## 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
After the shipment is completed, an oracle fetches delivery proof from an external system. This function verifies that the data are authentic before confirming delivery and emitting a confirmation event. This step strengthens traceability by linking physical delivery data with on-chain commitments. ```
Input:\(productID\),\(quantity\) Output:Boolean if\(productID\)=null or quantity\(\leq 0\)then returnfalse endif ifnotisWhitelisted(\(sender\)) then returnfalse endif emitOrderRequested( sender, productID, quantity) status[\(sender\)] \(\leftarrow\) \"PendingVerification\" returntrue
```  
**Algorithm 4**_requestOrder()_  
```
Input:\(productID\),\(quantity\) Output:Boolean if\(productID\)=null or quantity\(\leq 0\)then returnfalse endif if notisWhitelisted(\(sender\)) then returnfalse endif emitOrderRequested( sender, productID, quantity) status[\(sender\)] \(\leftarrow\) \"PendingVerification\" returntrue
```  
**Algorithm 5**_requestOrder()_  
```
Input:\(productID\),\(quantity\) Output:Boolean if\(productID\)=null or quantity\(\leq 0\)then returnfalse endifififnotisWhitelisted(\


```
Input: orderID, deliveryProof Output: Boolean iforderID = null or deliveryProof = null then return false endif ifverifyOracle(deliveryProof)=false then return false endif endif \(deliveries[orderID]\leftarrow\) \"Confirmed\" emit DeliveryConfirmed(orderID) return true
```
**Algorithm 4**_confirmDelivery()_
```
Input: orderID, zkProof Output: Boolean iforderID = null or zkProof = null then return false endif ifverifyZKP(orderID, zkProof) = false then return false endif \(amount\leftarrow\) calculateAmount(orderID) \(recipient\gets supplier[orderID]\) ifrecipient = null or amount \(\leq 0\)then return false endif success \(\leftarrow\) transfer(recipient, amount) ifsuccess = false then return false endif emit PaymentReleased(orderID) return true
```

**Algorithm 5**_releasePayment()_

Algorithm 5: _releasePayment()_ addresses privacy-preserving payments and represents the final phase in which a ZKP-enabled validation is required before any payment is issued. After verifying the zero-knowledge proof associated with order fulfillment, the contract initiates the payment transfer. This step encapsulates both integrity and privacy, with the payment being conditional on verifiable fulfillment, without exposing sensitive logistical details. ## 6 Sectoral Supply Chain Applications: Areas Secured by Blockchain Technology

Blockchain technology is increasingly adopted to ensure supply chain security across various industries. In sectors such as logistics, agriculture, healthcare, pharmaceuticals,food, and retail, blockchain addresses critical security concerns such as data integrity protection, counterfeit prevention, ensuring traceability, and secure data sharing. Smart contracts, distributed ledger architectures, and cryptographic verification mechanisms make supply chain processes more secure and transparent. Table 10 summarizes the security issues and proposed solutions addressed by blockchain-based approaches within various industry-specific supply chains.