思路：使用随机向量，把随机向量放入密文中，每次解密时从密文中截取前16位，其实就是我们之前加密的随机向量。

 

代码

public static string Encrypt(string plainText, string AESKey){    RijndaelManaged rijndaelCipher = new RijndaelManaged();    byte[] inputByteArray = Encoding.UTF8.GetBytes(plainText);//得到需要加密的字节数组     rijndaelCipher.Key = Convert.FromBase64String(AESKey);//加解密双方约定好密钥：AESKey    rijndaelCipher.GenerateIV();    byte[] keyIv = rijndaelCipher.IV;    byte[] cipherBytes = null;    using (MemoryStream ms = new MemoryStream())    {        using (CryptoStream cs = new CryptoStream(ms, rijndaelCipher.CreateEncryptor(), CryptoStreamMode.Write))        {            cs.Write(inputByteArray, 0, inputByteArray.Length);            cs.FlushFinalBlock();            cipherBytes = ms.ToArray();//得到加密后的字节数组            cs.Close();            ms.Close();        }    }    var allEncrypt = new byte[keyIv.Length + cipherBytes.Length];    Buffer.BlockCopy(keyIv, 0, allEncrypt, 0, keyIv.Length);    Buffer.BlockCopy(cipherBytes, 0, allEncrypt, keyIv.Length * sizeof(byte), cipherBytes.Length);    return Convert.ToBase64String(allEncrypt);}public static string Decrypt(string showText, string AESKey){    string result = string.Empty;    try    {        byte[] cipherText = Convert.FromBase64String(showText);        int length = cipherText.Length;        SymmetricAlgorithm rijndaelCipher = Rijndael.Create();        rijndaelCipher.Key = Convert.FromBase64String(AESKey);//加解密双方约定好的密钥        byte[] iv = new byte[16];        Buffer.BlockCopy(cipherText, 0, iv, 0, 16);        rijndaelCipher.IV = iv;        byte[] decryptBytes = new byte[length - 16];        byte[] passwdText = new byte[length - 16];        Buffer.BlockCopy(cipherText, 16, passwdText, 0, length - 16);        using (MemoryStream ms = new MemoryStream(passwdText))        {            using (CryptoStream cs = new CryptoStream(ms, rijndaelCipher.CreateDecryptor(), CryptoStreamMode.Read))            {                cs.Read(decryptBytes, 0, decryptBytes.Length);                cs.Close();                ms.Close();            }        }        result = Encoding.UTF8.GetString(decryptBytes).Replace("\0", "");   ///将字符串后尾的'\0'去掉    }    catch { }    return result;}

　　

调用：

string jiaMi = MyAESTools.Encrypt(textBox1.Text, "abcdefgh12345678abcdefgh12345678");string jieMi = MyAESTools.Decrypt(textBox3.Text, "abcdefgh12345678abcdefgh12345678");