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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Workshop on Cybersecurity Providing in Information and Telecommunication Systems, February</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Methods of Personal Data Protection in Retail: Practical Solutions⋆</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Svitlana Rzaieva</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Dmytro Rzaiev</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Nelya Mykytenko</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Yurii Dreis</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Viktor Grechaninov</string-name>
        </contrib>
      </contrib-group>
      <pub-date>
        <year>2025</year>
      </pub-date>
      <volume>28</volume>
      <issue>2025</issue>
      <fpage>0000</fpage>
      <lpage>0002</lpage>
      <abstract>
        <p>This paper explores key methods for protecting personal data in the retail sector. It describes modern encryption algorithms, such as AES and RSA, their mathematical models, and applications for ensuring data confidentiality and integrity. Special attention is given to multifactor authentication, network segmentation, cloud service and IoT device protection, and the use of innovative approaches including real-time monitoring and access control, which help minimize the risk of data breaches. The research emphasizes the importance of an integrated approach to cybersecurity in retail to enhance customer trust and ensure compliance with legal requirements.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;personal data protection</kwd>
        <kwd>retail</kwd>
        <kwd>encryption</kwd>
        <kwd>multifactor authentication</kwd>
        <kwd>network segmentation</kwd>
        <kwd>cloud service protection</kwd>
        <kwd>IoT devices</kwd>
        <kwd>cybersecurity</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        In today’s digital world, retail has become a key sector that processes large volumes of personal
data. These data include names, addresses, phone numbers, financial transactions, IoT devices, and
more. With the globalization of e-commerce and the growing popularity of online shopping,
personal data protection has become particularly important, as data breaches can not only cause
significant financial losses but also seriously undermine consumer trust in a brand [
        <xref ref-type="bibr" rid="ref1 ref2 ref3 ref4">1–4</xref>
        ].
      </p>
      <p>
        Digital security threats in retail include various forms of cyberattacks such as phishing
campaigns, database breaches, DDoS attacks, ransomware, and internal threats caused by human
error or intentional actions by personnel. Incidents such as the massive data breach at Target in
2013 or the attack on the Dixy network’s POS systems in 2020 highlight the critical nature of
information security for retailers. Attackers use various methods to gain access to confidential
information, underlining the need for robust security measures [
        <xref ref-type="bibr" rid="ref5 ref6 ref7 ref8 ref9">5–9</xref>
        ].
      </p>
      <p>
        Loss or compromise of personal data can result in substantial financial losses, reputational
damage, and legal consequences for retail networks. As a result, protecting data becomes a top
priority for any retailer. Therefore, modern methods of personal data protection in retail and the
technical aspects of implementing security solutions are highly relevant [
        <xref ref-type="bibr" rid="ref10 ref11 ref12">10–12</xref>
        ].
      </p>
      <p>
        Regulatory requirements in the field of personal data protection, such as the General Data
Protection Regulation (GDPR) in the European Union, the Payment Card Industry Data Security
Standard (PCI DSS), and ISO/IEC 27001, define security standards that are mandatory for
companies processing personal information. Failure to comply with these standards can lead not
only to data leaks but also to significant fines. This incentivizes retailers to implement effective
data protection methods aimed at minimizing risks and ensuring regulatory compliance [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ].
      </p>
      <p>One of the key approaches to protecting personal data in retail is a multi-layered security model
that includes:




</p>
      <p>Multifactor authentication (MFA) to implement additional levels of protection when
accessing payment systems and accounts.</p>
      <p>Network segmentation to divide the network infrastructure into isolated segments to
restrict access to critical resources.</p>
      <p>Role-based access control (RBAC) to restrict access to data according to the role of the
employee, which reduces the risk of unauthorized use of information
Encryption algorithms using modern cryptographic methods to ensure data security during
transmission and storage.</p>
      <p>Protection of IoT devices to ensure the security of smart devices used at points of sale to
optimize operations (for example, self-service cash registers).</p>
      <p>Particular attention should be paid to implementing cybersecurity best practices, such as regular
software updates, information security training for staff, and system security audits.</p>
      <p>
        This paper aims to explore the methods of personal data protection in the retail sector, with a
focus on practical solutions that minimize the risks of information leakage and comply with
international security standards. The experience of leading retail companies in Ukraine and Europe
will be reviewed, with a detailed analysis of the results of implementing MFA technologies,
network segmentation and role-based access control [
        <xref ref-type="bibr" rid="ref14 ref15 ref16">14–16</xref>
        ].
      </p>
      <p>
        An important aspect of the paper is also an assessment of the effectiveness of these methods
based on statistical data and analysis of real incidents, which demonstrate a significant reduction in
the number of data leaks and cyber threats after their implementation. Thus, the material will be
useful for both heads of retailers’ IT departments and researchers in the field of cybersecurity and
information risk management [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ].
