client using X.509 certificates, and the authentication of the client to the server is left to the application layer. TLS also offers client-to-server authentication using client-side X.509 authentication. As it requires provisioning of the certificates to the clients and involves less user-friendly experience, it's rarely used in end-user applications. Mutual TLS authentication (mTLS) is more often used in business-to-business (B2B) applications, where a limited number of programmatic and homogeneous clients are connecting to specific web services, the operational burden is limited, and security requirements are usually much higher as compared to consumer environments. mTLS is also used in microservices-based applications based on runtimes such as Dapr, via systems like SPIFFE. Lightweight schemes vs. secured schemes While lightweight schemes and secure schemes are not mutually exclusive, adding a mutual authentication step to data transmissions protocols can often increase performance runtime and computational costs. This can become an issue for network systems that cannot handle large amounts of data or those that constantly have to update for new real-time data (e.g. location tracking, real-time health data). Thus, it becomes a desired characteristic of many mutual authentication schemes to have lightweight properties (e.g. have a low memory footprint) in order to accommodate the system that is storing a lot of data. Many systems implement cloud computing, which allows quick access to large amounts of data, but sometimes large amounts of data can slow down communication. Even with edge-based cloud computing, which is faster than general cloud computing due to a closer proximity between the server and user, lightweight schemes allow for more speed when managing larger amounts of data. One solution to keep schemes lightweight during the mutual authentication process is to limit the number of bits used during communication. Applications that solely rely on device-to-device (D2D) communication, where multiple devices can communicate locally in close proximities, removes the third party network. This in turn can speed up communication time. However, the authentication still occurs through insecure channels, so researchers believe it is still important to ensure mutual authentication occurs in order to keep a secure scheme. Schemes may sacrifice a better runtime or storage cost when ensuring mutual authentication in order to prioritize protecting the sensitive data. Password-based schemes In mutual authentication schemes that require a user's input password as part of the verification process, there is a higher vulnerability to hackers because the password is human-made rather than a computer-generated certificate.