text: //----------------------------------------------------------------------------
  //
  // TSDuck - The MPEG Transport Stream Toolkit
  // Copyright (c) 2005-2019, Thierry Lelegard
  // All rights reserved.
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are met:
  //
  // 1. Redistributions of source code must retain the above copyright notice,
  //    this list of conditions and the following disclaimer.
  // 2. Redistributions in binary form must reproduce the above copyright
  //    notice, this list of conditions and the following disclaimer in the
  //    documentation and/or other materials provided with the distribution.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  // AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  // ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  // LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  // CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  // SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  // INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  // CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
  // THE POSSIBILITY OF SUCH DAMAGE.
  //
  //----------------------------------------------------------------------------
  //!
  //!  @file
  //!  Interface to be notified when an alert is raised on a block cipher.
  //!
  //----------------------------------------------------------------------------
  
  #pragma once
  #include "tsPlatform.h"
  
  namespace ts {
  
      class BlockCipher;
  
      //!
      //! Interface for classes which need to be notified when an alert is raised on a block cipher.
      //! @ingroup crypto
      //!
      class TSDUCKDLL BlockCipherAlertInterface
      {
      public:
          //!
          //! Reason for the alert.
          //!
          enum AlertReason {
              FIRST_ENCRYPTION,     //!< First encryption using the current key. Informational only.
              FIRST_DECRYPTION,     //!< First decryption using the current key. Informational only.
              ENCRYPTION_EXCEEDED,  //!< Too many encryptions for the current key. Normal processing is error.
              DECRYPTION_EXCEEDED,  //!< Too many decryptions for the current key. Normal processing is error.
          };
  
          //!
          //! This hook is invoked when an ECM is available.
          //! It is invoked in the context of an internal thread of the ECMG client object.
          //! @param [in,out] cipher The block cipher which raised the alert.
          //! @param [in] reason The reason for the alert.
          //! @return True when the alert is real and appropriate action shall be taken.
          //! False to ignore the alert and proceed normally.
          //! Some alerts are informational only and the return value is ignored.
          //!
          virtual bool handleBlockCipherAlert(BlockCipher& cipher, AlertReason reason) = 0;
  
          //!
          //! Virtual destructor.
          //!
          virtual ~BlockCipherAlertInterface();
      };
  }
  