## 1 Introduction  
Data has been the center of all innovations in the technology industry. This has encouraged various organizations and vendors to implement technologies that allow interconnectivity to establish communications with different services. One of the main technologies that hassupported this movement is blockchain. Blockchain has been utilized to decentralize communications between different clients while maintaining anonymity and immutability in a trustless environment with no central authority. Blockchain enthusiasts have been proposing blockchain for different types of services and solutions. One of the proposed solutions for adopting blockchain capabilities is the paradigm of Internet of Things (IoT). Despite blockchain's resilience and tamperproof capabilities, there have been some privacy and trust concerns raised due to its transparency. This research paper explores the privacy issues associated with the use of blockchains in Industrial Internet of Things (IIoT) solutions. Specifically, this paper explores the use of Ethereum blockchain in a proof of concept (PoC) environment while we perform threat modeling of external and internal threats as part of our research investigations. The results and outcomes from the experiments performed show clear issues with the privacy of the transactions occurring between the nodes in the blockchain, and present serious security risks to critical IIoT environments [1]. Encrypting sensitive information is the primary and essential strategy in cryptography when it comes to patient history details. The digital healthcare system is considered as the platform for transferring and receiving patient health records [2]. However, the existing healthcare systems lack security techniques, as most of them lack proper access control and encryption mechanisms. The distribution of healthcare data to authorized users is the critical requirement of efficient healthcare. More importantly, blockchain provides a peer-to-peer and decentralized network system. In general, blockchain can be classified into three different categories, namely, private, public, and consortium blockchain. It is a permission- and consortium-managed blockchain, which means all peers are known in the network. It provides trust and security to all the parties involved. Hyperledger Fabric is not domain-specific, and it supports Java, Go, Node.js, etc., for creating contracts and networks applications [3]. Several searchable encryption (SE) methods exist to provide a solution to the problems mentioned above, but they are not as efficient regarding flexibility and anonymity. SE can be categorized into different types based on several parameters such as single-write (SW), multiple-write (MW), single-read (SR) and multiple-read (MR) strategies. However, all searchable encryption approaches are inefficient when deploying to the cloud or server-based architecture systems. One of the most promising and secure approaches to solve these issues is secure, searchable encryption (SSE), which enables the users to encrypt the data at their side without the involvement of a third party. Secure, searchable encryption can be divided into two groups, named asymmetric SSE and symmetric SSE. Our proposed extended secure searchable encryption (ESSE) is based on the motivation of [PERSON] et al. [4]. [PERSON] et al. proposed the idea of an obvious cross tag (OXT) searchable mechanism. The idea of OXT is to distribute all master keys among the users to take more advantage of the protocol. The problem with OXT is the key loss or collusion attack, which make it more prone to vulnerabilities. Our proposed approach is more resilient to active collusion attacks, and key-loss situations [5]. Moreover, our proposed method can be applied to different platforms such as social media, fog computing, and other IoT-based applications [6]. In the Internet of Things, data is gathered via wireless networks and numerous physical sensors and analyzed in real time. The data gathered and analyzed is used to operate the actuators [7].