Debenu Quick PDF Library - PDF SDK Community Forum : Detached signature with sha256 digest http://www.quickpdf.org/forum/ Copyright (c) 2006-2013 Web Wiz Forums - All Rights Reserved. Sun, 05 Apr 2026 19:39:35 +0000 Mon, 02 Jan 2017 23:14:21 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 11.01 360 www.quickpdf.org/forum/RSS_post_feed.asp?TID=3428 <![CDATA[Debenu Quick PDF Library - PDF SDK Community Forum]]> http://www.quickpdf.org/forum/forum_images/QPDF_Forum_Title.png http://www.quickpdf.org/forum/ <![CDATA[Detached signature with sha256 digest : Hi,perhaps here you can learn...]]> http://www.quickpdf.org/forum/detached-signature-with-sha256-digest_topic3428_post13625.html#13625 Author: Ingo
Subject: 3428
Posted: 02 Jan 17 at 11:14PM

Hi,

perhaps here you can learn more about sha256:
https://msdn.microsoft.com/de-de/library/system.security.cryptography.sha256cryptoserviceprovider(v=vs.110).aspx

]]> Mon, 02 Jan 2017 23:14:21 +0000 http://www.quickpdf.org/forum/detached-signature-with-sha256-digest_topic3428_post13625.html#13625 <![CDATA[Detached signature with sha256 digest : Hello, i&#039;m trying to add...]]> http://www.quickpdf.org/forum/detached-signature-with-sha256-digest_topic3428_post13623.html#13623 Author: pinozzy
Subject: 3428
Posted: 02 Jan 17 at 6:00PM

Hello, i'm trying to add a visual sha-256 detached signature to my pdf.


I did it successfully with this example: http://www.debenu.com/kb/advanced-options-signing-pdf-files/

I edited this method

private byte[] SignData(byte[] inputData, X509Certificate2 cert)
        {
            // Create an SHA-1 hash of the file data
            SHA1 sha = new SHA1CryptoServiceProvider();
            byte[] sha1Result = sha.ComputeHash(inputData);

            // Sign the hash using the certificate
            // This could be changed to use a hardware device (eg. smartcard)
            ContentInfo content = new ContentInfo(sha1Result);
            SignedCms signedCms = new SignedCms(content);
            CmsSigner cmsSigner = new CmsSigner(cert);
            signedCms.ComputeSignature(cmsSigner);
            return signedCms.Encode();
        }

this way:

private byte[] SignData(byte[] inputData, X509Certificate2 cert)
    {
      // Create an SHA-1 hash of the file data
      var sha = new SHA256CryptoServiceProvider();
      byte[] sha1Result = sha.ComputeHash(inputData);

      // Sign the hash using the certificate
      // This could be changed to use a hardware device (eg. smartcard)

      var oid = new Oid("2.16.840.1.101.3.4.2.1");
      var content = new ContentInfo(oid, sha1Result);
      var signedCms = new SignedCms(content, true);

      var cmsSigner = new CmsSigner(cert);
      cmsSigner.DigestAlgorithm = oid;


      signedCms.ComputeSignature(cmsSigner);
      return signedCms.Encode();
    }

And i just added this: DPL.SetSignProcessSubFilter(signProcessID, 2);

For the detached signature.

I got an error from adobe reader, the document signature is visible but with red X and the message of damaged signature.

Does anyone have a working example of Detached sha-256 signature?

Many thanks all.



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