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

namespace Utils
{
    /// <summary>
    /// AES加密解密
    /// </summary>
    public class AESHelper
    {
        #region 加密
        /// <summary>
        /// AES 加密(高级加密标准，是下一代的加密算法标准，速度快，安全级别高，目前 AES 标准的一个实现是 Rijndael 算法)
        /// </summary>
        /// <param name="text">明文</param>
        /// <param name="key">密钥</param>
        /// <param name="iv">向量</param>
        public static string Encrypt(string text, string key, string iv)
        {
            if (text == null || text.Length == 0) { throw (new Exception("明文不得为空")); }
            if (string.IsNullOrWhiteSpace(key)) { throw (new Exception("密钥不得为空")); }
            if (string.IsNullOrWhiteSpace(iv)) { throw (new Exception("向量不得为空")); }
            if (key.Length < 16) { throw (new Exception("密钥长度不能小于16")); }
            if (iv.Length < 16) { throw (new Exception("向量长度不能小于16")); }

            byte[] textBytes = Encoding.UTF8.GetBytes(text);
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            byte[] ivBytes = Encoding.UTF8.GetBytes(iv);
            byte[] salt = Encoding.UTF8.GetBytes(iv);
            byte[] encryptedBytes;

            RijndaelManaged rijndaelManaged = new RijndaelManaged();
            ICryptoTransform transform = null;

            try
            {
                rijndaelManaged.Mode = CipherMode.CBC;
                rijndaelManaged.Padding = PaddingMode.PKCS7;
                rijndaelManaged.KeySize = 128;
                rijndaelManaged.BlockSize = 128;
                rijndaelManaged.Key = keyBytes;
                rijndaelManaged.IV = ivBytes;

                transform = rijndaelManaged.CreateEncryptor();
                encryptedBytes = transform.TransformFinalBlock(textBytes, 0, textBytes.Length);
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                rijndaelManaged.Clear();
                rijndaelManaged.Dispose();
                if (transform != null) transform.Dispose();
            }

            return Convert.ToBase64String(encryptedBytes);
        }
        #endregion

        #region 解密
        /// <summary>
        /// AES 解密(高级加密标准，是下一代的加密算法标准，速度快，安全级别高，目前 AES 标准的一个实现是 Rijndael 算法)
        /// </summary>
        /// <param name="encryptedString">密文</param>
        /// <param name="key">密钥</param>
        /// <param name="iv">向量</param>
        public static string Decrypt(string encryptedString, string key, string iv)
        {
            if (encryptedString == null || encryptedString.Length == 0) { throw (new Exception("密文不得为空")); }
            if (string.IsNullOrWhiteSpace(key)) { throw (new Exception("密钥不得为空")); }
            if (string.IsNullOrWhiteSpace(iv)) { throw (new Exception("向量不得为空")); }
            if (key.Length < 16) { throw (new Exception("密钥长度不能小于16")); }
            if (iv.Length < 16) { throw (new Exception("向量长度不能小于16")); }

            byte[] decryptedBytes;
            byte[] keyBytes = Encoding.UTF8.GetBytes(key);
            byte[] ivBytes = Encoding.UTF8.GetBytes(iv);
            byte[] salt = Encoding.UTF8.GetBytes(iv);
            byte[] encryptedBytes = Convert.FromBase64String(encryptedString);

            RijndaelManaged rijndaelManaged = new RijndaelManaged();
            ICryptoTransform transform = null;

            try
            {
                rijndaelManaged.Mode = CipherMode.CBC;
                rijndaelManaged.Padding = PaddingMode.PKCS7;
                rijndaelManaged.KeySize = 128;
                rijndaelManaged.BlockSize = 128;
                rijndaelManaged.Key = keyBytes;
                rijndaelManaged.IV = ivBytes;

                transform = rijndaelManaged.CreateDecryptor();
                decryptedBytes = transform.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length);
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                rijndaelManaged.Clear();
                rijndaelManaged.Dispose();
                if (transform != null) transform.Dispose();
            }

            return Encoding.UTF8.GetString(decryptedBytes);
        }
        #endregion

    }
}