Cryptography

Cjixoxv Qxvxtp qz ZBJCV 2022!

Wxz cjonx! Xfxgxw gxizxt djlcjoxtpxv ntvng djlgyofjvzcz?
Gnwxlxf gxizxt cjonx fntux cjoxtpxv uxtp cxox qjtpxtgn!
Cjoxtpxv vzqxg wxtux djlqxofxg fxqx gxizxt cxex, vjvxfz
enpx vjlwxqxf vjoxt-vjoxt gxizxt, exqz vjvxfixw cjoxtpxv!
Xuy xmxiz fjlenxtpxton qjtpxt ojojkxwgxt cyxi ztz!
Gxon fxcvz dzcx! ztz, bixptux xqx qzdxmxw ! 
ZBJCV22{1ii_cv4u_du_u0nl_c1q3_qdx943210}

Cjixoxv=Selamat Qxvxtp=Datang qz=di ZBJCV=IFEST cjonx=semua 
djlcjoxtpxv=bersemangat

from pwn import *
import string

length = 38
r = remote("103.185.38.244",9989)

r.recvuntil(b"Pilih: ")
r.sendline(b"3")
r.recvuntil(b"Hasil: ")
ct = r.recvline().strip().decode()
list_pt = string.printable[:-6]
list_map = [[] for _ in range(length)]
for i in list_pt:
	r.recvuntil(b"Pilih: ")
	r.sendline(b"1")
	r.recvuntil(b"string: ")
	payload = i.encode()*length
	r.sendline(payload)
	r.recvuntil(b"Hasil: ")
	tmp = r.recvline().strip().decode()
	for j in range(len(tmp)):
		list_map[j].append(tmp[j])
flag = ""
for i in range(len(ct)):
	flag += list_pt[list_map[i%length].index(ct[i])]
print(flag)

from Crypto.Cipher import AES
import random
from Crypto.Util.Padding import pad


# J: So for the key, I use 5 random digits and repeat it until i get 16 bytes
# M: What? Man, i was using the exact same formula!

first_key = b""
second_key = b""
FLAG = b"IFEST22{REDACTED}"

def generateKey():
	global first_key, second_key
	first_key = (str(random.randint(0, 99999)).zfill(5)*4)[:16].encode()
	second_key = (str(random.randint(0, 99999)).zfill(5)*4)[:16].encode()

def encrypt(plaintext, a, b):
	cipher = AES.new(a, mode=AES.MODE_ECB)
	ct = cipher.encrypt(pad(plaintext, 16))
	cipher = AES.new(b, mode=AES.MODE_ECB)
	ct = cipher.encrypt(ct)
	return ct.hex()

def main():
	generateKey()
	print("Here's your flag, but encrypted heheh:", encrypt(FLAG, first_key, second_key))
	while True:
		print("Text to encrypt:")
		plain = input(">> ")
		print("result:", encrypt(plain.encode(), first_key, second_key))

if __name__ == '__main__':
	main()

from Crypto.Cipher import AES
import random
from Crypto.Util.Padding import pad
from pwn import *

payload = b"a"
inp = pad(payload,16)
r = remote("kepapasan.user.cloudjkt01.com",9977)
r.recvuntil(b"heheh: ")
ct_flag = bytes.fromhex(r.recvline().strip().decode())
r.recvuntil(b">> ")
r.sendline(payload)
r.recvuntil(b"result: ")
enc_inp = bytes.fromhex(r.recvline().strip().decode())
r.close()
list_key1 = {}
list_key2 = {}
for i in range(0, 99999+1):
	key = (str(i).zfill(5)*4)[:16].encode()
	cipher1 = AES.new(key, AES.MODE_ECB)
	enc_msg = cipher1.encrypt(inp)
	dec_msg = cipher1.decrypt(enc_inp)
	list_key1[enc_msg] = key
	list_key2[dec_msg] = key

tmp = list_key1.keys() & list_key2.keys()
print(tmp)
index = tmp.pop()
key1 = list_key1[index]
key2 = list_key2[index]
print(f"Key 1 : {key1}")
print(f"Key 2 : {key2}")
cipher1 = AES.new(key1, AES.MODE_ECB)
cipher2 = AES.new(key2, AES.MODE_ECB)

enc_msg = cipher2.decrypt(ct_flag)
flag = cipher1.decrypt(enc_msg)
print(flag)

from Crypto.Util.number import *
import random
from sympy import *

FLAG = b"IFEST22{REDACTED}"
def generate_prime():
	p = getPrime(512)
	q = nextprime(p)
	while p%4 != 3 or q%4 !=3:
		p = getPrime(512)
		q = nextprime(p)
	return p, q

def encrypt(m, n):
	return pow(m, 32, n)

p, q = generate_prime()
n = p*q
m = bytes_to_long(FLAG)

ct = encrypt(m, n)

file = open('out.txt', 'w')
file.write(f"n = {n}\nct = {ct}")

from Crypto.Util.number import *
import gmpy2
from sympy import *

n = 167369799324048138104052175535407583505752871957215436773759031023017258211926244898005523956634683846521843112989667257058661590892952518940981897603075244277403071620405906110395876285850586645267366109871364424530232323323093329164542366451609555755793278574306885322737868611730986497942446035931912990173
c = 21531359371326785000813539498235533853399851284161815602787505606478539937473829218703225074127036671433545623422527404993307032442845415396127106566947516725271774364574823414757530290809389432379888075234068890851808191948433382743838583087849527954870829102252458108566336758346284806983878333023038231317
tmp = gmpy2.iroot(n,2)[0]
q = nextprime(tmp)
p = n//q
e = 32
phi = (p-1)*(q-1)
d = inverse(e,phi)
# m = pow(ct,d,n)

def egcd(a, b):
	if a == 0:
		return (b, 0, 1)
	else:
		g, y, x = egcd(b % a, a)
		return (g, x - (b // a) * y, y)

g ,yp,yq = egcd(p,q)

mp = pow(c,(p+1)//4,p)
mq = pow(c,(q+1)//4,q)

for i in range(4):
	mp = pow(mp,(p+1)//4,p)
	mq = pow(mq,(q+1)//4,q)

r = (yp*p*mq + yq*q*mp) % n
mr = n - r
s = (yp*p*mq - yq*q*mp) % n
ms = n - s
for num in [r,mr,s,ms]:
	print(long_to_bytes(num))