# Potential of Homomorphic Encryption for Cloud Computing Use Cases in Manufacturing
###### Abstract  
Homomorphic encryption enables secure cloud computing over the complete data lifecycle. As so-called in-use encryption methodology, it allows using encrypted data for e.g., data analysis--in contrast to classic encryption methods. In-use encryption enables new ways of value creation and an extensive use of cloud computing for manufacturing companies. However, homomorphic encryption is not widely implemented in practice yet. This is mainly since homomorphic encryption has higher computation times and is limited regarding its calculation operations. Nevertheless, for some use cases, the security requirements are a lot stricter than, e.g., timeliness requirements. Thus, homomorphic encryption might be beneficial. This paper, therefore, analyzes the potential of homomorphic encryption for cloud computing in manufacturing. First, the potential and limitations for both classic and homomorphic encryption are presented on the basis of a literature review. Second, to validate the limitations, simulations are executed, comparing the computation time and data transfer of classic and homomorphic encryption. The results show that homomorphic encryption is a tradeoff of security, time, and cost, which highly depends on the use case. Therefore, third, manufacturing use cases are identified; the two use cases of predictive maintenance and contract manufacturing are presented in detail, demonstrating how homomorphic encryption can be beneficial.  
homomorphic encryption; cloud computing; manufacturing +
Footnote †: journal: Cybersecurity and Privacy  
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level of data security depends on the state of data during cloud computing [1; 13]. The literature distinguishes among three different states of data: data in storage, data in transit, and data in use [13; 14; 15]. Data in storage and data in transit have been protected with classical methods of cryptography for years. However, classical encryption methods cannot be applied for data in use, as they do not allow executing calculations with cipher text. Thus, data are decrypted in the cloud to be used for analyses and, therefore, revealed to the cloud provider. This consequently results in the abovementioned security risks [13; 16]. To solve these risks, in-use encryption technologies are the focus of current research. They allow calculations with encrypted data. The in-use encryption technology \"homomorphic encryption\" promises a high potential to solve security risks within cloud computing [14; 15; 17; 18]. It requires, however, more computing efforts than classic encryption technologies and is limited regarding certain calculation operations [19].  
Considering both the advantages and the current challenges of homomorphic encryption, the goal of this paper is to evaluate the potential of homomorphic encryption for cloud computing use cases in manufacturing. Therefore, Section 2 presents the fundamentals within this field of research. Section 3 presents encryption for cloud computing, analyzing the limitations of classic encryption, as well as the potential and challenges of homomorphic encryption. Section 4 presents manufacturing use cases for cloud computing in manufacturing and analyzes their improvement when deploying homomorphic encryption. Section 5 summarizes the findings and gives an outlook for further research requirements. Sections 3.3 and 4 represent the main contribution and novelty of this paper, as the paper is the first to simulate, in detail, homomorphic encryption's applicability for manufacturing, along with manufacturing use cases.