In my previous post, I demonstrated how to migrate from ASP.NET Universal Membership Provider to ASP.NET Identity 2.1.0.

http://kosmisch.net/Blog/DotNetEssential/Archive/2015/1/31/migrate-from-systemwebproviders-to-aspnet-identity-10-and-then-to-210.html

Based on the researches, I have consolidated one ApplicationUserManager class to help you handle the password rehash. It also added two properties for keeping legacy password format.

Code for ApplicationUserManager class

using Microsoft.AspNet.Identity;
using Microsoft.AspNet.Identity.EntityFramework;
using System;
using System.Reflection;
using System.Security.Cryptography;
using System.Text;
using System.Threading.Tasks;

namespace KosmischStudio.Website.Models
{
    public class ApplicationUserManager : UserManager<ApplicationUser>
    {
        public ApplicationUserManager()
            : base(new UserStore<ApplicationUser>(new ApplicationDbContext()))
        {
            this.PasswordHasher = new SqlPasswordHasher()
            {
                KeepLegacyHashFormat = false,
                PasswordFormat = 1
            };
        }

        protected async override Task<bool> VerifyPasswordAsync(IUserPasswordStore<ApplicationUser, string> store, ApplicationUser user, string password)
        {
            var hash = await store.GetPasswordHashAsync(user).ConfigureAwait(false);

            if (this.PasswordHasher.VerifyHashedPassword(hash, password) == PasswordVerificationResult.SuccessRehashNeeded)
            {
                // Make our new hash
                hash = PasswordHasher.HashPassword(password);

                // Save it to the DB
                await store.SetPasswordHashAsync(user, hash).ConfigureAwait(false);

                // Invoke internal method to upgrade the security stamp
                BindingFlags bindingFlags = BindingFlags.Instance | BindingFlags.NonPublic;
                MethodInfo minfo = typeof(UserManager<ApplicationUser>).GetMethod("UpdateSecurityStampInternal", bindingFlags);
                var updateSecurityStampInternalTask = (Task)minfo.Invoke(this, new[] { user });
                await updateSecurityStampInternalTask.ConfigureAwait(false);

                // Update user
                await UpdateAsync(user).ConfigureAwait(false);
            }

            return PasswordHasher.VerifyHashedPassword(hash, password) != PasswordVerificationResult.Failed;
        }
    }

    public class SqlPasswordHasher : PasswordHasher
    {
        /// <summary>
        /// Whether to keep the legacy hash format: {$HashedPassword}|{$Format}|{$Salt}
        /// </summary>
        /// <returns></returns>
        public bool KeepLegacyHashFormat { get; set; }

        /// <summary>
        /// Format of the password: 1 : Hashed, 0 Clear, 2 Encrypt
        /// </summary>
        /// <returns></returns>
        public int PasswordFormat { get; set; }

        public override string HashPassword(string password)
        {

            if (KeepLegacyHashFormat)
            {
                StringBuilder passwordNew = new StringBuilder();
                string salt = GenerateSalt();
                string hashedPassword = EncryptPassword(password, PasswordFormat, salt);
                StringBuilder newPassword = new StringBuilder();
                newPassword.AppendFormat("{0}|{1}|{2}", hashedPassword, PasswordFormat, salt);
                return newPassword.ToString();
            }
            else
                return base.HashPassword(password);
        }

        private static string GenerateSalt()
        {
            string base64String;
            using (RNGCryptoServiceProvider rNGCryptoServiceProvider = new RNGCryptoServiceProvider())
            {
                byte[] numArray = new byte[16];
                rNGCryptoServiceProvider.GetBytes(numArray);
                base64String = Convert.ToBase64String(numArray);
            }
            return base64String;
        }

        public override PasswordVerificationResult VerifyHashedPassword(string hashedPassword, string providedPassword)
        {
            string[] passwordProperties = hashedPassword.Split('|');
            if (passwordProperties.Length != 3)
            {
                return base.VerifyHashedPassword(hashedPassword, providedPassword);
            }
            else
            {
                string passwordHash = passwordProperties[0];
                int passwordformat = 1;
                string salt = passwordProperties[2];
                if (String.Equals(EncryptPassword(providedPassword, passwordformat, salt), passwordHash, StringComparison.CurrentCultureIgnoreCase))
                {
                    if (!this.KeepLegacyHashFormat)
                        return PasswordVerificationResult.SuccessRehashNeeded;
                    else
                        return PasswordVerificationResult.Success;
                }
                else
                {
                    return PasswordVerificationResult.Failed;
                }
            }
        }



        //This is copied from the existing SQL providers and is provided only for back-compat.
        private string EncryptPassword(string pass, int passwordFormat, string salt)
        {
            if (passwordFormat == 0) // MembershipPasswordFormat.Clear
                return pass;

            byte[] bIn = Encoding.Unicode.GetBytes(pass);
            byte[] bSalt = Convert.FromBase64String(salt);
            byte[] bRet = null;

            if (passwordFormat == 1)
            { // MembershipPasswordFormat.Hashed 
                HashAlgorithm hm = HashAlgorithm.Create("SHA1");
                if (hm is KeyedHashAlgorithm)
                {
                    KeyedHashAlgorithm kha = (KeyedHashAlgorithm)hm;
                    if (kha.Key.Length == bSalt.Length)
                    {
                        kha.Key = bSalt;
                    }
                    else if (kha.Key.Length < bSalt.Length)
                    {
                        byte[] bKey = new byte[kha.Key.Length];
                        Buffer.BlockCopy(bSalt, 0, bKey, 0, bKey.Length);
                        kha.Key = bKey;
                    }
                    else
                    {
                        byte[] bKey = new byte[kha.Key.Length];
                        for (int iter = 0; iter < bKey.Length;)
                        {
                            int len = Math.Min(bSalt.Length, bKey.Length - iter);
                            Buffer.BlockCopy(bSalt, 0, bKey, iter, len);
                            iter += len;
                        }
                        kha.Key = bKey;
                    }
                    bRet = kha.ComputeHash(bIn);
                }
                else
                {
                    byte[] bAll = new byte[bSalt.Length + bIn.Length];
                    Buffer.BlockCopy(bSalt, 0, bAll, 0, bSalt.Length);
                    Buffer.BlockCopy(bIn, 0, bAll, bSalt.Length, bIn.Length);
                    bRet = hm.ComputeHash(bAll);
                }
            }

            return Convert.ToBase64String(bRet);
        }
    }
}
 

Issues – PasswordHarsher doesn’t work well for legacy password.

I have been spending almost one day to investigate why I could not get the same hashed password by using same clear password, salt and encryption algorithm.

Until, I have not found any issues with the code provided. A new post will be published to address this issue. Stay tuned.

About author
Disclaimer
The opinions and comments expressed herein are my own personal opinions and do not represent my employer's view in any way.
Comments

Re:Migrate from Universal Membership Provider to ASP.NET Identity 2.1.0 - PasswordHarsher

This issue has now been resolved, please refer to the following post: http://kosmisch.net/Blog/DotNetEssential/Archive/2015/2/1/aspnet-membership-default-password-hash-algorithms-in-net-4x-and-previous-versions.html Root cause: I was migrating from .NET 4.0 and the default hash algorithm is HMAC256 instead of SHA1.

Author: Raymond @ 2/1/2015 4:24:54 AM | [Reply]

Re:Migrate from Universal Membership Provider to ASP.NET Identity 2.1.0 - PasswordHarsher

HashPassword method can be constomed based on your previous settings.

Author: R @ 2/27/2015 5:21:12 PM | [Reply]

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