Question

一些插件和程序可以做到这一点;是否有任何示例或教程如何使用.net和itextSharp ??

执行此操作

我需要签名pdf并在所有页面上盖章并添加另一个签名。打开文件时，文档上的第一个签名必须有效。

提前致谢。

Answer 1

当您要求打开文件时文档上的第一个签名必须有效时，我假设您最初谈的是在当前Adobe Reader版本中打开。

在这种情况下，您首先必须知道允许和不允许的更改取决于第一个签名本身。请查看this answer，了解Adobe自Acrobat版本9以来所考虑的“允许和禁止更改”的信息。阅读器。

因此，采取签名的pdf并在所有页面上标记图像并添加另一个签名并且不会使（在Adobe软件的眼中）无效的过程中的初始签名，即签署的pdf必须

未经认证（即初始签名仅为批准签名）
或通过注释，表单填写和数字签名认证，允许（即初始签名是允许这些类型的更改的证书签名）并且具有空签名您可以在其中填写签名字段。

如果签名的pdf已经包含多个签名，则它们都不会通过锁定信息添加任何其他限制。

（此外，我认为PDF既不加密也不包含动态XFA表格;这会使事情变得更复杂。）

如果满足这些要求，您可以使用从静态PdfStamper方法检索的PdfStamper

public static PdfStamper CreateSignature(PdfReader reader, Stream os, char pdfVersion, string tempFile, bool append)

最终bool参数值必须为true（即您必须使用追加模式才能使初始签名无效。）

使用此PdfStamper，您可以通过注释在文档页面上添加图片。 iText in Action — 2nd Edition示例TimetableAnnotations3.java / TimetableAnnotations3.cs说明了如何使用PdfStampers.

添加注释

然后像往常一样添加签名，创建新签名字段或使用空签名字段。您可以在白皮书Digital Signatures for PDF documents中找到有关签名过程的详细信息;可以找到与该白皮书中的Java样本等效的C＃样本here on sourceforge。

PS：在这篇文章中，我总是在Adobe软件的眼中强调。在谈论经过认证的PDF时，Adobe非常接近PDF standard。对于已签名但未经证明的PDF，Adobe会应用与为认证文档指定的规则类似的规则。

Answer 2

Public Function sign(keystore As String, level As Integer, src As String, name As String, dest As String, sig As String, pass As String)
    ' Try
    'Dim store As System.Security.Cryptography.X509Certificates.X509Store = New System.Security.Cryptography.X509Certificates.X509Store
    'store.Open(System.Security.Cryptography.X509Certificates.OpenFlags.ReadOnly)
    'Dim sel As System.Security.Cryptography.X509Certificates.X509Certificate2Collection

    ' If sig <> "" And pass <> "" Then
    Try
        Dim y As Int16 = 200
        ' For i As Integer = 0 To sel.Count - 1
        Dim pdfReader As PdfReader = New PdfReader(src)
        Dim signedPdf = New FileStream(dest, FileMode.Create)
        Try
            Dim cert As X509Certificate2 = New X509Certificate2(sig, pass)
            Dim cp As Org.BouncyCastle.X509.X509CertificateParser = New Org.BouncyCastle.X509.X509CertificateParser()
            Dim chain As Org.BouncyCastle.X509.X509Certificate() = New Org.BouncyCastle.X509.X509Certificate() {cp.ReadCertificate(cert.RawData)}




            Dim stamper As PdfStamper
            stamper = PdfStamper.CreateSignature(pdfReader, signedPdf, "0"c, Nothing, True)
            Dim signatureAppearance As PdfSignatureAppearance = stamper.SignatureAppearance
            'signatureAppearance.SignatureGraphic = Image.GetInstance(pathToSignatureImage)
            signatureAppearance.SetVisibleSignature(name)

            signatureAppearance.CertificationLevel = level
            Dim externalSignature As IExternalSignature = New X509Certificate2Signature(cert, "SHA-1")
            ' Dim digest As IExternalSignature = New BouncyCastleDigest
            ' signatureAppearance.s 
            'signatureAppearance.SetVisibleSignature(New Rectangle(50,50,50,
            signatureAppearance.SignatureRenderingMode = PdfSignatureAppearance.RenderingMode.NAME_AND_DESCRIPTION
            MakeSignature.SignDetached(signatureAppearance, externalSignature, chain, Nothing, Nothing, Nothing, 0, CryptoStandard.CADES)
            ' MakeSignature. 

            ' End If

            ' Catch ex As Exception
            'MsgBox(ex.Message)
            ' End Try
        Catch ex As Exception

            MsgBox("Signature File Password is not correct for the user Id :" & error_userid)
            'Exit Function
        End Try
    Catch ex As Exception

    End Try
    Return 0
End Function

如何标记和签署pdf ALREADY签名而不会使之前的签名无效

2 个答案: