Category: ctf

A quick refresher on what opcodes look like in a disassembler, the three operand types (immediate, register, memory), and several common x86 instructions (MOV, LEA, NOP, SHL/SHR) plus the most common EFLAGS bits you’ll see referenced during reversing and exploitation.

Brief writeup and explaination from an old CTF involving the chinese remainder theorem word problem + a RSA problem showcasing similar priniples.

An incomplete but structured writeup for the “Secure Source” challenge. The app signs JWTs with a custom ECDSA implementation whose nonce comes from Python’s Mersenne Twister. Note IDs leak enough RNG output to recover MT state and predict the next nonce, enabling signature forgery. Also covers where the public key should come from and how to obtain it in practice.

title: "Parrot the Emu CTF writeup from DownUnderCTF" summary: "Parrot the Emu easy web CTF challenge writeup (DownUnderCTF)" tags: ["linux", "security", "sysadmin", "web"] published: true date: 2024-12-25T15:00:00Z

Writeup for the crypto challenge 'Magical Oracle' I designed and created for L3akCTF25

Writeup for the crypto challenge 'Hash Vegas' from NiteCTF2025

Intended solution writeup for 'Crypto On the Rocks' a challenge I made for L3akCTF2024 based off the P-521 curve and a MSB biased nonce vulnerability inspired directly by CVE-2024-31497.

NiteCTF24 'R Stands Alone' crypto writeup showing how the RSA modulus with three primes falls by factoring $r = a^3 + 16b^3$ in a cubic number field, recovering $p$ and $q$ to decrypt the flag.

Brief writeup/explaination of the challenge '2048 AI' from an old CTF.

Official solution write-up for the challenge 'CoCoracle' based off the COCONUT98 cipher and a SPN reduced round number implementation (5) in order to facilitate the **Boomerang Attack** within a reasonable amount of time for for GrizzHacks8 (2026)

Brief writeup/explaination of the challenge 'Smelter' from TamuCTF involving RSA signature forgery

Brief writeup/explaination of the challenge 'Cert' from P0lyglots24 involving RSA signature forgery

Write-up/solution explanation for one of many challenges I made for GrizzHacks8. This post goes over the **Boomerang** attack, more specifically as it relates to the COCONUT98 block cipher.

A quick refresher on what opcodes look like in a disassembler, the three operand types (immediate, register, memory), and several common x86 instructions (MOV, LEA, NOP, SHL/SHR) plus the most common EFLAGS bits you’ll see referenced during reversing and exploitation.

An incomplete but structured writeup for the “Secure Source” challenge. The app signs JWTs with a custom ECDSA implementation whose nonce comes from Python’s Mersenne Twister. Note IDs leak enough RNG output to recover MT state and predict the next nonce, enabling signature forgery. Also covers where the public key should come from and how to obtain it in practice.

Writeup for the crypto challenge 'Hash Vegas' from NiteCTF2025

NiteCTF24 'R Stands Alone' crypto writeup showing how the RSA modulus with three primes falls by factoring $r = a^3 + 16b^3$ in a cubic number field, recovering $p$ and $q$ to decrypt the flag.

Brief writeup/explaination of the challenge '2048 AI' from an old CTF.

Brief writeup/explaination of the challenge 'Smelter' from TamuCTF involving RSA signature forgery

Brief writeup/explaination of the challenge 'Cert' from P0lyglots24 involving RSA signature forgery