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I have a some C code which does some security checks. From a C# .NET application I can access this through a DLL by using a DLLimport. However this is insecure because anyone could replace the DLL with one which always returns true to all my security checks.
Is there anyway I could statically link to the C library form .NET.
Or is there a good way to ensure the C DLL (not a .NET assembly) has not been tampered with?
My recommnedation, get a simple commandline MD5 utility and call it from your C# program to verify the MD5 hash of your DLL before you load it. I believe md5checksum is a command line app, but not positive.
Erm....
.net has built in crypto libraries for doing an assortment of things including hashing and public key crypto. There are some good books out there on it such as - http://www.amazon.com/exec/obidos/tg...books&n=507846
as far as linking C libraries into the c# code you need to look into .net interop services and pinvoke. You'd probably need to write your own verification methods for what you want....
If it was me I'd probably re-write the .dll using C#.