Information Retrieval (IR) tool to index and retrieve
citizens’ EHR. The system creates a table for each
document which contains a table with every word in
the document along with its frequency rate. Taking
into consideration the query, the system locates and
retrieves the documents that contain the query
keywords at a high-frequency rate. The authors in
(Wan et al., 2019) dealt with geographic data
collected from the real world through sensors. Real-
time data creates a challenge since it can be
unpredictable. Hence, they proposed a
multidimensional data indexing scheme to handle
large queries. The proposed methods are utilizing
hierarchical indexing structures by running binary
space partitioning (BSP) algorithms like kd-tree,
quad-tree, k-means clustering, and Voronoi-based
methods striving for better efficiency with less
latency. After a set of detailed simulations, it resulted
that the Voronoi diagram data index model is the most
suitable since it minimizes the average query
response time and energy consumption. These are the
parameters that have stimulated the interest of the
researchers. Finally, a recent study (Yao et al., 2018)
demonstrates an indexing mechanism over EHRs.
The overall concept is referring to citizens as data
owners and they are responsible of their own data.
Doctors, health sensors or any source that can
generate data is referred as data provider. Given the
owner’s consent, they can upload EHR to the cloud
along with an index which will be used for the
retrieval. Coming from any source, the data is always
encrypted before being uploaded to the cloud. The
request for the health records is performed in the form
of a query from an authorized health provider. The
cloud service indexes the stored data according to the
corresponding indexes and returns the proper medical
data without decrypting it. Eventually, the provider
can access the records with the use of a decryption
key. The idea of uploading EHR to a publicly
reachable location with the proper security has
significantly enhanced the communication between
medical personnel and citizens. However, these
techniques have limited efficiency when it comes to
emergencies. In most cases, the proposed way to
identify the citizen is through credentials, which it
will be a major obstacle when the data accessing is
vital. Furthermore, the proposals are trying to deal
with specific problems and circumstances and are not
flexible enough to accommodate different conditions.
2.4 Encryption Mechanisms
When it comes to personal health data it is crucial to
study thoroughly the security aspects of the proposed
system. Therefore, encryption techniques are used to
prevent internal attacks as long as secure data
transfer. Since there is a large number of security
techniques, there are studies that focus on choosing
those that can be used in the health industry.
According to (Madnani et al., 2013) these are
symmetric-key cryptography, public-key
cryptography, and attribute-based encryption. In
(Abbas et al., 2014) the proposed system encrypts the
data using an encryption key known by the cloud
provider. However, this approach raises the concern
of internal attacks considering that acquiring that key
gives access to all the stored data connected to it. The
proposal in (Yang et al., 2019) presents a system that
combines attribute-based encryption and password-
based break-glass (Scafuro et al., 2019) key to create
a self-adaptive access control scheme. More recently,
(Oliveira et al., 2020) suggests the involvement of
ciphertext-policy ABE (CP-ABE) associated with
emergency situations’ policies.
2.5 Advancements beyond the Related
Work
Resulting from the previous studies and works it has
been obvious that the storage of medical records in
cloud repositories has been rapidly evolved regarding
the plurality of services, techniques, and consistency.
Nevertheless, the ability to handle emergency
situations is what challenges the researchers since it
is very demanding to combine punctual reaction and
security. Additionally, most of the proposals are
restricted to a certain country’s infrastructure or
adjusted to a specific scenario with known and tested
circumstances. As a result, this paper proposes a
system that tries to eliminate these gaps. This is
achieved by making the service centralized so that
authenticated personnel can gain access regardless of
the country where the citizen comes from. Moreover,
it attempts to create a paradigm that HCPs can use to
download the EHR even when the citizen is
unconscious. It is important to propose a way to
secure the data in every stage of the process. Finally,
the recommended service should be applicable to any
possible scenario while it complies with all the
parameters.
3 METHODOLOGY
3.1 Involved Applications
To better understand the overall methodology, the
involved terminologies should be presented and