using System;
using System.IO;
using System.Security.Cryptography;
using System.Text;

namespace FangYar.Common
{
    /// <summary>
    /// Aes加密帮助类
    /// </summary>
    public class AesHelper
    {
        //生成字节数组
        private static readonly byte[] salt = Encoding.Unicode.GetBytes("7BANANAS");
        //迭代次数  应最少设置1000
        private static readonly int iterations = 2000;
        /// <summary>
        /// 加密
        /// </summary>
        /// <param name="plainText">加密文本</param>
        /// <param name="password">密钥</param>
        /// <returns>返回加密后的字节字符串</returns>
        public static string Encrypt(string plainText, string password = "kndhurlp")
        {
            byte[] encryptedBytes;
            byte[] plainBytes = Encoding.Unicode.GetBytes(plainText);

            var aes = Aes.Create();

            var pbkdf2 = new Rfc2898DeriveBytes(password, salt, iterations);  //使用密码 字节数组 和 迭代次数 生成密钥

            aes.Key = pbkdf2.GetBytes(32);
            aes.IV = pbkdf2.GetBytes(16);

            using (var ms = new MemoryStream())
            {
                using (var cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(plainBytes, 0, plainBytes.Length);
                }
                encryptedBytes = ms.ToArray();
            }
            return Convert.ToBase64String(encryptedBytes);
        }

        /// <summary>
        /// 解密
        /// </summary>
        /// <param name="crytoText">字节文本</param>
        /// <param name="password">密钥：默认：kndhurlp</param>
        /// <returns>将字节文本解密为字符串返回</returns>
        public static string Decrypt(string crytoText, string password = "kndhurlp")
        {
            byte[] plainBytes;
            byte[] cryptoBytes = Convert.FromBase64String(crytoText);

            var aes = Aes.Create();
            var pbkdf2 = new Rfc2898DeriveBytes(password, salt, iterations);

            aes.Key = pbkdf2.GetBytes(32);
            aes.IV = pbkdf2.GetBytes(16);

            using (var ms = new MemoryStream())
            {
                using (var cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(cryptoBytes, 0, cryptoBytes.Length);
                }
                plainBytes = ms.ToArray();
            }
            return Encoding.Unicode.GetString(plainBytes);
        }
    }
}