C pKCS7智能卡数字签名-文件已被更改或损坏,因为它是签署的

我尝试用我的智能卡(USB令牌)签署PDF文件,但遇到 "Document has been altered or corrupted since it was signed" 在Adobe中打开签名的PDF文件时出错。这个错误并不是那么具有描述性,我不知道该看哪里,因为代码对我来说似乎很好,但显然不是。

我使用的代码是:

var signer = smartCardManager.getSigner("myTokenPassword");
var toBeSignedHash = GetHashOfPdf(File.ReadAllBytes(@"xxx\pdf.pdf"), cert.asX509Certificate2().RawData, "dsa", null, false);
var signature = signer.sign(toBeSignedHash);
var signedPdf = EmbedSignature(cert.getBytes(), signature);
File.WriteAllBytes(@"xxx\signedpdf.pdf", signedPdf);

public byte[] GetHashOfPdf(byte[] unsignedFile, byte[] userCertificate, string signatureFieldName, List<float> location, bool append)
{
    byte[] result = null;

    var chain = new List<Org.BouncyCastle.X509.X509Certificate>
    {
        Org.BouncyCastle.Security.DotNetUtilities.FromX509Certificate(new X509Certificate2(userCertificate))
    };
    Org.BouncyCastle.X509.X509Certificate certificate = chain.ElementAt(0);
    using (PdfReader reader = new PdfReader(unsignedFile))
    {
        using (var os = new MemoryStream())
        {
            PdfStamper stamper = PdfStamper.CreateSignature(reader, os, '\0', null, append);
            PdfSignatureAppearance appearance = stamper.SignatureAppearance;
            appearance.SetVisibleSignature(new iTextSharp.text.Rectangle(0,0,0,0), 1, signatureFieldName);
            appearance.Certificate = certificate;
            IExternalSignatureContainer external = new ExternalBlankSignatureContainer(PdfName.ADOBE_PPKLITE, PdfName.ADBE_PKCS7_DETACHED);
            MakeSignature.SignExternalContainer(appearance, external, 8192);
            Stream data = appearance.GetRangeStream();
            byte[] hash = DigestAlgorithms.Digest(data, "SHA256");
            var signatureContainer = new PdfPKCS7(null, chain, "SHA256", false);
            byte[] signatureHash = signatureContainer.getAuthenticatedAttributeBytes(hash, null, null, CryptoStandard.CMS);
            result = DigestAlgorithms.Digest(new MemoryStream(signatureHash), "SHA256");
            this.hash = hash;
            this.os = os.ToArray();
            File.WriteAllBytes(@"xxx\temp.pdf", this.os);
        }
    }

    return result;
}

public byte[] EmbedSignature(byte[] publicCert, byte[] sign)
{
    var chain = new List<Org.BouncyCastle.X509.X509Certificate>
    {
        Org.BouncyCastle.Security.DotNetUtilities.FromX509Certificate(new X509Certificate2(publicCert))
    };
    var signatureContainer = new PdfPKCS7(null, chain, "SHA256", false);
    using (var reader = new PdfReader(this.os))
    {
        using (var os2 = new MemoryStream())
        {
            signatureContainer.SetExternalDigest(sign, null, "RSA");
            byte[] encodedSignature = signatureContainer.GetEncodedPKCS7(this.hash, null, null, null, CryptoStandard.CMS);
            IExternalSignatureContainer external = new MyExternalSignatureContainer(encodedSignature);
            MakeSignature.SignDeferred(reader, "dsa", os2, external);
            return os2.ToArray();
        }
    }
}

我试图签署的pdf文件是 this 是的。

添加签名字段后创建的临时pdf文件是 this 是的。

签名的pdf文件是 this 是的。

签名的哈希的base64格式为: klh6CGp7DUzayt62Eusiqjr1BFCcTZT4XdgnMBq7QeY=

签名的base64格式为: Uam/J6W0YX99rVP4M9mL9Lg9l6YzC2yiR4OtJ18AH1PtBVaNPteT3oPS7SUc+6ak2LfijgJ6j1RgdLamodDPKl/0E90kbBenry+/g1Ttd1bpO8lqTn1PWJU2TxeGHwyRyaFBOUga2AxpErIHrwxfuKCBcodB7wvAqRjso0jovnyP/4DluyOPm97QWh4na0S+rtUWOdqVmKGOuGJ3sBXuk019ewpvFcqWBX4Mvz7IKV56wcxQVQuJLCiyXsMXoazwyDCvdteaDz05K25IVwgEEjwLrppnc/7Ue9a9KVadFFzXWXfia7ndmUCgyd70r/Z+Oviu9MIAZL8GuTpkD7fJeA==