Following up to my earlier post about improving the security of the ASP.NET SqlMembershipProvider, and to Troy Hunt's excellently thorough article Our Password Hashing Has No Clothes and further discussions with @thorsheim, @blowdart, and @klingsen (all of whom I recommend following), I took a second look at how to use the algorithms in the Zetetic.Security package without mucking about with machine.config and the .NET Global Assembly Cache, which really complicate the deployment picture.
The bad news is that the .NET base class libraries only read "name-to-algorithm" mappings from machine.config. I was pretty surprised to see this, but it's plain as day in System.Security.Cryptography.CryptoConfig.OpenCryptoConfig().
The good news is that adding to the HashAlgorithms an application can use is super, super easy. Start by grabbing the Zetetic.Security package from NuGet; next, one line of code will do the trick (in Global.asax's Application_Start, for example):
Adjust the membership settings in Web.config as per usual:
<membership hashAlgorithmType="pbkdf2_local"><!-- other stuff --><membership>
Voila, your ASP.NET application is now using a much, much stronger password hash algorithm than the (really rather embarrassing) defaults of SHA1 and SHA256.
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