Papers from this era, such as On the Security Verification of a Short Message Service Protocol , highlighted that SMS is not inherently secure because it travels over unencrypted mobile networks [35].
: A user enters their credentials (username/password) on a website or app [13]. SMS Verification Method 2019.pdf
: Attackers could intercept SMS codes by exploiting vulnerabilities in the SS7 protocol used by global telecommunications [22]. Papers from this era, such as On the
: This directive, which came into full effect in September 2019 , forced banks to implement Strong Customer Authentication (SCA). Many banks chose SMS-OTP as the most accessible second factor for compliance [6]. 3. Security Risks Identified in 2019 Research : This directive, which came into full effect
: The server generates a unique, time-sensitive code and sends it via the mobile network to the user's registered phone number [13].