Associate Professor He Jing of Shanghai Ocean University, et al.: Construction of food cold chain traceability system based on quantum blockchain

Cold chain food has high requirements for time and environmental control in the whole process of production, transportation, storage and sales, and problems in one of the links may trigger food safety incidents
。 At present, the food cold chain is gradually showing a trend of multi-channel, multi-subject and networking, the traditional chain traceability system between the enterprises information asymmetry, traceability broken chain, traceability link centralization, information authenticity doubtful, government regulatory authorities can not effectively supervise and other problems are still serious, the construction of high-level food cold chain traceability system can effectively prevent food safety problems in advance and traceability after the fact, therefore, how to continuously improve the level of traceability through the development of efficient traceability technology has become an important
。

At present, as one of the cutting-edge technologies of information, blockchain technology has the characteristics of non-tampering, distribution, decentralization and traceability, and is highly valued
by national governments, enterprises and institutions and experts and scholars in various fields.
Many scholars combine blockchain technology with the Internet of Things, radio frequency identification, wireless sensor network, visualization technology, etc.
, which has promoted the wide application of blockchain in the construction of food traceability systems, but in the process of information transmission and processing, data may still be exposed or tampered with, resulting in a lack of
trust.
Quantum communication enables both parties to establish a key distribution channel with information theory security on a channel with unknown security, which enhances system security
to a certain extent 。 Therefore, He Jing and Hu Xinyue* from the School of Economics and Management of Shanghai Ocean University proposed the idea of building a food cold chain traceability system based on quantum blockchain, using the unconditional security advantages of quantum cryptography in quantum blockchain, consensus mechanism, smart contract and other technologies to empower the food cold chain traceability system, with the help of quantum key communication technology to complete the identity verification evaluation between nodes, replace the traditional blockchain asymmetric encryption of digital signatures, and verify by the whole network broadcast to ensure the security of data transmission of multiple nodes in the food cold chain network.
Enhance the trust between traceability subjects to solve the current problems of cold chain traceability, and provide reference and reference
for the efficient and sustainable development of the cold chain food traceability system.

1.
Blockchain and quantum blockchain

The technical principle of blockchain and its limitations

Blockchain is a distributed ledger technology that stores data in blocks and cryptographically connects data blocks in chronological order, and establishes a shared database in a decentralized network that does not rely on third parties or core institutions, and all user nodes can access, supervise and use this database
.
As shown in Figure 1, in the blockchain, transactions are generated between network nodes, the transactions are broadcast across the network, the receiving nodes package the transactions into a new block, the network nodes execute the consensus algorithm, and the verification results are broadcast to the whole network, and the data block is added to the blockchain through the
consensus verification of the whole network nodes.

In recent years, blockchain technology has been applied in many fields, but in the process of promoting its application, it has also exposed some limitations: 1) System performance and efficiency have gradually declined
.
Different blockchain types and platforms have certain limitations in user access and data capacity, and as the number of blockchain network nodes increases, data storage redundancy increases, the time required for person-to-person (P2P) network propagation, processing and verification of transactions is also prolonged, and the performance efficiency of the system will gradually decline
.
2) There is a system security crisis
.
PoW-based consensus process nodes have the ability to successfully tamper with and falsify blockchain data
by mastering more than 51% of the computing power of the entire network.
In addition, due to the characteristics of the blockchain distributed system, it is inevitable that there will be a delay in transactions, and once harmful information is written into the chain, it will spread quickly and is not easy to change, which brings great challenges
to information security supervision.
In addition, blockchain also faces the threat
of traditional "double-spend" and "fork attacks" and quantum computing.
3) The risk of
user privacy leakage.
The current blockchain is authenticated by the public and private keys, and there is still a certain degree of anonymity between transaction objects, but with the development of authentication technology, the cracking of the public and private key systems and the identification of data transmission users will be possible, and attackers can launch different forms of attacks at the network layer, transaction layer and application layer to obtain copies of data in more locations to achieve the purpose of
stealing privacy, analyzing block data, and extracting user portraits.

Quantum blockchain

Quantum and quantum blockchain: The basic unit proposed by quantum theory is qubits, with superposition and entanglement states, quantum entanglement is that no matter how far apart two particles are, they are not affected by space and do not need any connection, as long as the state of one particle changes, it can immediately make the state of another particle change accordingly; Superposition is the ability of a quantum system to be in multiple states at the same time, which makes the state of the quantum information unit can be in a superposition state of multiple possibilities, resulting in higher potential
in quantum information processing than classical information processing in terms of efficiency.