Support of Digital Signatures (PKCS#7) + TSA timestamp #48

julienrffr · 2023-10-20T14:27:13Z

Adding:

ability to sign PDF documents, using PKCS#7 format.
ability to timestamp the signature with a TSA (via the DefaultSigner).

I tried to do minimal changes in existing classes (only PdfDocument class has been modified to add BeforeSave/AfterSave events, and PdfString in order to track position in stream).
PdfString could have not been modified if it was not sealed.

This is a port from empira/PDFsharp-1.5#11 but with way smaller footprint.

Usage example (files in demo-signature.zip):

Change image/pdf/certificate paths in Program.cs, change certificate password in Program.cs
Run Program

demo-signature.zip

Let me know any suggestions.

NB: this feature is available in PDFsharp-extended nuget package

This will make possible the implementation of document signature, because we need to exclude this specific byte range from the hash digest.

allows to sign pdf document using PKCS#7 detached format, digest algorithm should be SHA1 (only one supported in PDF 1.4)

as recommened by PDF specs. + renamings + use PdfSharp internal Hex conversion

julienrffr · 2023-10-24T13:32:48Z

Signature computation is working well,
Signature seems to be correctly added to the Sig dictionary (hex string of signature decodes properly in https://lapo.it/asn1js/),
BUT when opening the document in Adobe Reader, I still get this error message when clicking on signature:

`
Error during signature verification.

Signature contains incorrect, unrecognized, corrupted or suspicious data.
Support Information: SigDict /Contents illegal data
`

I don't get to know what is causing the issue.

Btw I tried to sign with an auto-signed certificate.

so that PDF readers can properly detect the signature

julienrffr · 2023-10-24T15:29:18Z

Signature feature is now working

Signature computation is working well, Signature seems to be correctly added to the Sig dictionary (hex string of signature decodes properly in https://lapo.it/asn1js/), BUT when opening the document in Adobe Reader, I still get this error message when clicking on signature:

` Error during signature verification.

Signature contains incorrect, unrecognized, corrupted or suspicious data. Support Information: SigDict /Contents illegal data `

I don't get to know what is causing the issue.

Btw I tried to sign with an auto-signed certificate.

With commit 80cdf02 I fixed the issue: the signature field was not properly added to the AcroForm array.

Now that it is in the AcroForm, Adobe properly detects it and display a more explicit message about my signature issue.
By using a PDF/signature checker like https://tte.kominfo.go.id/verifyPDF, I was able to see that my signature was problematic because issuer is not recognized (I tested with self-signed certificate and another certificate not in recognized authorities). But it should work (confirming soon) with a recognized authority's certificate.

There may be a bug on AcroForm.Fields

@ThomasHoevel @PDFsharp-Team I had to make PdfAcroField.PdfAcroFieldCollection's constructor internal instead of private in order to instanciate it. Indeed when accessing document.Catalog.AcroForm.Fields, _fields is null and it tries to create an instance via VCF.CreateIndirect parameter, but Reflection then fails to find a constructor.
Could you help on this particular commit 80cdf02 please?
This may be a bug? Or there may be a better way to instanciate it.

julienrffr · 2023-10-24T15:31:55Z

Last thing to handle now is the signature's appearance that seems to not be displayed properly.

ibrahimAliTecman · 2023-10-26T10:46:57Z

Signature feature is now working

Signature computation is working well, Signature seems to be correctly added to the Sig dictionary (hex string of signature decodes properly in https://lapo.it/asn1js/), BUT when opening the document in Adobe Reader, I still get this error message when clicking on signature:
Error during signature verification. Signature contains incorrect, unrecognized, corrupted or suspicious data. Support Information: SigDict /Contents illegal data
I don't get to know what is causing the issue.
Btw I tried to sign with an auto-signed certificate.

With commit 80cdf02 I fixed the issue: the signature field was not properly added to the AcroForm array.

Now that it is in the AcroForm, Adobe properly detects it and display a more explicit message about my signature issue. By using a PDF/signature checker like https://tte.kominfo.go.id/verifyPDF, I was able to see that my signature was problematic because issuer is not recognized (I tested with self-signed certificate and another certificate not in recognized authorities). But it should work (confirming soon) with a recognized authority's certificate.

