rwctf challenge Proof of work (PoW) solve script

solve.py

#!/usr/bin/env python3
from pwnlib.util.iters import mbruteforce
from hashlib import sha256
import string
import sys


"""
$ ncat -v [HOST] [PORT]
sha256("KOcNc"+"?") starts with 26bits of zero:

usage: $ python3 solve.py KOcNc
"""

prefixes = sys.argv[1]
def brute(cur):

    content = prefixes + str(cur)
    s = sha256(content.encode())
    if s.hexdigest().startswith("000000") and int(s.hexdigest()[6:8], 16) < 0x40:
        return True
    return False

import pwn
res =  mbruteforce(brute, string.ascii_lowercase + string.digits, method = 'upto', length=6,  threads = 20)
print(res)

rw666

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