C#中string与byte[]的转换帮助类

在写C＃程序时，string和byte[]之间的转换比较烦，在移植一些老程序时感觉很不好。我在C＃中使用DES和TripleDES时移植一块老代码时也遇到了同样的情况。为了下次不为同样的事情烦恼，就写了下面的帮助类。
主要实现了以下的函数：
 

using System;   
using System.Text;   
namespace SidleHelper   
{   
     /// <summary>   
     /// Summary description for StrHelper.   
     /// 命名缩写：   
     /// Str: unicode string   
     /// Arr: unicode array   
     /// Hex: 二进制数据   
     /// Hexbin: 二进制数据用ASCII字符表示 例 字符"1"的hex是0x31表示为hexbin是 "3""1"    
     /// Asc: ASCII   
     /// Uni: UNICODE   
     /// </summary>   
     public sealed class StrHelper   
     {  
          #region Hex与Hexbin的转换   
          public static void Hexbin2Hex(byte[] bHexbin, byte[] bHex, int nLen)   
          {   
                for (int i = 0; i < nLen / 2; i++)   
                {   
                     if (bHexbin[2 * i] < 0x41)   
                     {   
                          bHex[i] = Convert.ToByte(((bHexbin[2 * i] - 0x30) << 4) & 0xf0);   
                     }   
                     else   
                     {   
                          bHex[i] = Convert.ToByte(((bHexbin[2 * i] - 0x37) << 4) & 0xf0);   
                     }   
                     if (bHexbin[2 * i + 1] < 0x41)   
                     {   
                          bHex[i] |= Convert.ToByte((bHexbin[2 * i + 1] - 0x30) & 0x0f);   
                     }   
                     else   
                     {   
                          bHex[i] |= Convert.ToByte((bHexbin[2 * i + 1] - 0x37) & 0x0f);   
                     }   
                }   
          }   
          public static byte[] Hexbin2Hex(byte[] bHexbin, int nLen)   
          {   
                if (nLen % 2 != 0)   
                     return null;   
                byte[] bHex = new byte[nLen / 2];   
                Hexbin2Hex(bHexbin, bHex, nLen);   
                return bHex;   
          }   
          public static void Hex2Hexbin(byte[] bHex, byte[] bHexbin, int nLen)   
          {   
                byte c;   
                for (int i = 0; i < nLen; i++)   
                {   
                     c = Convert.ToByte((bHex[i] >> 4) & 0x0f);   
                     if (c < 0x0a)   
                     {   
                          bHexbin[2 * i] = Convert.ToByte(c + 0x30);   
                     }   
                     else   
                     {   
                          bHexbin[2 * i] = Convert.ToByte(c + 0x37);   
                     }   
                     c = Convert.ToByte(bHex[i] & 0x0f);   
                     if (c < 0x0a)   
                     {   
                          bHexbin[2 * i + 1] = Convert.ToByte(c + 0x30);   
                     }   
                     else   
                     {   
                          bHexbin[2 * i + 1] = Convert.ToByte(c + 0x37);   
                     }   
                }   
          }   
          public static byte[] Hex2Hexbin(byte[] bHex, int nLen)   
          {   
                byte[] bHexbin = new byte[nLen * 2];   
                Hex2Hexbin(bHex, bHexbin, nLen);   
                return bHexbin;   
          }  
          #endregion  
          #region 数组和字符串之间的转化   
          public static byte[] Str2Arr(String s)   
          {   
                return (new UnicodeEncoding()).GetBytes(s);   
          }   
          public static string Arr2Str(byte[] buffer)   
          {   
                return (new UnicodeEncoding()).GetString(buffer, 0, buffer.Length);   
          }   
          public static byte[] Str2AscArr(String s)   
          {   
                return System.Text.UnicodeEncoding.Convert(System.Text.Encoding.Unicode,   
                System.Text.Encoding.ASCII,   
                Str2Arr(s));   
          }   
          public static byte[] Str2HexAscArr(String s)   
          {   
                byte[] hex = Str2AscArr(s);   
                byte[] hexbin = Hex2Hexbin(hex, hex.Length);   
                return hexbin;   
          }   
          public static string AscArr2Str(byte[] b)   
          {   
                return System.Text.UnicodeEncoding.Unicode.GetString(   
                System.Text.ASCIIEncoding.Convert(System.Text.Encoding.ASCII,   
                System.Text.Encoding.Unicode,   
                b)   
                );   
          }   
          public static string HexAscArr2Str(byte[] buffer)   
          {   
                byte[] b = Hex2Hexbin(buffer, buffer.Length);   
                return AscArr2Str(b);   
          }  
          #endregion   
     }   
}