This repository contains the sources of my bachelor thesis where I developed a etherum based blockchain prototype to enhance the chain of custody and to make it possible for an exemplary organization to check their supply chain against the rules of the "Lieferkettengesetz".

The supply chain of the exemplary organization consists of 4 tiers and multiple suppliers. Every entity has an associated wallet and can interact with the blockchain prototype to simulate a supply chain. Physical goods are represented using a digital twin that moves along the supply chain as the phyiscal good does. This digital twin is realised using a ERC-721 token. The following graphic should give an overview of the situation:

The prototype consists of the following parts:

• a truffle project
• an ethereum blockchain provided by ganache
• a Node-RED project to visually interact with the blockchain

The following screenshot shows an example flow with multiple nodes defined in the Node-RED project:

The blockchain has 20 associated accounts with predefined roles. The following table displays the addresses, the roles and the meaning behind the accounts:

There are 4 Smart Contracts to simulate a supply chain:

• ChainOfCustodyToken: The token that is the digital twin for physical goods. Is used to mint new tokens and to transfer the tokens between entities
• Control: Enables the controllers to start and manage a control made for one of the entities
• LKGRegistry: The base registry that is the main data store. It holds references to all entities and their states. Is used to query circumstances or to administrate the supply chain
• RBAC: The contract that defines the roles (Role Based Access Control). It is not necessery to directly interact with it, because the 20 accounts already have the necessary roles

The Node-RED project contains a flow for every contract. Every flow has a description provided:

After you installed the prototype, you can interact with it in the following way using Node-RED:

• Start a control for an entity by using the Control flow. Make sure that the controller is one of the accounts with the Control role
• Simulate the producing and processing of goods with their digital twin by minting and transferring tokens in the Chain Of Custody Token flow. It must be noted that at the beginning, all accounts have a GSE status of false. This means that the accounts have not accepted the rules from the "Lieferkettengesetz" and every transaction with tokens made by these accounts adds a NonGSETransaction entry to the corresponding accounts. To set the GSE status to true, use the LKG Registry flow and execute the Acknowledge "Grundsatzerklärung" subflow
• Query information about entities, controls and non gse transactons using the LKG Registry flow

(Make sure that you have installed Node.js)

• First, install truffle from https://www.trufflesuite.com/truffle
• Then install ganache from https://www.trufflesuite.com/ganache
• Then install Node-RED locally as described in https://nodered.org/docs/getting-started/local
• Then make sure that you have the sources from this repsoitory and the package "node-red-contrib-ethereum" available locally

The nodes to interact with an ethererum blockchain are in the "node-red-contrib-ethereum" package and need to be added to your Node-RED installation. For this:

• Locate the .node-red directory on your system. It is usually located in your user directory. If not, then make sure that you start Node-RED before checking again. Node-RED can be started with the following command:

node-red

• Then run the following command from inside the .node-red directory:

npm install [path to the location of node-red-contrib-ethereum sources]

• Now start Node-RED and use to URL from the start command (usually http://127.0.0.1:1880) to check if the following nodes are present:

Now you need to set up a new ganache workspace that hosts your local ethereum blockchain.

• Open Ganache and select "New Workspace"
• In the "Workspace"-Tab choose a name and then click on the Add Project button to link a new truffle project. In the dialogue, choose the truffle-config.js from this repository

By adding this truffle project, you are able to see information in ganache such as smart contract addresses later on

• In the "Server"-Tab make sure that you set the Network ID to 4444. Otherwise Node-RED will not be able to connect to your blockchain
• In the "Accounts & Keys"-Tab set the number of total accounts to 20 and replace the choosen Mnemonic with the following:

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This Mnemonic is used by ganache to create the addresses. This makes sure that you have the same addresses as me

• Click on "Save Workspace"

Now you need to deploy the smart contracts to ganache, so they are available. The file migrations.jscontains the needed logic to deploy the contracts and also set's up the needed roles for the different addresses.

• Run the following commands from the directory that contains the truffle-config.jsfrom this repository:

truffle compile --all

truffle migrate --network ganache

The migrate command should display something like this:

• Depending on your system, this takes some minutes to be handled by ganache. It can occur that ganache becomes unresponsive after those two commands
• Now check the contracts tab in ganache and make sure that there are at least 5 deployed contracts: ChainOfCustodyToken, Control, LKGRegistry, Migrations, RBAC

Now you need to import the flows for the Smart Contracts to your Node-RED installation:

• In Node-RED go to "Import" and import the flows.jsonfile from this repository. It's inside the flows folder
• Restart Node-RED and you're done