A METHOD ENCODING TRANSMITTED MESSAGES IN THE ADS-B SYSTEM USING A CELLULAR AUTOMATIC

Abstract

The purpose of the study is to develop a method for encoding of transmitted ADS-B messages
between aircraft. The open format 1090ES of transmitted data is critical in terms of carrying
out various types of attacks that can lead to a violation of the safety of aircraft operations.
The work is aimed at using means of encoding and decoding messages with a private key. Research
methods are based on the application and development of streaming data encryption using
one-dimensional cellular automata. They operate as a generator of pseudo-random sequences that
transform the elementary states of a cell of a one-dimensional cellular automaton based on typical
hardware-oriented operations. The processes of encoding and decoding data fields are based on
an analytical expression using typical logical operations (or, xor). This property allows parallel
processing of message data fields. The result is the created method for ensuring the protection of
transmitted data, additionally encoding on transmission and decoding on message reception.
A distinctive feature of the method is the preservation of the protocol forma. The method uses a
one-dimensional cellular automaton that encodes and decodes the target fields (coordinates, heading,
etc.) using a pseudo-random number generator. The developed method belongs to the class of
hardware-oriented methods. Critical for encoding and decoding properties of periodicity of data
fields and key length are eliminated by choosing an initial irrational value and organizing the
“streaming” work of the encoder. If the encoding automaton is running in streaming mode, the
current value depends on the history of some depth, determining the length of the "automatic key"
from the ADS-B message will be algorithmically impossible due to data loss. The linear complexity
of the method allows you to perform transformations at the data rate. Conclusion: the development
of hardware-oriented methods of data encoding makes it possible to increase the efficiency of
using the ADS-B system by counteracting various types of destructive actions.