## 4 Structure of SFrame Video Conferencing System
### SFrame's Key Management System
Since the On-Nara video conferencing system is not publicly accessible, our implementation was restricted. Thus, our comparison was limited to the protocol level. Currently, the GPKI system uses RSA 2048 public key cryptography for key exchange and authentication. Therefore, we compared the cycles of the NTRU KEM with RSA 2048, which is used in GPKI. According to NIST's documentation, RSA 2048 has a 112-bit security level [16]. For a fair comparison, we chose 'ntruhps2048509', which has a similar 128-bit security level [14]. Since the GPKI is not open to the public, we referred to the RSA 2048 and 'ntruhps2048509' that are benchmarked in eBACS for our experiment. A comparison of these two protocols is presented in Table 3[17]. Eventually, we found that NTRU KEM is slightly slower than RSA 2048 for encapsulation. In contrast, it was significantly faster than RSA 2048 for decapsulation. Since CRYSTALS-KYBER is faster than NTRU, we expect more accelerated performance when applying CRYSTALS-KYBER to GPKI. For NTRU KEM, we implemented this protocol using an open source from NIST's PQC standardization contest's third round. We used an Intel Core i7-10700K 3.80 GHz with Windows 10 in 64-bit mode and compiled the code through _rdtsc() to measure the CPU's cycles. As a result, we derived a value of 0.66 megacycles/operation for encapsulation, and 1.41 megacycles/operation for decapsulation. It should be noted that the experimental environment differed from eBACS. The comparison between the proposed PQC KEM and other systems is presented in Table 4. PQC KEM for GPKI provides user authentication through a government top-level CA. Meanwhile, Zoom and SFrame provide it by a commercial sector CA, which is less reliable than that of a government. Furthermore, the PQC KEM for GPKI uses PQC for key agreement, offering a quantum-safe level. In contrast, commercial sector systems apply elliptic curve cryptography, which doesn't provide quantum safety. Both systems, however, provide E2 EE security. In the end, there are no international standards for security requirements of video conferencing systems. In Korea, standardization work is underway by the Telecommunica \begin{table}
\begin{tabular}{c c c} \hline \hline
**Property** & **Zoom and SFrame** & **PQC KEM for GPKI** \\ \hline User Authentication & By commercial sector CA & By government \\ \hline Key Agreement & Elliptic curve cryptography & Post-quantum cryptography \\ \hline Quantum Safe & \(\times\) & \(\Circle\) \\ \hline E2 EE & \(\Circle\) & \(\Circle\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison between other systems and PQC KEM for GPKI. \begin{table}
\begin{tabular}{c c} \hline \hline  & **NTRU KEM** \\  & **(ntruhps2048509)** \\ \hline
**Encapsulation** & 20226 cycles & 23696 cycles \\ \hline
**Decapsulation** & 2120310 cycles & 38141 cycles \\ \hline
**Environment** & amd64; Comet Lake; \\  & 2019 Intel Core i3-10110U; 2 \(\times\) 2100 MHz \\ \hline
**Security level** & 112-bit & 128-bit \\ \hline
**Quantum Safe** & \(\times\) & \(\Circle\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison between RSA 2048 and NTRU KEM [17]. tions Technology Association (TTA). This standard is now being organized into four major categories: conference environment setup, user authentication, conference content protection, and conference progression. The E2 EE PQC KEM protocol proposed in Section 5.2 meets the security requirements of the TTA standard. ## 6 Conclusions

We examined and compared two representative video conferencing systems, Zoom and SFrame, focusing on their E2 EE capabilities. Both systems were found to meet the necessary feature requirements of E2 EE; however, there was a difference between Zoom, which uses a symmetric key method, and SFrame, which uses an asymmetric key method for encrypting and decrypting shared keys. To improve the security of E2 EE protocols in GPKI-based video conferencing systems that are not in the commercial sector, we propose the application of PQC KEM during the key exchange process.