There may be a bug on AcroForm.Fields

@ThomasHoevel @PDFsharp-Team I had to make PdfAcroField.PdfAcroFieldCollection's constructor internal instead of private in order to instanciate it. Indeed when accessing document.Catalog.AcroForm.Fields, _fields is null and it tries to create an instance via VCF.CreateIndirect parameter, but Reflection then fails to find a constructor. Could you help on this particular commit 80cdf02 please? This may be a bug? Or there may be a better way to instanciate it.

Hi, I tried with a trusted certificate but get the same error

julienrffr · 2023-10-26T12:20:47Z

Hi, I tried with a trusted certificate but get the same error

Does the certificate has a root certificate (+ intermediate certificate) + end user certificate?
Is the root authority part of Adobe's AATL list?

ibrahimAliTecman · 2023-10-26T13:31:05Z

Hi, I tried with a trusted certificate but get the same error

Does the certificate has a root certificate (+ intermediate certificate) + end user certificate? Is the root authority part of Adobe's AATL list?

Yes the root is part of the Adobe AATL, the certificate was created using sectigo

in DEBUG, a space delimiter is added between entry key and entry value, but not in RELEASE

julienrffr · 2023-10-30T09:42:38Z

Hi, I tried with a trusted certificate but get the same error

Did you try in DEBUG or RELEASE build?
I just pushed a fix for Release mode.

ibrahimAliTecman · 2023-10-30T11:31:15Z

Hi, I tried with a trusted certificate but get the same error

Did you try in DEBUG or RELEASE build? I just pushed a fix for Release mode.

Was using DEBUG, below is the adobe errors.

sign with SHA256 instead

julienrffr · 2023-10-31T11:06:18Z

Was using DEBUG, below is the adobe errors.

Hi @ibrahimAliTecman, I fixed the issue on the byte range computation that was caused by extra spaces added in DEBUG mode due to Verbose writer layout.

Please test again and let me know, signature should be fine now.

Only thing remaining to do is the signature appearance to take care of. I'll do that in the next days.

ibrahimAliTecman · 2023-10-31T12:03:19Z

Was using DEBUG, below is the adobe errors.

Hi @ibrahimAliTecman, I fixed the issue on the byte range computation that was caused by extra spaces added in DEBUG mode due to Verbose writer layout.

Please test again and let me know, signature should be fine now.

Only thing remaining to do is the signature appearance to take care of. I'll do that in the next days.

Hi, Awesome! it is working now. Verifies signature correctly. Thank you!

julienrffr · 2023-10-31T15:08:29Z

I've just pushed 496c553 that allows to define a custom appearance for the signature field.

Since everything is working fine now, I'm setting the pr as ready for review.
I would love to get remarks or help from @PDFsharp-Team / @ThomasHoevel.

I'm totally willingful to adjust code so it could fit better in PDFsharp lib, if any chances that something would be merged some day.
In the meantime, I consider publishing a nuget package with all our additional features, based on branch https://github.com/KDS/PDFsharp/tree/pdfsharp-extended

Note: known limitation is that currently it can only sign unsigned documents.

ibrahimAliTecman · 2023-10-31T15:27:49Z

I've just pushed 496c553 that allows to define a custom appearance for the signature field.

Since everything is working fine now, I'm setting the pr as ready for review. I would love to get remarks or help from @PDFsharp-Team / @ThomasHoevel.

I'm totally willingful to adjust code so it could fit better in PDFsharp lib, if any chances that something would be merged some day. In the meantime, I consider publishing a nuget package with all our additional features, based on branch https://github.com/KDS/PDFsharp/tree/pdfsharp-extended

Note: known limitation is that currently it can only sign unsigned documents.

The signature is appearing blank still with the latest commit, is there anything that needs to be changed in the calling method?

julienrffr · 2023-10-31T16:40:41Z

The signature is appearing blank still with the latest commit, is there anything that needs to be changed in the calling method?

Please provide your code and the generated pdf.

Here is a working Program for me, with bith default appearance and custom appearance:
signature.txt

Hraezvelg · 2023-11-03T16:30:04Z

Hey, would it be hard to implement :

a) multiple signatures on a file (with only one open/save)
b) signing an already signed file ?

I've tried do make it work for several hours without success.
Even by changing the name of the signature so they are all unique, it does not seem to do anything.
An incremental save system seems the way to go.

Do you have anything almost working so I can try to help ?

julienrffr · 2023-11-03T16:52:23Z

Hey, would it be hard to implement :

a) multiple signatures on a file (with only one open/save) b) signing an already signed file ?

I've tried do make it work for several hours without success. Even by changing the name of the signature so they are all unique, it does not seem to do anything. An incremental save system seems the way to go.

