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| from pwn import *
from base64 import b64encode as enc
from Crypto.Util.number import *
import decimal
def oracle(c):
fuck = enc(long_to_bytes(c))
l = len(fuck)
r.recvuntil('want here')
r.sendline('2')
r.recvuntil('send how long you want to decrypt')
r.send(str(l))
r.recvuntil('send the message in base64 encode')
r.send(fuck)
res = r.recvline()
res = r.recvline()
log.info(res)
if 'res:1' in res:
return 1
elif 'res:0' in res:
return 0
def partial(n,e,c):
global c_of_2
k = n.bit_length()
decimal.getcontext().prec = k
lower = decimal.Decimal(0)
upper = decimal.Decimal(n)
c_of_2 = pow(2, e, n)
c = (c * c_of_2) % n
for i in range(k):
possible_plaintext = (lower + upper) / 2
flag = oracle(c)
if not flag:
upper = possible_plaintext
else:
lower = possible_plaintext
c = (c * c_of_2) % n
print i, flag, int(upper - lower)
return int(upper)
r = remote('121.37.174.33',9999)
r.recvuntil('n:')
n = r.recvuntil('\ne:',drop=True)
n = int(n)
r.recvuntil('flag:')
c = r.recvuntil('\nyou',drop=True)
c = int(c)
log.success(hex(n))
log.success(hex(c))
e = 65537
print(partial(n,e,c))
|