      </p>
    </sec>
    <sec id="sec-2">
      <title>2. Problem statement</title>
      <p>In today’s retail industry, customer personal data has become one of the key assets for businesses,
but also a potential threat to privacy. Retail companies process large amounts of information,
including full names, contact information, and purchase history, to conduct business efficiently,
making them attractive targets for cybercriminals. The problem is also the failure to minimize data
collection. Many retailers store more information than is necessary for their operations, which
increases the amount of potential losses in the event of a leak. A low level of transparency in
informing customers about the storage and processing of their data is also a problem. This can
reduce trust in the company and lead to reputational losses.</p>
      <p>One of the main problems is the growing number of cyberattacks on retail companies aimed at
stealing confidential information. Attackers may use phishing, social engineering, and database
hacking methods. Insufficient security of databases storing personal data is a significant threat.
Another problem is the storage of backup copies of data without proper encryption, which, in turn,
allows attackers to access data through backup media.</p>
      <p>Lack of proper control over access to personal data leads to the risk of internal threats. A low
level of authorization and authentication may allow unauthorized access to confidential
information. Insufficient integration of multi-factor authentication (MFA) systems, which is an
effective way to protect accounts, is a problem. The lack of a cybersecurity culture at the
company’s management level can be a key obstacle to implementing effective personal data
protection methods. Lack of staff awareness of data protection methods is another problem. Often,
employees are not sufficiently trained in security rules, which makes the company vulnerable to
phishing attacks. The spread of malware through phishing emails is another threat to retailers, as it
can lead to the compromise of information systems used in retail.</p>
      <p>The lack of regular security monitoring and auditing is also a threat. Companies often fail to
scan their systems for vulnerabilities, which can lead to confidential information leaks. The lack of
intrusion detection systems (IDS) and intrusion prevention systems (IPS) leaves companies
vulnerable to zero-day attacks. Another problem is the insufficient use of data encryption
technologies. Often, companies neglect modern encryption methods or use outdated algorithms,
which leaves data vulnerable. Many retailers lack end-to-end encryption, which makes information
vulnerable when it is transferred between systems. Data leaks can cause significant financial losses
for companies, including fines for violating legislation such as GDPR and CCPA. Companies often
do not have clear incident response policies in place. The lack of a pre-developed plan of action in
case of a data breach can make it difficult to control the situation.</p>
      <p>Using cloud services for data storage without proper access control is also a risk. Insufficiently
protected administrator accounts can cause leaks. Insufficient network segmentation allows
attackers to gain access to the entire corporate network after penetration.</p>
      <p>Using open APIs to integrate third-party services without proper security controls can lead to
leaks. The problem is also the lack of compliance with international standards, such as ISO/IEC
27001, which regulate approaches to information security.</p>
    </sec>
    <sec id="sec-3">
      <title>3. Main Material</title>
      <p>The protection of personal data in retail is defined by several key standards and legislative norms
that regulate the processing, storage and transfer of information. These include the GDPR, ISO/IEC
27001:2022 (International Information Security Management Standard), and PCI DSS. Each of these
standards has its own peculiarities, which we will discuss below.</p>
      <p>
        The GDPR General Principles is a European regulation governing the processing of personal
data of individuals located in the European Union, which entered into force on May 25, 2018 [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ].
The main goal of the GDPR is to ensure the confidentiality and control over personal data of EU
citizens. Personal data includes names, addresses, IP addresses, credit card information, and other
information that can be used to identify a person. Implementation in retail:
1. Restriction of access to personal data, access to them should be available only to authorized
persons.
2. Data protection by default, i.e. the principle of ensuring security at the stage of
development of data processing systems.
3. Collecting a minimum amount of data. For example, when creating an account, only the
data necessary for the purchase (name, address, contact number) is requested.
4. All customer data, including purchase history, should be encrypted.
5. Introduce automation of data deletion requests, i.e. retailers should provide tools that allow
customers to easily delete their data.
