## 5 Blockchain-Based Supply Chain Security Solutions and Integration Models
### Data Privacy with Zero-Knowledge Proof (ZKP) and Confidential Transactions
#### 5.3.2 Architectural Model for Cross-Chain Supply Chains and Smart Contract Design
Regulatory and ethical challenges, such as the absence of unified legal frameworks, continue to limit the broader adoption and deployment of these systems [163]. Many implementations in this field remain at the proof-of-concept stage, lacking scalability and long-term viability. Some projects have been critiqued for prioritizing funding appeal over addressing underlying systemic issues [164]. These initiatives highlight the potential of blockchain to enhance security, traceability, and data integrity in refugee logistics and identity management. However, challenges related to interoperability, adoption barriers, and regulatory compliance persist. Table 12 presents key contributions and gaps identified across the reviewed studies. \begin{table}
\begin{tabular}{p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt} p{42.7 pt}} \hline \hline
**Ref. ** & **Application Focus** & **Blockchain Role** & **Key Technologies** & **Technical Challenges** & **Security Feature** & **Traceability Feature** & **Data Integrity Feature** \\ \hline \multirow{4}{*}{[160]} & Refugee identity via SSI & Self-sovereign identity (SSI) & GaaP architecture, wallets for refugees. & GaaP architecture, digital ID. & Scalability, cross-organization integration. & Private key operation, user-controlled access. & Credential assistance and access logs. & Immutable storage of verified ID records. \\ \cline{1-1} \cline{2-10}  & Refugee identity via SSI (Ukraine; Switzerland). & Self-sovereign identity (SSI) & GaaP architecture, wallets for refugees. & Scalability, architecture, digital ID. & Private key organization integration. & Credential assistance and access logs. & Immutable storage of verified ID records. \\ \cline{1-1} \cline{2-10}  & &



#### 6.1.3 Pandemic and Medical Relief Logistics

The COVID-19 pandemic exposed critical vulnerabilities in global medical supply chains, including widespread shortages, delays, and the proliferation of counterfeit medical products. In these frameworks, blockchain technology has been rapidly explored and adopted as a means to improve the security, traceability, and data integrity of pandemic-related logistical processes. From vaccine distribution and personal protective equipment (PPE) tracking to cold-chain monitoring for pharmaceuticals, blockchain-enabled systems demonstrated measurable impacts in enhancing transparency and coordination across global and local supply networks [165; 166]. Several studies investigated blockchain's role in maintaining cold-chain compliance, particularly for temperature-sensitive supplies. For example, one system implemented smart contracts to automatically verify that pharmaceuticals were transported under proper conditions, logging every event on-chain and issuing alerts upon threshold violations [165; 166]. In other cases, smart contracts were integrated with QR codes and IoT sensors to confirm supply authenticity and enforce regulatory compliance [167]. These efforts notably improved stakeholder trust, auditability, and response times. In addition, blockchain has been applied to support vaccine supply network design, helping address route instability and fluctuating demand across logistics partners [168]. Emerging approaches also explored the fusion of AI with blockchain to forecast supply demands using social data, contributing to more responsive pandemic logistics strategies [11]. From a security perspective, blockchain provided protection against data tampering and the unauthorized manipulation of supply records. For traceability, distributed ledger technologies ensured continuous visibility from manufacturers to points of care, enabling real-time validation of origin, handling, and delivery milestones. In terms of data integrity, immutability and consensus mechanisms facilitated transparent, verifiable, and auditable records: critical features for post-crisis evaluation and policy development.