چالش Blex¶

import sys
from Crypto.Util.number import *
from flag import flag

def die(*args):
    pr(*args)
    quit()

def pr(*args):
    s = " ".join(map(str, args))
    sys.stdout.write(s + "\n")
    sys.stdout.flush()

def sc(): 
    return sys.stdin.buffer.readline()

def keygen(r):
    assert len(r) <= 60
    v, l = int(r, 16), len(r)
    e = (64 - l) << 4
    u, w = v << e, 2 ** (e >> 1)
    for _ in range(110):
        r = getRandomRange(1, w)
        p = r + u
        while p >> e == v:
            if isPrime(p):
                while True:
                    x, y = [2 * getRandomNBitInteger(p.bit_length() >> 2) for _ in '__']
                    P, Q = x * p | 1, y * p | 1
                    if isPrime(P) and isPrime(Q):
                        return P, Q
            p += 1

def main():
    border = "|"
    pr(border*72)
    pr(border, f"Welcome to Blex task! Your mission is break our complex cryptosystem", border)
    pr(border*72)
    pr(border, f"please provide your desired seed to generate key in hex:")
    seed = sc().decode()
    try:
        _b = len(seed) <= 60 and int(seed, 16) >= 0
    except:
        die(border, f"The seed you provided is either not in hex or is not valid!")
    if _b:
        pr(border, f"Generating keypair, please wait...")
        p, q = keygen(seed)
        e, n =  65537, p * q
        m = bytes_to_long(flag)
        assert m < n
        c = pow(m, e, n)
        pr(border, f'n = {n}')
        pr(border, f'c = {c}')
    else:
        die(border, f"Your seed is too long!!!")

if __name__ == '__main__':
    main()

from Crypto.Util.number import *
p=967779994343424298972799836410726382421
q=1906290831706106101563543378153882219493
c=561549521363482185023346141805060013137561099778218746283913794237812517123464
e=65537
n=p*q
phi=(p-1)*(q-1)
d=pow(e,-1,phi)
print(long_to_bytes(pow(c,d,n)))