签署 PDF 文件答案

【问题标题】：Signing a PDF file签署 PDF 文件
【发布时间】：2010-12-20 15:55:49
【问题描述】：

我使用 iTextSharp 签署 PDF 文件。但是 Adobe Reader 无法验证我的签名。我使用由证书颁发机构生成的 SHA-2 测试证书（我也尝试过 SHA-1）。我已经为这个机构的测试证书安装了根证书。

public static void SignHashed(X509Certificate2 card, Stream input, Stream output) {
    Org.BouncyCastle.X509.X509CertificateParser cp = new Org.BouncyCastle.X509.X509CertificateParser();
    Org.BouncyCastle.X509.X509Certificate[] chain = new Org.BouncyCastle.X509.X509Certificate[] { cp.ReadCertificate(card.RawData) };

    PdfReader reader = new PdfReader(input);
    PdfStamper stp = PdfStamper.CreateSignature(reader, output, '\0');
    PdfSignatureAppearance sap = stp.SignatureAppearance;
    sap.SignDate = DateTime.Now;
    sap.SetCrypto(null, chain, null, PdfSignatureAppearance.WINCER_SIGNED);
    sap.Reason = "Testování";
    sap.Location = "Praha";
    sap.Acro6Layers = true;
    sap.Render = PdfSignatureAppearance.SignatureRender.GraphicAndDescription;
    PdfSignature dic = new PdfSignature(PdfName.ADOBE_PPKMS, PdfName.ADBE_PKCS7_SHA1);
    dic.Date = new PdfDate(sap.SignDate);
    dic.Name = PdfPKCS7.GetSubjectFields(chain[0]).GetField("CN");
    if (sap.Reason != null) dic.Reason = sap.Reason;
    if (sap.Location != null) dic.Location = sap.Location;
    sap.CryptoDictionary = dic;
    int csize = 4000;
    Hashtable exc = new Hashtable();
    exc[PdfName.CONTENTS] = csize * 2 + 2;
    sap.PreClose(exc);

    System.Security.Cryptography.HashAlgorithm sha = new System.Security.Cryptography.SHA1CryptoServiceProvider();

    Stream s = sap.RangeStream;
    int read = 0;
    byte[] buff = new byte[8192];
    while ((read = s.Read(buff, 0, 8192)) > 0) {
        sha.TransformBlock(buff, 0, read, buff, 0);
    }
    sha.TransformFinalBlock(buff, 0, 0);
    byte[] pk = SignMsg(sha.Hash, card, false);

    byte[] outc = new byte[csize];

    PdfDictionary dic2 = new PdfDictionary();

    Array.Copy(pk, 0, outc, 0, pk.Length);

    dic2.Put(PdfName.CONTENTS, new PdfString(outc).SetHexWriting(true));
    sap.Close(dic2);
}

有没有人知道更好的 PDF 签名解决方案？

【问题讨论】：

Adobe 给出的准确错误是什么？ IE。是签名无效还是 CA 未知？

标签： pdf digital-signature digital-certificate x509certificate2

【解决方案1】：

Adobe Reader 无法验证签名，因为需要在高级菜单中的“管理可信身份”选项中将 CA 链导入 Adobe Reader。祝你好运！

【讨论】：