AES加密和解密

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

namespace AES
{
    public class AESEncryption
    {
        private static string strKey = "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx";
        /// <summary>
        /// AES加密算法
        /// </summary>
        /// <param name="plainText">明文字符串</param>
        /// <param name="strKey">密钥</param>
        /// <returns>返回加密后的密文字节数组</returns>
        public static string AESEncrypt(string plainText)
        {
            try
            {
                //分组加密算法
                RijndaelManaged aes = new RijndaelManaged();
                byte[] inputByteArray = Encoding.UTF8.GetBytes(plainText);//得到需要加密的字节数组

                //设置密钥及密钥向量
                aes.Key = Encoding.UTF8.GetBytes(GetMD5(strKey));
                aes.IV = Encoding.UTF8.GetBytes(GetMD5(strKey).Substring(8, 16));
                aes.Mode = CipherMode.CBC;
                aes.Padding = PaddingMode.PKCS7;

                ICryptoTransform transform = aes.CreateEncryptor();
                byte[] buffer= transform.TransformFinalBlock(inputByteArray, 0, inputByteArray.Length);

                //System.IO.MemoryStream ms = new System.IO.MemoryStream();
                
                //CryptoStream cs = new CryptoStream(ms, aes.CreateEncryptor(), CryptoStreamMode.Write);
                
                //cs.Write(inputByteArray, 0, inputByteArray.Length);
                //cs.FlushFinalBlock();

                StringBuilder ret = new StringBuilder();
                foreach (byte b in buffer)
                {
                    ret.AppendFormat("{0:x2}", b);
                }
                return ret.ToString(); 
            }
            catch
            {
                return plainText;
            }
        }

        /// <summary>
        /// AES解密
        /// </summary>
        /// <param name="cipherText">密文字节数组</param>
        /// <param name="strKey">密钥</param>
        /// <returns>返回解密后的字符串</returns>
        public static string AESDecrypt(string cipherText)
        {
            try
            {
                RijndaelManaged aes = new RijndaelManaged();

                int len;
                len = cipherText.Length / 2;
                byte[] inputByteArray = new byte[len];
                int x, i;
                for (x = 0; x < len; x++)
                {
                    i = Convert.ToInt32(cipherText.Substring(x * 2, 2), 16);
                    inputByteArray[x] = (byte)i;
                }

                //byte[] inputByteArray = Encoding.UTF8.GetBytes(cipherText);
                //设置密钥及密钥向量
                aes.Key = Encoding.UTF8.GetBytes(GetMD5(strKey));
                aes.IV = Encoding.UTF8.GetBytes(GetMD5(strKey).Substring(8, 16));
                aes.Mode = CipherMode.CBC;
                aes.Padding = PaddingMode.PKCS7;

                ICryptoTransform transform = aes.CreateDecryptor();
                byte[] buffer = transform.TransformFinalBlock(inputByteArray, 0, inputByteArray.Length);

                //System.IO.MemoryStream ms = new System.IO.MemoryStream();
                //CryptoStream cs = new CryptoStream(ms, aes.CreateDecryptor(), CryptoStreamMode.Write);
                //cs.Write(inputByteArray, 0, inputByteArray.Length);
                //cs.FlushFinalBlock();
                string strDecrypt = Encoding.UTF8.GetString(buffer);
                return strDecrypt; 

            }
            catch
            {
                return cipherText;
            }
        }

        public static string GetMD5(string str)
        {
            StringBuilder sb = new StringBuilder();
            foreach (byte b in System.Security.Cryptography.MD5.Create().ComputeHash(Encoding.UTF8.GetBytes(str)))
            {
                sb.Append(b.ToString("X2"));
            }
            return sb.ToString();
        }


    }
}