C#对称加密（AES加密）每次生成的结果都不同的实现思路和代码实例

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");