I have an application that I originally built when I was young and foolish and its authentication is set up using the SimpleMembership framework, with all user data contained in a webpages_Membership table. I am very interested in rebuilding my backend as an AspNetCore Web API with AspNetCore Identity via SQL Server, without losing user information.
I've had good luck with coming up with SQL scripts to move everything into an AspNetUsers table in preparation for working with Identity instead of SimpleMembership, but where I'm running into an issue is password hashing. I gather from articles like this and this that my best bet is to override PasswordHasher<IdentityUser> to duplicate the SimpleMembership crypto flow, and then rehash passwords as they come in to gradually migrate the database.
The trouble is I can't find out how to achieve this flow duplication in .NET Core. The latter article linked above states that the SimpleMembership flow is achieved via the System.Web.Helpers.Crypto package, which does not appear to exist in the .NET Core library, and I can't figure out if its implementation is documented anywhere. (Its MSDN documentation says that it is using RFC2898 hashing but I don't know enough about crypto to know if that's enough to go on by itself. This isn't my area of expertise. :( )
Any insight on how to approach this would be much appreciated. Thank you!