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Pad encryption parameters that are too short (fixes #96)
This commit is contained in:
Jay Berkenbilt
parent
0c99cf874b
commit
8fe0b06cd8
@ -1,3 +1,8 @@
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2017-08-11 Jay Berkenbilt <ejb@ql.org>
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* Handle encrypted files whose encryption parameters are too
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short. Fixes #96.
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2017-08-10 Jay Berkenbilt <ejb@ql.org>
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* Remove dependency on libpcre.
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@ -340,6 +340,16 @@ hash_V5(std::string const& password,
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return result;
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}
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static
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void pad_short_parameter(std::string& param, unsigned int max_len)
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{
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if (param.length() < max_len)
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{
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QTC::TC("qpdf", "QPDF_encryption pad short parameter");
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param.append(max_len - param.length(), '\0');
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}
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}
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std::string
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QPDF::compute_data_key(std::string const& encryption_key,
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int objid, int generation, bool use_aes,
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@ -876,6 +886,8 @@ QPDF::initializeEncryption()
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if (V < 5)
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{
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pad_short_parameter(O, key_bytes);
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pad_short_parameter(U, key_bytes);
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if (! ((O.length() == key_bytes) && (U.length() == key_bytes)))
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{
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throw QPDFExc(qpdf_e_damaged_pdf, this->file->getName(),
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@ -899,6 +911,11 @@ QPDF::initializeEncryption()
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UE = encryption_dict.getKey("/UE").getStringValue();
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Perms = encryption_dict.getKey("/Perms").getStringValue();
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pad_short_parameter(O, OU_key_bytes_V5);
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pad_short_parameter(U, OU_key_bytes_V5);
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pad_short_parameter(OE, OUE_key_bytes_V5);
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pad_short_parameter(UE, OUE_key_bytes_V5);
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pad_short_parameter(Perms, Perms_key_bytes_V5);
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if ((O.length() < OU_key_bytes_V5) ||
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(U.length() < OU_key_bytes_V5) ||
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(OE.length() < OUE_key_bytes_V5) ||
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@ -293,3 +293,4 @@ QPDF ignore first space in xref entry 0
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QPDF ignore first extra space in xref entry 0
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QPDF ignore second extra space in xref entry 0
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QPDF ignore length error xref entry 0
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QPDF_encryption pad short parameter 0
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@ -232,7 +232,7 @@ foreach my $d (@bug_tests)
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show_ntests();
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# ----------
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$td->notify("--- Miscellaneous Tests ---");
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$n_tests += 87;
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$n_tests += 88;
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$td->runtest("qpdf version",
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{$td->COMMAND => "qpdf --version"},
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@ -676,6 +676,16 @@ $td->runtest("recoverable xref errors",
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$td->EXIT_STATUS => 3},
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$td->NORMALIZE_NEWLINES);
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# A file was emailed privately with issue 96. short-O-U.pdf was
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# created by copying encryption parameters from that file. It exhibits
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# the same behavior as the original file.
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$td->runtest("short /O or /U",
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{$td->COMMAND =>
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"qpdf --password=19723102477 --check short-O-U.pdf"},
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{$td->FILE => "short-O-U.out",
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$td->EXIT_STATUS => 0},
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$td->NORMALIZE_NEWLINES);
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show_ntests();
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# ----------
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$td->notify("--- Single Page ---");
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20
qpdf/qtest/qpdf/short-O-U.out
Normal file
20
qpdf/qtest/qpdf/short-O-U.out
Normal file
@ -0,0 +1,20 @@
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checking short-O-U.pdf
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PDF Version: 1.6
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R = 4
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P = -4
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User password = 19723102477
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extract for accessibility: allowed
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extract for any purpose: allowed
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print low resolution: allowed
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print high resolution: allowed
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modify document assembly: allowed
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modify forms: allowed
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modify annotations: allowed
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modify other: allowed
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modify anything: allowed
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stream encryption method: AESv2
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string encryption method: AESv2
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file encryption method: AESv2
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File is not linearized
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No syntax or stream encoding errors found; the file may still contain
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errors that qpdf cannot detect
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39
qpdf/qtest/qpdf/short-O-U.pdf
Normal file
39
qpdf/qtest/qpdf/short-O-U.pdf
Normal file
@ -0,0 +1,39 @@
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%PDF-1.6
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%¿÷¢þ
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1 0 obj
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<< /Pages 2 0 R /Type /Catalog >>
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endobj
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2 0 obj
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<< /Count 1 /Kids [ 3 0 R ] /Type /Pages >>
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endobj
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3 0 obj
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<< /Contents 4 0 R /MediaBox [ 0 0 612 792 ] /Parent 2 0 R /Resources << /Font << /F1 5 0 R >> /ProcSet 6 0 R >> /Type /Page >>
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endobj
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4 0 obj
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<< /Length 80 /Filter /FlateDecode >>
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stream
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õÓt‘iº’ðU– j,òB\h½lI—-Z¦ä’ä ¢<C2A0>ŽDÃ@B;¢–dh«ŠR“‹.<2E>ºrYbàÿÈÔâ™û\Æ{˜cBø c¡C?{av<¹h·endstream
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endobj
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5 0 obj
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<< /BaseFont /Helvetica /Encoding /WinAnsiEncoding /Name /F1 /Subtype /Type1 /Type /Font >>
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endobj
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6 0 obj
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[ /PDF /Text ]
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endobj
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7 0 obj
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<< /CF << /StdCF << /AuthEvent /DocOpen /CFM /AESV2 /Length 16 >> >> /Filter /Standard /Length 128 /O <e9aa816e7e5861b853c9259303e9cbd1135453cc10e93f73a5c740de28649a75> /P -4 /R 4 /StmF /StdCF /StrF /StdCF /U <82f858c956fc27a1d051b09b9fb19b72> /V 4 >>
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endobj
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xref
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0 8
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0000000000 65535 f
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0000000015 00000 n
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0000000064 00000 n
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0000000123 00000 n
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0000000266 00000 n
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0000000416 00000 n
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0000000523 00000 n
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0000000553 00000 n
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trailer << /Root 1 0 R /Size 8 /ID [<35653732633166343063386438346132><e6a5593287c9d6485cf6706c8d97902c>] /Encrypt 7 0 R >>
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startxref
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820
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%%EOF
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