import requests
from time import sleep
from base64 import b64decode
import sys

URL = 'https://t800.codectf.localos.io/challenge'
OUTPUT = 'challenges.csv'
SIGCOUNT = 4
INTERVAL = 30 # chall ändert sich alle 30s
ORDER = 115792089210356248762697446949407573529996955224135760342422259061068512044369 #NIST256p

HPNAME = "ctf2023"
HPPASS = "t,FcUGJ>h:7=.woy"

def sigdecode(sig, order):
	bl = (order.bit_length() + 7) // 8 # bytelength
	sig = b64decode(sig.encode('utf-8'))
	assert len(sig) == 2 * bl
	r = int.from_bytes(sig[:bl], 'big') # ab bytelength
	s = int.from_bytes(sig[bl:], 'big') # bis bytelength
	return r % order, s % order

if __name__ == '__main__':
	with open(OUTPUT, 'w') as outfile:
		count = 0
		last_chal = None
		
		while count < SIGCOUNT:
			s = requests.Session()
			s.auth = (HPNAME, HPPASS) # session auth
			
			resp = s.get(URL, verify = False)
			data = resp.json()
			r, s = sigdecode(data['sig'], ORDER)
			chal = data['challenge']
			
			if chal != last_chal:
				print(chal, r, s, sep=',', file=outfile)
				last_chal = chal
				count += 1
			
			sleep(INTERVAL / 2)