## 2 Literature Review and Related Work
In the following, we discuss some of the commonly used authentication methods for securing ATM transactions as of now. 1. EMV EMV is a widely adopted global standard for chip-based payment cards. EMV cards contain embedded microchips that generate dynamic authentication codes for each transaction [3; 4; 8]. When the card is inserted into an EMV-enabled ATM or POS terminal, the chip communicates with the terminal to verify the card's authenticity and the cardholder's identity. This method makes it difficult for fraudsters to clone or counterfeit cards [26; 27; 28; 29]. 2. PIN For ATM transactions, PIN-based authentication is widely used. The cardholder must enter their unique PIN to complete the transaction, ensuring that only the authorized user can access the funds [5; 6; 7]. 3. Biometric authentication Some modern ATMs and POS systems are equipped with biometric authentication methods, such as fingerprint scanners or facial recognition. Biometric data provides a highly secure way to verify the cardholder's identity [21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32]. However, the major drawback of biometric approaches is that they require large systems with very high power and processing capability with high implementation and deployment costs. 4. OTP The use of OTPs as a second layer of authentication has been extensively studied. OTPs sent via SMS, email, or generated through authenticator apps add an extra security layer, protecting against unauthorized access even if the primary authentication credentials (e.g., PIN) are compromised [3; 4; 5]. However, concerns have been raised regarding the reliance on mobile networks and email security. Voice recognition technology has also been investigated for ATM authentication. Early studies indicate that voice-based systems can be vulnerable to voice-mimicking attacks, which raises concerns about their reliability as a standalone authentication method. However, when used in conjunction with other factors, such as location-based authentication, voice recognition can be a valuable component of a multi-layered security approach [9; 21; 22; 23; 33; 34; 35]. To provide a better understanding, Table 1 summarizes the authentication methods employed in the context of payment transactions, according to the latest state of the art we reviewed. \begin{table}
\begin{tabular}{p{56.9 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline  
According to the research summarized in Table 2, only a few studies have been conducted on securing ATM transactions where most of the work focused on securing mobile and online transactions. Apart from the summarized research in Table 2, [PERSON] et al. (2010) proposed a novel protocol for multi-factor authentication based on a transaction identification code and SMS to secure wireless payments., especially for securing e-commerce-related transactions. In [17], [PERSON] et al. (2018) discussed the design of a secure transaction system that can be used for mobile payments that are based on cryptographic smart contracts. However, their proposed authentication schema is limited to mobile payment transactions. According to the contributors to Geolocation Drives Future of Payments (2020), geolocation technology is an important part of identity verification and authentication in payment transactions, especially when it is combined with other sophisticated technologies such as biometric-based authentication and voice recognition. In [26], [PERSON] and [PERSON] (2021) presented a unique security architecture for the purpose of safeguarding e-wallet apps by making use of MFA. Overall, their suggested system will verify the user's identity by making use of the user's password, fingerprint, and OTP. Overall, compared to our approach, all the work we summarized contains drawbacks such as higher implementation costs, usability issues, and vulnerability to security attacks.