      </p>
      <p>The International Standard for Information Security Management ISO/IEC 27001:2022 is an
international standard that defines the requirements for an information security management
system (ISMS). It is aimed at protecting the confidentiality, integrity and availability of information
in organizations in various fields, including retail. The standard establishes an approach to risk
management and data protection.</p>
      <p>Implementation in retail: asset inventory, i.e. assets that process or store data must be identified
and classified; delimitation and restriction of access to customer databases, only authorized
employees have access to data; regular backup of information to prevent leaks.</p>
      <p>PCI DSS is a standard created to ensure the security of payment transactions. It was developed
by VISA, MasterCard, American Express, and others. The main goal is to protect against fraud and
financial data leaks. Implementation in retail: implementation and use of POS systems (terminals)
that support PCI DSS; replacement of real card data with unique tokens; staff training on the basics
of payment data security.</p>
      <p>Compliance with GDPR, ISO/IEC 27001, and PCI DSS standards is key to ensuring data security
in retail. They help to minimize the risk of leaks, increase customer confidence, and ensure
compliance with the law. The implementation of these standards should take into account the
specifics of retail operations, integrating encryption, tokenization and access control technologies.</p>
      <p>Methods of personal data protection are a set of technical, organizational and procedural
measures aimed at ensuring the confidentiality, integrity and availability of personal data
processed within the retail sector. In this industry, data often includes customer, transactional,
logistical, and behavioral information that can be targeted by cybercriminals. Successful protection
involves the use of multiple layers of protection, including technical solutions, security policies,
and staff training. So, in this paper, we will consider the following main methods of personal data
protection:</p>
      <sec id="sec-3-1">
        <title>1. Data encryption. 2. Access control. 3. Protection of cloud services. 4. Protection of IoT devices.</title>
        <p>So, let’s take a closer look at these methods of personal data protection that should be applied in
retail.</p>
        <p>Data encryption is the main tool for ensuring the confidentiality and security of personal data in
retail. Its purpose is to convert data into an unreadable format that can only be decrypted with a
special key. Encryption creates an additional layer of protection, ensuring that data cannot be
accessed without a decryption key. In retail, it is necessary to use symmetric encryption algorithms
such as AES (Advanced Encryption Standard) and DES (Data Encryption Standard). AES uses key
lengths of 128, 192, or 256 bits, which ensures high cryptographic strength.</p>
        <p>The AES algorithm is based on complex mathematical operations that guarantee the protection
of information even if it is intercepted by intruders. Retail, as one of the largest industries that
processes huge amounts of personal data, actively uses AES to protect its customers and business.
This algorithm works on the basis of permutations and substitutions in several rounds. The main
stages include: SubBytes, ShiftRows, MixColumns, and AddRoundKey.</p>
        <p>The basis of the AES algorithm is a sequence of operations performed in the GF (28) field. These
operations include byte-by-byte substitutions, row shifts, column mixing, and key addition. In the
retail industry, these mathematical expressions are used to encrypt data during transaction
processing, transfer information between cash registers and servers, and store data in cloud
storage. AES mathematical expressions are adapted to specific retail scenarios, creating unique
security algorithms.</p>
        <p>For example, the SubBytes function, which is usually used for byte-by-byte nonlinear
substitution, can be used in retail to encrypt bank card numbers. ShiftRows and MixColumns
provide additional confusion to the data, making it impossible to decrypt it even if some of the
information is compromised. This is important for maintaining customer privacy and protecting
commercial information.</p>
        <p>SubBytes (Byte substitution) in retail, this feature can be used to encrypt personal customer
data, such as bank card numbers. The mathematical expression SubBytes (Byte substitution):
Pout = M×(Pin (-1)) ⊕ b,
(1)
where Pin is a byte representing a part of the card number (for example, the last four digits); Pout is
encrypted part of the number; M and b are predefined constants.</p>
        <p>Example. If the card number is 1234, each digit is represented by a byte. After the SubBytes
transformation, the result is a set of encrypted bytes that are transmitted through the POS terminal.</p>
        <p>ShiftRows is an operation that cyclically shifts the bytes in each row of the data matrix by a
specified number of positions. In retail, this can be used to encrypt transactions between the cash
register and the server, ensuring that the order of the data is reversed, making it difficult to
analyze. The mathematical expression ShiftRows:</p>
        <p>Tout[i][j] = Tin[i] [(j + shift[i]) mod N],
(2)
where Tin[i] is input data matrix (for example, transaction amount, date, time); shift[i] is number of
shifts for the third line; N is number of columns.</p>
        <p>Example. A transaction transmits encrypted data in the form of a matrix. The matrix contains:
1.
2.
3.
4.</p>
        <p>The amount of the purchase
Time of the transaction
Cash register number</p>
        <p>Transaction id.</p>
        <p>The data matrix before encryption can look like this (each element is a byte):
[$100, 12:30, POS01, TRX001]
[$200, 12:45, POS02, TRX002]
[$50, 13:00, POS03, TRX003]
[$300, 13:15, POS04, TRX004]
The ShiftRows function shifts each row:
• The first row remains unchanged.
• In the second row, the elements are shifted first position to the left: [12:45, POS02, TRX002,
$200].
• In the third line, shift by second positions: [POS03, TRX003, $50, 13:00].
• In the fourth, it moved up third positions: [TRX004, $300, 13:15, POS04].</p>
        <p>Encrypted matrix after ShiftRows:
[$100, 12:30, POS01, TRX001]
[12:45, POS02, TRX002, $200]
[POS03, TRX003, $50, 13:00]
[TRX004, $300, 13:15, POS04]</p>
        <p>Line shifting changes the order of information, which makes it difficult to decrypt without
knowing the key. An attacker cannot understand what information corresponds to a particular
field (amount, time, or ID). If an attacker intercepts the encrypted matrix, it is difficult to
understand the relationships between the data because the order is broken.</p>
        <p>ShiftRows is useful for securing transaction data in POS systems or when synchronizing cash
registers with a central server. This is important to prevent the theft of sensitive information even
if an attacker has access to some of the encrypted data.</p>
        <p>The MixColumns feature in retail can be used to encrypt data on sales, products, or inventory.
