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ststeigerststeiger
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Merge pull request #274 from packdat/EnhancedEncryption
Enhance encryption capabilities
2 parents 4d8dea0 + 6033e93 commit 98ee2e9

23 files changed

+1170
-85
lines changed

‎PdfSharpCore.Test/Assets/AesEncrypted.pdf‎

61 KB
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‎PdfSharpCore.Test/Assets/protected-adobe.pdf‎

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‎PdfSharpCore.Test/Assets/protected-ilovepdf.pdf‎

19 KB
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‎PdfSharpCore.Test/Assets/protected-pdfencrypt.pdf‎

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‎PdfSharpCore.Test/Assets/protected-sodapdf.pdf‎

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‎PdfSharpCore.Test/IO/PdfReader.cs‎

Lines changed: 5 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1,9 +1,9 @@
1-
using System;
2-
using System.IO;
3-
using FluentAssertions;
1+
using FluentAssertions;
42
using PdfSharpCore.Pdf;
53
using PdfSharpCore.Pdf.IO;
64
using PdfSharpCore.Test.Helpers;
5+
using System;
6+
using System.IO;
77
using Xunit;
88

99
namespace PdfSharpCore.Test.IO
@@ -26,11 +26,12 @@ public void WillThrowExceptionWhenReadingInvalidPdf()
2626
act.Should().Throw<InvalidOperationException>().WithMessage("The file is not a valid PDF document.");
2727
}
2828

29-
private void AssertIsAValidPdfDocumentWithProperties(PdfDocument inputDocument, int expectedFileSize)
29+
internal static void AssertIsAValidPdfDocumentWithProperties(PdfDocument inputDocument, int expectedFileSize)
3030
{
3131
inputDocument.Should().NotBeNull();
3232
inputDocument.FileSize.Should().Be(expectedFileSize);
3333
inputDocument.Info.Should().NotBeNull();
34+
inputDocument.PageCount.Should().BeGreaterThan(0);
3435
}
3536
}
3637
}

‎PdfSharpCore.Test/PdfSharpCore.Test.csproj‎

Lines changed: 15 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -30,6 +30,9 @@
3030
</ItemGroup>
3131

3232
<ItemGroup>
33+
<None Update="Assets\AesEncrypted.pdf">
34+
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
35+
</None>
3336
<None Update="Assets\FamilyTree.pdf">
3437
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
3538
</None>
@@ -39,6 +42,18 @@
3942
<None Update="Assets\NotAValid.pdf">
4043
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
4144
</None>
45+
<None Update="Assets\protected-adobe.pdf">
46+
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
47+
</None>
48+
<None Update="Assets\protected-ilovepdf.pdf">
49+
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
50+
</None>
51+
<None Update="Assets\protected-pdfencrypt.pdf">
52+
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
53+
</None>
54+
<None Update="Assets\protected-sodapdf.pdf">
55+
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
56+
</None>
4257
<None Update="Assets\test.pdf">
4358
<CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>
4459
</None>

‎PdfSharpCore.Test/Security/PdfSecurity.cs‎

Lines changed: 93 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -1,15 +1,24 @@
1-
using System.IO;
2-
using FluentAssertions;
1+
using FluentAssertions;
32
using PdfSharpCore.Drawing;
43
using PdfSharpCore.Pdf;
54
using PdfSharpCore.Pdf.IO;
65
using PdfSharpCore.Pdf.Security;
6+
using PdfSharpCore.Test.Helpers;
7+
using System.IO;
78
using Xunit;
9+
using Xunit.Abstractions;
810

