Delphi To C# 加密解密类

/// <summary>
/// Delphi To C# 加密解密类 
/// 2010-09-02
/// </summary>
public class Crypt
{
    /// <summary>
    /// 16进制转字节数组
     /// </summary>
    /// <param name="hex">16进制字符串</param>
    /// <returns>字节数组</returns>
    private static byte[] HexToByte(string hex)
    {
        int L = (int)(hex.Length / 2);
        byte[] bytes = new byte[L];

        for (int i = 0; i < bytes.Length; i++)
        {
            try
            {
                bytes[i] = byte.Parse(hex.Substring(i * 2, 2),
                    System.Globalization.NumberStyles.HexNumber);
            }
            catch
            {

            }
        }

        return (bytes);
    }

    /// <summary>
    /// 加密函数
     /// </summary>
    /// <param name="original">需要加密的字符串</param>
    /// <param name="key">加密密匙(0..65535)</param>
    /// <returns>加密后的字符串</returns>
    public static string Encrypt(string original, ushort key)
    {
        string result = "";

        if (original != null && original != string.Empty)
        {
            byte[] bt = Encoding.Default.GetBytes(original);
            byte[] enbt = new byte[bt.Length];

            for (int i = 0; i < bt.Length; i++)
            {
                int k = bt[i] ^ (key >> 8);
                enbt[i] = (byte)k;
                key = (ushort)(enbt[i] + key);
                if (enbt[i] == (char)'\0')
                {
                    enbt[i] = bt[i];
                }
            }

            // 转为16进制
            for (int i = 0; i < enbt.Length; i++)
            {
                result += enbt[i].ToString("X2");
            }
        }

        return (result);
    }

    /// <summary>
    /// 解密函数 (重载)
    /// </summary>
    /// <param name="original">加密后的字符串</param>
    /// <param name="key">解密的密匙(0..65535)</param>
    /// <returns>解密后的字符串</returns>
    public static string Decrypt(string original, ushort key)
    {
        if (original == null || original == string.Empty)
        {
            return original;
        }
        else
        {
            byte[] bt = HexToByte(original);
            byte[] debt = new byte[bt.Length];

            for (int i = 0; i < bt.Length; i++)
            {
                int k = bt[i] ^ (key >> 8);
                debt[i] = (byte)k;
                if (debt[i] == (char)'\0')
                {
                    debt[i] = bt[i];
                    key = (ushort)((byte)(char)'\0' + key); 
                }
                else
                {
                    key = (ushort)(bt[i] + key);
                }
            }

            return (Encoding.Default.GetString(debt));
        }
    }
}