updates

Unibw 2023/crypto/T800 - I'm Back/00_create_chall_sig_csv.py

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+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)