public class EncryptionAndDecryption
	{
		const char CharacterToFill = '@';
		static string Key = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

		static public string EnCrypt(string str)
		{
			int count;
			int ctr;
			int size = str.Length;
			string R="";

			for (count = 0; count < size; ++count)
			{
				ctr = (str[count] >> 2) & 0x3f;
				R +=Key[ctr];
				ctr = (str[count] << 4) & 0x3f;
				if (++count < size)
					ctr |= (str[count] >> 4) & 0x0f;

				R += Key[ctr];
				if (count < size)
				{
					ctr = (str[count] << 2) & 0x3f;
					if (++count < size)
						ctr |= (str[count] >> 6) & 0x03;

					R += Key[ctr];
				}
				else
				{
					++count;
					R += CharacterToFill;
				}

				if (count < size)
				{
					ctr = str[count] & 0x3f;
					R += Key[ctr];
				}
				else
				{
					R += CharacterToFill;
				}
			}

			return(R);
		}

		static public string DeCrypt(string str)
		{
			string R="";
			int count;
			char ctr;
			char ctrNext;
			int size = str.Length;

			for (count = 0; count < size; ++count)
			{
				ctr = (char) Key.IndexOf(str[count]);
				++count;
				ctrNext = (char) Key.IndexOf(str[count]);
				ctr = ((char)((ctr << 2) | ((ctrNext >> 4) & 0x3)));
				R += ctr;
				if (++count < size)
				{
					ctr = str[count];
					if (CharacterToFill == ctr)
						break;

					ctr = (char) Key.IndexOf(ctr);
					ctrNext = (char)(((ctrNext << 4) & 0xf0) | ((ctr >> 2) & 0xf));
					R += ctrNext;
				}

				if (++count < size)
				{
					ctrNext = str[count];
					if (CharacterToFill == ctrNext)
						break;

					ctrNext = (char) Key.IndexOf(ctrNext);
					ctr = (char)(((ctr << 6) & 0xc0) | ctrNext);
					R += ctr;
				}
			}
			return(R);
		}
	}