Its main task is to create confusion, which makes it difficult to decrypt the original data even if you
get some of the encrypted information. The mathematical expression MixColumns:
Cout[j] = M×Cin[j],
(3)
where Cin[j] is column of the input matrix (for example, sales volumes by product category); M is
coefficient matrix (defines the conversion rules); Cout[j] is mixing result (encrypted column).</p>
        <p>Example. Suppose there is data on sales of goods in a store for the last day:
Product A: 50 units.</p>
        <p>Product B: 30 units.</p>
        <p>Product C: 20 units.</p>
        <p>Product D: 10 units.</p>
        <p>
          This data can be presented in the form of a column: Cin = [
          <xref ref-type="bibr" rid="ref10">50, 30, 20, 10</xref>
          ].
After applying MixColumns, the data column is multiplied by a predefined matrix:
M = [ [
          <xref ref-type="bibr" rid="ref1 ref1 ref2 ref3">2, 3, 1, 1</xref>
          ],
[
          <xref ref-type="bibr" rid="ref1 ref1 ref2 ref3">1, 2, 3, 1</xref>
          ],
[
          <xref ref-type="bibr" rid="ref1 ref1 ref2 ref3">1, 1, 2, 3</xref>
          ],
[
          <xref ref-type="bibr" rid="ref1 ref1 ref2 ref3">3, 1, 1, 2</xref>
          ] ].
        </p>
        <p>The result is calculated in the field GF(28). The new column looks like this:
Cout = [150, 120, 100, 80].</p>
        <p>This encrypted data is stored in the database or transferred to the cloud. Without knowledge of
the matrix M and the inverse transformation mechanism, an attacker will not be able to decrypt the
real sales volumes.</p>
        <p>Thus, encrypted data on the volume of goods in the store makes it impossible for competitors or
intruders to use it even in the event of a leak. When transferring sales data from cash registers to
the server, mixing columns makes it impossible to intercept clear data. The data obtained from
sales analytics can be encrypted to protect it from unauthorized persons when transferred to
analytical systems or partner services.</p>
        <p>The next feature, AddRoundKey, which adds a unique key to the data at each encryption round,
is crucial in retail. It allows you to generate unique encrypted data for each transaction, reducing
the risk of reuse by attackers. The AddRoundKey function adds a unique encryption key to the
input data using bitwise XOR (⊕). The KeyExpansion process ensures dynamic key generation,
which is also critical for ensuring a high level of security in high-intensity retail operations. The
mathematical expression AddRoundKey:</p>
        <p>Dout = Din ⊕ K,
(4)
where Din is input data (for example, information on the sale of goods); K is encryption key; Dout is
encrypted data.</p>
        <p>Example. Information about the sale of goods for a customer:
Name: Olga.</p>
        <p>Order number: #45678.</p>
        <p>Amount: $100.</p>
        <p>After the encryption key is applied, the data is converted into an encrypted sequence of bytes.
The unique key for this session looks like this:</p>
        <p>Key: 00101100 11010010 10110101.</p>
        <p>The data after the bitwise operation will look like this: 10101010 01101101 01011010.</p>
        <p>As a result, even if the data is intercepted, it cannot be recovered without the session key. This
ensures the protection of the client’s personal data and order details.</p>
        <p>The KeyExpansion function generates a set of keys that is used in each round of AES
encryption. In retail, this is especially important for providing dynamic transaction protection,
which makes it difficult to compromise data. The keys are generated from the base key Kmain and
use the auxiliary operations g(W), bitwise XOR (⊕), and iterative addition of the constants Ri. The
mathematical expression of this key, for which the AES algorithm operates with key blocks that
are four words long (4 bytes in each word), is as follows:</p>
        <p>W [ i ]={W [ i−1]⊕ g (W [ i−4 ])⊕ Ri , i mod 4=0</p>
        <p>W [ i−1]⊕ W [ i−4 ] , i mod 4 ≠ 0
(5)
where W[i] is new 32-bit key segment; g(W[i−4]) is nonlinear transformation, including SubBytes,
ShiftRows and cyclic byte shifting; Ri is a round constant that is unique for each round.</p>
        <p>Example. Consider a POS terminal in a supermarket that generates unique keys for each
transaction. The initial key for the terminal (primary key) looks like this:</p>
        <p>
          Kmain = [10101100 11010011 01101001 10011101]
The process of generating a new key:
1. The first segment of the new key uses the formula: W[i] = W[i−1] ⊕ g(W[i−4]) ⊕ Ri.
W[0] = W[
          <xref ref-type="bibr" rid="ref3">3</xref>
          ] ⊕ g(W[0]) ⊕ R1.
        </p>
        <p>
          Let W[
          <xref ref-type="bibr" rid="ref3">3</xref>
          ] = 10011101, g(W[0]) = 01101100, and R1 = 00000001.
