using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
 
namespace Amadiere.Com.Utilities
{
    public static class Cryptography
    {
        /// <summary>
        /// Encrypts a password based on the passed in Encryption method (SHA512Managed is a good starting
        /// point if you don't know which to use).
        /// </summary>
        /// <remarks>
        /// The passwordSalt parameter is required to ensure that rainbow tables cannot be used to
        /// lookup all usernames if the salt is discovered. This salt is OK to store in the database,
        /// along with the hashedPassword generated by this function.
        /// </remarks>
        /// <param name="password">The password to be encrypted.</param>
        /// <param name="passwordSalt">The individual grain of salt for that password.</param>
        /// <param name="method">The method by which to encrypt.</param>
        /// <returns>An string representing the hashed password (88 characters long).</returns>
        public static string Hash(string password, string passwordSalt, HashMethods method)
        {
            string siteWideSalt = "THIS IS A SITE WIDE SALT, BUT COULD BE A GUID";
            string encryptedPassword;
            switch (method)
            {
                default:
                    encryptedPassword = HashSHA512Managed(siteWideSalt + password + passwordSalt);
                    break;
            }
            return encryptedPassword;
        }
 
        /// <summary>
        /// One-way encrypts the password into oblivion. If the same password and salt are provided, the
        /// same end string will be churned out the other end of this sausage machine.
        /// </summary>
        /// <see cref="http://msdn.microsoft.com/en-us/library/system.security.cryptography.sha512managed.aspx"/>
        /// <example>HashSHA512Managed("bobsYourUncle_SALT-GOES-HERE");</example>
        /// <param name="password">Unencoded pre-salted password.</param>
        /// <returns>An 88 character string, representing the originally encoded password.</returns>
        private static string HashSHA512Managed(string saltedPassword)
        {
            UnicodeEncoding uniEncode = new UnicodeEncoding();
            SHA512Managed sha = new SHA512Managed();
            byte[] bytePassword = uniEncode.GetBytes(saltedPassword);
            byte[] hash = sha.ComputeHash(bytePassword);
            return Convert.ToBase64String(hash);
        }
    }
 
    public enum HashMethods
    {
        SHA512
    }
}

Function Hash(strPassword, strIndividualSalt)
 
  Const strSiteWideSalt = "THIS IS A SITE WIDE SALT, BUT COULD BE A GUID"
  Hash = HashSHA512Managed(strSiteWideSalt & strPassword & strIndividualSalt)
 
End Function
 
Function HashSHA512Managed(saltedPassword)
 
  Dim objMD5, objUTF8
  Dim arrByte
  Dim strHash
  Set objUnicode = CreateObject("System.Text.UnicodeEncoding")
  Set objSHA512 = Server.CreateObject("System.Security.Cryptography.SHA512Managed")
 
  arrByte = objUnicode.GetBytes_4(saltedPassword)
  strHash = objSHA512.ComputeHash_2((arrByte))
 
  HashSHA512Managed = ToBase64String(strHash)
 
End Function
 
Function ToBase64String(rabyt)
 
  'Ref: http://stackoverflow.com/questions/1118947/converting-binary-file-to-base64-string
  Dim xml: Set xml = CreateObject("MSXML2.DOMDocument.3.0")
  xml.LoadXml ""
  xml.documentElement.dataType = "bin.base64"
  xml.documentElement.nodeTypedValue = rabyt
  ToBase64String = Replace(xml.documentElement.Text,VbLf, "")
 
End Function