DicomObjects.NET - why 10 seconds delay on loading first DICOM image

We are sometimes getting report from our users about this particular problem which was "caused" by our CDLicense checking code - "CDLicense" (perhaps not the best term!) is what we use to describe the process you use to authenticate by strong name rather than license server (as it was first used for CD viewers).

It appears that Microsoft did a modification via a recent Windows update which causes CLR4 programs to check for certificate revocation whenever asked for the "evidence" in the call chain (which is the only way for us currently to find/check the strong name) – it seems that this did NOT happen until recently as we only had 3 reports so far, otherwise we would have noticed it a lot sooner. There IS a workaround which involves using a specific call to ONLY retrieve strong names (rather than other "evidence" such as authenticode signatures), but the downside is that this call is ONLY available to CLR 4 code (and of course at the moment, DicomObjects is still CLR 2 for maximum compatibility – which has never caused any such issues before!).


Short-term Solutions:

Turn off CRL checking via Internet Options (If you are using our CD Version):

  • Internet Options -> Advanced -> security, uncheck the Check for publisher's certificate revocation option, or
  • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\WinTrust\Trust Providers\Software Publishing. Change Value State to 146944 Decimal or 0x00023e00 Hexadecimal

DicomGlobal property (if you are using Non-CD versions)

  • Set DicomGlobal.CheckCDLicenses to 0


Long-term Solution:

We have started the process of moving to CLR 4 and we will have the update on our main page when it's complete.



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