        </p>
        <p>
          Then W[
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] = 10011101 ⊕ 01101100 ⊕ 00000001 = 11110000
2. Other segments: we use W[i] = W[i−1] ⊕ W[i−4] for the following segments.
        </p>
        <p>
          If W[
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] = 11110000 and W[0] = 10101100, then:
W[
          <xref ref-type="bibr" rid="ref5">5</xref>
          ] = W[
          <xref ref-type="bibr" rid="ref4">4</xref>
          ] ⊕ W[0] = 11110000 ⊕ 10101100 = 01011100.
3. A complete new key: After several iterations, a unique key is generated for the next round:
K1 = [11110000 01011100 ...].
        </p>
        <p>Thus, unique keys are created for each transaction based on the initial key, taking into account
the specifics of transactions, such as payment for goods, returns, or transfers. The round constants
Ri can be associated with the data of a particular transaction, such as its identifier or time, which
makes it difficult for attackers to find keys.</p>
        <p>Another popular method is asymmetric encryption, in particular the RSA
(Rivest-ShamirAdleman) algorithm. It is based on the difficulty of factorizing large prime numbers.</p>
        <p>The RSA algorithm uses a pair of keys: a public key for encryption and a private key for
decryption. Mathematically, it is based on the exponentiation of a large prime number modulo a
field of integers.</p>
        <p>The process begins with the generation of two large prime numbers p and q, which are used to
calculate the modulus n = p · q. The value of n determines the size of the encryption key. Next, the
Euler function is calculated ϕ(n) = (p – 1) · (q – 1). The public exponent e is then chosen, usually
65537 due to cryptographic efficiency. The private key d is calculated as the multiplicative inverse
of e modulo ϕ(n) This step ensures the creation of key pairs for encryption and decryption. The
private key is calculated as d · mod ϕ(n) = 1.</p>
        <p>The next step is to encrypt the card number along with the transaction context:
c = (M×H (T, KPOS))e mod   n,
(6)
where M is credit card number (16-digit number divided into blocks); T is a unique transaction
identifier (for example, the time of the transaction or a unique check number); KPOS is identifier of
the sales terminal (for binding to a specific device); H(T, KPOS) is a hash function to verify the
integrity of the transaction; C is ciphertext for storage in the retailer’s database or transmission
over the network.</p>
        <p>This algorithm takes into account the context of the transaction through the parameters: a
unique transaction identifier T and the identifier of the point-of-sale terminal KPOS. To increase
security, transaction data is used as an additional factor included in the mathematical expression.
They are combined through the hash function H(T, KPOS), which creates a checksum that uniquely
identifies the transaction. This makes replay attacks more difficult. During the transaction, the
credit card number M is encrypted along with the control data, which is achieved by multiplying
the card number by the result of the hash function. After that, the resulting value is raised to the
power of the public key e and the remainder is calculated by dividing by the modulus n. Thus, due
to the presence of dynamic parameters, the ciphertext C becomes unique for each transaction, even
if the card number is the same.</p>
        <p>Decryption is performed by raising the ciphertext to the power of the private key d by the
module n. However, to verify the authenticity of the data, the result is additionally divided by the
checksum H(T, KPOS):</p>
        <p>M dec=</p>
        <p>C d mod n
H (T , K POS )
(7)</p>
        <p>If the result matches the original card number, the transaction is considered authentic: Mdec =
= M is the transaction is considered valid.</p>
        <p>IF Mdec ≠ M is the transaction could be modified or retried.</p>
        <p>This approach provides an increased level of security for retailers, reducing the risk of data
reuse attacks and transaction fraud. It is ideal for POS terminals, mobile payment systems, and
online stores where it is important to protect both the card number and the transaction context
itself. The inclusion of additional parameters increases the cryptographic complexity and ensures
the uniqueness of each ciphertext. This mathematical expression is unique because it adapts classic
RSA to the needs of retailers, including protection against replay attacks and data integrity.</p>
        <p>Access control involves restricting access to personal data only to those who are authorized to
do so. The main methods are multifactor authentication (MFA), role-based access control (RBAC),
and network segmentation. In retail, this can be used to restrict access to databases with customer
information to employees of the relevant departments only. To do this, implement:



multifactor authentication (MFA);
network segmentation;
role-based access control (RBAC).</p>
        <p>Multi-factor authentication (MFA) is a strategy that provides an additional layer of security
when accessing personal customer data in retail. It is important not only to protect banking data
but also to prevent unauthorized access to customer and employee accounts. In the retail
environment, where huge amounts of sensitive customer data (such as payment cards) are
constantly stored, MFA helps minimize the risk of data theft or unauthorized access.</p>
        <p>Multifactor authentication in retail includes three main factors:


</p>
        <p>What does the user know? These can be passwords or PINs to access the customer or
administrator account.</p>
        <p>What does the user have? Examples include one-time passwords sent via SMS or generated
through applications such as Google Authenticator.</p>
        <p>What does the user have? Biometric data (such as fingerprint scanning or facial
recognition) that is added for a higher level of security when making purchases through
mobile apps or online stores.</p>
        <p>The importance of MFA in retail is evident when customers make purchases through online
stores or use mobile applications to store personal data. Hacking a password can lead to the theft of
personal information, but entering an additional code or biometric data significantly reduces the
likelihood of unauthorized access.</p>
        <p>The MFA algorithm in retail looks like this:
1. The user enters their login information (password, login).
2. The system checks the entered information against the database.
3. If the password is correct, a one-time code is sent to the mobile device, which the user must
enter.
