# GynvaelEN mission 009

# cat mission_09.py
import datetime

# Microsoft rand
def rand():
 global seed
 seed = (seed * 214013 + 2531011) % 2147483648
 return seed / 65536


key = [0] * 31
secret = [0] * 31
xor = [0x9a, 0x60, 0x76, 0x14, 0x8b, 0x36, 0x5a, 0x10, 0x2b, 0x91, 0xc4, 0x6c, 0xab, 0x27, 0x92, 0x99, 0xf8, 0x6a, 0xec, 0x5d, 0x32, 0x20, 0x3d, 0x61, 0x8f, 0xc7, 0xfb, 0xdd, 0x02, 0x72, 0xbf]


for s in range(1500336000, 1500508800):
 seed = s
 for i in range(31):
  eax = rand()
  rdx = (2139127681 * eax) >> 39
  ecx = eax >> 31
  edx = (rdx & 0xffffffff) - ecx
  ecx = edx << 8
  edx += ecx
  eax -= edx
  key[i] = eax & 0xff

 for i in range(31):
  secret[i] = (xor[i] ^ key[i]) & 0xff

 if all(c < 128 for c in secret):
  print 'seed =', s
  print 'time = ', datetime.datetime.fromtimestamp(s)
  print ''.join([chr(c) for c in secret])
  break

# python mission_09.py
seed = 1500483661
time =  2017-07-19 18:01:01
Who needs to store keys anyway.

Source

https://www.youtube.com/watch?v=7RotbY17tKk (1:47:55)

Reference

https://en.wikipedia.org/wiki/COFF