Hi
.I need to ask one think that whether i can sign at client end in a web
application with itextsharp.The signature is on smart cad which is at client
end.If not,i am signing at client end and i am generating signature.Now i
want to put that signature on pdf using itextsharp.I tried following
code,But when i open pdf and click on signature it shows following errors:-
1."Error while verification(BER Encoding)
2.Non-empty content info is required
3.Error during signature verification
A little help will be appreciated.Hope for a quick and positve reply
public static void SignHashed(byte[] pdf, string path,string
path1,byte[]pdf_sign)
{
PdfReader reader = new PdfReader(path);
PdfStamper stp = PdfStamper.CreateSignature(reader, new
FileStream(path1, FileMode.Create), '\0');
PdfSignatureAppearance sap = stp.SignatureAppearance;
sap.SetVisibleSignature(new Rectangle(100, 100, 300, 200), 1, null);
sap.SignDate = DateTime.Now;
sap.SetExternalDigest(pdf_sign, pdf, "RSA");
//sap.SetCrypto(null, chain, null, null);
sap.Reason = "I like to sign";
sap.Location = "Universe";
sap.Acro6Layers = true;
sap.Render =
PdfSignatureAppearance.SignatureRender.NameAndDescription;
PdfSignature dic = new PdfSignature(PdfName.ADOBE_PPKMS,
PdfName.ADBE_PKCS7_SHA1);
dic.Date = new PdfDate(sap.SignDate);
dic.Name = "AshishD";
if (sap.Reason != null)
dic.Reason = sap.Reason;
if (sap.Location != null)
dic.Location = sap.Location;
sap.CryptoDictionary = dic;
int csize = 4000;
Dictionary<PdfName, int> dic_ex = new Dictionary<PdfName, int>();
dic_ex.Add(PdfName.CONTENTS, csize * 2 + 2);
Hashtable dic_hasht = new Hashtable(dic_ex);
sap.PreClose(dic_hasht);
HashAlgorithm sha = new 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(pdf_sign, 0, outc, 0, pdf_sign.Length);
dic2.Put(PdfName.CONTENTS, new PdfString(outc).SetHexWriting(true));
sap.Close(dic2);
reader.Close();
stp.Reader.Close();
}
--
Thanks and Regards,
Ashish Dhingra,
Software Engineer,
M-09467783146
God first everything else next
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