Page 113 - Handbook of Deep Learning in Biomedical Engineering Techniques and Applications

Chapter 4 A critical review on using blockchain technology in education domain 101

7 1 B
78 48 2 1
1 4
13 4
3 2 D
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3
3 1
2 C
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Figure 4.6 Tangle DAG and random walk. DAG, directed acyclic graph.

approval (C) as shown in the figure using weighted random walk
approach. To attach a new transaction X, tips C and D are
selected, and these are then validated by transaction X by finding
their nonce. Then new transaction X is attached to C and D. The
major challenge in IOTA is that all the transactions go through the
centralized coordinator node, and hence, it is susceptible to 34%
attack. Cryptographic function used in IOTA is proprietary. Other
DAG-based systems include Byteball, Phantom, BlockDAG, and
HashGraph.
Based on the types of BC, a consortium-based BC is highly
suitable for e-governance applications. Table 4.4 presents a com-
parison of various consensus protocols along with their suitability
for e-governance applications in education domain. A DAG-based
DLT is highly suitable for such e-governance applications.
Lifelong learning is accessed using certificates. These certifi-
cates are susceptible to forgery when they are maintained in a
centralized database without suitable auditing procedures.
Hence, BCs can be used. BC-based functional prototypes for stor-
age of student grades at University of Glasgow [15], University
transcript system [16], and OpenLearn have been built on Ether-
eum platform. European Credit Transfer and Accumulation Sys-
tem (ECTS) at University of Maribor has been built on ARK BC.
These systems are based on PoW/PoS and dPoS consensus mech-
anisms. Management of alternative credentials earned from
nanodegrees, massive open online courses (MOOCs), and certifi-
cates is carried out by Blockcerts created by MIT Media Lab [17].
This system is based on Bitcoin based on PoW consensus mecha-
nism. A functional prototype of a BC-based learning analytics
platform is built on Ethereum [18]. Current BCs in education
domain are based on PoW/PoS based proof mechanisms. These
systems are more suitable for public BCs. As already suggested,
consortium BCs are more suitable in education domain. The ac-
cess control offered by these BCs can facilitate simple and
energy-efficient consensus mechanisms such as vote-based
mechanisms such as SBFT or round robin consensus