DigitalSignatureValidation.cs

#region Copyright Syncfusion Inc. 2001-2016.
// Copyright Syncfusion Inc. 2001-2016. All rights reserved.
// Use of this code is subject to the terms of our license.
// A copy of the current license can be obtained at any time by e-mailing
// licensing@syncfusion.com. Any infringement will be prosecuted under
// applicable laws. 
#endregion
using System;
using System.IO;
using System.Reflection;
using Syncfusion.Drawing;
using Syncfusion.Pdf;
using Syncfusion.Pdf.Parsing;
using Syncfusion.Pdf.Security;
using MessageUI;
using System.Security.Cryptography.X509Certificates;
using System.Text;
#if __UNIFIED__
using Foundation;
using UIKit;
using CoreGraphics;
#else
using MonoTouch.Foundation;
using MonoTouch.UIKit;
using MonoTouch.CoreGraphics;
using CGRect = System.Drawing.RectangleF;
using CGPoint = System.Drawing.PointF;
using CGSize = System.Drawing.SizeF;
#endif

namespace SampleBrowser
{
    public partial class DigitalSignatureValidation : SampleView
    {
        CGRect frameRect = new CGRect();
        float frameMargin = 8.0f;
        UILabel label1;
        UIButton button;
        UILabel label2;
        public DigitalSignatureValidation()
        {
           
            label1 = new UILabel();
            label2 = new UILabel();
            label2.Hidden = true;
            button = new UIButton(UIButtonType.System);
            button.TouchUpInside += OnButtonClicked;
        }

        void LoadAllowedTextsLabel()
        {

            label1.Frame = frameRect;
            label1.TextColor = UIColor.FromRGB(38 / 255.0f, 38 / 255.0f, 38 / 255.0f);
            label1.Text = "This sample demonstrates how to validate digitally signed PDF document signature.";
            label1.Font = UIFont.SystemFontOfSize(15);
            label1.Lines = 0;
            label1.LineBreakMode = UILineBreakMode.WordWrap;
            if (UIDevice.CurrentDevice.UserInterfaceIdiom == UIUserInterfaceIdiom.Pad)
            {
                label1.Font = UIFont.SystemFontOfSize(18);
                label1.Frame = new CGRect(0, 12, frameRect.Location.X + frameRect.Size.Width, 50);
            }
            else
            {
                label1.Frame = new CGRect(frameRect.Location.X, 12, frameRect.Size.Width, 50);

            }
            this.AddSubview(label1);


          
            button.SetTitle("Validate signature", UIControlState.Normal);
            if (UIDevice.CurrentDevice.UserInterfaceIdiom == UIUserInterfaceIdiom.Pad)
            {
                button.Frame = new CGRect(0, 70, frameRect.Location.X + frameRect.Size.Width, 10);
            }
            else
            {
                button.Frame = new CGRect(frameRect.Location.X, 70, frameRect.Size.Width, 10);

            }

            this.AddSubview(button);

            label2.Frame = frameRect;
            label2.TextColor = UIColor.FromRGB(38 / 255.0f, 38 / 255.0f, 38 / 255.0f);
            label2.Text = "";
            label2.Font = UIFont.SystemFontOfSize(15);
            label2.Lines = 0;
            label2.LineBreakMode = UILineBreakMode.WordWrap;
            if (UIDevice.CurrentDevice.UserInterfaceIdiom == UIUserInterfaceIdiom.Pad)
            {
                label2.Font = UIFont.SystemFontOfSize(18);
                label2.Frame = new CGRect(0, 90, frameRect.Location.X + frameRect.Size.Width, frameRect.Size.Height - 100);
            }
            else
            {
                label2.Frame = new CGRect(frameRect.Location.X, 90, frameRect.Size.Width, frameRect.Size.Height - 100);

            }
            this.AddSubview(label2);
        }

        void OnButtonClicked(object sender, EventArgs e)
        {
            label2.Hidden = false;

            StringBuilder builder = new StringBuilder();

            Stream docStream = typeof(DigitalSignatureValidation).GetTypeInfo().Assembly.GetManifestResourceStream("SampleBrowser.Samples.PDF.Assets.SignedDocument.pdf");
            //Load the PDF document into the loaded document object.
            PdfLoadedDocument loadedDocument = new PdfLoadedDocument(docStream);

            //Get signature field
            PdfLoadedSignatureField lSigFld = loadedDocument.Form.Fields[0] as PdfLoadedSignatureField;

            //X509Certificate2Collection to check the signer's identity using root certificates
            X509CertificateCollection collection = new X509CertificateCollection();

            //Get the certificate stream from .pfx file.
            Stream certificateStream = typeof(DigitalSignatureValidation).GetTypeInfo().Assembly.GetManifestResourceStream("SampleBrowser.Samples.PDF.Assets.PDF.pfx");

            byte[] data = new byte[certificateStream.Length];
            certificateStream.Read(data, 0, data.Length);

            //Create new X509Certificate2 with the root certificate
            X509Certificate2 certificate = new X509Certificate2(data, "password123");

            //Add the certificate to the collection
            collection.Add(certificate);

            //Validate signature and get the validation result
            PdfSignatureValidationResult result = lSigFld.ValidateSignature(collection);

            builder.AppendLine("Signature is " + result.SignatureStatus);
            builder.AppendLine();
            builder.AppendLine("--------Validation Summary--------");
            builder.AppendLine();

            //Checks whether the document is modified or not
            bool isModified = result.IsDocumentModified;
            if (isModified)
                builder.AppendLine("The document has been altered or corrupted since the signature was applied.");
            else
                builder.AppendLine("The document has not been modified since the signature was applied.");

            //Signature details
            builder.AppendLine("Digitally signed by " + lSigFld.Signature.Certificate.IssuerName);
            builder.AppendLine("Valid From : " + lSigFld.Signature.Certificate.ValidFrom);
            builder.AppendLine("Valid To : " + lSigFld.Signature.Certificate.ValidTo);
            builder.AppendLine("Signature Algorithm : " + result.SignatureAlgorithm);
            builder.AppendLine("Hash Algorithm : " + result.DigestAlgorithm);

            //Revocation validation details
            builder.AppendLine("OCSP revocation status : " + result.RevocationResult.OcspRevocationStatus);
            if (result.RevocationResult.OcspRevocationStatus == RevocationStatus.None && result.RevocationResult.IsRevokedCRL)
                builder.AppendLine("CRL is revoked.");

            //Close the PDF document
            loadedDocument.Close(true);

            label2.Text = builder.ToString();
        }

        public override void LayoutSubviews()
        {
            if (UIDevice.CurrentDevice.UserInterfaceIdiom == UIUserInterfaceIdiom.Pad)
            {
                frameMargin = 0.0f;
            }
            frameRect = Bounds;
            frameRect.Location = new CGPoint(frameRect.Location.X + frameMargin, frameRect.Location.Y + 1.5f * frameMargin);
            frameRect.Size = new CGSize(frameRect.Size.Width - (frameRect.Location.X + frameMargin), frameRect.Size.Height - (frameRect.Location.Y + 1.5f * frameMargin));

            LoadAllowedTextsLabel();

            base.LayoutSubviews();
        }
    }
}