2022. 12. 13. 15:18, CTF/Crypto
$U[i] // T[i]$ is very similar with $x$. So just calculate $U[i] // T[i]$ and manually check the near integer which has the last 5 chars are _cfrt
.
from sage.all import *
from pwn import *
from Crypto.Util.number import *
r = remote("190.92.234.114", 23334)
r.recvuntil(b" = ")
q = int(r.recvline())
r.recvuntil(b" = ")
T = eval(r.recvline())
r.recvuntil(b" = ")
U = eval(r.recvline())
for i in range(90):
z = U[i] // T[i]
print(long_to_bytes(z), z)
for j in range(-3,3):
print(long_to_bytes(j+z), j+z)
r.interactive()
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