## 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
Meanwhile, on the Ethereum side,  
Figure 8: Conceptual cross-chain architecture for blockchain-based supply chain management, illustrating how permissioned and permissionless platforms can securely exchange data through interoperability layers. In this example, Hyperledger Fabric and Ethereum are connected via a Chain-link bridge with zero-knowledge proof validation, supporting the principles of security, traceability, and integrity (STI). outward-facing processes, including _requestOrder_(), _confirmDelivery_(), and _releasePayment_(), are executed as smart contracts, often triggered by cross-chain events and external data sources, such as oracles or zero-knowledge proof verifiers. These components, as further detailed in Algorithms 1 through 5, are designed to work synergistically through the Chainlink bridge, which orchestrates secure data exchange and enables trustless validation between disparate networks. By linking smart contracts and chaincode modules across blockchain layers, the system not only ensures interoperability and traceability but also satisfies core requirements of security, traceability, and integrity (STI) in distributed SCM systems. What follows is a breakdown of five core functions, each of which corresponds directly to a process stage depicted in Figure 8. These algorithms are intentionally abstracted for clarity, yet they reflect realistic logic structures used in practical blockchain applications. Their role in managing decentralized operations is explained below, prior to the pseudocode listings. The following pseudocode routines illustrate typical operations executed on each side of the system. These are simplified abstractions, serving to demonstrate how logic components are structured around key supply chain events. The integration of oracle inputs and cryptographic proofs, such as ZKPs, further strengthens trust and auditability. Algorithms 1 and 2 are executed on the permissioned blockchain (Hyperledger Fabric), modeling the internal logic of supply chain actors such as suppliers or auditors. ```
Input: orderID, productID, quantity Output: Boolean if not isAuthorized(caller) then return false endif order \(\leftarrow\) getOrderDetails(orderID) iforder.productID\(\
eq\)productID or order.quantity\(\
eq\)quantity then return false endif ifcheckInventory(productID)\(<\)quantitythen return false endif logAudit Trail(\"Order verified\", orderID) return true
```  
**Algorithm 1**_verifyOrder_()  
Algorithm 1: _verifyOrder_() corresponds to the initial step in the supplier network, where an internal chaincode function validates incoming orders. It ensures that the caller is authorized, the product and quantity match expectations, and sufficient inventory is available. This verification step is essential for establishing trust before engaging in cross-chain interaction. Algorithm 2: _logProduction_() reflects the supplier's internal process of logging production data on a permissioned ledger. This function records batch-specific metadata with a timestamp, providing a verifiable trace for downstream auditing. In Figure 8, this corresponds to the flow of production data from the supplier to the bridge. Algorithms 3-5 represent public smart contracts deployed on the Ethereum blockchain. ```
Input:\(batchID\),\(productID\),\(timestamp\) Output:Boolean if\(batchID\)Exists(\(batchID\))then returnfalse endif iftimestamp=nullthen returnfalse endif productionRecord\(\leftarrow\){ batchID: batchID,\(productID\):\(productID\),\(timestamp\): timestamp,\(status\): \"Completed\" } success\(\leftarrow\) ledger.append(\(productionRecord\)) ifsuccess=falsethen returnfalse endif returntrue
```  
**Algorithm 2**_logProduction()_  
Algorithm 3: _requestOrder()_ is executed on the public blockchain side, where a retailer (or other requester) initiates an order. By emitting a verifiable event and updating the requester's status, this function creates a signal that can be captured by the bridge and verified against internal order records. Algorithm 4: _confirmDelivery()_ captures the delivery validation phase.