Storing Sha256 Hashed Passwords with Nhibernate

I have a simple web app that has a login page, the front end domain has a simple model with:

string username {get;set;}
string password {get;set;}

However it is encrypted with sha256 before it is sent over to the data domain object, originally the data domain w开发者_StackOverflow社区as:

string username {get;set;}
string password {get;set;}

So I would take the password from the ui, encrypt it then using the Encoding.GetString() method, get back a string for persisting. However when I try to persist the data it just seems to give an exception, which I believe to be down to the characters in the string not being valid.

After looking around some people have recommended storing it as a varbinary(32) and using a byte[] password {get;set;} within the data layer, however I couldn't get Nhibernate to map it correctly.

So can anyone tell me the best practise on storing hashed passwords with Nhibernate and SqlServer or MySql. (The app supports both dbs)

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You shouldn't use Encoding.GetString() on a SHA value since it will produce text that may not store correctly, or worse, give an exception. Rather use something like Convert.ToBase64String.