      DelimitedPdfDataSource dds = new DelimitedPdfDataSource(pdf, fpr.next_index);

+//     

+//      String text;

+//      try {

+//        text = PdfAS.extractNormalizedTextTextual(dds);

+//      } catch (PresentableException e) {

+//        throw new VerificationFilterException(e);

+//      }

+//

+//      if (prev_text == null) {

+//        prev_text = text;

+//      } else {

+//        String texttmp = text.substring(prev_text.length());

+//        prev_text = text;

+//        text = texttmp;

+//      }

+//

+//      List sig_holders = null;

+//      try {

+//        sig_holders = AbsoluteTextSignature.extractSignatureHoldersFromText(text);

+//      } catch (SignatureException e) {

+//        throw new VerificationFilterException(e);

+//      } catch (SignatureTypesException e) {

+//        throw new VerificationFilterException(e);

+//      }

+//      

+//      if((sig_holders != null) && (sig_holders.size() > 0)) {

+//        sig_detected = true;

+//        sig_in_current_block = true;

+//      }

+//

+//      if((sig_detected) && (!sig_in_current_block)) {

+//        throw new VerificationFilterException(ErrorCode.MODIFIED_AFTER_SIGNATION, "The document has been modified after being signed.");

+//      }       

+//    }            

+//  }

   // tzefferer: added method

   protected void checkBinaryOnly(PdfDataSource pdf, boolean considerOldSigs) throws VerificationFilterException {