NahamCon CTF23

Cryptography / Rsa Intro writeup

Description: What is RSA? Really Spicy Applesauce? Ridiculously Smart Alpaca? Random Squirrel Alliance? Nope, not at all. Just some dudes who made a cool public-key cryptosystem!

from Crypto.Util.number import getStrongPrime, getPrime, bytes_to_long as b2l

FLAG = open('flag.txt', 'r').read().strip()
OUT = open('output.txt', 'w')
l = len(FLAG)
flag1, flag2, flag3 = FLAG[:l//3], FLAG[l//3:2*l//3], FLAG[2*l//3:]
# PART 1
e = 0x10001
p = getStrongPrime(1024)
q = getStrongPrime(1024)
n = p*q
ct = pow(b2l(flag1.encode()), e, n)
OUT.write(f'*** PART 1 …

cryptography ctf ctf-writeup rsa