using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;

namespace LSServerService
{
	/// <summary>
    /// AES对称加密
    /// </summary>
    public class AESUtil
    {
        private static string key = "lserpasebygyc222";

        #region AES加解密
        /// <summary>
        ///AES加密（加密步骤）
        ///1，加密字符串得到2进制数组；
        ///2，将2进制数组转为16进制；
        ///3，进行base64编码
        /// </summary>
        /// <param name="toEncrypt">要加密的字符串</param>
        /// <param name="key">密钥</param>
        public static string Encrypt(string toEncrypt)
        {
            if (string.IsNullOrEmpty(toEncrypt)) return "";
            byte[] _key = Encoding.ASCII.GetBytes(key);
            byte[] _source = Encoding.UTF8.GetBytes(toEncrypt);

            Aes aes = Aes.Create("AES");
            aes.Mode = CipherMode.ECB;
            aes.Padding = PaddingMode.PKCS7;
            aes.Key = _key;
            ICryptoTransform cTransform = aes.CreateEncryptor();
            byte[] cryptData = cTransform.TransformFinalBlock(_source, 0, _source.Length);
            string hexCryptString = Hex_2To16(cryptData);
            byte[] hexCryptData = Encoding.UTF8.GetBytes(hexCryptString);
            return Convert.ToBase64String(hexCryptData);
        }

        /// <summary>
        /// AES解密（解密步骤）
        /// 1，将BASE64字符串转为16进制数组
        /// 2，将16进制数组转为字符串
        /// 3，将字符串转为2进制数据
        /// 4，用AES解密数据
        /// </summary>
        /// <param name="encryptedSource">已加密的内容</param>
        /// <param name="key">密钥</param>
        public static string Decrypt(string toDecrypt)
        {
            if (string.IsNullOrEmpty(toDecrypt)) return "";
            try
            {
                byte[] _key = Encoding.ASCII.GetBytes(key);
                Aes aes = Aes.Create("AES");
                aes.Mode = CipherMode.ECB;
                aes.Padding = PaddingMode.PKCS7;
                aes.Key = _key;
                ICryptoTransform cTransform = aes.CreateDecryptor();

                byte[] encryptedData = Convert.FromBase64String(toDecrypt);
                string encryptedString = Encoding.UTF8.GetString(encryptedData);
                byte[] _source = Hex_16To2(encryptedString);
                byte[] originalSrouceData = cTransform.TransformFinalBlock(_source, 0, _source.Length);
                return Encoding.UTF8.GetString(originalSrouceData);
            }
            catch (Exception)
            {
                return "";
            }           
        }

        /// <summary>
        /// 2进制转16进制
        /// </summary>
        static string Hex_2To16(byte[] bytes)
        {
            string hexString = string.Empty;
            Int32 iLength = 65535;
            if (bytes != null)
            {
                StringBuilder strB = new StringBuilder();

                if (bytes.Length < iLength)
                {
                    iLength = bytes.Length;
                }

                for (int i = 0; i < iLength; i++)
                {
                    strB.Append(bytes[i].ToString("X2"));
                }
                hexString = strB.ToString();
            }
            return hexString;
        }

        /// <summary>
        /// 16进制转2进制
        /// </summary>
        static byte[] Hex_16To2(string hexString)
        {
            if ((hexString.Length % 2) != 0)
            {
                hexString += " ";
            }
            byte[] returnBytes = new Byte[hexString.Length / 2];
            for (Int32 i = 0; i < returnBytes.Length; i++)
            {
                returnBytes[i] = Convert.ToByte(hexString.Substring(i * 2, 2), 16);
            }
            return returnBytes;
        }
        #endregion
    }
}