FrameControl - Framework for creating web applications

using System;
using System.Security.Cryptography;
using System.Text;

namespace JobMorning
{
	
	public class CryptoEncrypt
	{
		public static string encrypt (string original)
		{
			string                         encrypted, password;
			TripleDESCryptoServiceProvider des;
			MD5CryptoServiceProvider       hashmd5;
			byte[]                         pwdhash, buff;

			//create a secret password. the password is used to encrypt
			//and decrypt strings. Without the password, the encrypted
			//string cannot be decrypted and is just garbage. You must
			//use the same password to decrypt an encrypted string as the
			//string was originally encrypted with.
			password = "urayasu";
            
			//generate an MD5 hash from the password. 
			//a hash is a one way encryption meaning once you generate
			//the hash, you cant derive the password back from it.
			hashmd5 = new MD5CryptoServiceProvider();
			pwdhash = hashmd5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(password));
			hashmd5 = null;

			//implement DES3 encryption
			des = new TripleDESCryptoServiceProvider();

			//the key is the secret password hash.
			des.Key = pwdhash;

			//the mode is the block cipher mode which is basically the
			//details of how the encryption will work. There are several
			//kinds of ciphers available in DES3 and they all have benefits
			//and drawbacks. Here the Electronic Codebook cipher is used
			//which means that a given bit of text is always encrypted
			//exactly the same when the same password is used.
			des.Mode = CipherMode.ECB; //CBC, CFB


			//----- encrypt an un-encrypted string ------------
			//the original string, which needs encrypted, must be in byte
			//array form to work with the des3 class. everything will because
			//most encryption works at the byte level so you'll find that
			//the class takes in byte arrays and returns byte arrays and
			//you'll be converting those arrays to strings.
			buff = ASCIIEncoding.ASCII.GetBytes(original);

			//encrypt the byte buffer representation of the original string
			//and base64 encode the encrypted string. the reason the encrypted
			//bytes are being base64 encoded as a string is the encryption will
			//have created some weird characters in there. Base64 encoding
			//provides a platform independent view of the encrypted string 
			//and can be sent as a plain text string to wherever.
			encrypted = Convert.ToBase64String(
				des.CreateEncryptor().TransformFinalBlock(buff, 0, buff.Length)
				);


			//cleanup
			des = null;

			return encrypted;

		}

	}
	
	/// <summary>
	/// Summary description for CryptoDecrypt.
	/// </summary>
	public class CryptoDecrypt
	{
		public static string Decrypt (string encrypted)
		{
			string                         Decrypted, password;
			TripleDESCryptoServiceProvider des;
			MD5CryptoServiceProvider       hashmd5;
			byte[]                         pwdhash, buff;

			//create a secret password. the password is used to encrypt
			//and Decrypt strings. Without the password, the encrypted
			//string cannot be Decrypted and is just garbage. You must
			//use the same password to Decrypt an encrypted string as the
			//string was originally encrypted with.
			password = "urayasu";
            
			//generate an MD5 hash from the password. 
			//a hash is a one way encryption meaning once you generate
			//the hash, you cant derive the password back from it.
			hashmd5 = new MD5CryptoServiceProvider();
			pwdhash = hashmd5.ComputeHash(ASCIIEncoding.ASCII.GetBytes(password));
			hashmd5 = null;

			//implement DES3 encryption
			des = new TripleDESCryptoServiceProvider();
			//the key is the secret password hash.
			des.Key = pwdhash;

			//the mode is the block cipher mode which is basically the
			//details of how the encryption will work. There are several
			//kinds of ciphers available in DES3 and they all have benefits
			//and drawbacks. Here the Electronic Codebook cipher is used
			//which means that a given bit of text is always encrypted
			//exactly the same when the same password is used.
			des.Mode = CipherMode.ECB; //CBC, CFB

			//whenever you Decrypt a string, you must do everything you
			//did to encrypt the string, but in reverse order. To encrypt,
			//first a normal string was des3 encrypted into a byte array
			//and then base64 encoded for reliable transmission. So, to 
			//Decrypt this string, first the base64 encoded string must be 
			//decoded so that just the encrypted byte array remains.
			buff = Convert.FromBase64String(encrypted);

			//Decrypt DES 3 encrypted byte buffer and return ASCII string
			Decrypted = ASCIIEncoding.ASCII.GetString(
				des.CreateDecryptor().TransformFinalBlock(buff, 0, buff.Length)
				);

			//cleanup
			des = null;

			return Decrypted;
		}
	}
}