context: // Copyright (c) 2004-2008 MySQL AB, 2008-2009 Sun Microsystems, Inc.
  //
  // MySQL Connector/NET is licensed under the terms of the GPLv2
  // <http://www.gnu.org/licenses/old-licenses/gpl-2.0.html>, like most 
  // MySQL Connectors. There are special exceptions to the terms and 
  // conditions of the GPLv2 as it is applied to this software, see the 
  // FLOSS License Exception
  // <http://www.mysql.com/about/legal/licensing/foss-exception.html>.
  //
  // This program is free software; you can redistribute it and/or modify 
  // it under the terms of the GNU General Public License as published 
  // by the Free Software Foundation; version 2 of the License.
  //
  // This program is distributed in the hope that it will be useful, but 
  // WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
  // or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
  // for more details.
  //
  // You should have received a copy of the GNU General Public License along 
  // with this program; if not, write to the Free Software Foundation, Inc., 
  // 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA
  
  using System;
  using System.Globalization;
  using System.Text;
  using MySql.Data.Common;
  using MySql.Data.MySqlClient.Properties;
  //using System.Security.Cryptography;
  //#if CF
  //using OpenNETCF.Security.Cryptography;
  //#endif
  
  namespace MySql.Data.MySqlClient
  {
      /// <summary>
      /// Summary description for Crypt.
      /// </summary>
      internal class Crypt
      {
          // private ctor to prevent creating a default one
          private Crypt()
          {
          }
  
  /*		private void Create41Password( string password )
  		{
  			SHA1 sha = new SHA1CryptoServiceProvider(); 
  			byte[] firstPassBytes = sha.ComputeHash( System.Text.Encoding.Default.GetBytes( password ));
  
  			byte[] salt = packet.GetBuffer();
  			byte[] input = new byte[ firstPassBytes.Length + 4 ];
  			salt.CopyTo( input, 0 );
  			firstPassBytes.CopyTo( input, 4 );
  			byte[] outPass = new byte[100];
  			byte[] secondPassBytes = sha.ComputeHash( input );
  
  			byte[] cryptSalt = new byte[20];
  			Security.ArrayCrypt( salt, 4, cryptSalt, 0, secondPassBytes, 20 );
  
  			Security.ArrayCrypt( cryptSalt, 0, firstPassBytes, 0, firstPassBytes, 20 );
  
  			// send the packet
  			packet = CreatePacket(null);
  			packet.Write( firstPassBytes, 0, 20 );
  			SendPacket(packet);
  		}
  */
  
          /// <summary>
          /// Simple XOR scramble
          /// </summary>
          /// <param name="from">Source array</param>
          /// <param name="fromIndex">Index inside source array</param>
          /// <param name="to">Destination array</param>
          /// <param name="toIndex">Index inside destination array</param>
          /// <param name="password">Password used to xor the bits</param>
          /// <param name="length">Number of bytes to scramble</param>
          private static void XorScramble(byte[] from, int fromIndex, byte[] to, int toIndex,
                                          byte[] password, int length)
          {
              // make sure we were called properly
              if (fromIndex < 0 || fromIndex >= from.Length)
                  throw new ArgumentException(Resources.IndexMustBeValid, "fromIndex");
              if ((fromIndex + length) > from.Length)
                  throw new ArgumentException(Resources.FromAndLengthTooBig, "fromIndex");
              if (from == null)
                  throw new ArgumentException(Resources.BufferCannotBeNull, "from");
              if (to == null)
                  throw new ArgumentException(Resources.BufferCannotBeNull, "to");
              if (toIndex < 0 || toIndex >= to.Length)
                  throw new ArgumentException(Resources.IndexMustBeValid, "toIndex");
              if ((toIndex + length) > to.Length)
                  throw new ArgumentException(Resources.IndexAndLengthTooBig, "toIndex");
              if (password == null || password.Length < length)
                  throw new ArgumentException(Resources.PasswordMustHaveLegalChars, "password");
              if (length < 0)
                  throw new ArgumentException(Resources.ParameterCannotBeNegative, "count");
  
              // now perform the work
              for (int i = 0; i < length; i++)
                  to[toIndex++] = (byte) (from[fromIndex++] ^ password[i]);
          }
  
          /// <summary>
          /// Generate a scrambled password for 4.1.0 using new passwords
          /// </summary>
          /// <param name="password">The password to scramble</param>
          /// <param name="seedBytes">The seedbytes used to scramble</param>
          /// <returns>Array of bytes containing the scrambled password</returns>
          public static byte[] Get410Password(string password, byte[] seedBytes)
          {
              SHA1Hash sha = new SHA1Hash();
              //SHA1 sha = new SHA1CryptoServiceProvider(); 
  
              // clean it and then digest it
              password = password.Replace(" ", "").Replace("\t", "");
              byte[] passBytes = Encoding.Default.GetBytes(password);
              byte[] firstPass = sha.ComputeHash(passBytes);
  
              byte[] input = new byte[24];
              Array.Copy(seedBytes, 0, input, 0, 4);
              Array.Copy(firstPass, 0, input, 4, 20);
              byte[] secondPass = sha.ComputeHash(input);
  
              byte[] scrambledBuff = new byte[20];
              XorScramble(seedBytes, 4, scrambledBuff, 0, secondPass, 20);
  
              byte[] finalBuff = new byte[20];
              XorScramble(scrambledBuff, 0, finalBuff, 0, firstPass, 20);
  
              return finalBuff;
          }
  
          /// <summary>
          /// Generates a proper hash for old style 4.1.0 passwords.  This would be used
          /// if a 4.1.0 server contained old 16 byte hashes.
          /// </summary>
          /// <param name="password">The password to hash</param>
          /// <param name="seedBytes">Seed bytes received from the server</param>
          /// <returns>Byte array containing the password hash</returns>
          public static byte[] GetOld410Password(string password, byte[] seedBytes)
          {
              long[] passwordHash = Hash(password);
              string passHex = String.Format(CultureInfo.InvariantCulture,
                                             "{0,8:X}{1,8:X}", passwordHash[0], passwordHash[1]);
  
              int[] salt = getSaltFromPassword(passHex);
  
