Hi,

It was a long time ago and i believe the project got abandoned before going live. But i did implement it not sure how well but here goes.

heres an articale i used on help extending Membership provider https://24days.in/umbraco-cms/2015/extending-membership/

I created a history new table to store hashed passwords against a username. which i populated on password change, after a member has a pssword set you can access the Rawvalue using this _memberService.GetByUsername(user.UserName).RawPasswordValue

then simply on each password request change fed in the new password (unhashed) and ran it against the above method looping through the hashed pwhistory table values.

Change password controller

 public ActionResult ChangePassword([Bind(Prefix = "viewModel")]ChangePasswordViewModel model)
        {
        var _memberService = Services.MemberService;
        var user = Membership.GetUser();
        var pwHistory = user.UserName.GetHistory();

        if (Membership.ValidateUser(Membership.GetUser().UserName, model.OldPassword))
        {

            var provider = Membership.Provider.AsUmbracoMembershipProvider() as CustomMembershipProvider;
            foreach (var pw in pwHistory)
            {
                if (provider.CheckPasswordHistory(model.NewPassword, pw))
                {
                    return CurrentUmbracoPage();
                }
            }

            var attempt = Members.ChangePassword(Membership.GetUser().UserName, new Umbraco.Web.Models.ChangingPasswordModel()
            {
                NewPassword = model.NewPassword,
                OldPassword = model.OldPassword
            }, Membership.Provider);
            if (attempt.Success)
            {
                var newPasswordhash = _memberService.GetByUsername(user.UserName).RawPasswordValue;
                user.UserName.AddPassword(newPasswordhash);

                TempData["ResetSuccess"] = true;
                return CurrentUmbracoPage();
            }
        }

        return CurrentUmbracoPage();
    }

Custom MembershipProvider

 public class CustomMembershipProvider : MembersMembershipProvider
 {
    string twilioSid = ConfigurationManager.AppSettings["twilioSid"];
    string tiwlioAuthToken = ConfigurationManager.AppSettings["twilioAuthToken"];

    public bool CheckPasswordHistory(string password,string rawPasword)
    {
        return CheckPassword(password,rawPasword);
    }
 }

this is what i was looking for

CheckPassword(password,rawPasword)

only exposed in a custom implementation of MembersMembershipProvider as far as i remember