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C#利用Spire.Pdf包实现为PDF添加数字签名
背景
对PDF文档进行数字签名的需求
对PDF文档添加水印的需求
网上资料版本不一或不全
本文章提到的Spire.Pdf均是使用的Spire.Pdf for .NET，除此之前还有其他语言的版本，如Spire.Pdf for JAVA；
Spire.Pdf主要用于操作PDF，另外还有Spire.Excel、Spire.Doc等
主要介绍了在C#中使用Spire.Pdf组件包对PDF文档进行数字签名、添加水印功能，旨在引导大家快速、轻松的对PDF文档进行数字签名和添加水印功能；
简介
Spire.PDF for .NET 是一款专业的基于.NET平台的PDF文档控制组件。它能够让开发人员在不使用Adobe Acrobat和其他外部控件的情况下，运用.NET 应用程序创建，阅读，编写和操纵PDF 文档。Spire.PDF for .NET 功能丰富，除了基本的功能比如：绘制多种图形，图片，创建窗体字段，插入页眉页脚，输入数据表，自动对大型表格进行分页外，Spire.PDF for .NET还支持PDF数字签名，将HTML转换成PDF格式，提取PDF文档中的文本信息和图片等，目前Spire.PDF for .NET共有两个版本，一个是免费版本一个是付费版本，免费版本如果只是处理简单的pdf是没问题的，但是如果涉及到输出为pdf则会只显示前10页，第十一页则是预定的购买页介绍，我这里主要是对PDF文档的数字签名和水印，所以不涉及输出pdf；
依赖
本文示例代码依赖于Spire.Pdf，可以在项目中使用NuGet程序包引入。
源码
核心代码
public class DigitalSignature
{
/// <summary>
/// 页顶部红色警告字样覆盖白色图片Base64.
/// </summary>
private const string WatermarkCoverBase64 = "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";
/// <summary>
/// 构造函数.
/// </summary>
/// <param name="waitSignFile">待签名文件.</param>
/// <param name="imageSign">签名图片.</param>
/// <param name="pfx">签名证书.</param>
/// <param name="pfxPwd">签名证书密码.</param>
public DigitalSignature(byte[] waitSignFile, byte[] imageSign, byte[] pfx, string pfxPwd)
{
this.WaitSignFile = waitSignFile;
this.ImageSign = imageSign;
this.Pfx = pfx;
this.PfxPwd = pfxPwd;
}
/// <summary>
/// 构造函数.
/// </summary>
/// <param name="waitSignFile">待签名文件.</param>
/// <param name="charactersSign">签名文字.</param>
/// <param name="signRightLeftWidth">签名右向左宽度.</param>
/// <param name="signBottomUpHeight">签名低向上高度.</param>
/// <param name="pfx">签名证书.</param>
/// <param name="pfxPwd">签名证书密码.</param>
public DigitalSignature(byte[] waitSignFile, string charactersSign, float signRightLeftWidth, float signBottomUpHeight, byte[] pfx, string pfxPwd)
{
this.WaitSignFile = waitSignFile;
this.CharactersSign = charactersSign;
this.SignRightLeftWidth = signRightLeftWidth;
this.SignBottomUpHeight = signBottomUpHeight;
this.Pfx = pfx;
this.PfxPwd = pfxPwd;
}
/// <summary>
/// 构造函数.
/// </summary>
/// <param name="waitSignFile">待签名文件.</param>
/// <param name="imageSign">签名图片.</param>
/// <param name="charactersSign">签名文字.</param>
/// <param name="pfx">签名证书.</param>
/// <param name="pfxPwd">签名证书密码.</param>
public DigitalSignature(byte[] waitSignFile, byte[] imageSign, string charactersSign, byte[] pfx, string pfxPwd)
{
this.WaitSignFile = waitSignFile;
this.ImageSign = imageSign;
this.CharactersSign = charactersSign;
this.Pfx = pfx;
this.PfxPwd = pfxPwd;
}
/// <summary>
/// Gets or sets 待签名文件.
/// </summary>
public byte[] WaitSignFile { get; set; }
/// <summary>
/// Gets or sets 图签名.
/// </summary>
public byte[] ImageSign { get; set; }
/// <summary>
/// Gets or sets 文字签名.
/// </summary>
public string CharactersSign { get; set; }
/// <summary>
/// Gets or sets 签名右向左的宽度.
/// </summary>
public float? SignRightLeftWidth { get; set; }
/// <summary>
/// Gets or sets 签名顶向上高度.
