## 5 Academic Efforts to Blockchain-Based Supply Chain Management:
### Efforts against Computational Attacks
#### 5.2.1 Security of Transactions and Operations  
Since blockchain transactions actually implement a contract among various stakeholders, therefore, it is critically important to ensure that the encoded contracts are compliant with desired directives/policies and are privacy-aware and secure. To ensure traceability and privacy in logistics, an effort has been made in developing a flow-shop scheduling mechanism using blockchain [52]. Also, to ensure transaction compliance among cryotcurrencies, another solution is developed for a voucher based compliance mechanism [54]. Furthermore, to achieve traceability and privacy among real-estate agents, a decentralized coordination based security mechanisms have been implemented [59]. For instance, [PERSON] et al., [53] designed 'Ekiden', which is a system to address lack of blockchain inherited confidentiality and poor performance of smart contracts. To this end, the system combines blockchains with trusted execution environments (TEEs). Ekiden architecture separates consensus mechanism from smart contract execution, enabling efficient TEE-backed confidentiality-preserving smart contracts and high scalability. The system-prototype outperformed the Ethereum mainnet by 600\(\times\) increased throughput and 400\(\times\) reduced latency with 1000\(\times\) lesser cost. Moreover, the system identifies and treats the pitfalls arising from the integration of TEEs and blockchains. Handling TEEs and blockchains separately guarantees stronger security, but their integration endangers new attacks. For example, in naive designs, privacy in TEE-backed contracts can be jeopardized by forgery \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Paper** & **Application Areas** & **Target** & **Key** & **Affected** & **Potential Attack** \\  & & **Operations** & **Contributions** & **Requirements** & **Mechanisms** \\ \hline \multirow{3}{*}{[52; 53; 54; 59; 60; 61]} & Healthcare prediction, & \multirow{3}{*}{\begin{tabular}{c} Healthcare prediction, \\ Financial credit scoring, \\ Smart buildings \\ \end{tabular} } & Transaction privacy and compliance & Flow shop scheduling, & Traceability, & Execution modification \\  & & & & Decentralized coordination & Privacy & (rewriting attacks) \\ \hline \multirow{3}{*}{[53; 55; 56; 57; 58; 62]} & \multirow{3}{*}{\begin{tabular}{c} Real-state, \\ Investors \\ \end{tabular} } & \multirow{3}{*}{\begin{tabular}{c} Vulnerability detection \\ in smart contracts \\ \end{tabular} } & \multirow{3}{*}{\
\begin{tabular}{c} Fairness, \\ Transfer amount vs required \\ amount, \\ Transaction disorder, \\ Non-validated arguments, \\ Exception handling, \\ Overflow and Underflow \\ \end{tabular} } & \multirow{3}{*}{
\begin{tabular}{c} Traceability, \\ Transparency, \\ Frequency \\ Execution modification \\ \end{tabular} } \\  & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Handling Computational Attacks—Academic Efforts. of blocks, a seemingly unrelated attack vector. The insights learned from Ekiden are of great importance in integrated and hybrid TEE-blockchain systems. Still, the Ekiden's preserve the limited end-to-end privacy to data across the supply chain journey, particularly when the journey include cross-chains. In [52], a design model of smart contract for the supply chain with multiple logistics service providers was proposed. Authors tested the model to show that the problem can be presented as a multi-processor flexible flow shop scheduling problem. The model introduced a \"virtual operation\" that allowed to describe the execution of physical operations inside the start and completion of cyber information services. The constructed model has been tested in an experimental environment that constitutes an event-driven dynamic approach to task and service composition when designing the smart contract. The model also uses state control variables that enables operations status updates in the Blockchain that in turn, feeds automated information feedback, disruption detection, and control of contract execution.