Category: ctf

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.

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.

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.

Writeup for the crypto challenge 'Hash Vegas' from NiteCTF2025