Digital Signature LTV

[Mohamed]

How can I read LTV of digital signature from signed document . i try to read LTV but i get all result false but in adobe reader is true

 

my Attached file below Containing Example

Attachment: TestLTV_in_Signed_Document_a8427c37.zip

[Surya Venkatesan]

Hi Mohamed,

We were able to reproduce the reported issue with the provided details on our end. Currently, we are analyzing on this and we will update the further details on April 11th 2022.

Regards,

Surya V

[Gowthamraj Kumar]

Hi Mohamed

We have support to validate signature details from an existing PDF document. Using this, we can check the revocation status of the certificate with OCSP and CRL from the signed signature.

Please refer to the UG documentation below,

https://help.syncfusion.com/file-formats/pdf/working-with-digitalsignature#digital-signature-validation

Please update the below-highlighted changes in your sample to get signature details

Dim strtexthdr As String = ""

Dim strtext As String = ""

Dim DigitalDocument As New PdfLoadedDocument(mypath, True)

Dim PdfSignatures As List(Of String) = New List(Of String)

Dim form As PdfLoadedForm = TryCast(DigitalDocument.Form, PdfLoadedForm)

Dim i As Integer = 0

Dim SignatureDetailsLTV As String = ""

 

If form IsNot Nothing Then

If form.Fields.Count > 0 Then

strtexthdr = "Information Data in Signature" + Environment.NewLine

End If

strtext = strtexthdr

While i < form.Fields.Count

SignatureDetailsLTV = ""

Dim field As PdfLoadedSignatureField = TryCast(form.Fields, PdfLoadedSignatureField)

If field IsNot Nothing AndAlso field.Signature IsNot Nothing Then

Dim result As PdfSignatureValidationResult = field.ValidateSignature()

strtext = strtext + $"LTV of Signature {i}" + " : " + "RevocationResult : IsRevokedCRL : " + result.RevocationResult.IsRevokedCRL.ToString() + Environment.NewLine

strtext = strtext + $"LTV of Signature {i}" + " : " + "OcspRevocationStatus : " + result.RevocationResult.OcspRevocationStatus.ToString() + Environment.NewLine

End If

i = i + 1

End While

End If

MessageBox.Show(strtext)

 

Please let us know, you need any further assistance in this

Regards,

Gowthamraj K

[Mohamed]

result not correct it always give me 

[Gowthamraj Kumar]

Hi Mohamed,

Yes, To achieve long-term validation, all the necessary signature information, Certificate Revocation List (CRL), and an Online Certificate Status Protocol (OCSP) are embedded in the signed PDF. But on investigating the shared PDF documents do not have OCSP responses or CRLs information that you shared earlier in this ticket. It is not an issue from signature validation result details.

Please refer to the sample CRL and OCSP information certificate and result details below

Please refer to the below link for more information about PAdES - LT-Level

https://www.cryptomathic.com/news-events/blog/pades-and-long-term-archival-lta

Please let us know, you need any further assistance in this,

Regards,

Gowthamraj K

[David]

whate difference when using EnableLtv = True and CreateLongTermValidity()  for document Sign ?

[Mohamed]

when  we sign  document normally adobe   give me " CRL that is  contained in local cache" 

it give me  

and when we sign and using 

DigitalSignature.CreateLongTermValidity(New List(Of X509Certificate2) From {Certificate})

 adobe   give me " CRL that is   embedded  in the document  "

we want to ask how can we   read that   " CRL that is   embedded  in the document  " ?

[Mohamed]

we want to ask how can we   read that   " CRL that is   embedded  in the document  " ?

[Gowthamraj Kumar]

Hi Mohamed,

As of now, we don't have support to get the CRL details from the certificate using the Syncfusion PDF library.  Please refer to the documentation link about Digital Signature support features,

https://help.syncfusion.com/file-formats/pdf/working-with-digitalsignature   

Regards,

Gowthamraj K