Tuesday, December 10, 2013

C# Encryption Decryption Class AES

Sometimes you may need to use encryption and decryption class in your C# project. Here is a simple class you can use for above purpose feel free to use it and feedback with improvement. This class use Advance Encryption Standers. and RijndaelManaged method.





/*******************************************************************
File:         Crypter.cs
Author:       Nayana Adassuriya
Description:  Uses to encrypt or decrypt any string by symettric way (AES,RijndaelManaged) 
Language:     C#
Limitations:  Encription key genaration hashes are hardcoded in the class. 
              If some one knows these hashes, they can crate programe to decript the encripted strings. 
Thread Safe:  no  
Extendable:   yes 
Platform Depend:   Windows,.NET 3.5
Project:           None
*******************************************************************/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.IO;

namespace StorageService
{
  internal class Crypter
  {
    //Data members
    private static byte[] m_salt = Encoding.ASCII.GetBytes("41fb5b5ae4d57c5ee528adb00e5e8e74");
    private static string m_encrypt_key = "200911381f7899d2482ab61fe8d15684469b17fc690";


    /************************************************************************
    Purpose :         This is the method uses to encrypt plan strings.
    Parameters :      plan_test: text that need to be encrypted
    Returns :         encrypted string
    Exception :       If any exception while getting values from xml, pass to the upper level
    Algorithm :       C# manage code
    Output :          None
    Notes :           User can encrypt multiple times recursively if more security needs. If that
                      need to decrypt same number of rounds accordingly
    *************************************************************************/
    internal static string aesEncrypt(string plan_test)
    {
      string output = null;
      RijndaelManaged aes_alg = null;
      try
      {
        Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(m_encrypt_key, m_salt);
        aes_alg = new RijndaelManaged();
        aes_alg.Key = key.GetBytes(aes_alg.KeySize / 8);
        ICryptoTransform encryptor = aes_alg.CreateEncryptor(aes_alg.Key, aes_alg.IV);

        using (MemoryStream encrypt_ms = new MemoryStream())
        {
          encrypt_ms.Write(BitConverter.GetBytes(aes_alg.IV.Length), 0, sizeof(int));
          encrypt_ms.Write(aes_alg.IV, 0, aes_alg.IV.Length);
          using (CryptoStream encrypt_cs = new CryptoStream(encrypt_ms, encryptor, CryptoStreamMode.Write))
          {
            using (StreamWriter encrypt_sw = new StreamWriter(encrypt_cs))
            {
              encrypt_sw.Write(plan_test);
            }
          }
          output = Convert.ToBase64String(encrypt_ms.ToArray());
        }
      }
      catch (Exception e)
      {
        throw e;
      }
      finally
      {
        if (aes_alg != null)
        {
          aes_alg.Clear();
        }
      }
      return output;
    }

    /************************************************************************
    Purpose :         This is the method uses to decrypt the encrypted strings.
    Parameters :      cipher_text: decrypted string need to decrypt to plan text
    Returns :         Plan text after decrypted
    Exception :       If any exception while getting values from xml, pass to the upper level
    Algorithm :       C# manage code
    Output :          None
    Notes :           User can encrypt multiple times recursively if more security needs. If
                      that need to decrypt same number of rounds accordingly.
    *************************************************************************/
    internal static string aesDecrypt(string cipher_text)
    {
      RijndaelManaged aes_alg = null;
      string plain_text = null;
      try
      {
        Rfc2898DeriveBytes key = new Rfc2898DeriveBytes(m_encrypt_key, m_salt);
        byte[] bytes = Convert.FromBase64String(cipher_text);
        using (MemoryStream decrypt_ms = new MemoryStream(bytes))
        {
          aes_alg = new RijndaelManaged();
          aes_alg.Key = key.GetBytes(aes_alg.KeySize / 8);
          aes_alg.IV = ReadByteArray(decrypt_ms);

          ICryptoTransform decryptor = aes_alg.CreateDecryptor(aes_alg.Key, aes_alg.IV);
          using (CryptoStream decrypt_cs = new CryptoStream(decrypt_ms, decryptor, CryptoStreamMode.Read))
          {
            using (StreamReader decrypt_sr = new StreamReader(decrypt_cs))
              plain_text = decrypt_sr.ReadToEnd();
          }
        }
      }
      catch (Exception e)
      {
        throw e;
      }
      finally
      {
        if (aes_alg != null)
          aes_alg.Clear();
      }
      return plain_text;
    }

    /************************************************************************
    Purpose :         Use to read first few bytes from cipher string( this helps to generate
                      the same key used in encrypt method again) 
    Parameters :      stream: stream that use to read the cipher text bytes from memory.
    Returns :         return byte array filled with first few bytes of the cipher string.
    Exception :       If any exception while getting values from xml, pass to the upper level
    Algorithm :       C# manage code
    Output :          None
    Notes :           None
    *************************************************************************/
    private static byte[] ReadByteArray(Stream stream)
    {
      byte[] buffer;
      byte[] row_length = new byte[sizeof(int)];
      try
      {
        if (stream.Read(row_length, 0, row_length.Length) != row_length.Length)
        {
          throw new SystemException("encrypted string not contain properly formatted byte array");
        }
        int temp = BitConverter.ToInt32(row_length, 0);
        buffer = new byte[temp];

        if (stream.Read(buffer, 0, buffer.Length) != buffer.Length)
        {
          throw new SystemException("Did not read encrypted string properly");
        }
      }
      catch (Exception e)
      {
        throw e;
      }
      return buffer;
    }
  }
}

13 comments:

  1. hank you for benefiting from time to focus on this kind of, I feel firmly about it and also really like comprehending far more with this particular subject matter. In case doable, when you get know-how, is it possible to thoughts modernizing your site together with far more details? It’s extremely useful to me 
    Data science training in Bangalore
    Data Science training in marathahalli
    Data Science training in btm
    Data Science training in rajaji nagar
    Data Science training in chennai
    Data Science training in kalyan nagar
    Data Science training in electronic city
    Data Science training in USA

    ReplyDelete
  2. Wonderful article, very useful and well explanation. Your post is extremely incredible. I will refer this to my candidates...
    java training in chennai | java training in bangalore

    java training in tambaram | java training in velachery

    java training in omr | oracle training in chennai

    ReplyDelete
  3. I am happy for sharing on this blog its awesome blog I really impressed. thanks for sharing.

    Became an Expert In Google Cloud Platform Training in Bangalore! Learn from experienced Trainers and get the knowledge to crack a coding interview, @Softgen Infotech Located in BTM Layout.

    ReplyDelete
  4. Sharing the same interest, Infycle feels so happy to share our detailed information about all these courses with you all! Do check them out
    oracle training in chennai & get to know everything you want to about software trainings.

    ReplyDelete
  5. Lucky Bird Casino: kasyno online z licencjÄ…: recenzja, bonusy , recenzje - https://top10casinoexpert.pl/casino/lucky-bird-casino/

    ReplyDelete
  6. I appreciate you spending the time to write this. Browse this article with ease—it's a quick read Minecraft Tricks. Minecraft's creative mode opens up countless possibilities.

    ReplyDelete
  7. Good information. I'm grateful. Consult this article Butterfly Drag Click Test. Do you want to test your drag-click speed? Take a look at the Butterfly Drag Click Test!

    ReplyDelete