Page 207 - ITU KALEIDOSCOPE, ATLANTA 2019

ICT for Health: Networks, standards and innovation

4.2 dBFT consensus mechanism in the platform

Unlike the current mainstream blockchain system, the
CB-EHRs platform uses the dBFT consensus mechanism.
dBFT is an improved Byzantine fault-tolerant protocol based
on PBFT. The protocol first selects the accounting node in
the network by voting, and after the process is simplified for
the PBFT, the accounting nodes have a consensus [29]. This
consensus mechanism simplifies the process and improves
efficiency compared to PBFT, but retains all the excellent
performance of PBFT.
The choice of consensus algorithm is motivated by the
application scenario. Based on the analysis and comparison Figure 3 – Blockchain EHRs distributed in the network
of Table 1, PoW and PoS are mainly applicable to the digital
currency system. They all need to consume a certain amount
of resources and are not suitable for commercial application
services. DPoS is suitable for blockchain systems that rely
on token operations, but has poor support for blockchain
systems that operate without tokens. RPCA is currently only
available in the currency or electronic asset clearing area and
has poor support for other applications. PBFT and dBFT are
widely available for commercial applications because they
do not have an underlying token mechanism. However, on
the one hand PBFT is currently unable to dynamically add
nodes and cannot be applied to applications with large node
sizes due to complex communication processes. On the other
hand, the more nodes that join PBFT consensus, the quicker
the performance drops, as the time complexity of the PBFT
is O(n ) [27]. For this reason, NEO proposes an algorithm
2
named dBFT, which combines the characteristics of dPoS. By
voting on the blockchain, it decides the name list of consensus
nodes for next round, namely authorizing a few nodes to Figure 4 – Process of user registration and identity
reach consensus [30]. Therefore, combined with the business information validation
characteristics of EHRs application, this paper applies the the blockchain-based EHRs platform need to convert the
core consensus process of dBFT to the construction of the actual operations into a one-off transaction and attach the
EHRs platform, and realizes a special mechanism which is user information to the storage of transaction at the same
efficient and scalable. time.

4.3 Network structure
4.4.1 User registration operation
The network structure of the platform draws on the underlying
core code of bitcoin technology, the P2P network [21]. A medical institution has a large number of new patients
According to the characteristics of the P2P network, we each year, and each patient needs an electronic medical
design a special electronic medical P2P network. In the record. On one hand, if medical institutions are required
special structure of the designed P2P network, each node to collect patients’ public key information, the workload will
in the network has the complete EHRs data replication. be heavy, and easy to make mistakes. If medical institutions
According to the rules of the alliance chain, the nodes in are required to generate and distribute patient key pairs, the
the blockchain network are composed of various medical workload will also be enormous. On the other hand, if the
institutions throughout the country. The user’s device does key pair comes from a medical institution, the private key of
not need to store a huge electronic health record. Each the patient may be controlled by the medical institution. This
medical institution has equal status in the network, they have situation also does not meet the actual requirements from the
the same rights and need to assume the same obligations, as perspective of security.
can be seen in the overview presented in Figure 3. In user registration operation, firstly, the user need to submit
his or her personal information, then the EHRs platform will
generate a set of key pairs that represent his or her identity
4.4 Platform workflow
and generate the hash value as the user’s unique identifier.
While blockchain is essentially a decentralized distributed Figure 4 shows the process of user registration and identity
database, all its data exists in the form of transactions. If users information validation.
want to store electronic health record data on the blockchain, In our proposed blockchain-based EHRs platform, the

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