/// </summary>
public float? SignBottomUpHeight { get; set; }
/// <summary>
/// Gets or sets 签名索引页面（不指定默认所有页进行签名）.
/// </summary>
public int? SignIndexPages { get; set; }
/// <summary>
/// Gets or sets Pfx证书.
/// </summary>
public byte[] Pfx { get; set; }
/// <summary>
/// Gets or sets Pfx证书密码.
/// </summary>
public string PfxPwd { get; set; }
public Stream Signature()
{
///加载PDF文档
PdfDocument pdf = new PdfDocument();
pdf.LoadFromBytes(this.WaitSignFile);
if (pdf?.Pages?.Count <= 0)
{
throw new Exception("文件有误");
}
X509Certificate2 x509 = new X509Certificate2(this.Pfx, this.PfxPwd);
PdfOrdinarySignatureMaker signatureMaker = new PdfOrdinarySignatureMaker(pdf, x509);
var appearance = new PdfCustomSignatureAppearance(this.CharactersSign, this.ImageSign, this.SignRightLeftWidth, this.SignBottomUpHeight);
IPdfSignatureAppearance signatureAppearance = appearance;
// 绘画白底图片
PdfRubberStampAnnotation logoStamp = new PdfRubberStampAnnotation(new RectangleF(new PointF(0, 0), new SizeF(350, 22)));
PdfAppearance logoApprearance = new PdfAppearance(logoStamp);
//var logoPath = AppDomain.CurrentDomain.BaseDirectory + "\\white.jpg";
byte[] byt = Convert.FromBase64String(WatermarkCoverBase64);
Stream streamByLogo = new MemoryStream(byt);
PdfImage image = PdfImage.FromStream(streamByLogo);
PdfTemplate template = new PdfTemplate(350, 22);
template.Graphics.DrawImage(image, 0, 0);
logoApprearance.Normal = template;
logoStamp.Appearance = logoApprearance;
if (this.SignIndexPages.HasValue)
{
if (this.SignIndexPages.Value < 0 || this.SignIndexPages.Value > pdf?.Pages?.Count)
{
throw new Exception("签名索引页有误");
}
var page = pdf.Pages[this.SignIndexPages.Value];
// 添加白底图片覆盖页面顶部印记
page.AnnotationsWidget.Add(logoStamp);
// 在页面中的指定位置添加可视化签名
signatureMaker.MakeSignature("signName_", page, page.ActualSize.Width - appearance.SignRightLeftWidth, page.ActualSize.Height - appearance.SignBottomUpHeight, appearance.SignRightLeftWidth, appearance.SignBottomUpHeight, signatureAppearance);
}
else
{
foreach (PdfPageBase page in pdf.Pages)
{
// 添加白底图片覆盖页面顶部印记
page.AnnotationsWidget.Add(logoStamp);
// 在页面中的指定位置添加可视化签名
signatureMaker.MakeSignature("signName_", page, page.ActualSize.Width - appearance.SignRightLeftWidth, page.ActualSize.Height - appearance.SignBottomUpHeight, appearance.SignRightLeftWidth, appearance.SignBottomUpHeight, signatureAppearance);
}
}
MemoryStream stream = new MemoryStream();
pdf.SaveToStream(stream, FileFormat.PDF);
pdf.Close();
return stream;
}
/// <summary>
/// 使用第三方插件 =》 去除 Evaluation Warning : The document was created with Spire.PDF for .NET.
/// </summary>
/// <param name="sourcePdfs">原文件地址</param>
//private static MemoryStream ClearPdfFilesFirstPage(MemoryStream sourcePdf)
//{
// iTextSharp.text.pdf.PdfReader reader = null;
// iTextSharp.text.Document document = new iTextSharp.text.Document();
// iTextSharp.text.pdf.PdfImportedPage page = null;
// iTextSharp.text.pdf.PdfCopy pdfCpy = null;
// int n = 0;
// reader = new iTextSharp.text.pdf.PdfReader(sourcePdf);
// reader.ConsolidateNamedDestinations();
// n = reader.NumberOfPages;
// document = new iTextSharp.text.Document(reader.GetPageSizeWithRotation(1));
// MemoryStream memoryStream = new MemoryStream();
// pdfCpy = new iTextSharp.text.pdf.PdfCopy(document, memoryStream);
// document.Open();
// for (int j = 2; j <= n; j++)
// {
// page = pdfCpy.GetImportedPage(reader, j);
// pdfCpy.AddPage(page);
// }
// reader.Close();
// document.Close();
// return memoryStream;
//}
}
public class PdfCustomSignatureAppearance : IPdfSignatureAppearance
{
public PdfCustomSignatureAppearance(string charactersSign, byte[] sign, float? signRightLeftWidth, float? signBottomUpHeight)
{
this.CharactersSign = charactersSign;
if (sign != null && sign.Length > 0)
{
this.Sign = sign;
MemoryStream ms = new MemoryStream(sign);
var image = System.Drawing.Image.FromStream(ms);
if (!signRightLeftWidth.HasValue)
{
signRightLeftWidth = image.Width;
}
if (!signBottomUpHeight.HasValue)
{
signBottomUpHeight = image.Height;
}
}
this.SignRightLeftWidth = signRightLeftWidth.Value;
this.SignBottomUpHeight = signBottomUpHeight.Value;
}
/// <summary>
/// Gets or sets 签名.
