C# -AES加解密帮助类

/**
*┌──────────────────────────────────────────────────────────────┐
*│　描    述：AES加解密帮助类                                                    
*│　作    者：yilezhu                                             
*│　版    本：1.0                                                 
*│　创建时间：2019/1/1 21:11:02                             
*└──────────────────────────────────────────────────────────────┘
*┌──────────────────────────────────────────────────────────────┐
*│　命名空间： Helper                                   
*│　类    名： DESEncryptHelper                                      
*└──────────────────────────────────────────────────────────────┘
*/
using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace Czar.Cms.Core.Helper
{
    /// <summary> 
    /// AES加密解密
    /// </summary> 
    public class AESEncryptHelper
    {
        //默认密钥向量
        private static byte[] Keys = { 0x41, 0x72, 0x65, 0x79, 0x6F, 0x75, 0x6D, 0x79, 0x53, 0x6E, 0x6F, 0x77, 0x6D, 0x61, 0x6E, 0x3F };

        #region ========加密========
        public static string Encode(string encryptString, string encryptKey)
        {
            encryptKey = GetSubString(encryptKey, 0, 32, "");
            encryptKey = encryptKey.PadRight(32, ' ');

            RijndaelManaged rijndaelProvider = new RijndaelManaged();
            rijndaelProvider.Key = Encoding.UTF8.GetBytes(encryptKey.Substring(0, 32));
            rijndaelProvider.IV = Keys;
            ICryptoTransform rijndaelEncrypt = rijndaelProvider.CreateEncryptor();

            byte[] inputData = Encoding.UTF8.GetBytes(encryptString);
            byte[] encryptedData = rijndaelEncrypt.TransformFinalBlock(inputData, 0, inputData.Length);

            return Convert.ToBase64String(encryptedData);
        }
        #endregion

        #region ========解密========
        public static string Decode(string decryptString, string decryptKey)
        {
            try
            {
                decryptKey = GetSubString(decryptKey, 0, 32, "");
                decryptKey = decryptKey.PadRight(32, ' ');

                RijndaelManaged rijndaelProvider = new RijndaelManaged();
                rijndaelProvider.Key = Encoding.UTF8.GetBytes(decryptKey);
                rijndaelProvider.IV = Keys;
                ICryptoTransform rijndaelDecrypt = rijndaelProvider.CreateDecryptor();

                byte[] inputData = Convert.FromBase64String(decryptString);
                byte[] decryptedData = rijndaelDecrypt.TransformFinalBlock(inputData, 0, inputData.Length);

                return Encoding.UTF8.GetString(decryptedData);
            }
            catch
            {
                return "";
            }

        }
        #endregion

        public static string GetSubString(string p_SrcString, int p_StartIndex, int p_Length, string p_TailString)
        {
            string myResult = p_SrcString;

            Byte[] bComments = Encoding.UTF8.GetBytes(p_SrcString);
            foreach (char c in Encoding.UTF8.GetChars(bComments))
            {    //当是日文或韩文时(注:中文的范围:u4e00 - u9fa5, 日文在u0800 - u4e00, 韩文为xAC00-xD7A3)
                if ((c > 'u0800' && c < 'u4e00') || (c > 'xAC00' && c < 'xD7A3'))
                {
                    //if (System.Text.RegularExpressions.Regex.IsMatch(p_SrcString, "[u0800-u4e00]+") || System.Text.RegularExpressions.Regex.IsMatch(p_SrcString, "[xAC00-xD7A3]+"))
                    //当截取的起始位置超出字段串长度时
                    if (p_StartIndex >= p_SrcString.Length)
                        return "";
                    else
                        return p_SrcString.Substring(p_StartIndex,
                                                       ((p_Length + p_StartIndex) > p_SrcString.Length) ? (p_SrcString.Length - p_StartIndex) : p_Length);
                }
            }

            if (p_Length >= 0)
            {
                byte[] bsSrcString = Encoding.Default.GetBytes(p_SrcString);

                //当字符串长度大于起始位置
                if (bsSrcString.Length > p_StartIndex)
                {
                    int p_EndIndex = bsSrcString.Length;

                    //当要截取的长度在字符串的有效长度范围内
                    if (bsSrcString.Length > (p_StartIndex + p_Length))
                    {
                        p_EndIndex = p_Length + p_StartIndex;
                    }
                    else
                    {   //当不在有效范围内时,只取到字符串的结尾

                        p_Length = bsSrcString.Length - p_StartIndex;
                        p_TailString = "";
                    }

                    int nRealLength = p_Length;
                    int[] anResultFlag = new int[p_Length];
                    byte[] bsResult = null;

                    int nFlag = 0;
                    for (int i = p_StartIndex; i < p_EndIndex; i++)
                    {
                        if (bsSrcString[i] > 127)
                        {
                            nFlag++;
                            if (nFlag == 3)
                                nFlag = 1;
                        }
                        else
                            nFlag = 0;

                        anResultFlag[i] = nFlag;
                    }

                    if ((bsSrcString[p_EndIndex - 1] > 127) && (anResultFlag[p_Length - 1] == 1))
                        nRealLength = p_Length + 1;

                    bsResult = new byte[nRealLength];

                    Array.Copy(bsSrcString, p_StartIndex, bsResult, 0, nRealLength);

                    myResult = Encoding.Default.GetString(bsResult);
                    myResult = myResult + p_TailString;
                }
            }

            return myResult;
        }

    }
}

引自：依乐祝CMS项目——https://www.cnblogs.com/yilezhu/p/9977862.html