External signature not valid

I am trying to create external signature using SmartCard.

1) I hash PDF's ByteStream data using SHA1
2) this hash is being encrypted using SmartCard internals (mechanism
SHA1_RSA)
3) can't use MS API like described here:
http://itextpdf.sourceforge.net/howtosign.html#signextitextsharp2.

I end up with Reader error complayining  "an error occured while
attempting to validate this signature". What am I doing wrong ?


public static void SignUsingMartCard(string filename, string outfile)
{
    X509Certificate2 card = GetCertificate();
    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(filename);
    PdfStamper stp = PdfStamper.CreateSignature(reader, new
FileStream(outfile, FileMode.Create), '\0');
    PdfSignatureAppearance sap = stp.SignatureAppearance;
    sap.SetVisibleSignature(new Rectangle(100, 100, 300, 200), 1, null);

    sap.SignDate = DateTime.Now;
    sap.SetCrypto(null, chain, null, null);
    sap.Reason = "I like to sign using C#";
    sap.Location = "Universe";
    sap.Acro6Layers = true;
    sap.Render =
PdfSignatureAppearance.SignatureRender.NameAndDescription;
    PdfSignature dic = new PdfSignature(PdfName.ADOBE_PPKLITE,
PdfName.ADBE_PKCS7_DETACHED);
    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 = 2048;
    Hashtable exc = new Hashtable();
    exc[PdfName.CONTENTS] = csize * 2 + 2;
    sap.PreClose(exc);

    Stream s = sap.RangeStream;
    MemoryStream ss = new MemoryStream();
    int read = 0;
    byte[] buff = new byte[8192];
    while ((read = s.Read(buff, 0, 8192)) > 0)
    {
        ss.Write(buff, 0, read);
    }

    GetExternalBytes(ss.ToArray(), ref digest, ref signature);

    PdfPKCS7 pk7 = new PdfPKCS7(null, chain, null, "SHA1", true);
    pk7.SetExternalDigest(digest, signature, "RSA");
    byte[] pk = pk7.GetEncodedPKCS7();

    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);
}

------------------------------------------------------------------------------
_______________________________________________
itextsharp-questions mailing list
itextsharp-questions@...
https://lists.sourceforge.net/lists/listinfo/itextsharp-questions