crypto2_solve_matess3r4

crypto2_solve_matess3r4.py

from telnetlib import *
import json
import hashlib
from Crypto.Util.number import *
from libnum import *
r = Telnet('125.235.240.166', 13337)


def get_key():
	data = json.loads(r.read_until("\n").strip())
	N, g, k = data['N'], data['g'], data['k']
	return N,g,k

def exchanged_key(A, usn):
    data = '{"A":%s,"username":"%s"}' % (A, usn)
    r.write(data + "\n")

def get_back():
	data = json.loads(r.read_until("\n").strip())
	salt, B = data['salt'], data['B']
	return salt,B

def check_token(token):
    data = '{"token":"%s"}' % str(token)
    r.write(data + "\n")
    r.interact()
    

def hmac(salt, data, hex):
    if hex:
        return hashlib.sha512(salt + data).hexdigest()
    return hashlib.sha512(salt + data).digest()


def create_key(salt,A,B,k,g,rand_num,N,password):
    xH = hmac(str(salt), password, 0)
    x = bytes_to_long(xH)
    uH = hmac(str(A), str(B), 0)
    u = bytes_to_long(uH)
    S = pow(B - k * pow(g, x, N), rand_num  + u * x, N)
    K = hmac('', str(S), 0)
    return hmac(K, str(salt), 1)

N,g,k = get_key()

exchanged_key(str(N**2), "peterjson")

salt,B = get_back()

K = hmac('', str(0), 0)

h = hmac(K, str(salt), 1)
print h

check_token(h)

# h = create_key(salt, A, B, k, g, 17, N, "hehe")

# check_token(h,str(s))