Need hashing algorithm and cyber security expert

1. There are three main variants on hashing algorithms – a simple hash, a keyed hash (HMAC), and an iterated hash (PBKDF2, for example). Briefly describe a use case for each of the three variants where this variant is the best choice, and also an anti-pattern, where using that variant would lead to problems. 2. Your app has connected to a server using TLS, and the server has responded with the leaf certificate, the intermediate certificate, and a stapled OCSP response showing that the leaf certificate is not revoked. Unfortunately, some of the server instances have an out of date intermediate certificate that is expired, and connections are failing. Due to the fact that not all of them are failing tells you that a valid intermediate certificate exists. To stop the outages, you need to reconfigure your TLS library to attempt to retrieve the newest copy of the intermediate certificate. Which certificate extension do you need to write a parser for so that you can fetch the new intermediates? How is it that there can be two intermediates that form valid chains between the leaf certificate and the same root? 3. When building a certificate chain, a candidate issuer certificate could be a name match, a key match, or a preferred match. Which portions of an X509v3 certificate have to match for each of the above? 4. How does the basic constraints certificate extension work, and what attacks does it prevent? 5. Explain the major variants of cross site scripting bugs, and why this problem continues to be a popular attack 20 years after its discovery? Rest will be in chats