# Internet of Things and Blockchain Integration: Security, Privacy, Technical, and Design Challenges
## 3 RQ 1 and RQ 2--Current Challenges and Recommendations to Enhance BIoT Integration
### BC-Based Privacy
#### 3.2.1 Identity Privacy  
When it comes to privacy, anonymity is a huge worry for BC platforms, and it may be a key deciding factor in which platform to choose. The fundamental challenge is that all transactions are openly documented and accessible to anybody, on public platforms [164]. The selected anonymity strategy fails if the transactions can be connected to their owners or if the owners' identities are revealed [127]. The owners of transactions should not be identified by any participants in the network in an ideal scenario [62]. BIoT shares transactions with other parties and will identify its users by public or hash key, which means that, if attackers analyze the traffic and transactions of the BC, they will \begin{table}
\begin{tabular}{l l l l} \hline \hline
**Category** & **Challenge** & **Best Practice** \\ \hline \multirow{8}{*}{Privacy} & & \(\bullet\) & Change address approach, Zerocash, Zerocoin, and Monero in Bitcoin \\  & & \(\bullet\) & Zcash and zkSNARK in Ethereum \\  & Identity [10, 26, 46] & \(\bullet\) & Identity control service in HLF \\  & & \(\bullet\) & User permissions in Multichain \\  & & \(\bullet\) & Techniques such as ring and blind signatures, pseudonymization, \\  & & & homomorphic commitments, and zero-knowledge proof \\ \hline \multirow{8}{*}{Privacy} & & \(\bullet\) & Hawk, DHT, and splitting data in Bitcoin \\  & & \(\bullet\) & Encryption in Ethereum \\  & Data [10, 25, 46] & \(\bullet\) & User permissions in Multichain \\  & & \(\bullet\) & Identity control service in HLF \\  & & \(\bullet\) & Off-chain data saving \\  & & \(\bullet\) & Confidential transactions, homomorphic encryption, BC segregation \\ \hline \multirow{2}{*}{Location [10, 57]} & \(\bullet\) & BC segregation \\  & & \(\bullet\) & Stealth addresses (one-time address) \\ \cline{1-1}  & & \(\bullet\) & Pseudonymization technique \\ \hline \multirow{2}{*}{Usage [10, 26]} & \(\bullet\) & BC segregation \\ \cline{1-1}  & & \(\bullet\) & Cryptographic commitment methods and Ouroboros Crypsinous BC \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Recommendations for reducing the negative impact of privacy challenges. be able to identify the actual identity of the users [112]. Furthermore, the devices that will be used as nodes also present another privacy challenge. These node devices may vary in terms of security policies implemented due to limitations in specifications, capabilities, manufacturer restrictions, or challenges in the configurations and programming [63]. Existing systems have used a variety of tactics with varying degrees of anonymity. Because the identity of the users is unknown and should not become known, public BCs necessitate a higher level of privacy [46]. To improve the amount of anonymity, Bitcoin uses the change address approach, which involves using various addresses for various transactions [113]. Zerocash and Zerocoin, two popular proposals to address Bitcoin's anonymity problem, suggest that Bitcoin extensions have unidentified transactions, obscuring the sender, recipient, and information itself. On the other hand, to make transactions undetectable, Monero uses a ring of signatures., making it impossible to link them to a specific person or machine [46]. The Ethereum team is working with Zcash to implement a zero-knowledge succinct non-interactive argument of knowledge (zkSNARK) transaction mechanism. The method allows you to conceal a transaction and keep it fully confidential [62]. HLF offers a control service for identity and access using private channels to enable privacy control on BC networks. Users may regulate and restrict access to their shared information in the network [133]. Members of the network are identified by their public identities; however, they are not required to be aware of the information exchanged in the network [46]. Pseudonymization is the dispensation of personal data in such a way that it can no longer be linked to a specific person without the help of supplementary information.