def encrypt(pt):
pt = junk() + pt + junk()
k, iv = util.rbytes(16), util.rbytes(16)
if util.rbool():
return "ECB", util.AesEcbCipher(k).encrypt(pt)
else:
return "CBC", util.AesCbcCipher(k, iv).encrypt(pt)
def __init__(self):
self.ecb = util.AesEcbCipher(util.rbytes(16))
self.suffix = base64.b64decode(INPUT)
def create_ct(known_pt):
seed = util.rint(0, 0xFFFF)
pt = util.rbytes(util.rint(1, 20)) + known_pt
return seed, MtCipher(seed).crypt(pt)
def __init__(self):
self.key = util.rbytes(16)
def create_token(self, userdata: str) -> bytes:
if ";" in userdata or "=" in userdata:
raise ValueError("invalid userdata")
s = f"comment1=cooking%20MCs;userdata={userdata};comment2=%20like%20a%20pound%20of%20bacon"
nonce = util.rbytes(8)
return nonce + util.AesCtrCipher(self.key, nonce).crypt(s.encode())
def test_solve():
ecb = util.AesEcbCipher(b"YELLOW SUBMARINE")
ctr = AesCtrEditingCipher(util.rbytes(16), util.rbytes(8))
with open("files/25.txt") as f:
pt = ecb.decrypt(base64.b64decode(f.read()))
assert recover_pt(ctr, ctr.crypt(pt)) == pt
def test_aes_ecb_cipher():
for n in range(1, 33):
k, pt = util.rbytes(16), util.rbytes(n)
cipher = util.AesEcbCipher(k)
assert cipher.decrypt(cipher.encrypt(pt)) == pt
def test_aes_ctr_cipher():
for n in range(1, 33):
k, n, pt = util.rbytes(16), util.rbytes(8), util.rbytes(n)
cipher = util.AesCtrCipher(k, n)
assert cipher.crypt(cipher.crypt(pt)) == pt
def test_aes_cbc_cipher():
for n in range(1, 33):
k, iv, pt = util.rbytes(16), util.rbytes(16), util.rbytes(n)
cipher = util.AesCbcCipher(k, iv)
assert cipher.decrypt(cipher.encrypt(pt)) == pt
def junk():
return util.rbytes(util.rint(5, 10)) # 5-10 random bytes.
def __init__(self):
self.key = util.rbytes(16)
self.cbc = util.AesCbcCipher(self.key, self.key)
def create_token(self):
iv, pt = util.rbytes(16), util.rchoice(self.secrets)
return iv + util.AesCbcCipher(self.key, iv).encrypt(pt)
def __init__(self):
self.key = util.rbytes(16)
self.secrets = [base64.b64decode(s) for s in INPUT.split()]
def __init__(self):
self.ecb = util.AesEcbCipher(util.rbytes(16))
def create_cts(s):
pts = [base64.b64decode(line) for line in s.split()]
k, n = util.rbytes(16), util.rbytes(8)
return [util.AesCtrCipher(k, n).crypt(pt) for pt in pts]
