Here is a collection of write ups and discussions of the challenges I have solved in various capture the flag competitions. The focus is usually the cryptographic challenges.

CTF Writeups

CTF Category
Crypto CTF 2021 Elliptic & Edwards Curves, RSA, Diophantine Eqns.
Cyber Apocalypse CTF 2021 RSA, Elliptic & Hyperelliptic Curves, Multivariate, Maths
Zer0pts 2021 Elliptic Curves, Polynoimial Rings
TetCTF 2021 Gaussian Integers, Discrete Log Problem, Finite Fields
CryptoCTF 2020 Moebius Inversion, Unsolved (Unsolvable?)
CryptoCTF 2020 Team Writeup, all challenges
Chujowy Elliptic Curves
ASIS Quals 2020 Elliptic Curves, RSA, Blum-Goldwasser, Diophantine Eqns.
0CTF 2020 DSA, Hyperelliptic Curves
redpwn 2020 RSA, ECDSA, Elliptic Curves
HackTM Crypto, OSint
SecurityFest Modular Arithmetic
HSCTF 2019 Crypto
picoCTF 2019 General, Binary, Crypto, Forensics, Web


Some other CTF-like problems I’ve looked into, with some code and thoughts (this is very much a work in progress).

Elliptic Curves