Base65 Encoding

Base65Encoding.cs

namespace Utils
{
  using System;
	using System.Collections.Generic;
	using System.Linq;
	using System.Text;

	public class Base65Encoding
	{
		private const string Characters = "0123456789AaBbCcDdEeFfGgHhIiJjKklLMmNnOoPpQqRrSsTtUuVvWwXxYyZz._-";

		public static string Encode(byte[] inArray)
		{
			var sb = new StringBuilder();

			foreach (string val in inArray.Select(b => IntToString(b, Characters)))
			{
				if (val.Length == 1)
					sb.Append("0").Append(val);
				else
					sb.Append(val);
			}

			return sb.ToString();
		}

		public static byte[] Decode(string inString)
		{
			if (string.IsNullOrEmpty(inString))
				throw new ArgumentNullException("inString");

			if (inString.Length%2 != 0)
				throw new ArgumentException("Invalid string length", "inString");

			var bytes = new List<byte>();

			for (int i = 0; i < inString.Length; i += 2)
			{
				char ch = inString[i];
				char ch2 = inString[i + 1];
				int index = Characters.IndexOf(ch);
				int index2 = Characters.IndexOf(ch2);

				if (index < 0 || index2 < 0)
					throw new ArgumentException("Invalid character: " + ch);

				int val = 0;
				val += (index*Characters.Length) + index2;

				bytes.Add((byte) val);
			}

			return bytes.ToArray();
		}

		public static string IntToString(int value, string baseChars)
		{
			int i = 32;
			var buffer = new char[i];
			int targetBase = baseChars.Length;

			do
			{
				buffer[--i] = baseChars[value%targetBase];
				value = value/targetBase;
			} while (value > 0);

			var result = new char[32 - i];
			Array.Copy(buffer, i, result, 0, 32 - i);

			return new string(result);
		}
	}
}

EncodingExtensions.cs

namespace Utils
{  
  public static class EncodingExtensions
	{
		public static string ToBase65(this byte[] inArray)
		{
			return Base65Encoding.Encode(inArray);
		}

		public static byte[] FromBase65(this string inString)
		{
			return Base65Encoding.Decode(inString);
		}
	}
}