1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
| import socketserver
import os, sys, signal
import string, random, time, json
from hashlib import sha256
from secret import flag
from Crypto.Cipher import AES
from Crypto.Util.Padding import pad,unpad
from ast import literal_eval as eval
key = os.urandom(32)
def decrypt(ciphertext:str,iv):
try:
iv = bytes.fromhex(iv)
ciphertext = bytes.fromhex(ciphertext)
cipher = AES.new(key, AES.MODE_CBC, iv)
decrypted = unpad(cipher.decrypt(ciphertext),16)
if not b'Admin' in decrypted:
return 'Permissino denied !'
except ValueError as e:
return str(e)
return decrypted
def encrypt(plaintext:str,admin=False):
try:
iv = os.urandom(16)
payload = {'permission':'Guest','Time':f'{time.time()}','data':plaintext}
print(payload)
payload = pad(json.dumps(payload).encode(),16)
cipher = AES.new(key, AES.MODE_CBC, iv)
encrypted = cipher.encrypt(payload)
except ValueError as e:
return str(e)
return iv.hex() + encrypted.hex()
class Task(socketserver.BaseRequestHandler):
def _recvall(self):
BUFF_SIZE = 2048
data = b''
while True:
part = self.request.recv(BUFF_SIZE)
data += part
if len(part) < BUFF_SIZE:
break
return data.strip()
def send(self, msg, newline=True):
if type(msg) is str:
msg = msg.encode()
try:
if newline:
msg += b'\n'
self.request.sendall(msg)
except:
pass
def recv(self, prompt=b'> '):
self.send(prompt, newline=False)
return self._recvall()
def close(self):
self.send(b"Bye~")
self.request.close()
def proof_of_work(self):
random.seed(os.urandom(8))
proof = ''.join([random.choice(string.ascii_letters+string.digits) for _ in range(20)])
_hexdigest = sha256(proof.encode()).hexdigest()
self.send(f"sha256(XXXX+{proof[4:]}) == {_hexdigest}".encode())
x = self.recv(prompt=b'Give me XXXX: ')
if len(x) != 4 or sha256(x+proof[4:].encode()).hexdigest() != _hexdigest:
return False
return True
def handle(self):
if 0 and not self.proof_of_work():
return
menu = '''1. Encrypt data\n2. Decrypt data\n3. Get encrypted flag\n'''
while 1:
self.send('\n' + menu)
try:
r = int(self.recv())
except:
continue
if r == 3:
self.send(b'Encrypted flag:\n')
self.send(encrypt(flag.hex()))
elif r == 2:
iv,data = self.recv(prompt=b'Data to decrypt:').strip().split(b'||')
self.send(decrypt(data.decode(),iv.decode()))
elif r == 1:
data = self.recv(prompt=b'Data to encrypt:').strip()
self.send(encrypt(data.decode()))
self.close()
class ThreadedServer(socketserver.ThreadingMixIn, socketserver.TCPServer):
pass
class ForkedServer(socketserver.ThreadingMixIn, socketserver.TCPServer):
pass
if __name__ == "__main__":
HOST, PORT = '0.0.0.0', 10000
server = ForkedServer((HOST, PORT), Task)
server.allow_reuse_address = True
server.serve_forever()
|
