Get timestamp from Authenticode Signed files in .NET

We need to verify that binary files are signed properly with digital signature (Authenticode). This can be achieved with signtool.exe pretty easily. However, we need an automatic way that also verifies signer name and timestamp. This is doable in native C++ with CryptQueryObject() API as shown in this wonderful sample: How To Get Information from Authenticode Signed Executables

However we live in a managed world :) hence looking for C# solution to the same problem. Straight approach would be to pInvoke Crypt32.dll and all is done. But there is similar managed API in System.Security.Cryptography.X509Certificates Namespace. X509Certificate2 Class seems to provide some information but no timestamp. Now we came to the original question how can we get that timestamp of a digital signature in C Sharp?

Edit Report

Thank you guys,

You help me a lot :)

BTW: I found simpler way how to obtain the time stamp.

here it is:

foreach (var signerInfo in signedCms.SignerInfos)
{
  foreach (var unsignedAttribute in signerInfo.UnsignedAttributes)
  {
    if (unsignedAttribute.Oid.Value == WinCrypt.szOID_RSA_counterSign)
    {
      foreach (var counterSignInfo in signerInfo.CounterSignerInfos)
      {
        foreach (var signedAttribute in counterSignInfo.SignedAttributes)
        {
          if (signedAttribute.Oid.Value == WinCrypt.szOID_RSA_signingTime)
          {
            Pkcs9SigningTime signingTime = (Pkcs9SigningTime)signedAttribute.Values[0];
            Console.Out.WriteLine("Signing Time UTC: " + signingTime.SigningTime);
          }
        }
      }
      return true;
    }
  }
}

answered 2011-09-09T10:22:41.547

Get timestamp from Authenticode Signed files in .NET

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