4. If the entered code is correct, the user is granted access to personal data or to make a
purchase
MFA for retail can be mathematically expressed as follows:</p>
        <p>PMFA = PPassword × PCode × PBiometrics
(8)
where Ppassword is probability of correct password entry; PCode is probability of correct entry of a
onetime code, PBiometrics is probability of successful biometric verification (e.g., fingerprint).</p>
        <p>Example. Many large retailers use multifactor authentication (MFA) to protect customer data.
Let’s take a look at three companies from the Ukrainian and European markets that have applied
MFA to improve the security of payment transactions: Silpo (Ukraine), H&amp;M (Europe), and
Carrefour (Europe).</p>
        <p>The Silpo retail chain decided to implement multifactor authentication (MFA) after noticing an
increase in fraudulent transactions in its online store. Prior to the implementation of MFA, the
number of fraudulent transactions was high (35 per month). After the MFA system was
implemented, this figure decreased, in particular in the first 6 months, the number of such cases
decreased to 10 per month. During the analysis, it was noticed that the number of unauthorized
accesses decreased significantly after the introduction of an additional level of protection. Thus,
MFA has not only provided improved security but also increased customer confidence in the
payment system.</p>
        <p>The well-known European retailer H&amp;M also decided to implement multifactor authentication
in its online system to ensure the security of its customers’ payment data. Initially, before
implementing MFA, the company had 50 fraud cases per month. After the launch of the MFA
system, the number of frauds was reduced to 40 in the first few months. In the following months,
the situation stabilized, and after 12 months, this figure dropped to 20 cases per month. The
implementation of MFA at H&amp;M has significantly reduced the risk of financial losses and provided
more reliable protection for customers.</p>
        <p>Carrefour, one of the largest retail chains in Europe, has also implemented multifactor
authentication to protect customer data from fraudulent attacks. Before MFA was implemented, the
chain had 40 cases of fraudulent transactions per month. After the introduction of multifactor
authentication, the company saw a 25% reduction in fraudulent attempts in the first month and a
62% reduction in fraudulent attempts a year later. This significantly reduced the risk of financial
losses and increased the security of all transactions.
1 month after implementation
3 months after implementation
6 months after implementation
40
30
20
15
50
40
25
20
35
25
15
10</p>
        <p>Sources: Interviews with IT departments of Silpo, H&amp;M, and Carrefour retail networks, 2024
Network segmentation is critical to ensuring the security of personal data in retail, as a retailer
may store customer data on numerous servers serving different functions (e.g., payment
processing, storing transaction information, product management, etc.). If the network is not
properly segmented, attackers can gain access to the entire system, which can lead to data
breaches.
Methods of network segmentation:
1. Logical segmentation uses VLANs to divide the network into segments, allowing you to
isolate critical data from the rest of the network. For example, one for payment processing
and another for normal order processing.
2. Physical segmentation uses separate servers or data centers to store sensitive data. This
reduces the likelihood of penetration into the main database, even if an attacker gains
access to part of the network.</p>
        <p>To protect the data transmitted between segments, powerful encryption algorithms for
segmented networks are used, such as AES (Advanced Encryption Standard), for an encrypted
channel between two parts of the network. If M is the message (data) to be encrypted, K is the
encryption key, and E is the encryption operation, then the CCC encrypted message is expressed
as</p>
        <p>C = E (K, M).
(9)</p>
        <p>In retail, this can be used to secure payment transactions or store customer card data in
encrypted form so that only authorized segments have access to it.</p>
        <p>Network segmentation is important to protect customer payment and personal data from
attacks. Let’s look at three retailers in Ukraine and Europe that have used segmentation to improve
security: Auchan (Ukraine), Zara (Europe), and Metro (Europe).</p>
        <p>Network segmentation helped Auchan divide access to internal systems into segments, each of
which has limited access rights. This has significantly improved the security of payment data
processing. Before implementing network segmentation, the company had 25 security incidents per
year. After its implementation, this figure dropped by 50% during the first year, and by 68% in two
years. The main success factor was restricting access to financial and sensitive data to a limited
number of employees, which significantly reduced the risk of leaks and attacks on internal systems.</p>
        <p>Zara, a European retailer, has also applied network segmentation to protect its customers’
personal and financial data. Before implementing segmentation, the company faced a significant
number of security incidents—45 cases per year. After segmentation, the number of incidents
decreased to 20 in one year and 15 in two years. This result was achieved through improved access
control to important systems and data security, in particular by isolating critical network segments
that had access to customer payment and personal data.</p>
        <p>The European retail chain Metro implemented network segmentation to divide its internal
systems into several zones, each with individual access and security rules. Before segmentation, the
company had 30 security incidents per year. After implementing the segmentation, this figure
dropped to 15 incidents in the first year, and to 10 in two years. This provided better protection for
customer payment data and personal information, and prevented the possibility of data leaks
through weaknesses in the network.