              // compute binary password
              byte[] binaryPassword = new byte[20];
              int offset = 0;
              for (int i = 0; i < 2; i++)
              {
                  int val = salt[i];
  
                  for (int t = 3; t >= 0; t--)
                  {
                      binaryPassword[t + offset] = (byte) (val%256);
                      val >>= 8; /* Scroll 8 bits to get next part*/
                  }
  
                  offset += 4;
              }
  
              //SHA1 sha = new SHA1CryptoServiceProvider(); 
              SHA1Hash sha = new SHA1Hash();
              byte[] temp = new byte[8];
              Buffer.BlockCopy(binaryPassword, 0, temp, 0, 8);
              byte[] binaryHash = sha.ComputeHash(temp);
  
              byte[] scrambledBuff = new byte[20];
              XorScramble(seedBytes, 4, scrambledBuff, 0, binaryHash, 20);
  
              string scrambleString = Encoding.Default.GetString(scrambledBuff, 0, scrambledBuff.Length).Substring(0, 8);
  
              long[] hashPass = Hash(password);
              long[] hashMessage = Hash(scrambleString);
  
              long max = 0x3FFFFFFFL;
              byte[] to = new byte[20];
              int msgPos = 0;
              int msgLength = scrambleString.Length;
              int toPos = 0;
              long seed1 = (hashPass[0] ^ hashMessage[0])%max;
              long seed2 = (hashPass[1] ^ hashMessage[1])%max;
  
              while (msgPos++ < msgLength)
                  to[toPos++] = (byte) (Math.Floor(rand(ref seed1, ref seed2, max)*31) + 64);
  
              /* Make it harder to break */
              byte extra = (byte) (Math.Floor(rand(ref seed1, ref seed2, max)*31));
  
              for (int i = 0; i < 8; i++)
                  to[i] ^= extra;
  
              return to;
          }
  
          /// <summary>
          /// Returns a byte array containing the proper encryption of the 
          /// given password/seed according to the new 4.1.1 authentication scheme.
          /// </summary>
          /// <param name="password"></param>
          /// <param name="seed"></param>
          /// <returns></returns>
          public static byte[] Get411Password(string password, string seed)
          {
              // if we have no password, then we just return 1 zero byte
              if (password.Length == 0) return new byte[1];
  
              //SHA1 sha = new SHA1CryptoServiceProvider(); 
              SHA1Hash sha = new SHA1Hash();
  
              byte[] firstHash = sha.ComputeHash(Encoding.Default.GetBytes(password));
              byte[] secondHash = sha.ComputeHash(firstHash);
              byte[] seedBytes = Encoding.Default.GetBytes(seed);
  
              byte[] input = new byte[seedBytes.Length + secondHash.Length];
              Array.Copy(seedBytes, 0, input, 0, seedBytes.Length);
              Array.Copy(secondHash, 0, input, seedBytes.Length, secondHash.Length);
              byte[] thirdHash = sha.ComputeHash(input);
  
              byte[] finalHash = new byte[thirdHash.Length + 1];
              finalHash[0] = 0x14;
              Array.Copy(thirdHash, 0, finalHash, 1, thirdHash.Length);
  
              for (int i = 1; i < finalHash.Length; i++)
                  finalHash[i] = (byte) (finalHash[i] ^ firstHash[i - 1]);
              return finalHash;
          }
  
          private static int[] getSaltFromPassword(String password)
          {
              int[] result = new int[6];
  
              if (password == null || password.Length == 0)
                  return result;
  
              int resultPos = 0;
              int pos = 0;
  
              while (pos < password.Length)
              {
                  int val = 0;
  
                  for (int i = 0; i < 8; i++)
                      val = (val << 4) + HexValue(password[pos++]);
  
                  result[resultPos++] = val;
              }
  
              return result;
          }
  
          private static int HexValue(char c)
          {
              if (c >= 'A' && c <= 'Z') return (c - 'A') + 10;
              if (c >= 'a' && c <= 'z') return (c - 'a') + 10;
              return c - '0';
          }
  
  
          private static double rand(ref long seed1, ref long seed2, long max)
          {
              seed1 = (seed1*3) + seed2;
              seed1 %= max;
              seed2 = (seed1 + seed2 + 33)%max;
              return (seed1/(double) max);
          }
  
          /// <summary>
          /// Encrypts a password using the MySql encryption scheme
          /// </summary>
          /// <param name="password">The password to encrypt</param>
          /// <param name="seed">The encryption seed the server gave us</param>
          /// <param name="new_ver">Indicates if we should use the old or new encryption scheme</param>
          /// <returns></returns>
          public static String EncryptPassword(String password, String seed, bool new_ver)
          {
              long max = 0x3fffffff;
              if (! new_ver)
                  max = 0x01FFFFFF;
              if (password == null || password.Length == 0)
                  return password;
  
              long[] hash_seed = Hash(seed);
              long[] hash_pass = Hash(password);
  
              long seed1 = (hash_seed[0] ^ hash_pass[0])%max;
              long seed2 = (hash_seed[1] ^ hash_pass[1])%max;
              if (! new_ver)
                  seed2 = seed1/2;
  
              char[] scrambled = new char[seed.Length];
              for (int x = 0; x < seed.Length; x++)
              {
  
gt:                 double r = rand(ref seed1, ref seed2, max);