Do you have anything almost working so I can try to help ?

Hi,

a) applying multiple signatures on a file in a single open/save seems at least complicated, not sure if it's feasable.
b) signing an already signed file is something we want too, but right now we do not have time to implement it. I have no draft for this sorry, feel free to open a pull request to https://github.com/KDS/PDFsharp/tree/signature-feature

NB: signature feature is now available in PDFsharp-extended nuget package

julienrffr · 2024-02-23T16:12:00Z

Added the ability (for the DefaultSigner only for the moment) to attach a timestamp from a TSA to the signature.
This is one step closer to PADES requirements.

value 10 is arbitrary, I hope this is enough for all scenarios. trailing zeros have no incidence on signature decoding so this is OK to have trailing zeros.

ivvitikhonov · 2024-03-26T14:19:28Z

Hi,
Why there is not adding of ContactInfo filed for signature properties in GetSignatureDictionary method? At the same time this option is in PdfSignatureOptions.

julienrffr · 2024-04-30T15:14:49Z

Hey, would it be hard to implement :
a) multiple signatures on a file (with only one open/save) b) signing an already signed file ?
I've tried do make it work for several hours without success. Even by changing the name of the signature so they are all unique, it does not seem to do anything. An incremental save system seems the way to go.
Do you have anything almost working so I can try to help ?

Hi,

a) applying multiple signatures on a file in a single open/save seems at least complicated, not sure if it's feasable. b) signing an already signed file is something we want too, but right now we do not have time to implement it. I have no draft for this sorry, feel free to open a pull request to https://github.com/KDS/PDFsharp/tree/signature-feature

NB: signature feature is now available in PDFsharp-extended nuget package

Update on the 'signing an already signed document' question:
To accomplish this, we would first need to be able to work with 'incremental updates'. Right now this is not supported by pdfSharp as far as I know. This is a requirement for applying a second signature on a file without invalidating the first signature.

StLange · 2024-06-07T15:33:25Z

Julien, thank you for your work!
Digital Signatures are the number one on our to-do list for PDFsharp 6.2 Preview 1.

ThomasHoevel · 2024-06-10T15:28:10Z

Maybe I'm doing something wrong, but I got the PR using gh pr checkout 48 and cannot get it to compile.
Is the PR compatible with .NET 4.7.2, .NET 6, and .NETstandard 2.0?

Does anybody have some useful tips for me?

3>D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(7,18,7,22): error CS0234: The type or namespace name 'Http' does not exist in the namespace 'System.Net' (are you missing an assembly reference?)
3>D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(9,36,9,40): error CS0234: The type or namespace name 'Pkcs' does not exist in the namespace 'System.Security.Cryptography' (are you missing an assembly reference?)
3>D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(56,53,56,62): error CS0246: The type or namespace name 'SignedCms' could not be found (are you missing a using directive or an assembly reference?)
3>Done building project "PdfSharp-wpf.csproj" -- FAILED.
2>D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(7,18,7,22): error CS0234: The type or namespace name 'Http' does not exist in the namespace 'System.Net' (are you missing an assembly reference?)
2>D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(9,36,9,40): error CS0234: The type or namespace name 'Pkcs' does not exist in the namespace 'System.Security.Cryptography' (are you missing an assembly reference?)
2>D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(56,53,56,62): error CS0246: The type or namespace name 'SignedCms' could not be found (are you missing a using directive or an assembly reference?)
2>Done building project "PdfSharp-gdi.csproj" -- FAILED.
2>PdfSharp-gdi -> D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp-gdi\bin\Debug\net6.0-windows\PdfSharp-gdi.dll
2>Done building project "PdfSharp-gdi.csproj".
5>------ Build started: Project: MigraDoc.RtfRendering-gdi, Configuration: Debug Any CPU ------
6>------ Build started: Project: PdfSharp.Charting-gdi, Configuration: Debug Any CPU ------
7>------ Build started: Project: PdfSharp.Quality-gdi, Configuration: Debug Any CPU ------
4>D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(69,27,69,50): error CS0103: The name 'Rfc3161TimestampRequest' does not exist in the current context
4>D:\THHO\Repos\PDFsharp_PR\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(76,31,76,52): error CS0246: The type or namespace name 'ReadOnlyMemoryContent' could not be found (are you missing a using directive or an assembly reference?)
4>Done building project "PdfSharp.csproj" -- FAILED.

julienrffr · 2024-06-11T07:51:14Z

Maybe I'm doing something wrong, but I got the PR using gh pr checkout 48 and cannot get it to compile. Is the PR compatible with .NET 4.7.2, .NET 6, and .NETstandard 2.0?

