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ICT for Health: Networks, standards and innovation

as a public-key infrastructure (PKI) [22]. The basic idea of • Decentralization: The blockchain system is based on
applying PKI to the EHRs platform is to have the trusted a peer-to-peer distributed network, this feature makes
user digitally sign documents certifying that a particular it not to rely on a centralized management agency.
cryptographic key belongs to a particular user. The EHRs Therefore, the operation of the CB-EHRs platform is
platform in the Internet brings convenience to users, but it jointly accomplished and maintained by all medical
also increases the possibility of privacy leaks. Using the PKI institutions in the blockchain. If any medical institution
to generate a public key and identity identifier for him/her node is lost or damaged, the system can still function
during the user registration process. Users are active and effectively.
authenticated in the EHRs platform in this particular state.
This approach not only ensures the user’s legal identity but • Tamper-proof: The chained structure of the blockchain
also protects the user’s privacy. The purpose of PKI is to ensures the tamper resistance of the data in the
manage keys and certificates. blockchain system. If the information of a block is
Digital signature, also known as public key digital signature changed, the block header hash of the next block will
[23], usually defines two corresponding operations, one for also change. Therefore, if the attacking node wants
the signature (private key) and the other for the authentication to successfully change the transaction information, it
(public key). The process of signing is as follows. First, the only recalculates all subsequent blocks of the changed
sender uses the hash algorithm to obtain a digital abstract, block and catches up with the progress of the legal
and the signature private key encrypts the digital abstract to blockchain in the network. In the current state of
obtain a digital signature. The original text and the digital network technology development, such an attack is
signature will be sent to the recipient together. The receiver difficult to achieve [33]. Therefore, applying blockchain
then verifies the signature by decrypting the digital signature technology to the CB-EHRs platform makes EHRs data
with the sender’s public key to obtain a digital abstract. The more secure.
receiver will use the same hash algorithm to get a new digital • Anonymity: Transaction data on the blockchain is
abstract and compare the two abstracts. If the two match, the open and transparent. However, the owner’s identity
digitally-signed electronic file is successfully transmitted. corresponding to the transaction is anonymous. The
CB-EHRs platform can use blockchain encryption to
3.3 Consensus mechanism hash user identity information. The resulting hash value
Consensus refers to the process by which network nodes is used as the unique identifier for the user, similar
adhere to a common rule and achieves consistent results to the bitcoin’s wallet address. The user’s behavior
for certain problems through asynchronous interaction. The on the CB-EHRs platform is associated with the hash
consensus mechanism in the blockchain is mainly used to value obtained earlier, rather than with the user identity
make the network nodes agree on block generation and information. This separation of user identity and user
benefit distribution. The major difference between different data protects patient privacy.
blockchain networks comes from the difference in consensus In what follows, we present the detail of the proposed
mechanisms. Therefore, the characteristics and performance CB-EHRs, its associated features and potential benefits.
of different blockchain networks are also different, depending
on the choice of consensus mechanism.
Currently, Proof of Work (PoW) is used in the bitcoin 4. DESIGN APPROACH OF CB-EHRS PLATFORM
network [24]; Ethereum also uses PoW, and tend to gradually This section provides a detailed explanation of related
replace PoW with Proof of Stake (POS) [25]; Ripple uses features and functioning of the proposed credible blockchain
Ripple Proof of Consensus Algorithm (RPCA) [26]; Fabric electronic health records (CB-EHRs) platform.
uses Practical Byzantine Fault Tolerance (PBFT) [27]; in
addition, there are Delegated Proof of Stake (DPoS) [28] 4.1 Platform architecture
and Delegated Byzantine Fault Tolerance (dBFT) [29]. The
CB-EHRs platform uses the dBFT consensus mechanism. The proposed architecture of the CB-EHRs platform is
This consensus mechanism was proposed by NEO [30], which designed as a layered architecture. The entire platform
is an open source blockchain project driven by the community. is divided into three layers, which comprise: (i) the user
A comparison [31,32] of the characteristics of several major interface layer, which is at the top; (ii) the business logic
consensus mechanisms is shown in Table 1. layer, which is in the middle; and (iii) the data access layer,
positioned at the bottom of the framework. Figure 2 presents
3.4 Blockchain and CB-EHRs platform an overview of the CB-EHRs architectural framework and
details of the architecture is presented hereafter.
• Openness: The blockchain system code is open source.
The system’s interface and data are also open to everyone 4.1.1 User Interface layer
[33]. Each node in the system is allowed to obtain the
complete copy of the database. Based on this feature, The user interface layer is used to display data and receive
the CB-EHRs platform enables medical data to be shared user’s input information. It provides users with a graphic
among medical institutions. interface that can interoperate with the entire blockchain

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