911
namespace PdfSharpCore.Test.Security
1012
{
1113
public class PdfSecurity
1214
{
15+
private readonly ITestOutputHelper output;
16+
17+
public PdfSecurity(ITestOutputHelper testOutputHelper)
18+
{
19+
output = testOutputHelper;
20+
}
21+
1322
[Theory]
1423
[InlineData(PdfDocumentSecurityLevel.Encrypted40Bit, "hunter1")]
1524
[InlineData(PdfDocumentSecurityLevel.Encrypted128Bit, "hunter1")]
@@ -19,6 +28,8 @@ public void CreateAndReadPasswordProtectedPdf(PdfDocumentSecurityLevel securityL
1928
var pageNewRenderer = document.AddPage();
2029
var renderer = XGraphics.FromPdfPage(pageNewRenderer);
2130
renderer.DrawString("Test Test Test", new XFont("Arial", 12), XBrushes.Black, new XPoint(12, 12));
31+
// validate correct handling of unicode strings (issue #264)
32+
document.Outlines.Add("The only page", pageNewRenderer);
2233
document.SecuritySettings.DocumentSecurityLevel = securityLevel;
2334
document.SecuritySettings.UserPassword = password;
2435

@@ -30,6 +41,86 @@ public void CreateAndReadPasswordProtectedPdf(PdfDocumentSecurityLevel securityL
3041
delegate(PdfPasswordProviderArgs args) { args.Password = password; });
3142

3243
loadDocument.PageCount.Should().Be(1);
44+
loadDocument.Outlines[0].Title.Should().Be("The only page");
45+
loadDocument.Info.Producer.Should().Contain("PDFsharp");
46+
}
47+
48+
[Fact]
49+
public void ShouldBeAbleToOpenAesEncryptedDocuments()
50+
{
51+
// this document has a V value of 4 (see PdfReference 1.7, Chapter 7.6.1, Table 20)
52+
// and an R value of 4 (see PdfReference 1.7, Chapter 7.6.3.2, Table 21)
53+
// see also: Adobe Supplement to the ISO 32000, BaseVersion: 1.7, ExtensionLevel: 3
54+
// Chapter 3.5.2, Table 3.19
55+
var file = PathHelper.GetInstance().GetAssetPath("AesEncrypted.pdf");
56+
var fi = new FileInfo(file);
57+
var document = Pdf.IO.PdfReader.Open(file, PdfDocumentOpenMode.Import);
58+
59+
// verify document was actually AES-encrypted
60+
var cf = document.SecurityHandler.Elements.GetDictionary("/CF");
61+
var stdCf = cf.Elements.GetDictionary("/StdCF");
62+
stdCf.Elements.GetString("/CFM").Should().Be("/AESV2");
63+
64+
IO.PdfReader.AssertIsAValidPdfDocumentWithProperties(document, (int)fi.Length);
65+
}
66+
67+
[Fact]
68+
public void DocumentWithUserPasswordCannotBeOpenedWithoutPassword()
69+
{
70+
var file = PathHelper.GetInstance().GetAssetPath("AesEncrypted.pdf");
71+
var document = Pdf.IO.PdfReader.Open(file, PdfDocumentOpenMode.Import);
72+
73+
// import pages into a new document
74+
var encryptedDoc = new PdfDocument();
75+
foreach (var page in document.Pages)
76+
encryptedDoc.AddPage(page);
77+
78+
// save enrypted
79+
encryptedDoc.SecuritySettings.UserPassword = "supersecret!11";
80+
var saveFileName = PathHelper.GetInstance().GetAssetPath("SavedEncrypted.pdf");
81+
encryptedDoc.Save(saveFileName);
82+
83+
// should throw because no password was provided
84+
var ex = Assert.Throws<PdfReaderException>(() =>
85+
{
86+
var readBackDoc = Pdf.IO.PdfReader.Open(saveFileName, PdfDocumentOpenMode.Import);
87+
});
88+
ex.Message.Should().Contain("A password is required to open the PDF document");
89+
90+
// check with password
91+
// TODO: should be checked in a separate test, but i was lazy...
92+
var fi = new FileInfo(saveFileName);
93+
var readBackDoc = Pdf.IO.PdfReader.Open(saveFileName, "supersecret!11", PdfDocumentOpenMode.Import);
94+
IO.PdfReader.AssertIsAValidPdfDocumentWithProperties(readBackDoc, (int)fi.Length);
95+
readBackDoc.PageCount.Should().Be(document.PageCount);
96+
}
97+
98+
// Same PDF protected by different tools or online-services
99+
[Theory]
100+
// https://www.ilovepdf.com/protect-pdf, 128 bit, /V 2 /R 3
101+
[InlineData(@"protected-ilovepdf.pdf", "test123")]
102+
103+
// https://www.adobe.com/de/acrobat/online/password-protect-pdf.html, 128 bit, /V 4 /R 4
104+
[InlineData(@"protected-adobe.pdf", "test123")]
105+
106+
// https://pdfencrypt.net, 256 bit, /V 5 /R 5
107+
[InlineData(@"protected-pdfencrypt.pdf", "test123")]
108+
109+
// https://www.sodapdf.com/password-protect-pdf/
110+
// this is the only tool tested, that encrypts with the latest known algorithm (256 bit, /V 5 /R 6)
111+
// Note: SodaPdf also produced a pdf that would be considered "invalid" by PdfSharp, because of incorrect stream-lengths
112+
// (in the Stream-Dictionary, the length was reported as 32, but in fact the length was 16)
113+
// this needed to be handled as well
114+
[InlineData(@"protected-sodapdf.pdf", "test123")]
115+
public void CanReadPdfEncryptedWithSupportedAlgorithms(string fileName, string password)
116+
{
117+
var path = PathHelper.GetInstance().GetAssetPath(fileName);
118+
119+
var doc = Pdf.IO.PdfReader.Open(path, password, PdfDocumentOpenMode.Import);
120+
doc.Should().NotBeNull();
121+
doc.PageCount.Should().BeGreaterThan(0);
122+
output.WriteLine("Creator : {0}", doc.Info.Creator);
123+
output.WriteLine("Producer: {0}", doc.Info.Producer);
33124
}
34125
}
35126
}

