2
The main contributions of this work are as follows:
•To the best of our knowledge, we are the first to study and
formally model the high-efficiency issue in blockchain-
based supply chain traceability.
•We propose a novel parallel search algorithm based on the
maximum matching algorithm, which significantly boosts
product tracking efficiency.
•We conduct extensive experiments on the proposed al-
gorithm, which indicates up to 85.1% time reduction for
product tracking.
The rest of this paper is organized as follows. Sec. II
introduces the related work of this work. Sec. III provides the
preliminaries of the problem. In Sec. IV, we explain the system
model and formally define the problem of high-efficiency
blockchain-based supply chain traceability. Sec. V gives the
traditional approach and the proposed algorithm for solving the
traceability problem. Sec. VI demonstrates the experimental
results. Finally, Sec. VII concludes this work and discusses
the future directions.
II. RELATED WORK
In this section, we survey the related work about high-
efficiency blockchain-based supply chain traceability, i.e., sup-
ply chain traceability and searching over blockchain, and
articulate the motivations and novelty of this work.
A. Supply Chain Traceability
The research on supply chain traceability can be roughly
divided into two categories, i.e., unified data representation
methods for various stakeholders along the supply chain,
and digital technologies to facilitate reliable and ubiquitous
information storage.
A large number of stakeholders along the supply chain
have their own data management systems with diversified
data formats. Supply chain traceability needs to retrieve the
data from the stakeholders, and a unified data representation
method is demanded. The unified data representation methods
for supply chain information have been studied for years. In
[6], Bechini et al. investigate the issues for supply chain trace-
ability, introduce a traceability data model and a set of suitable
patterns, discuss the suitable technological standards to define,
register, and enable business collaborations, and implement a
real-world system for food supply chain traceability. In [5],
Hu et al. propose a Unified Modeling Language (UML) model
for traceability along with a set of suitable patterns, develop
a series of UML class diagrams to conceive a method for
modeling the product, process, and quality information along
the supply chain, and conduct a case study on vegetable supply
chain traceability.
Regarding digital technologies for supply chain traceability,
radio-frequency identification (RFID) and blockchain are rep-
resentative. In particular, RFID is a sensing technology that
helps to collect the data along supply chains ubiquitously,
while blockchain is a distributed ledger technology to provide
secure and reliable data storage services.
The usage of RFID in supply chain traceability can be traced
back to as early as 2003 [25], at which time Karkkainen
proposed to develop an RFID-based data capture system to
solve the problems associated with the logistics of short shelf-
life products. In 2007, RFID was widely recognized as a
promising technology for supply chain traceability [4], [26]
because the passive RFID tags on the products are cheap,
do not need to be within the line of sight of the RFID
reader (compared with barcodes), and do not need batteries
(compared with other sensors). Later, there are also surveys
about RFID-enabled supply chain traceability [27]–[29].
The potential of using blockchain technology for supply
chain traceability was investigated by Tian in 2016 for the
first time [20], in which a traceability system was designed
for agri-food supply chains combining RFID and blockchain
technologies. Although the work is a pioneer, it is concep-
tual without real-world deployment. We see that the product
information recorded on a blockchain is immutable, i.e., it
cannot be modified once stored, making the traceability results
reliable. Similar works include [30]–[35] in the supply chains
of construction, wine, etc., some of which are implemented in
real-world settings.
B. Searching over Blockchain
Blockchain-based supply chain traceability requires
blockchain data to be searched given a product item. We
present the related work about searching over blockchain in
this subsection. In particular, searching over blockchain refers
to the process that the users (with no local storage) request
blockchain full nodes (with full storage) to search data on
a blockchain, in which the search requests can be keyword
search, range query, etc. In literature, integrity, privacy, and
efficiency are the three concerned performance metrics of
searching over blockchain, in which integrity means whether
the search results are sound and complete, privacy means
whether data leakage happens during searching, and efficiency
means the time and communication overhead.
The naive procedure of searching over the blockchain is
as follows. First, the user sends a searching request to a
blockchain full node. Then, the full node proceeds with the
request by scanning the data on the blockchain block by
block and transaction by transaction, and recording all the data
satisfying the searching request. Finally, the full node returns
the search result. As we can see, the integrity of the search
result cannot be guaranteed, the privacy can be disclosed
because of the raw data on the blockchain, and the efficiency
is low because scanning transactions one by one takes a long
time. The research community has been developing solutions
to improve integrity, privacy, and efficiency.
Smart contracts and verifiable computation are the two
approaches to guarantee searching integrity. The basic idea
of the smart contract is to send the searching requests to all
the blockchain nodes rather than a single one. The incentive
mechanism of blockchain will motivate the majority of the
blockchain nodes to return sound and complete search results,
which guarantees integrity. The advantage of using smart con-
tracts is that the method is general and can be easily adapted
to all kinds of data and queries. However, the drawback
lies in the high cost of executing smart contracts. In terms