text: /*
   * Copyright (c)2019 ZeroTier, Inc.
   *
   * Use of this software is governed by the Business Source License included
   * in the LICENSE.TXT file in the project's root directory.
   *
   * Change Date: 2023-01-01
   *
   * On the date above, in accordance with the Business Source License, use
   * of this software will be governed by version 2.0 of the Apache License.
   */
  /****/
  
  #ifndef ZT_POLY1305_HPP
  #define ZT_POLY1305_HPP
  
  namespace ZeroTier {
  
  #define ZT_POLY1305_KEY_LEN 32
  #define ZT_POLY1305_MAC_LEN 16
  
  /**
   * Poly1305 one-time authentication code
   *
   * This takes a one-time-use 32-byte key and generates a 16-byte message
   * authentication code. The key must never be re-used for a different
   * message.
   *
   * In Packet this is done by using the first 32 bytes of the stream cipher
   * keystream as a one-time-use key. These 32 bytes are then discarded and
   * the packet is encrypted with the next N bytes.
   */
  class Poly1305
  {
  public:
  	/**
  	 * Compute a one-time authentication code
  	 *
  	 * @param auth Buffer to receive code -- MUST be 16 bytes in length
  	 * @param data Data to authenticate
  	 * @param len Length of data to authenticate in bytes
  	 * @param key 32-byte one-time use key to authenticate data (must not be reused)
  	 */
  	static void compute(void *auth,const void *data,unsigned int len,const void *key);
  };
  
  } // namespace ZeroTier
  
  #endif
  