‎PdfSharpCore/Pdf.Advanced/PdfObjectStream.cs‎

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -56,6 +56,12 @@ public PdfObjectStream(PdfDocument document)
5656
internal PdfObjectStream(PdfDictionary dict)
5757
: base(dict)
5858
{
59+
// while objects inside an object-stream are not encrypted, the object-streams themself ARE !
60+
// 7.5.7, Page 47: In an encrypted file (i.e., entire object stream is encrypted),
61+
// strings occurring anywhere in an object stream shall not be separately encrypted.
62+
if (_document._trailer.Elements[PdfTrailer.Keys.Encrypt] is PdfReference)
63+
_document.SecurityHandler.EncryptObject(dict);
64+
5965
int n = Elements.GetInteger(Keys.N);
6066
int first = Elements.GetInteger(Keys.First);
6167
Stream.TryUnfilter();

‎PdfSharpCore/Pdf.Advanced/PdfTrailer.cs‎

Lines changed: 3 additions & 9 deletions
Original file line numberDiff line numberDiff line change
@@ -201,15 +201,9 @@ internal void Finish()
201201
iref = _document._trailer.Elements[Keys.Encrypt] as PdfReference;
202202
if (iref != null)
203203
{
204-
iref = _document._irefTable[iref.ObjectID];
205-
Debug.Assert(iref.Value != null);
206-
_document._trailer.Elements[Keys.Encrypt] = iref;
207-
208-
// The encryption dictionary (security handler) was read in before the XRefTable construction
209-
// was completed. The next lines fix that state (it took several hours to find these bugs...).
210-
iref.Value = _document._trailer._securityHandler;
211-
_document._trailer._securityHandler.Reference = iref;
212-
iref.Value.Reference = iref;
204+
_document._irefTable.Remove(_document._irefTable[iref.ObjectID]);
205+
_document._irefTable.Add(_document._trailer._securityHandler);
206+
_document._trailer.Elements[Keys.Encrypt] = _document._trailer._securityHandler;
213207
}
214208

215209
Elements.Remove(Keys.Prev);

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