The CTL_CONTEXT must be freed by calling CertFreeCTLContext. CertDuplicateCTLContext can be called to make a duplicate. CertSetCTLContextProperty and CertGetCTLContextProperty can be called to store and read properties for the CTL.

            CertFreeCTLContext(ctlContextPtr);

    public static extern IntPtr CertFreeCTLContext(IntPtr pCtlContext);

Declare Function CertFreeCTLContext Lib "crypt32.dll" (TODO) As TODO