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SECCON CTF 13 決勝観戦CTF

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Beginner & Welcome

Welcome!
100 pts (167 solves)

Author:

minaminao

Beginner & Crypto
100 pts (152 solves)

Author:

Beginner & Web
100 pts (139 solves)

Author:

Rev & Beginner
100 pts (121 solves)

Author:

Beginner & Misc
100 pts (89 solves)

Author:

Beginner & Pwn
100 pts (31 solves)

Author:

Pwn
100 pts (75 solves)

Author:

100 pts (78 solves)

Author:

100 pts (21 solves)

Author:

100 pts (6 solves)

Author:

Crypto
100 pts (40 solves)

Author:

100 pts (81 solves)

Author:

100 pts (10 solves)

Author:

100 pts (11 solves)

Author:

Rev
100 pts (38 solves)

Author:

100 pts (10 solves)

Author:

100 pts (3 solves)

Author:

Web
100 pts (8 solves)

Author:

100 pts (15 solves)

Author:

100 pts (6 solves)

Author:

Misc
100 pts (19 solves)

Author:

42*

100 pts (10 solves)
Crypto

Author:

minaminao

出力からフラグを復元してください🐍

import os
import random
from Crypto.Util.number import bytes_to_long

x = bytes_to_long(os.getenv("FLAG").encode())
for _ in range(42):
    x *= random.getrandbits(42)
print(x)

出力:

302825260919317779466638288706941757478119936504864503289299111810878557424069832851837952929397907929396668240458993245662741522591539210493306557224673507192171095532552008396687356525313836501117714017702880902013061423179550493813470620956236263763510927657899587551000326509836294794948423351121777067521675908878203343378571238778872260377769563951765315203164771192344115744888944635103673374760547507150197387248980588584664707496184797486345139870127142403853041203948936595396757260050089360185668376949219377211437731767603055237909466371770346897408000000000000000
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