var gcm = new AesGcm(Encoding.UTF8.GetBytes(key));             byte[] cipherTextBytes = Convert.FromBase64String(_ciphertext);             byte[] nonce = Encoding.UTF8.GetBytes(_nonce);             byte[] ciphertext = cipherTextBytes.Take(cipherTextBytes.Length - 16).ToArray();             byte[] plaintext = new byte[ciphertext.Length];             byte[] tag = cipherTextBytes.Skip(ciphertext.Length).Take(16).ToArray();             byte[] associatedData = Encoding.UTF8.GetBytes(_associated_data);             gcm.Decrypt(nonce, ciphertext, tag, plaintext, associatedData);             string text = Encoding.UTF8.GetString(plaintext); 提示错误 System.Security.Cryptography.CryptographicException:“The computed authentication tag did not match the input authentication tag.” [图片]