Sources: Data from the annual reports of Auchan, Zara, Metro for 2023–2024.
Role-based access control (RBAC) is one of the main methods of managing access to data in retail.
Using RBAC allows you to determine exactly who has access to what data, which is critical to
ensuring privacy and preventing data breaches.</p>
        <p>Basic principles of RBAC:



each employee or user is assigned a role (for example, “Cashier”, “Manager”,
“Administrator”) and this role determines the level of access to the data.
each role is assigned specific access rights, for example, only reading, editing or deleting
data.</p>
        <p>users can interact with data only through authorized interfaces, according to their roles.</p>
        <p>Using role-based access control allows you to restrict access to sensitive information depending
on the role of the employee in the organization. Consider three retail chains that have implemented
RBAC: Epicenter (Ukraine), IKEA (Europe), and Lidl (Europe).</p>
        <p>The implementation of role-based access control (RBAC) allowed Epicenter to restrict access to
sensitive data only to employees whose role required such access. Before RBAC was implemented,
the number of data access errors was 20 per month. After implementing access control, this figure
dropped to 12 per month after the first month and to 5 after six months. Implementation of RBAC
significantly reduced the likelihood of errors in accessing important data, which helped improve
security and reduce possible data leaks.</p>
        <p>European retailer IKEA has implemented role-based access control (RBAC) to minimize the
likelihood of unauthorized access to its financial and personal data. Before implementing RBAC,
the company had 25 data access errors per month. After implementing the system, the number of
errors decreased by 40% after the first month and by 80% after six months. This prevented
unauthorized access and kept customer data more secure.</p>
        <p>Lidl also decided to implement a role-based access control system to limit access to critical data
to only the appropriate employees. Before implementing RBAC, the company had 18 access errors
per month. After implementing RBAC, this figure dropped to 10 per month in the first month, and
after three months, to 6 errors per month. This proves that role-based access control is an effective
tool for ensuring data security in a large organization that works with a large amount of personal
and payment data.</p>
        <p>Sources: Internal reports and interviews with IT departments of Epicenter, IKEA, and Lidl</p>
        <p>Period
Before RBAC implementation
1 month after implementation
3 months after implementation
6 months after implementation</p>
      </sec>
      <sec id="sec-3-2">
        <title>Lidl</title>
        <p>18
10
6
4</p>
      </sec>
      <sec id="sec-3-3">
        <title>Epicenter</title>
        <p>20
12
8
5</p>
      </sec>
      <sec id="sec-3-4">
        <title>IKEA</title>
        <p>25
15
10
5
Protecting cloud services</p>
        <p>In modern retail, cloud technologies have become a key element for storing and processing
customer personal data. This is due to the need for prompt access to information, scalability, and
efficiency of working with large amounts of data. However, the use of cloud services also increases
the risk of data leakage, which makes the issue of data protection particularly relevant.</p>
        <p>Firewalls are the first line of defense for cloud services. They allow you to control incoming and
outgoing traffic by blocking potentially dangerous requests. In the context of retail, firewalls help
to protect customers’ personal data from unauthorized access.</p>
        <p>Firewalls provide traffic filtering, preventing attacks such as DDoS that can lead to system
outages. This is especially important for large retail chains that process thousands of transactions
every day.</p>
        <p>For example, the Auchan supermarket chain has implemented modern firewalls to protect its
infrastructure, which has reduced the number of security incidents by 30%. Another European
chain, Lidl, also uses multi-level protection with firewalls, which allows it to block up to 95% of
unsafe connections in the early stages.</p>
        <p>Number of attacks before
implementation</p>
      </sec>
      <sec id="sec-3-5">
        <title>Number of attacks after</title>
        <p>implementation
Reduction in the
number of attacks
500
1000
600
350
50
420
30%
95%
30%
Network</p>
      </sec>
      <sec id="sec-3-6">
        <title>Auchan Lidl Silpo Sources: Data from the annual reports of Auchan, Lidl, Silpo</title>
        <p>Real-time security monitoring allows you to detect and respond to threats instantly. This is
especially important in retail, as any security breach can lead to significant financial losses and a
decrease in customer confidence.</p>
        <p>Monitoring tools, such as intrusion detection and prevention systems (IDS/IPS), allow you to
detect abnormal activities and automatically take measures to neutralize them. For example, Tesco
has implemented a real-time monitoring system, which has reduced the response time to incidents
from 6 hours to 30 minutes.</p>
        <p>In the Metro network, the use of the monitoring system allowed to detect 85% of threats at the
stage of attempted access to the system, which significantly increased the overall level of security.
