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

namespace DG.Tool
{
    public class AesUtil
    {
        /// <summary>
        /// AES加密算法
        /// </summary>
        /// <param name="input">明文字符串</param>
        /// <returns>字符串</returns>
        public static string EncryptByAES(string input, string key, string iv)
        {
            if (string.IsNullOrWhiteSpace(input))
            {
                return input;
            }
            using (RijndaelManaged rijndaelManaged = new RijndaelManaged())
            {
                rijndaelManaged.Mode = CipherMode.CBC;
                rijndaelManaged.Padding = PaddingMode.PKCS7;
                rijndaelManaged.FeedbackSize = 128;
                rijndaelManaged.Key = Encoding.UTF8.GetBytes(key);
                rijndaelManaged.IV = Encoding.UTF8.GetBytes(iv);
                ICryptoTransform encryptor = rijndaelManaged.CreateEncryptor(rijndaelManaged.Key, rijndaelManaged.IV);
                using (MemoryStream msEncrypt = new MemoryStream())
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))
                    {
                        using (StreamWriter swEncrypt = new StreamWriter(csEncrypt))
                        {
                            swEncrypt.Write(input);
                        }
                        byte[] bytes = msEncrypt.ToArray();
                        return Convert.ToBase64String(bytes);
                    }
                }
            }
        }

        /// <summary>
        /// AES解密
        /// </summary>
        /// <param name="input">密文字节数组</param>
        /// <returns>返回解密后的字符串</returns>
        public static string DecryptByAES(string input, string key, string iv)
        {
            if (string.IsNullOrWhiteSpace(input))
            {
                return input;
            }
            var buffer = Convert.FromBase64String(input);
            using (RijndaelManaged rijndaelManaged = new RijndaelManaged())
            {
                rijndaelManaged.Mode = CipherMode.CBC;
                rijndaelManaged.Padding = PaddingMode.PKCS7;
                rijndaelManaged.FeedbackSize = 128;
                rijndaelManaged.Key = Encoding.UTF8.GetBytes(key);
                rijndaelManaged.IV = Encoding.UTF8.GetBytes(iv);
                ICryptoTransform decryptor = rijndaelManaged.CreateDecryptor(rijndaelManaged.Key, rijndaelManaged.IV);
                using (MemoryStream msEncrypt = new MemoryStream(buffer))
                {
                    using (CryptoStream csEncrypt = new CryptoStream(msEncrypt, decryptor, CryptoStreamMode.Read))
                    {
                        using (StreamReader srEncrypt = new StreamReader(csEncrypt))
                        {
                            return srEncrypt.ReadToEnd();
                        }
                    }
                }
            }
        }
    }
}