# Security Establishment in ADS-B by Format-Preserving Encryption and Blockchain Schemes
## 6 Conclusions  
Deploying secure ADS-B leads to the improved protection of data and information against potential threats to ADS-B, including eavesdropping, message injection, and deletion. This paper assesses the FFX algorithm's features and the possibility of its implementation in both Simulink and C++ with SDR BladeRF for both ADS-B Out/In systems. Real flight data entropy, serial correlation, and plain and cipher data correlation were selected as metrics with which to evaluate the system security level for various scenarios. The FFX \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Category** & **Data Integrity** & **Location** & **Confidentiality** & **Authentication** & **Remarks** \\ \hline Public key & Y & Y & Y & Y & Adding extra load \\ Message Authentication Code & N & N & N & Y & Adding extra load \\ SADS-B with PSK & N & N & N & Y & Adding extra load \\ Holistic framework & Y & Y & Y & Y & Adding extra load \\ SVM & P (detection injection) & N & N & N & P = partially addressed \\ Physical layer protection & P (detection injection) & Y & N & N & P = partially addressed \\ supervised deep learning & P (detection injection) & Y & N & N & P = partially addressed \\ FPE \& Blockchain (this paper) & Y & Y & Y & Y \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Security requirement comparison of various solutions. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
\begin{tabular}{c} Yes \\ Requires key management, agreement modification \\ Requirement key management, agreement modification \\ Requirement key management, additional software \\ Requirement key management, additional software \\ Requirement key management, additional software \\ Requirement key management, additional software \\ Requirement key management, additional software \\ Requirement key management, additional software \\ \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of various solutions. algorithm provides sufficient diffusion and confusion to protect sensitive information in ADS-B data. Moreover, the ADS-B system capacity is not reduced, as message data length is preserved. In addition, the effects of SADS-B on standard ADS-B performance were explored. Although the SADS-B sensitivity performance was not altered, its computational time was increased. As explained in the discussion section, SADS-B Out's performance is not impacted by this computational time increment. The SADSB In computational time could be enhanced by applying a threading feature on the FFX algorithm to alleviate processing time issues due to cascading blocks. The novelty of this work is summarized as follows:  
* Investigating the FFX algorithms' impact on ADS-B messages and how its utilization brings about security advantages to ADS-B sensitive data. * Designing and implementing FFX algorithms in an SDR system (BladeRF) which is compatible with the standard ADS-B for both the transmitter and receiver. * Offering a new solution for the key exchange for encryption via the blockchain scheme
* Experimenting with lab and flight tests without any degradation in standard ADS-B performance and key requirements. It might be argued that, by applying FPE encryption, ADS-B's desirable openness feature will be lost, and this is mostly true. However, aviation authorities can implement the FFX algorithm as a contingency response during active attack circumstances. This would protect ADS-B systems from any serious consequences due to attacks. Although the work examined SADS-B Out/In in an operational environment, performing experimental tests on a large scale with a high number of various aircraft to validate its performance is required to convince the aviation industry to utilize the advantages of SADS-B. In addition, it is suggested to establish the experimental procedure for examining the proposed system behaviour against the various threats and attacks. [PERSON] was responsible for the algorithm design, prepared the literature review, and wrote the contents of the paper.