Does anybody have some useful tips for me?

Hi @ThomasHoevel ,
Glad to hear that signatures are in the pipe!

Indeed, I've just synchronized this pull request with your new release 6.1.0 (which now includes netstandard support) and I started to work on the compatibility because the last feature I introduced recently (signature timestamp) is not compatible yet.

To compile, for now you could just comment the method AddTimestampFromTSAAsync and its call in \src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs (and removing the not-compatible usings of course).

I'm working on this compatibility for this recent feature but it's not my top priority right now. I'll try to push something that compiles out-of-the-box ASAP.

In the meantime feel free to contact me for any support (here, via mail or Teams or Zoom).

ThomasHoevel · 2024-06-11T07:59:44Z

Thanks for the feedback. I already figured out that TSA is the problem and used "#if NET6_0_OR_GREATER" to exclude that.

Now I get a warning I cannot yet resolve:
Found conflicts between different versions of "System.Memory" that could not be resolved.
There was a conflict between "System.Memory, Version=4.0.1.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" and "System.Memory, Version=4.0.1.2

It's a company policy that projects compile without warnings.

Sooner or later I will also have to address the following compile-time warnings:
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.AcroForms\PdfSignatureField.cs(18,18,18,35): warning CS8618: Non-nullable property 'CustomAppearanceHandler' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.AcroForms\PdfSignatureField.cs(22,18,22,35): warning CS8618: Non-nullable property 'CustomAppearanceHandler' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\RangedStream.cs(79,20,79,114): warning CS8603: Possible null reference return.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\RangedStream.cs(106,35,106,47): warning CS8602: Dereference of a possibly null reference.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureOptions.cs(11,45,11,62): warning CS8618: Non-nullable property 'AppearanceHandler' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureOptions.cs(12,23,12,34): warning CS8618: Non-nullable property 'ContactInfo' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureOptions.cs(13,23,13,31): warning CS8618: Non-nullable property 'Location' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureOptions.cs(14,23,14,29): warning CS8618: Non-nullable property 'Reason' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureHandler.cs(52,41,52,63): warning CS8622: Nullability of reference types in type of parameter 'sender' of 'void PdfSignatureHandler.AddSignatureComponents(object sender, EventArgs e)' doesn't match the target delegate 'EventHandler' (possibly because of nullability attributes).
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureHandler.cs(53,40,53,64): warning CS8622: Nullability of reference types in type of parameter 'sender' of 'void PdfSignatureHandler.ComputeSignatureAndRange(object sender, PdfDocumentEventArgs e)' doesn't match the target delegate 'EventHandler' (possibly because of nullability attributes).
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureHandler.cs(62,16,62,35): warning CS8618: Non-nullable field 'signatureFieldContentsPdfString' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureHandler.cs(62,16,62,35): warning CS8618: Non-nullable field 'signatureFieldByteRangePdfArray' must contain a non-null value when exiting constructor. Consider declaring the field as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureHandler.cs(62,16,62,35): warning CS8618: Non-nullable property 'Document' must contain a non-null value when exiting constructor. Consider declaring the property as nullable.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\PdfSignatureHandler.cs(88,39,88,93): warning CS8602: Dereference of a possibly null reference.
3>D:\THHO\Repos\PDFsharp\src\foundation\src\PDFsharp\src\PdfSharp\Pdf.Signatures\DefaultSigner.cs(97,17,97,57): warning CS8602: Dereference of a possibly null reference.

julienrffr · 2024-06-11T08:26:32Z

Thanks for the feedback. I already figured out that TSA is the problem and used "#if NET6_0_OR_GREATER" to exclude that.

Now I get a warning I cannot yet resolve: Found conflicts between different versions of "System.Memory" that could not be resolved. There was a conflict between "System.Memory, Version=4.0.1.1, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51" and "System.Memory, Version=4.0.1.2

It's a company policy that projects compile without warnings.

I'll try to take a look on that also when I have some time.

By the way, do you have an idea of how you'll introduce signatures feature?
Basing on this PR, or re-writing entirely from scratch?

ThomasHoevel · 2024-06-11T08:35:21Z

I have no idea yet.
The old PR modified PdfItem to get the address of the signature data block. You modified PdfString for that purpose.
I'll discuss with Stefan how we will handle that. But first I must get a basic understanding of what is going on.

