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| author | Masamichi Hosoda <trueroad@trueroad.jp> | 2019-09-27 14:00:30 +0200 |
|---|---|---|
| committer | Jay Berkenbilt <ejb@ql.org> | 2019-10-22 22:16:16 +0200 |
| commit | 06b818dcd39b5aeaeeee5c247483633a02a0222e (patch) | |
| tree | d8547c0a002738368913b24685ffdb24b077ee3f | |
| parent | 5e0ba126871c57a8a688b36614f2b8d78c2675b3 (diff) | |
| download | qpdf-06b818dcd39b5aeaeeee5c247483633a02a0222e.tar.zst | |
Exclude signature dictionary from compressible objects
It seems better not to compress signature dictionaries. Various PDF
digital signing tools, including Adobe Acrobat Reader DC, do not
compress signature dictionaries.
Table 8.93 "Entries in a signature dictionary" in PDF 1.5 reference
describes that /ByteRange in the signature dictionary shall be used to
describe a digest that does not include the signature value
(/Contents) itself.
The byte ranges cannot be determined if the dictionary is compressed.
| -rw-r--r-- | libqpdf/QPDF.cc | 8 | ||||
| -rw-r--r-- | qpdf/qtest/qpdf.test | 4 |
2 files changed, 9 insertions, 3 deletions
diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc index c546fbe1..6c0c700a 100644 --- a/libqpdf/QPDF.cc +++ b/libqpdf/QPDF.cc @@ -2673,7 +2673,13 @@ QPDF::getCompressibleObjGens() { QTC::TC("qpdf", "QPDF exclude encryption dictionary"); } - else if (! obj.isStream()) + else if ((! obj.isStream()) && + (! (obj.isDictionary() && + obj.hasKey("/ByteRange") && + obj.hasKey("/Contents") && + obj.hasKey("/Type") && + obj.getKey("/Type").isName() && + obj.getKey("/Type").getName() == "/Sig"))) { result.push_back(og); } diff --git a/qpdf/qtest/qpdf.test b/qpdf/qtest/qpdf.test index 9fdf9ba2..d5caa9ad 100644 --- a/qpdf/qtest/qpdf.test +++ b/qpdf/qtest/qpdf.test @@ -3998,9 +3998,9 @@ $td->runtest("fix-qdf with big object stream", # > 255 objects in a stream show_ntests(); # ---------- $td->notify("--- Signature Dictionary ---"); -$n_tests += 4; +$n_tests += 6; -foreach my $i (qw(preserve disable)) +foreach my $i (qw(preserve disable generate)) { $td->runtest("sig dict contents hex (object-streams=$i)", {$td->COMMAND => |