cracktheflag.py

#!/usr/bin/env python2

def try_numb_part1(last2):
    ecx = 0x1

    while last2 > 0:
        last2 = last2 - ecx
        ecx += 2
    if last2 != 0:
        return False
    return True

def try_numb_part2(first_4, last2):
    ebx = last2*last2
    eax = first_4
    result = (eax ^ ebx) >> 8
    if result == 0:
        return True
    else:
        return False

def brute_part1():
    possible_vals = []
    for i in range(0, 100)[::-1]:
        if try_numb_part1(i):
            print('Last 2 digits may be... %02d' % i)
            possible_vals.append(i)
    return possible_vals

def brute_part2():
    solutions = []
    possible_vals = brute_part1()
    for i in range(0,10000)[::-1]:
        for last in possible_vals:
            if try_numb_part2(i,last):
                solutions.append((i,last))

    print('# of possible solutions: %d' % len(solutions))
    print('First possible solution: %04d%02d' % solutions[0])
    return solutions

#https://stackoverflow.com/a/15285588/5948112
def isprime(n):
    if n==2 or n==3: return True
    if n%2==0 or n<2: return False
    for i in range(3,int(n**0.5)+1,2):   # only odd numbers
        if n%i==0:
            return False    

    return True

def brute_prime_numbs():
    primes = []
    for i in range(0,999999+1):
        numb = '%06d' % i
        if not isprime(int(numb)):
            continue
        if not isprime(int(numb[:2])):
            continue
        if not isprime(int(numb[2:4])):
            continue
        primes.append(numb)

    return primes

possible_vals = brute_part2()
primes = brute_prime_numbs()
prime_solutions = []
for vals in possible_vals:
    val = '%04d%02d' % vals
    if val not in primes:
        continue
    prime_solutions.append(val)

print('Calculated %d possible solutions.' % len(prime_solutions))
print(prime_solutions)