bitcrypto

solver.py

from Crypto.Util.number import *
from pwn import *

r = remote("crypto.kosenctf.com", 13003)

r.recvuntil("your query: ")
r.sendline('b')

l = r.recvuntil('\n')
c = [int(x) for x in l.split('[')[1].split(']')[0].split(",")]
one, zero = c[0], c[2]

keyword = "yoshiking, give me ur flag"
bits = [int(b) for b in "{:b}".format(bytes_to_long(keyword))]

new_c = []
for b in bits:
    if b == 1:
        new_c.append(one)
        one *= 4
    else:
        new_c.append(zero)
        zero *= 4

r.sendline('[' + ','.join(str(v) for v in new_c) + ']')
r.interactive()
r.close()