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Certificates and resource management

Last month I had two posts where I tacked a little about certificates in .NET (12).
In this post I want to discuss about resource management when X5099Certificate2 is used. This is applicable for X509Certificate also.
When we use a .NET object we usually check if IDisposable interface is implemented. If yes, than we will call ‘Dispose’ method. But unfortunately X509Certificate don’t implement this interface.
Behind this class there is a handle (SafeCertContextHandle) to unmanaged resources. Because of this, each new instance of the certificate will have a handle to unmanaged resources. If you need to process 2.000 certificates from the store it will be very easy for you to get a wonderful “OutOfMemoryException”.
To be able to release all the resources that are used by a reference to a certificate you will need to call the ‘Reset’ method. This method will release all the resources that are associated with the specific certificate.
X509Certificate2 cert = …
X509Store has the same story and you will need to call ‘Close’ method.
X509Store store = …
The ‘Close’ method is pretty simple to be seen when you look over the methods that are available. The name gives you an hint that there are some resources that needs to be released, but the ‘Reset’ method name don’t help you too much with this. Because of this it is very simple to end up with an “OutOfMemoryException”.
I don’t understand why X509Certificate2 doesn’t implement IDisposable interface. The resource-free idiom should be apply also in this case also.


  1. Somebody at MS seems to be to busy to implement this:

    1. The status is 'CLOSED - Won't fixed'. The ticket was open in 2009.


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