I will try to resolve the compile-time warnings, so there is no need for you to work on that, too.

julienrffr · 2024-06-11T09:36:58Z

I fixed the build by making the timestamp feature only available on net6+.

There would be 2 things to handle to make it available for netfx/netstandard2 too:

usage of HttpClient (todo: find a compatible alternative or extract it from PdfSharp)
usage of Rfc3161 classes (available only on netstandard2.1 and net6+)

For the basic 'how it works':
Signature is a hash of the whole document so in order to sign, the full document must be generated/written by PdfSharp (at .Save() time).
'Whole document' except a placeholder actually, where we will put the signature data. So the reality is, we have to compute a series of byte ranges that indicates to readers what is the part of data that is actually signed. That's why we need to determine the byte position of some elements.

julienrffr · 2024-06-11T09:41:58Z

@ThomasHoevel

I have no idea yet. The old PR modified PdfItem to get the address of the signature data block. You modified PdfString for that purpose. I'll discuss with Stefan how we will handle that. But first I must get a basic understanding of what is going on.

Regarding design of the signature feature,
A big limitation of this PR is that it cannot sign already signed document.
The reason is because we would need support of incremental updates in PdfSharp to accomplish that.

…gnatures

packdat · 2024-06-15T11:18:37Z

This has become an increasingly hot topic for us as well.

Expanding on my initial proposal for incremental updates (#112) and building upon the excellent work by @julienrffr it was surprisingly straightforward to support multiple signatures.
See example usage in this test case.

Opening such a document in Acrobat Reader:

Because signing a document is always applied as an incremental update, a 2-step process is required for every signature:

Create or open a document
Apply signature (optionally updating the document before signing)

This is a POC that demonstrates how signing could look like in PDFSharp.
Eagerly awaiting what you guys come up with 😉

Side-Note:
It would be cool, if we could use fonts already present in a document.
At the moment, every incremental update with a text-based signature also adds a new font...
(this POC also supports image-based signatures to avoid that)

julienrffr · 2024-06-17T08:03:36Z

Thank you @packdat that's awesome!

CrunchTech · 2024-07-18T10:26:00Z

This has become an increasingly hot topic for us as well.

Expanding on my initial proposal for incremental updates (#112) and building upon the excellent work by @julienrffr it was surprisingly straightforward to support multiple signatures. See example usage in ...

Any chance this could be merged into KDS:signature-feature or made available in a separate KDS branch? Would really like to experiment with this!

julienrffr · 2024-07-18T14:25:01Z

This has become an increasingly hot topic for us as well.
Expanding on my initial proposal for incremental updates (#112) and building upon the excellent work by @julienrffr it was surprisingly straightforward to support multiple signatures. See example usage in ...

Any chance this could be merged into KDS:signature-feature or made available in a separate KDS branch? Would really like to experiment with this!

@packdat could you create a PR to https://github.com/KDS/PDFsharp/tree/signature-feature with your work?

packdat · 2024-07-20T15:42:25Z

@CrunchTech @julienrffr
Just created a PR.

CrunchTech · 2024-07-21T11:59:52Z

@CrunchTech @julienrffr Just created a PR.

Much appreciated!

julienrffr · 2024-07-22T07:31:01Z

@ThomasHoevel

I have no idea yet. The old PR modified PdfItem to get the address of the signature data block. You modified PdfString for that purpose. I'll discuss with Stefan how we will handle that. But first I must get a basic understanding of what is going on.

Regarding design of the signature feature, A big limitation of this PR is that it cannot sign already signed document. The reason is because we would need support of incremental updates in PdfSharp to accomplish that.

@ThomasHoevel
This limitation has been resolved by @packdat and I guess you'll be interested
Full integrated PR is here KDS#5

julienrffr added 2 commits October 18, 2023 15:19

expose PdfString's start and end bytes positions in Stream

adaf57e

This will make possible the implementation of document signature, because we need to exclude this specific byte range from the hash digest.

