Remove erroneous handling of /EFF for stream decryption

I thought /EFF was supposed to be used as a default for decrypting
embedded file streams, but actually it's supposed to be advice to a
conforming writer about handling new ones. This makes sense since the
findAttachmentStreams code, which is not actually needed, was never
right.

2 files changed, 20 insertions, 53 deletions

diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index 89c6ed74..3209903f 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -18,7 +18,6 @@
 #include <qpdf/FileInputSource.hh>
 #include <qpdf/BufferInputSource.hh>
 #include <qpdf/OffsetInputSource.hh>
-#include <qpdf/QPDFNameTreeObjectHelper.hh>
 
 #include <qpdf/QPDFExc.hh>
 #include <qpdf/QPDF_Null.hh>
@@ -98,7 +97,6 @@ QPDF::ForeignStreamData::ForeignStreamData(
     int foreign_generation,
     qpdf_offset_t offset,
     size_t length,
-    bool is_attachment_stream,
     QPDFObjectHandle local_dict)
     :
     encp(encp),
@@ -107,7 +105,6 @@ QPDF::ForeignStreamData::ForeignStreamData(
     foreign_generation(foreign_generation),
     offset(offset),
     length(length),
-    is_attachment_stream(is_attachment_stream),
     local_dict(local_dict)
 {
 }
@@ -508,7 +505,6 @@ QPDF::parse(char const* password)
     }
 
     initializeEncryption();
-    findAttachmentStreams();
     this->m->parsed = true;
 }
 
@@ -2648,8 +2644,6 @@ QPDF::replaceForeignIndirectObjects(
                     foreign.getGeneration(),
                     stream->getOffset(),
                     stream->getLength(),
-                    (foreign_stream_qpdf->m->attachment_streams.count(
-                        foreign.getObjGen()) > 0),
                     dict);
             this->m->copied_stream_data_provider->registerForeignStream(
                 local_og, foreign_stream_data);
@@ -2882,7 +2876,6 @@ QPDF::pipeStreamData(PointerHolder<EncryptionParameters> encp,
                      int objid, int generation,
 		     qpdf_offset_t offset, size_t length,
 		     QPDFObjectHandle stream_dict,
-                     bool is_attachment_stream,
 		     Pipeline* pipeline,
                      bool suppress_warnings,
                      bool will_retry)
@@ -2892,7 +2885,7 @@ QPDF::pipeStreamData(PointerHolder<EncryptionParameters> encp,
     {
 	decryptStream(encp, file, qpdf_for_warning,
                       pipeline, objid, generation,
-                      stream_dict, is_attachment_stream, to_delete);
+                      stream_dict, to_delete);
     }
 
     bool success = false;
@@ -2968,14 +2961,11 @@ QPDF::pipeStreamData(int objid, int generation,
                      bool suppress_warnings,
                      bool will_retry)
 {
-    bool is_attachment_stream = (
-        this->m->attachment_streams.count(
-            QPDFObjGen(objid, generation)) > 0);
     return pipeStreamData(
         this->m->encp, this->m->file, *this,
         objid, generation, offset, length,
-        stream_dict, is_attachment_stream,
-        pipeline, suppress_warnings, will_retry);
+        stream_dict, pipeline,
+        suppress_warnings, will_retry);
 }
 
 bool
@@ -2992,36 +2982,8 @@ QPDF::pipeForeignStreamData(
         foreign->encp, foreign->file, *this,
         foreign->foreign_objid, foreign->foreign_generation,
         foreign->offset, foreign->length,
-        foreign->local_dict, foreign->is_attachment_stream,
-        pipeline, suppress_warnings, will_retry);
-}
-
-void
-QPDF::findAttachmentStreams()
-{
-    QPDFObjectHandle root = getRoot();
-    QPDFObjectHandle names = root.getKey("/Names");
-    if (! names.isDictionary())
-    {
-        return;
-    }
-    QPDFObjectHandle embedded_files = names.getKey("/EmbeddedFiles");
-    if (! embedded_files.isDictionary())
-    {
-        return;
-    }
-    QPDFNameTreeObjectHelper ef_tree(embedded_files, *this);
-    for (auto const& i: ef_tree)
-    {
-        QPDFObjectHandle item = i.second;
-        if (item.isDictionary() &&
-            item.getKey("/EF").isDictionary() &&
-            item.getKey("/EF").getKey("/F").isStream())
-        {
-            QPDFObjectHandle stream = item.getKey("/EF").getKey("/F");
-            this->m->attachment_streams.insert(stream.getObjGen());
-        }
-    }
+        foreign->local_dict, pipeline,
+        suppress_warnings, will_retry);
 }
 
 void
diff --git a/libqpdf/QPDF_encryption.cc b/libqpdf/QPDF_encryption.cc
index 00bd697e..2ff48df9 100644
--- a/libqpdf/QPDF_encryption.cc
+++ b/libqpdf/QPDF_encryption.cc
@@ -1022,6 +1022,20 @@ QPDF::initializeEncryption()
 	this->m->encp->cf_string = interpretCF(this->m->encp, StrF);
 	if (EFF.isName())
 	{
+            // qpdf does not use this for anything other than
+            // informational purposes. This is intended to instruct
+            // conforming writers on which crypt filter should be used
+            // when new file attachments are added to a PDF file, but
+            // qpdf never generates encrypted files with non-default
+            // crypt filters. Prior to 10.2, I was under the mistaken
+            // impression that this was supposed to be used for
+            // decrypting attachments, but the code was wrong in a way
+            // that turns out not to have mattered because no writers
+            // were generating files the way I was imagining. Still,
+            // providing this information could be useful when looking
+            // at a file generated by something else, such as Acrobat
+            // when specifying that only attachments should be
+            // encrypted.
 	    this->m->encp->cf_file = interpretCF(this->m->encp, EFF);
 	}
 	else
@@ -1224,7 +1238,6 @@ QPDF::decryptStream(PointerHolder<EncryptionParameters> encp,
                     QPDF& qpdf_for_warning, Pipeline*& pipeline,
                     int objid, int generation,
 		    QPDFObjectHandle& stream_dict,
-                    bool is_attachment_stream,
 		    std::vector<PointerHolder<Pipeline> >& heap)
 {
     std::string type;
@@ -1296,15 +1309,7 @@ QPDF::decryptStream(PointerHolder<EncryptionParameters> encp,
 	    }
 	    else
 	    {
-                if (is_attachment_stream)
-                {
-                    QTC::TC("qpdf", "QPDF_encryption attachment stream");
-                    method = encp->cf_file;
-                }
-                else
-                {
-                    method = encp->cf_stream;
-                }
+                method = encp->cf_stream;
 	    }
 	}
 	use_aes = false;