Concise Christmas Cryptography Challenges 2019

In December 2018, Cloudflare published a series of cryptography quizzes for users to solve during the festive season. The challenges included decoding a hex string from Wireshark, generating Time-Based One-Time Passwords (TOTP) without a shared secret, and finding hidden messages in RPKI data. The first five participants who solved all the puzzles correctly were promised some Cloudflare swag. The quiz was closed on January 1st, with many responses received, including 15 correct ones. Hints and solutions to the challenges are provided for those interested in learning more about cryptography and its applications.