SignIncremental.vb
- ''
- '' This code is part of Document Solutions for PDF demos.
- '' Copyright (c) MESCIUS inc. All rights reserved.
- ''
- Imports System.IO
- Imports System.Drawing
- Imports GrapeCity.Documents.Pdf
- Imports GrapeCity.Documents.Pdf.AcroForms
- Imports GrapeCity.Documents.Text
- Imports System.Security.Cryptography.X509Certificates
-
- '' This sample generates and signs a PDF (using code that is similar to SignDoc sample),
- '' and then signs the generated PDF with a second signature without invalidating the original
- '' signature, by using incremental update (default when using the Sign() method).
- Public Class SignIncremental
- Function CreatePDF(ByVal stream As Stream) As Integer
- Dim doc = New GcPdfDocument()
-
- '' Load a signed document (we use code similar to the SignDoc sample):
- doc.Load(CreateAndSignPdf())
-
- '' Init a second certificate:
- Dim pfxPath = Path.Combine("Resources", "Misc", "JohnDoe.pfx")
- Dim cert = New X509Certificate2(File.ReadAllBytes(pfxPath), "secret",
- X509KeyStorageFlags.MachineKeySet Or X509KeyStorageFlags.PersistKeySet Or X509KeyStorageFlags.Exportable)
- Dim sp2 = New SignatureProperties() With {
- .SignatureBuilder = New Pkcs7SignatureBuilder() With {.CertificateChain = New X509Certificate2() {cert}},
- .Location = "DsPdfWeb Demo Browser",
- .SignerName = "Jaime Smith",
- .SigningDateTime = Util.TimeNow()
- }
-
- '' Find the 2nd (not yet filled) signature field:
- Dim sfld2 = CType(doc.AcroForm.Fields("SecondSignature"), SignatureField)
- '' Connect the signature field and signature props:
- If sfld2 Is Nothing Then
- Throw New Exception("Unexpected: could not find 'SecondSignature' field")
- End If
- sp2.SignatureField = sfld2
-
- '' Sign and save the document:
- doc.Sign(sp2, stream)
-
- '' Rewind the stream to read the document just created
- '' into another GcPdfDocument and verify all signatures:
- stream.Seek(0, SeekOrigin.Begin)
- Dim doc2 = New GcPdfDocument()
- doc2.Load(stream)
- For Each fld In doc2.AcroForm.Fields
- If TypeOf fld Is SignatureField Then
- Dim sfld = CType(fld, SignatureField)
- If Not sfld.Value.VerifySignatureValue() Then
- Throw New Exception($"Failed to verify signature for field {sfld.Name}")
- End If
- End If
- Next
- ''
- '' Done (the generated and signed document has already been saved to 'stream').
- Return doc.Pages.Count
- End Function
-
- '' This method is almost exactly the same as the SignDoc sample,
- '' but adds a second signature field (does not sign it though):
- Private Function CreateAndSignPdf() As Stream
- Dim doc = New GcPdfDocument()
- Dim page = doc.NewPage()
- Dim tf = New TextFormat() With {.Font = StandardFonts.Times, .FontSize = 14}
- page.Graphics.DrawString("Hello, World!" + vbLf +
- "Signed TWICE by DsPdfWeb SignIncremental sample.",
- tf, New PointF(72, 72))
-
- '' Init a test certificate:
- Dim pfxPath = Path.Combine("Resources", "Misc", "DsPdfTest.pfx")
- Dim cert = New X509Certificate2(File.ReadAllBytes(pfxPath), "qq",
- X509KeyStorageFlags.MachineKeySet Or X509KeyStorageFlags.PersistKeySet Or X509KeyStorageFlags.Exportable)
- Dim sp = New SignatureProperties() With {
- .SignatureBuilder = New Pkcs7SignatureBuilder() With {
- .CertificateChain = New X509Certificate2() {cert}
- },
- .Location = "DsPdfWeb Demo Browser",
- .SignerName = "DsPdfWeb",
- .SigningDateTime = Util.TimeNow()
- }
-
- '' Init a signature field to hold the signature:
- Dim sf = New SignatureField()
- sf.Widget.Rect = New RectangleF(72, 72 * 2, 72 * 4, 36)
- sf.Widget.Page = page
- sf.Widget.BackColor = Color.LightSeaGreen
- '' Add the signature field to the document:
- doc.AcroForm.Fields.Add(sf)
-
- '' Connect the signature field and signature props:
- sp.SignatureField = sf
-
- '' Add a second signature field:
- Dim sf2 = New SignatureField() With {.Name = "SecondSignature"}
- sf2.Widget.Rect = New RectangleF(72, 72 * 3, 72 * 4, 36)
- sf2.Widget.Page = page
- sf2.Widget.BackColor = Color.LightYellow
- '' Add the signature field to the document:
- doc.AcroForm.Fields.Add(sf2)
-
- Dim ms = New MemoryStream()
- doc.Sign(sp, ms)
- Return ms
- End Function
- End Class
-