# A Class of Perfectly Secret Autonomous Low-Bit-Rate Voice Communication Systems
## 7 Experimental Evaluation
### Comparison with State-of-the-Art QKD Methods
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Feature** & **LSP-Based Synthesizer** & **QKD Systems** \\ \hline \begin{tabular}{c} Randomness source \\ parameters and independent true randomness \\ \end{tabular} & \begin{tabular}{c} Artificially synthesized speech with LSP \\ parameters and independent true randomness \\ \end{tabular} & \begin{tabular}{c} Quantum states (e.g., photon polarization, \\ phase encoding) \\ \end{tabular} \\ \hline \begin{tabular}{c} Autonomy \\ \end{tabular} & \begin{tabular}{c} Fully autonomous; does not require an \\ external infrastructure \\ \end{tabular} & \begin{tabular}{c} Requires quantum hardware, optical links, \\ or satellite-based transmission \\ \end{tabular} \\ \hline \begin{tabular}{c} Synchronization \\ \end{tabular} & \begin{tabular}{c} Ensured by deterministic control over \\ speech synthesis \\ \end{tabular} & \begin{tabular}{c} Requires precise alignment of \\ quantum detectors \\ \end{tabular} \\ \hline \begin{tabular}{c} Scalability \\ \end{tabular} & \
\begin{tabular}{c} Easily deployable over existing \\ digital networks \\ \end{tabular} &
\begin{tabular}{c} Limited by quantum optical \\ infrastructure requirements \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Key generation and common randomness source. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Feature** & **LSP-Based Synthesizer** & **QKD Systems** \\ \hline \begin{tabular}{c} Hardware \\ Requirements \\ \end{tabular} & \begin{tabular}{c} Software-implemented; requires only a \\ standard vocoder \\ \end{tabular} & \begin{tabular}{c} Requires quantum transmitters, detectors, \\ and optical fiber/satellite links \\ \end{tabular} \\ \hline \begin{tabular}{c} Network \\ Compatibility \\ \end{tabular} & \begin{tabular}{c} Operates over existing VoIP, GSM, LTE, and \\ secure radio links \\ \end{tabular} & \begin{tabular}{c} Requires a dedicated quantum \\ communication channel \\ \end{tabular} \\ \hline \begin{tabular}{c} Real-World \\ Deployability \\ \end{tabular} & \
\begin{tabular}{c} Can be implemented on secure mobile and \\ tactical communication devices \\ \end{tabular} &
\begin{tabular}{c} Limited to specialized government, military, \\ and financial institutions \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Security guarantees and theoretical limits. Key Advantage: The LSP-based system provides common randomness generation without specialized hardware, making it significantly more practical and scalable compared to QKD. Key Advantage: The LSP-based synthesizer ensures continuous key generation synchronized with speech encryption rates, while QKD systems often struggle with lower key refresh rates, requiring buffering or hybrid encryption approaches. Key Advantage: Our LSP-based solution can be integrated into existing secure voice systems, whereas QKD demands costly and specialized infrastructure, limiting its practical use for low-bit-rate real-time speech encryption. Key Advantage: While QKD offers provable key exchange security, it does not inherently provide perfect secrecy for real-time speech without additional encryption. However, our approach directly enables perfectly secret communication in real time, eliminating reliance on additional cryptographic layers. Final Verdict: For a real-time, low-bit-rate, perfectly secret speech communication, the LSP-based artificial speech synthesizer is significantly more practical, autonomous, and scalable than QKD-based approaches. While QKD remains valuable for a high-security key exchange, it is impractical for direct application in real-time speech encryption due to infrastructure constraints and lower key refresh rates.