Creating a basic MD5 Dictionary

Question

I am trying to make a dictionary from 1 digit to 3 digits long containing a,b,c,d,...7,8,9 ; aa,bb,cc,dd,...,77,88,99 & aaa,bbb,...888,999 MD5 Hashed functions and store it in the SQL. I tried using 3 for nested loops to fill my sql columns -palintext and MD5 hashes columns- I am quite new to C# and this is what i tested ;i have serious problems with this code. How should the correct form look like and how can i edit it?

I tried:

private void button1_Click(object sender, EventArgs e)
{

  var list = "abcdefghijklmnopqrstuvwxyz0123456789".ToString();

  for ( int i = 0 ; i < list.Length ; i++ )
  {

    com.Connection = con;
    com.CommandText = "insert into CryptographyTable(PlainText,MD5Hash) values(@PlainText,@MD5Hash)";
    com.Parameters.AddWithValue("@PlainText", List);
    com.Parameters.AddWithValue("@MD5Hash", md[List]);
    MessageBox.Show(com.ExecuteNonQuery().ToString());

    for (int j = 0; j < list.Length; j++)
    {

      com.Connection = con;
      com.CommandText = "insert into CryptographyTable(PlainText,MD5Hash) values(@PlainText,@MD5Hash)";
      com.Parameters.AddWithValue("@PlainText", List);
      com.Parameters.AddWithValue("@MD5Hash", md[List]);
      MessageBox.Show(com.ExecuteNonQuery().ToString());

      for (int k = 0; k < list.Length; k++)
      {
        com.Connection = con;
        com.CommandText = "insert into CryptographyTable(PlainText,MD5Hash) values(@PlainText,@MD5Hash)";
        com.Parameters.AddWithValue("@PlainText", List);
        com.Parameters.AddWithValue("@MD5Hash", md[List]);
        MessageBox.Show(com.ExecuteNonQuery().ToString());
      }
    }
  }
}

public string md(string input)
{
  MD5 md5 = MD5.Create();
  byte[] inputBytes = Encoding.UTF8.GetBytes(input);
  byte[] hash = md5.ComputeHash(inputBytes);  

  string sb;
  sb = "";

  for (int i = 0; i < hash.Length; i++)
  {
    sb  += hash[i].ToString("X2");
  }
  return sb;
}
}
}

Answer 1

this code wouldn't even compile.

What is (var[]List)? Did you mean list?

This statement: var[] list = "abcdefghijklmnopqrstuvwxyz0123456789".ToString(); should be var list = "abcdefghijklmnopqrstuvwxyz0123456789".ToString();

This statement com.CommandText = "insert into CryptographyTable(PlainText,MD5Hash) has no closing double quote or semicolon.

Answer 2

Building a rainbow table, are you?

You need to learn about the concept of problem decomposition. Breaking problems up into smaller, simpler pieces makes things much simpler.

First, you'll need a method to insert data into your rainbow table:

static void InsertIntoDb( string key , string value )
{
  string connectString = "your-connect-string-here" ;
  Func<string,string> qt = s => s.Replace("'" , "''") ;
  using( SqlConnection sql = new SqlConnection(connectString) )
  using ( SqlCommand    cmd = sql.CreateCommand() )
  {
    cmd.CommandText = string.Format( @"insert dbo.RainbowTable( md5 , text ) values ( '{0}' , '{1}' )" , qt(key) , qt(value) ) ;
    cmd.CommandType = CommandType.Text;
    sql.Open();
    cmd.ExecuteNonQuery() ;
    sql.Close() ;
  }
  return ;
}

Then you need a method to compute the MD5 hash for a piece of text and return a string containing its hex representation:

static string ComputeMd5Hash( string s , Encoding e )
{
  MD5 md5       = MD5.Create() ;
  byte[] octets = e.GetBytes(s) ;
  byte[] hash   = md5.ComputeHash(octets) ;
  string hex    = "0x" + hash.Aggregate( new StringBuilder("0x") , (sb,x) => sb.Append(x) ).ToString() ;
  return hex ;
}

Finally, you'll need a method to generate the strings you need (**hint: the concept of recursion might be useful here.)

static IEnumerable<string> GetStringsToBeHashed()
{
  // your string generation code here
}

Each of these pieces does just one thing and is easy to build and easy to test.

Once you've got all the pieces in place, then its easy to put it all together:

foreach ( string s in GetStringsToBeHashed() )
{
  string hash = ComputeMd5Hash(s,Encoding.UTF8) ;
  InsertIntoDb( hash, s ) ;
}