# Enhancing Resilience in Digital Twins: ASCON-Based Security Solutions for Industry 4.0
## 3 Proposed Solution
### Implementation Approach  
To validate the applicability and effectiveness of our proposed solution, which relies on lightweight cryptographic algorithms, we conducted an experiment employing an ESP32 as a resource-constrained IoT device and Ditto as an open-source framework for constructing Digital Twins. We chose the ESP32 boards for the experiment because they are known for their cost-effectiveness and low-power characteristics in the market ([21]). Furthermore, we selected Ditto based on its being easily customized through Java-based plugins and its extensive usage within the open-source community. Figure 1 illustrates the research experiment setup. The measurement tool in the research experiment set-up in Figure 1 was used for performance analysis.  
Payload encryption is a technique for ensuring message confidentiality at the application level. In other words, this approach can be used to establish an end-to-end secure channel between the sender and receiver at the application level to provide confidentiality over transmitted data. However, in this paper, we extend the scope beyond message confidentiality and introduce the use of the ASCON ([4]), a family of authenticated encryption with associated data (AEAD) algorithms, to provide both message authenticity and confidentiality [4].  
We chose to utilize the MQTT protocol for three reasons. Firstly, MQTT is a commonly used communication protocol in IoT applications. Secondly, it is a lightweight messaging protocol, that can be configured and programmed to support payload encryption using any encryption algorithm, like the algorithms we chose for comparison, namely ASCON and AES-GCM (family of AEAD based on AES). Thirdly, Eclipse Ditto [20] supports the MQTT protocol, i.e., through Eclipse Mosquitto [22], as a connection.  
To assess the practicality and efficiency of our proposed solution, centered around lightweight cryptographic algorithms, an experiment was conducted using an ESP32 device, a cost-effective and low-power IoT board [21]. We employed Ditto, an open-source framework for Digital Twins, recognized for its customization capabilities through Java-based plugins and widespread usage in the open-source community. The experimental set-up is depicted in Figure 1.  
Traditionally, payload encryption is utilized to ensure message confidentiality, establishing a secure channel between sender and receiver at the application level. In this study, we expand this concept by introducing ASCON, a family of authenticated encryption with associated data (AEAD) algorithms [4]. ASCON not only ensures message confidentiality but also guarantees message authenticity, enhancing security measures. The choice of MQTT protocol was deliberate for several reasons. Firstly, MQTT is widely used in IoT applications. Secondly, it is a lightweight messaging protocol that can be configured to support payload encryption using various algorithms, including ASCON and AES-GCM (an AEAD algorithm based on AES), which we utilized for comparison. Lastly, Eclipse Ditto, supported by Eclipse Mosquitto [22], integrates seamlessly with the MQTT protocol, enabling a robust connection for secure data transmission [23]. This strategic selection of  
Figure 1: Research experiment set-up.  
components allowed us to thoroughly evaluate the effectiveness and practicality of our proposed approach.