Add optional /Length key in crypt filter dictionary

Jay Berkenbilt
1 parent a3576a73
Showing 9 changed files with 13 additions and 5 deletions
ChangeLog
libqpdf/QPDFWriter.cc
qpdf/qtest/qpdf/V4-aes-clearmeta.pdf
qpdf/qtest/qpdf/V4-aes.pdf
qpdf/qtest/qpdf/V4-clearmeta.pdf
qpdf/qtest/qpdf/V4.pdf
qpdf/qtest/qpdf/c-r4.pdf
qpdf/qtest/qpdf/c-r5-in.pdf
qpdf/qtest/qpdf/c-r6-in.pdf
 2013-06-14  Jay Berkenbilt  <ejb@ql.org>
  
+	* Add /Length key to crypt filter dictionary for encrypted files.
+	This key is optional, but some version of MacOS reportedly fail to
+	open encrypted PDF files without this key.
+
 	* Bug fix: properly handle object stream generation when the
 	original file has some compressible objects with generation != 0.
  
@@ -726,8 +726,12 @@ QPDFWriter::setEncryptionParametersInternal(
 	std::string method = (this->encrypt_use_aes
                               ? ((V < 5) ? "/AESV2" : "/AESV3")
                               : "/V2");
+        // The PDF spec says the /Length key is optional, but the PDF
+        // previewer on some versions of MacOS won't open encrypted
+        // files without it.
 	encryption_dictionary["/CF"] =
-	    "<< /StdCF << /AuthEvent /DocOpen /CFM " + method + " >> >>";
+	    "<< /StdCF << /AuthEvent /DocOpen /CFM " + method +
+            " /Length " + std::string((V < 5) ? "16" : "32") + " >> >>";
     }
  
     this->encrypted = true;