/// 

    ///  MD5加密及验证
    /// 
    public static class MD5_Encrypt
    {
        /// 

        /// 获得32位的MD5加密
        /// 
        /// 
        /// 
        public static string GetMD5_32(string input)
        {
            System.Security.Cryptography.MD5 md5 = System.Security.Cryptography.MD5.Create();
            byte[] data = md5.ComputeHash(System.Text.Encoding.Default.GetBytes(input));
            StringBuilder sb = new StringBuilder();
            for (int i = 0; i < data.Length; i++)
            {
                sb.Append(data[i].ToString("x2"));
            }
            return sb.ToString();
        }

        /// 

        /// 获得16位的MD5加密
        /// 
        /// 
        /// 
        public static string GetMD5_16(string input)
        {
            return GetMD5_32(input).Substring(8, 16);
        }
        /// 

        /// 获得8位的MD5加密
        /// 
        /// 
        /// 
        public static string GetMD5_8(string input)
        {
            return GetMD5_32(input).Substring(8, 8);
        }
        /// 

        /// 获得4位的MD5加密
        /// 
        /// 
        /// 
        public static string GetMD5_4(string input)
        {
            return GetMD5_32(input).Substring(8, 4);
        }

    }