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Tag: Factorization

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Factorization

Factorization is the process of expressing a number or expression as a product of simpler factors. This often means breaking a polynomial into lower-degree polynomials.

In cryptography, integer factorization is important because the security of some systems depends on how hard it is to factor large numbers. (automatically translated from Japanese)

minaminao
·Updated Apr 24, 2026
Factorization Challenges

42*

SECCON CTF 13 決勝観戦CTF
18 solves
Crypto

by

minaminao

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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