java - Merging of pdf with digital signature with itext 5.4.0 or greatest gives error

Question

I have a big problem in trying to merge some pdf, created with itext, with digital signature.

This is the code:

             ByteArrayOutputStream  bos = new ByteArrayOutputStream();

             Document document = new Document();
             PdfCopy writer = new PdfCopy(document, bos);

             writer.setMergeFields();                

             document.addTitle("");
             document.open();

             PdfReader reader = null;
             for (int i = 0; i < iss.length; i++) {

                 reader = new PdfReader(iss[i]);                     
                 writer.addDocument(reader);
                 reader.close();
             }
             document.close();
             bos.close();

On execute i receive this error:

java.lang.IllegalStateException: Already closed
at com.itextpdf.text.io.ArrayRandomAccessSource.get(ArrayRandomAccessSource.java:65)
at com.itextpdf.text.io.IndependentRandomAccessSource.get(IndependentRandomAccessSource.java:78)
at com.itextpdf.text.pdf.RandomAccessFileOrArray.read(RandomAccessFileOrArray.java:226)
at com.itextpdf.text.pdf.RandomAccessFileOrArray.readFully(RandomAccessFileOrArray.java:248)
at com.itextpdf.text.pdf.RandomAccessFileOrArray.readFully(RandomAccessFileOrArray.java:242)
at com.itextpdf.text.pdf.PdfReader.getStreamBytesRaw(PdfReader.java:2522)
at com.itextpdf.text.pdf.PdfReader.getStreamBytesRaw(PdfReader.java:2559)
at com.itextpdf.text.pdf.PRStream.toPdf(PRStream.java:230)
at com.itextpdf.text.pdf.PdfIndirectObject.writeTo(PdfIndirectObject.java:158)
at com.itextpdf.text.pdf.PdfWriter$PdfBody.write(PdfWriter.java:420)
at com.itextpdf.text.pdf.PdfWriter$PdfBody.add(PdfWriter.java:398)
at com.itextpdf.text.pdf.PdfWriter$PdfBody.add(PdfWriter.java:377)
at com.itextpdf.text.pdf.PdfWriter.addToBody(PdfWriter.java:868)
at com.itextpdf.text.pdf.PdfCopyFieldsImp.closeIt(PdfCopyFieldsImp.java:439)
at com.itextpdf.text.pdf.PdfCopyFieldsImp.close(PdfCopyFieldsImp.java:397)
at com.itextpdf.text.pdf.PdfCopyFields.close(PdfCopyFields.java:159)
at it.almavivaitalia.commons.crystal.utils.ReportClientDocumentManager.mergePdfs(ReportClientDocumentManager.java:310)
at it.almavivaitalia.commons.crystal.utils.ReportClientDocumentManager.exportReportSchedulationPDFMerged(ReportClientDocumentManager.java:632)
at it.consip.pat.common.web.controller.AbstractReportCtrl.exportPDFMerged(AbstractReportCtrl.java:388)
at it.consip.pat.common.web.controller.AbstractReportCtrl.exportReportSchedulationPDFMerged(AbstractReportCtrl.java:334)
at it.consip.fgen.web.interrogazioni.controllers.RicEseConsStampeCtrl.stampaAll(RicEseConsStampeCtrl.java:530)
at it.consip.fgen.web.interrogazioni.controllers.RicEseConsStampeCtrl$$FastClassByCGLIB$$d94d9dbb.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:688)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:67)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:621)
at it.consip.fgen.web.interrogazioni.controllers.RicEseConsStampeCtrl$$EnhancerByCGLIB$$b8912b3f_2.stampaAll(<generated>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.springframework.web.bind.annotation.support.HandlerMethodInvoker.invokeHandlerMethod(HandlerMethodInvoker.java:176)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.invokeHandlerMethod(AnnotationMethodHandlerAdapter.java:426)
at org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter.handle(AnnotationMethodHandlerAdapter.java:414)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:790)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:719)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1093)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:368)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:83)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:100)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:78)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:35)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.authentication.preauth.AbstractPreAuthenticatedProcessingFilter.doFilter(AbstractPreAuthenticatedProcessingFilter.java:89)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:169)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:726)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:206)
at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:324)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:505)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:842)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:648)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:380)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:395)
at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:450)

If I comment the code writer.setMergeFields(); everything works fine but the fields are not copied.

If I use the itext 5.3.6 version everything works fine (using PdfCopyField).

Why?

Answer 1

There are two errors in your reasoning. One that can be fixed, one that is a not a technical error, but a reasoning error that can't be fixed.

The technical error: You close the reader before you close the document. That's too early. PdfCopy and Document need access to the reader when document.close() is invoked. You've already closed the reader instance in the loop, hance the java.lang.IllegalStateException informing you that the resource is Already closed.

The problem with your assumption: Digital signatures are a way to guarantee the integrity of a document. When somebody signs a document with 5 pages, that person wants to make sure he signed those 5 pages, not more, not less. You are now going to add pages. That will always break the signature!

If you want to combine PDF documents that are digitally signed: - it is forbidden to assemble those documents: if you do, the signatures will either disappear or break. - your only option is to combine the documents in a portable collection. In this case, a master PDF acts as a package or portfolio to store the separate PDFs. The PDFs as such are kept intact (if not: the signature shall break).