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Spire.PDF for .NET 是一款独立 PDF 控件，用于 .NET 程序中创建、编辑和操作 PDF 文档。使用 Spire.PDF 类库，开发人员可以新建一个 PDF 文档或者对现有的 PDF 文档进行处理，且无需安装 Adobe Acrobat。

E-iceblue 功能类库Spire 系列文档处理组件均由中国本土团队研发，不依赖第三方软件，不受其他国家的技术或法律法规限制，同时适配国产操作系统如中科方德、中标麒麟等，兼容国产文档处理软件 WPS（如 .wps/.et/.dps 等格式

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数字时间戳用时间和日期标记 PDF 签名，作为完整性证明。时间戳表明文档的内容在某个时间点存在且未更改。本文将介绍如何使用 Spire.PDF 通过时间戳服务器对 PDF 文档进行数字签名。

代码片段

[C＃]

using Spire.Pdf;
using Spire.Pdf.Graphics;
using Spire.Pdf.Security;
using System.Drawing;

namespace SignPDFwithTimestamp
{
class Program
{
static void Main(string[] args)
{
//create a PdfDocument object and load a PDF file
PdfDocument doc = new PdfDocument();
doc.LoadFromFile(@"C:\Users\Administrator\Desktop\Example.pdf");

//load the certificate .pfx file
PdfCertificate cert = new PdfCertificate(@"C:\Users\Administrator\Desktop\gary.pfx", "e-iceblue");

//add a signature to the specified position
PdfSignature signature = new PdfSignature(doc, doc.Pages[0], cert, "signature");
signature.Bounds = new RectangleF(new PointF(350, 700), new SizeF(180, 90));

//set the signature content
signature.NameLabel = "Digitally signed by:Gary";
signature.LocationInfoLabel = "Location:";
signature.LocationInfo = "CN";
signature.ReasonLabel = "Reason: ";
signature.Reason = "Ensure authenticity";
signature.ContactInfoLabel = "Contact Number: ";
signature.ContactInfo = "028-81705109";
signature.DocumentPermissions = PdfCertificationFlags.AllowFormFill | PdfCertificationFlags.ForbidChanges;
signature.GraphicsMode = GraphicMode.SignImageAndSignDetail;
signature.SignImageSource = PdfImage.FromFile(@"C:\Users\Administrator\Desktop\company-logo.jpg");

//configure a timestamp server
string url = "//timestamp.wosign.com/rfc3161";
signature.ConfigureTimestamp(url);

//save to file
doc.SaveToFile("output.pdf");
}
}
}

[VB.NET]

Imports Spire.Pdf
Imports Spire.Pdf.Graphics
Imports Spire.Pdf.Security
Imports System.Drawing

Namespace SignPDFwithTimestamp
Class Program
Private Shared Sub Main(args As String())
'create a PdfDocument object and load a PDF file
Dim doc As PdfDocument = New PdfDocument()
doc.LoadFromFile("C:\Users\Administrator\Desktop\Example.pdf")

'load the certificate .pfx file
Dim cert As PdfCertificate = New PdfCertificate("C:\Users\Administrator\Desktop\gary.pfx","e-iceblue")

'add a signature to the specified position
Dim signature As PdfSignature = New PdfSignature(doc,doc.Pages(0),cert,"signature")
signature.Bounds = New RectangleF(New PointF(350, 700), New SizeF(180, 90))

'set the signature content
signature.NameLabel = "Digitally signed by:Gary"
signature.LocationInfoLabel = "Location:"
signature.LocationInfo = "CN"
signature.ReasonLabel = "Reason: "
signature.Reason = "Ensure authenticity"
signature.ContactInfoLabel = "Contact Number: "
signature.ContactInfo = "028-81705109"
signature.DocumentPermissions = PdfCertificationFlags.AllowFormFill | PdfCertificationFlags.ForbidChanges
signature.GraphicsMode = GraphicMode.SignImageAndSignDetail
signature.SignImageSource = PdfImage.FromFile("C:\Users\Administrator\Desktop\company-logo.jpg")

'configure a timestamp server
Dim url As String = "//timestamp.wosign.com/rfc3161"
signature.ConfigureTimestamp(url)

'save to file
doc.SaveToFile("output.pdf")
End Sub
End Class
End Namespace

以上便是如何用时间戳服务器对 PDF 进行数字签名，如果您有其他问题也可以继续浏览本系列文章，获取相关教程，你还可以给我留言或者加入我们的官方技术交流群。

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