add PKCS#7 detached signature feature

a545b4c

allows to sign pdf document using PKCS#7 detached format, digest algorithm should be SHA1 (only one supported in PDF 1.4)

julienrffr mentioned this pull request Oct 20, 2023

expose PdfString's start and end bytes positions in Stream #47

Closed

julienrffr changed the title ~~Signature feature~~ Support of Digital Signatures Oct 20, 2023

julienrffr added 3 commits October 20, 2023 17:22

compatibility for wpf and gdi projects

3dd39c2

incorporate BouncySigner in PdfSharp + internally cache signature length

349dacc

exclude whole /Contents entry from digest instead of just its value

7c055f6

as recommened by PDF specs. + renamings + use PdfSharp internal Hex conversion

properly add signature field to acroform array

80cdf02

so that PDF readers can properly detect the signature

julienrffr changed the title ~~Support of Digital Signatures~~ Support of Digital Signatures (PKCS#7 detached) Oct 26, 2023

fix wrong position in Release mode

15675dc

in DEBUG, a space delimiter is added between entry key and entry value, but not in RELEASE

julienrffr added 2 commits October 31, 2023 11:14

do not sign using obsolete SHA1 algorithm

052ad9e

sign with SHA256 instead

fix signature byte ranges computation

e8f82c5

enable display of custom appearance for signature fields

496c553

julienrffr marked this pull request as ready for review October 31, 2023 15:10

get rid from obsolete X509Certificate2.PrivateKey

11e34ae

julienrffr changed the title ~~Support of Digital Signatures (PKCS#7 detached)~~ Support of Digital Signatures (PKCS#7) Feb 13, 2024

DefaultSigner: add the ability to attach a signature timestamp from TSA

55ddebb

fix issue of varying TSA answer size by adding a 10 byte margin

8a90349

value 10 is arbitrary, I hope this is enough for all scenarios. trailing zeros have no incidence on signature decoding so this is OK to have trailing zeros.

julienrffr changed the title ~~Support of Digital Signatures (PKCS#7)~~ Support of Digital Signatures (PKCS#7) + TSA timestamp Feb 27, 2024

julienrffr added 4 commits June 7, 2024 15:02

Merge branch 'master' into signature-feature

5f8cc24

compatibility of ArgumentNullException.ThrowIfNull

712ef3a

DSA not supported in netstandard2.0

7d5c01b

use long instead of int for Stream Position

68d42bb

fix build (making signatures timestamp feature only available on net6+)

eb1e4bb

update BouncyCastle.Cryptography (vulnerability warning)

22352a1

packdat added a commit to packdat/PDFsharp-net6 that referenced this pull request Jun 15, 2024

POC: Document signing based on empira#48 with support for multiple si…

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…gnatures

packdat mentioned this pull request Jul 20, 2024

Support multiple signatures KDS/PDFsharp#5

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Support of Digital Signatures (PKCS#7) + TSA timestamp #48

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Support of Digital Signatures (PKCS#7) + TSA timestamp #48

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julienrffr commented Oct 20, 2023 • edited Loading

julienrffr commented Oct 24, 2023

julienrffr commented Oct 24, 2023

Signature feature is now working

There may be a bug on AcroForm.Fields

julienrffr commented Oct 24, 2023

ibrahimAliTecman commented Oct 26, 2023

Signature feature is now working

There may be a bug on AcroForm.Fields

julienrffr commented Oct 26, 2023

ibrahimAliTecman commented Oct 26, 2023

julienrffr commented Oct 30, 2023

ibrahimAliTecman commented Oct 30, 2023

julienrffr commented Oct 31, 2023 • edited Loading

ibrahimAliTecman commented Oct 31, 2023

julienrffr commented Oct 31, 2023 • edited Loading

ibrahimAliTecman commented Oct 31, 2023

julienrffr commented Oct 31, 2023

Hraezvelg commented Nov 3, 2023

julienrffr commented Nov 3, 2023

julienrffr commented Feb 23, 2024

ivvitikhonov commented Mar 26, 2024

julienrffr commented Apr 30, 2024

StLange commented Jun 7, 2024

ThomasHoevel commented Jun 10, 2024

julienrffr commented Jun 11, 2024 • edited Loading

ThomasHoevel commented Jun 11, 2024

julienrffr commented Jun 11, 2024

ThomasHoevel commented Jun 11, 2024

julienrffr commented Jun 11, 2024

julienrffr commented Jun 11, 2024

packdat commented Jun 15, 2024

julienrffr commented Jun 17, 2024

CrunchTech commented Jul 18, 2024

julienrffr commented Jul 18, 2024

packdat commented Jul 20, 2024

CrunchTech commented Jul 21, 2024

julienrffr commented Jul 22, 2024

julienrffr commented Oct 20, 2023 •

edited

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julienrffr commented Oct 31, 2023 •

edited

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julienrffr commented Oct 31, 2023 •

edited

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julienrffr commented Jun 11, 2024 •

edited

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