/// </summary>
public byte[] Sign { get; set; }
/// <summary>
/// Gets or sets 签名右向左的宽度.
/// </summary>
public float SignRightLeftWidth { get; set; }
/// <summary>
/// Gets or sets 签名顶向上高度.
/// </summary>
public float SignBottomUpHeight { get; set; }
/// <summary>
/// Gets or sets 文字签名.
/// </summary>
public string CharactersSign { get; set; }
public void Generate(PdfCanvas g)
{
if (!string.IsNullOrWhiteSpace(CharactersSign))
{
float fontSize = 15;
var font = new System.Drawing.Font("Arial", fontSize);
PdfTrueTypeFont fontByPdf = new PdfTrueTypeFont(font, true);
g.DrawString(CharactersSign, fontByPdf, PdfBrushes.Black, new PointF(0, 0));
}
if (this.Sign != null && this.Sign.Length > 0)
{
Stream stream = new MemoryStream(this.Sign);
g.DrawImage(Spire.Pdf.Graphics.PdfImage.FromStream(stream), new PointF(20, 20));
}
}
}
调用实现
static void Main(string[] args)
{
/*
前言：最近有个需求是需要对文档进行数字签名；
描述：本示例基于Spire.Pdf组件对PDF进行数字签名，演示了
签名证书使用项目
CreateSelfSignedCertificateByBouncyCastle(https://github.com/daileass/CreateSelfSignedCertificateByBouncyCastle.git)
生成的自签名证书pfx，解决了数字签名后文档头部有警告
*/
var fileCert = System.Environment.CurrentDirectory + "\\Cert\\";
var file = System.Environment.CurrentDirectory + "\\File\\";
var filePath = file + "dome.pdf";
var newFilePath = file + $"dome_{DateTime.Now.ToString("yyyyMMddHHmmss")}.pdf";
var pfxFilePath = fileCert + "edd9386229324d969692dcabf97ac095dpps.fun.pfx";
var pfxFilePwd = "ABCD123456";
var signFilePath = file + "sign.png";
// 数字签名
var digitalSignature = new DigitalSignature(
File2Bytes(filePath),
File2Bytes(signFilePath),
"Sign Here:",
File2Bytes(pfxFilePath),
pfxFilePwd
);
var stream = digitalSignature.Signature();
// 保存签名后的文件
using (var fileStream = File.Create(newFilePath))
{
stream.Seek(0, SeekOrigin.Begin);
stream.CopyTo(fileStream);
}
Console.WriteLine("OK");
Console.ReadLine();
}
/// <summary>
/// 将文件转换为byte数组
/// </summary>
/// <param name="path">文件地址</param>
/// <returns>转换后的byte数组</returns>
public static byte[] File2Bytes(string path)
{
if (!System.IO.File.Exists(path))
{
return new byte[0];
}
FileInfo fi = new FileInfo(path);
byte[] buff = new byte[fi.Length];
FileStream fs = fi.OpenRead();
fs.Read(buff, 0, Convert.ToInt32(fs.Length));
fs.Close();
return buff;
}
源码下载：https://github.com/daileass/PDFDigitalSignatureBySelfSignedCertificate
到此这篇关于C#利用Spire.Pdf包实现为PDF添加数字签名的文章就介绍到这了,更多相关C# PDF添加数字签名内容请搜索以前的文章或继续浏览下面的相关文章希望大家以后多多支持
原文链接：https://www.cnblogs.com/PingleDay/p/16643493.html
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