Is it possible to create a Logon System with ASP.NET MVC but not use the MembershipProvider?

I had this exact same requirement. I had my own user and role schema and did not want to migrate to the asp.net membership schema but I did want to use the ASP.NET MVC action filters for checking authorization and roles. I had to do a fair amount of digging to find out exactly what needed to be done, but in the end it was relatively easy. I’ll save you the trouble and tell you what I did.

1) I created a class that derived from System.Web.Security.MembershipProvider. MembershipProvider has a ton of abstract methods for all sorts of authentication-related functions like forgot password, change password, create new user, etc. All I wanted was the ability to authenticate against my own schema. So my class contained mainly empty overrides. I just overrode ValidateUser:

public override bool ValidateUser(string username, string password)
{
    if (string.IsNullOrWhiteSpace(username) ||
        string.IsNullOrWhiteSpace(password))
      return false;

    string hash = EncryptPassword(password);
    User user = _repository.GetByUserName(username);
    if (user == null) return false;

    return user.Password == hash;
}

2) I created a class that derived from System.Web.Security.RoleProvider. Again, I just had empty implementations for all the fluff I did not need like creating and changing roles. I just overrode two methods:

public override string[] GetRolesForUser(string username)
{
    User user = _repository.GetByUserName(username);
    string[] roles = new string[user.Role.Rights.Count + 1];
    roles[0] = user.Role.Description;
    int idx = 0;
    foreach (Right right in user.Role.Rights)
        roles[++idx] = right.Description;
    return roles;
}

public override bool IsUserInRole(string username, string roleName)
{
    User user = _repository.GetByUserName(username);
    if(user!=null)
        return user.IsInRole(roleName);
    else
        return false;
}

3) Then I plugged these two classes into my web.config:

<membership defaultProvider="FirstlookMemberProvider" userIsOnlineTimeWindow="15">
  <providers>
    <clear/>
    <add name="FirstlookMemberProvider" type="FirstlookAdmin.DomainEntities.FirstlookMemberProvider, FirstlookAdmin" />
  </providers>
</membership>
<roleManager defaultProvider="FirstlookRoleProvider" enabled="true" cacheRolesInCookie="true">
  <providers>
    <clear/>
    <add name="FirstlookRoleProvider" type="FirstlookAdmin.DomainEntities.FirstlookRoleProvider, FirstlookAdmin" />
  </providers>
</roleManager>

That’s it. The default authorization action filters will use these classes. You will still have to handle the login page sign in and sign off. Just use the standard forms authentication classes for this like you normally would.