Foreword I participated in HackTM CTF 2023 with NUS Greyhats. We managed to get 15th place. Overall I am quite happy with my performance this CTF, I managed to solve 1 challenge solo and collaborated with mechfrog88 to solve another Crypto challenge. The Crypto challenges of this CTF are quite tough, and it is an interesting read of the solution given by the creator. I think the given writeups by the author are good enough, and should provide a better view of the educational values after solving the challenges.