/// <summary>Signs a PDF where space was already reserved.</summary>
/// <param name="document">the original PDF</param>
/// <param name="fieldName">the field to sign. It must be the last field</param>
/// <param name="outs">the output PDF</param>
/// <param name="externalSignatureContainer">
/// the signature container doing the actual signing. Only the
/// method ExternalSignatureContainer.sign is used
/// </param>
/// <exception cref="System.IO.IOException"/>
/// <exception cref="Org.BouncyCastle.Security.GeneralSecurityException"/>
public static void SignDeferred(PdfDocument document, String fieldName, Stream outs, IExternalSignatureContainer
externalSignatureContainer)
{
SignatureUtil signatureUtil = new SignatureUtil(document);
PdfDictionary v = signatureUtil.GetSignatureDictionary(fieldName);
if (v == null)
{
throw new PdfException(PdfException.ThereIsNoFieldInTheDocumentWithSuchName1).SetMessageParams(fieldName);
}
if (!signatureUtil.SignatureCoversWholeDocument(fieldName))
{
new PdfException(PdfException.SignatureWithName1IsNotTheLastItDoesntCoverWholeDocument).SetMessageParams(fieldName
);
}
PdfArray b = v.GetAsArray(PdfName.ByteRange);
long[] gaps = SignatureUtil.AsLongArray(b);
// TODO: refactor
if (b.Size() != 4 || gaps[0] != 0)
{
throw new ArgumentException("Single exclusion space supported");
}
IRandomAccessSource readerSource = document.GetReader().GetSafeFile().CreateSourceView();
Stream rg = new RASInputStream(new RandomAccessSourceFactory().CreateRanged(readerSource, gaps));
byte[] signedContent = externalSignatureContainer.Sign(rg);
int spaceAvailable = (int)(gaps[2] - gaps[1]) - 2;
if ((spaceAvailable & 1) != 0)
{
throw new ArgumentException("Gap is not a multiple of 2");
}
spaceAvailable /= 2;
if (spaceAvailable < signedContent.Length)
{
throw new PdfException(PdfException.AvailableSpaceIsNotEnoughForSignature);
}
StreamUtil.CopyBytes(readerSource, 0, gaps[1] + 1, outs);
ByteBuffer bb = new ByteBuffer(spaceAvailable * 2);
foreach (byte bi in signedContent)
{
bb.AppendHex(bi);
}
int remain = (spaceAvailable - signedContent.Length) * 2;
for (int k = 0; k < remain; ++k)
{
bb.Append((byte)48);
}
byte[] bbArr = bb.ToByteArray();
outs.Write(bbArr);
StreamUtil.CopyBytes(readerSource, gaps[2] - 1, gaps[3] + 1, outs);
}
/// <exception cref="Org.BouncyCastle.Security.SecurityUtilityException"/>
/// <exception cref="System.IO.IOException"/>
private PdfName GetSignatureHashKey(String signatureName)
{
PdfDictionary dic = sgnUtil.GetSignatureDictionary(signatureName);
PdfString contents = dic.GetAsString(PdfName.Contents);
byte[] bc = PdfEncodings.ConvertToBytes(contents.GetValue(), null);
byte[] bt = null;
if (PdfName.ETSI_RFC3161.Equals(dic.GetAsName(PdfName.SubFilter)))
{
Asn1InputStream din = new Asn1InputStream(new MemoryStream(bc));
Asn1Object pkcs = din.ReadObject();
bc = pkcs.GetEncoded();
}
bt = HashBytesSha1(bc);
return(new PdfName(ConvertToHex(bt)));
}