The Ukrainian ATB network has also implemented similar systems, which reduced the number of
successful attacks by 40%.
Sources: Data from the annual reports of Tesco, Metro, ATB retails network</p>
      </sec>
      <sec id="sec-3-7">
        <title>Reaction time after</title>
        <p>implementation
30 minutes</p>
      </sec>
      <sec id="sec-3-8">
        <title>Reduction of</title>
        <p>reaction time
90%
75%
40%</p>
      </sec>
      <sec id="sec-3-9">
        <title>Daily</title>
      </sec>
      <sec id="sec-3-10">
        <title>Daily</title>
      </sec>
      <sec id="sec-3-11">
        <title>Daily 400 500 450</title>
        <p>Backups are critical to protect against data loss in the event of cyberattacks or technical failures. In
retail, where large volumes of personal data are processed, backups ensure that information can be
restored in the event of loss or damage.</p>
        <p>For example, the European Carrefour chain backs up customer data on a daily basis, which
allows it to keep information up-to-date and recover quickly from incidents. The Billa network
uses cloud-based backup solutions to ensure reliable data protection even in the event of physical
damage to servers. Novus Ukrainian network has also implemented a backup system that allows
data to be stored in several geographically distributed locations, which minimizes the risk of data
loss in the event of disasters.
Implementing these security methods allows retailers to ensure a high level of security for cloud
services, which in turn increases customer trust and reduces the risk of personal data leakage.</p>
      </sec>
      <sec id="sec-3-12">
        <title>Protecting IoT devices</title>
        <p>IoT devices, such as self-service terminals, smart surveillance cameras, or inventory monitoring
systems, are widely used in retail. Vulnerabilities of these devices can be used for attacks. Securing
IoT includes regular software updates, the use of built-in encryption, and physical protection of
devices.</p>
        <p>In retail, where IoT devices are used to process personal customer data, software updates are
critical.</p>
        <p>For example, supermarket chain Tesco has implemented automatic software updates on all of its
IoT devices. This helped reduce the number of successful attacks by 25% in the first year after
implementation. Similarly, Metro uses a centralized update management system to ensure a rapid
response to new threats. The Ukrainian chain Silpo has also implemented a similar system, which
has significantly increased the level of customer data protection.</p>
        <p>Number of attacks before
implementation</p>
      </sec>
      <sec id="sec-3-13">
        <title>Number of attacks after</title>
        <p>implementation</p>
        <p>Reduction in the
number of attacks
300
375
337
25%
25%
25%</p>
        <p>Sources: Data from the annual reports of the Tesco, Metro, Silpo retail networks
Outdated communication protocols are another significant threat to the security of IoT devices.
They can be vulnerable to attacks that have been known for a long time. Eliminating the use of
such protocols and switching to modern standards significantly increases the level of security.</p>
        <p>For example, Carrefour conducted an audit of its IoT devices and abandoned outdated protocols.
This helped reduce the number of successful attacks by 40%. The European network Billa has also
updated its systems by implementing new security protocols, which has significantly increased the
level of protection. The Ukrainian network Novus has implemented similar measures, which also
led to a decrease in the number of successful attacks.
Access control to IoT devices is an important component of their protection. Built-in access control
allows you to restrict access to devices to only authorized users, which reduces the risk of
unauthorized access.</p>
        <p>For example, Auchan has implemented built-in access control on all of its self-service terminals.
This helped reduce the number of unauthorized access incidents by 50%. The European Lidl chain
has also taken similar measures, which has significantly improved security. The Ukrainian ATB
chain has implemented similar measures, which helped reduce the number of incidents.
Implementation of these security methods allows retailers to ensure a high level of security for IoT
devices, which in turn increases customer trust and reduces the risk of personal data leakage.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Conclusions</title>
      <p>Implementing modern encryption algorithms such as AES and RSA is critical to protecting personal
data in retail. Their use helps to increase the level of consumer confidence and compliance with
security standards such as PCI DSS and GDPR.</p>
      <p>The use of multi-factor authentication (MFA) to protect access to customer and employee
accounts, the use of probabilistic models to assess the effectiveness of various authentication
factors significantly increases the level of information security in the retail sector.</p>
      <p>Protecting cloud services, including the use of firewalls and real-time monitoring systems,
allows you to detect and prevent threats at an early stage, minimizing potential data loss. The use
of modern security protocols, regular software updates, and access control to devices were
recognized as critical to ensuring the security and protection of IoT devices, which are an
important element of modern retail.</p>
      <p>Implementation of modern mathematical models, encryption algorithms, multi-factor
authentication, network segmentation and cloud service protection are key elements of ensuring
reliable information security. This allows not only to protect confidential information but also to
increase customer confidence in retail companies.
While preparing this work, the authors used the AI programs Grammarly Pro to correct text
grammar and Strike Plagiarism to search for possible plagiarism. After using this tool, the authors
reviewed and edited the content as needed and took full responsibility for the publication’s content.</p>
    </sec>
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