Cousin Wu Ka Lok

First-year PhD student in the Computer Science Department at Stony Brook University. CTF, Maths enthusiast. A member of the Black Bauhinia (blackb6a) CTF team based in Hong Kong.

The personal website for Wu "Cousin" Ka Lok (also known as Cosine, usin, …). This website contains blogs and write-ups to CTF challenges that I find interesting. I would also like to share the mathematics behind cryptography, and how the designed may be exploited for attacks. I also made some visualizations of (sometimes seemingly abstract) mathematical concepts.

Recent posts

Coppersmith’s Method (Part I): Introduction

49 minute read ★★★☆☆

The Coppersmith’s method is an application of lattice basis reduction algorithms (like LLL) to find small solutions to polynomials modulo (N). The applicatio...

Basics of Lattice-based Cryptography

55 minute read ★★★☆☆

Lattice is a very important construct for modern day cryptography, especially when we know that in the future, quantum computers will break both ECC and RSA,...

HKCERT CTF 2021 Selected Write-ups

29 minute read ★★☆☆☆

Last Friday to Sunday there was the HKCERT CTF competition 2021 held by HKCERT. I am not allowed to join the competition (for obvious reasons). Nonetheless I...