def Handshake(password, reader, writer):
myPrivateKey = Private()
myNonce = os.urandom(32)
WriteBin(writer, myPrivateKey.get_public().serialize())
WriteBin(writer, myNonce)
theirPublicKey = ReadBin(reader)
theirNonce = ReadBin(reader)
if myNonce == theirNonce:
return None
if theirPublicKey in (b'\x00' * 32, b'\x01' + (b'\x00' * 31)):
return None
theirPublicKey = Public(theirPublicKey)
sharedKey = myPrivateKey.get_shared_key(theirPublicKey)
myProof = ComputeProof(sharedKey, theirNonce + password)
WriteBin(writer, myProof)
theirProof = ReadBin(reader)
if not VerifyProof(sharedKey, myNonce + password, theirProof):
return None
return sharedKey
def test_basic(self):
secret1 = b"abcdefghijklmnopqrstuvwxyz123456"
self.assertEqual(len(secret1), 32)
secret2 = b"654321zyxwvutsrqponmlkjihgfedcba"
self.assertEqual(len(secret2), 32)
priv1 = Private(secret=secret1)
pub1 = priv1.get_public()
priv2 = Private(secret=secret2)
pub2 = priv2.get_public()
shared12 = priv1.get_shared_key(pub2)
e = b"b0818125eab42a8ac1af5e8b9b9c15ed2605c2bbe9675de89e5e6e7f442b9598"
self.assertEqual(hexlify(shared12), e)
shared21 = priv2.get_shared_key(pub1)
self.assertEqual(shared12, shared21)
pub2a = Public(pub2.serialize())
shared12a = priv1.get_shared_key(pub2a)
self.assertEqual(hexlify(shared12a), e)
#!/usr/bin/env python3
from curve25519 import Private, Public
from binascii import hexlify
keys = set()
for i in range(30):
myPrivate = Private()
val = int.to_bytes(
325606250916557431795983626356110631294008115727848805560023387167927233504,
32, 'little')
theirPublic = Public(val)
shared = myPrivate.get_shared_key(theirPublic)
print(hexlify(shared))
keys.add(shared)
print("[~] Num of different keys: {}".format(len(keys)))
#!/usr/bin/env python3
from curve25519 import Public
import nacl.secret
import socket
import binascii
socket_server = ("mitm.ctfcompetition.com", 1337)
public_key_val = Public(int.to_bytes(325606250916557431795983626356110631294008115727848805560023387167927233504, 32, 'little'))
shared_key = binascii.unhexlify(b'68b59f127c671255346e099c3b9ea067a5595ba2adf26daa5e69d6a8a29d191a')
def make_sockets():
server = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server.connect(socket_server)
client = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
client.connect(socket_server)
return server, client
def attack():
s, c = make_sockets()
s.send(b's\n')
c.send(b'c\n')
server_pub = s.recv(4096)[:-1]
print(server_pub.decode())
server_nonce = s.recv(4096)[:-1]
print(server_nonce.decode())
import logging
import sys
import os
from curve25519 import Private, Public
import nacl.secret
import hmac
import hashlib
from pwn import *
context.log_level = 'debug'
sk = Private()
mypk = b'\xed\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\x7f'
pk = Public(mypk)
myshare = sk.get_shared_key(pk)
def getmac(myn):
c = remote('mitm.ctfcompetition.com', 1337)
c.sendline('c')
pk = c.recvline()
n0 = c.recvline()
c.sendline(hexlify(mypk))
c.sendline(myn)
mac = c.recvline()
c.close()
return mac