Add Signature to PDF in .NET SDK

    
	public static async Task AddSignatureField()
	{
	    const string localPdfFileName = @"C:\Samples\sample.pdf";
	    const string storageFileName = "sample.pdf";
	    const string localFolder = @"C:\Samples";
	    const string resultFileName = "output_add_signature.pdf";
	    const string storageTempFolder = "YourTempFolder";

	    // Get your AppSid and AppSecret https://dashboard.aspose.cloud (free registration required).
	    var pdfApi = new PdfApi(AppSecret, AppSid);

	    using var file = File.OpenRead(localPdfFileName);
	    var uploadResult = pdfApi.UploadFile(Path.Combine(storageTempFolder, storageFileName), file);
	    Console.WriteLine(uploadResult.Uploaded[0]);

	    Signature signature = new Signature(
	        SignaturePath: Path.Combine(storageTempFolder, SIGNATURE_PFX),
	        SignatureType: SignatureType.PKCS7,
	        Password: SIGNATURE_PASSWORD,
	        Contact: SIGNATURE_CONTACT,
	        Location: SIGNATURE_LOCATION,
	        Visible: true,
	        Rectangle: new Rectangle(100, 100, 500, 500),
	        FormFieldName: SIGNATURE_FORM_FIELD,
	        Authority: SIGNATURE_AUTHORITY,
	        Date: SIGNATURE_DATE,
	        ShowProperties: true);

	    SignatureField field = new SignatureField(
	        PageIndex: 1,
	        Signature: signature,
	        PartialName: fieldName,
	        Rect: config.SIGNATURE_RECT);

	    var response = await pdfApi.PostSignatureFieldAsync(storageFileName, field, folder: storageTempFolder);

	    if (response == null)
	        Console.WriteLine("AddSignatureField(): Unexpected error!");
	    else if (response.Code < 200 || response.Code > 299)
	        Console.WriteLine("AddSignatureField(): Failed to append Pdf document signature.");
	    else {
	        using Stream downloadStream = pdfApi.DownloadFile(Path.Combine(storageTempFolder, storageFileName));
	        using FileStream localStream = File.Create(Path.Combine(localFolder, resultFileName));
	        downloadStream.CopyTo(localStream);
	        Console.WriteLine("AddSignatureField(): Signature appended successfully to the Pdf document '{0}'.", resultFileName);
	    }
	}