public static string SignFile(string fileName, PdfSignatureParameters parameters, IDigitalSignatureCertificateSelector certificateSelector)
{
if (string.IsNullOrWhiteSpace(fileName))
{
throw new ArgumentException("Filename must be given", nameof(fileName));
}
if (!File.Exists(fileName))
{
throw new ArgumentException($"File {fileName} not found.");
}
if (parameters == null)
{
throw new ArgumentNullException(nameof(parameters));
}
if (certificateSelector == null)
{
throw new ArgumentNullException(nameof(certificateSelector));
}
string tempPath = string.Empty;
try
{
tempPath = GetTempPath(parameters.TempFolderPath);
string targetFilePath = GetTargetFilePath(parameters.TempFolderPath, parameters.TargetFilePath);
var signingCertificates = CertificateHelper.GetSigningCertificates(certificateSelector);
// Two clients for checking certificate revocation
// * Online Certificate Status Protocol (OCSP) client
// * Certificate Revocation Lists (CRL) client with online checking
// Certificate will be checked when the signature is made
OcspClientBouncyCastle oscpClient = new OcspClientBouncyCastle(null);
List<ICrlClient> clrClients = new List<ICrlClient> { new CrlClientOnline(signingCertificates.FinalChain) };
using (FileStream targetFileStream = new FileStream(targetFilePath, FileMode.Create))
using (PdfReader reader = new PdfReader(fileName))
{
PdfStamper stamper = PdfStamper.CreateSignature(reader, targetFileStream, '0', tempPath, true);
PdfSignatureAppearance appearance = GetPdfSignatureAppearance(signingCertificates, stamper, reader, parameters);
CreateSignature(signingCertificates, appearance, clrClients, oscpClient);
}
return targetFilePath;
}
finally
{
if (!string.IsNullOrWhiteSpace(tempPath) && File.Exists(tempPath))
{
File.Delete(tempPath);
}
}
}
private static Rectangle GetSignatureLocation(Rectangle cropBox, PdfSignatureParameters parameters)
{
return new Rectangle(cropBox.GetLeft(parameters.SignatureLeftMargin),
cropBox.GetTop(parameters.SignatureYLocation + parameters.SignatureHeight),
cropBox.Width - parameters.SignatureRightMargin,
cropBox.GetTop(parameters.SignatureYLocation));
}
private static string GetSignatureText(X509Certificate x509Certificate, PdfSignatureParameters parameters)
{
Dictionary<string, string> subjectFields = CertificateHelper.GetSubjectFields(x509Certificate);
string surName = subjectFields.Keys.Contains("SURNAME") ? subjectFields["SURNAME"] : string.Empty;
string givenName = subjectFields.Keys.Contains("GIVENNAME") ? subjectFields["GIVENNAME"] : string.Empty;
string signDate = DateTime.Now.ToString("d.M.yyyy");
return parameters.SignatureTemplate
.Replace("{lastname}", UppercaseFirst(surName))
.Replace("{firstname}", UppercaseFirst(givenName))
.Replace("{signdate}", signDate);
}
private static PdfSignatureAppearance GetPdfSignatureAppearance(SigningCertificates signingCertificates, PdfStamper stamper, PdfReader reader, PdfSignatureParameters parameters)
{
PdfSignatureAppearance appearance = stamper.SignatureAppearance;
appearance.Reason = "";
appearance.LocationCaption = "";
appearance.Location = "";
appearance.Layer4Text = "";
appearance.Layer2Text = GetSignatureText(signingCertificates.X509Certificate, parameters);
appearance.Acro6Layers = true;
Rectangle cropBox = reader.GetCropBox(parameters.SignaturePageNumber);
Rectangle rectangle = GetSignatureLocation(cropBox, parameters);
appearance.SetVisibleSignature(rectangle, parameters.SignaturePageNumber, parameters.SignatureName);
return appearance;
}
