code: def get_sign_key(exported_session_key, magic_constant):
      
  
      sign_key = hashlib.md5(exported_session_key + magic_constant).digest()
  
      return sign_key
docs: 3.4.5.2 SIGNKEY
  
      @param exported_session_key: A 128-bit session key used to derive signing and sealing keys
      @param magic_constant: A constant value set in the MS-NLMP documentation (constants.SignSealConstants)
      @return sign_key: Key used to sign messages