33c3 mario

mario.py

import itertools
import struct

# Rotate left: 0b1001 --> 0b0011
rol = lambda val, r_bits, max_bits: \
    (val << r_bits%max_bits) & (2**max_bits-1) | \
    ((val & (2**max_bits-1)) >> (max_bits-(r_bits%max_bits)))
 
# Rotate right: 0b1001 --> 0b1100
ror = lambda val, r_bits, max_bits: \
    ((val & (2**max_bits-1)) >> r_bits%max_bits) | \
    (val << (max_bits-(r_bits%max_bits)) & (2**max_bits-1))


def go(x, a):
	return int(bin(x)[2:].zfill(8)[a:a+2], 2)

def permute(x, y):
	result = [x[go(y, 6-i)] for i in range(0, 8, 2)]
	return result

def ipermute(x, y):
	a = [0] * 4
	for i in range(0, 8, 2):
		b = go(y, 6-i)
		a[b] = i / 2
	# print a
	result = [x[a[i]] for i in range(4)]
	return result

arr = [10, 80, 50, 60]
assert ipermute(permute(arr, 0x8d), 0x8d) == arr

MASK = 0xffffffffffffffff

low = lambda x: x & MASK
high = lambda x: x >> 32

text = str(bytearray(range(32)))
text = bytearray(struct.pack("<4Q", 0x8A76639879E2196CL, 0xAF7AEA900F7D0218L, 0xC23662B9AEFABDB2L, 0x74C0A7F29FF2FC80L))
l1, l2, r1, r2 = struct.unpack("<4Q", text)
l = l1 | (l2 << 64)
r = r1 | (r2 << 64)
split = lambda x: [(x >> (16 * i)) & 0xffff for i in range(8)]
def merge(x, bits=16):
	result = 0
	for i in range(len(x)):
		result |= x[i] << (bits * i)
	return result
RKey = merge([0xC0D3, 0x4D00, 0x00D3, 0xB4BE] + [0xC4FE, 0x3700, 0x0013, 0x33C3])

if 0:
	for i in range(42):
		l, r = split(l), split(r)
		print map(hex, l), map(hex, r)
		l, r = l[4:] + r[4:], r[:4] + l[:4]
		l = permute(l[:4], 0x8d) + permute(l[4:], 0xd2)
		r = permute(r[:4], 0x39) + permute(r[4:], 0x87)
		print map(hex, l), map(hex, r)
		l1, l2, r1, r2 = merge(l[:4]), merge(l[4:]), merge(r[:4]), merge(r[4:])
		print hex(merge([l1, l2])), hex(merge([r1, r2]))
		print hex(l1), 'l1'
		l1 = ror(l1, 0x33, 0x33+0xD) ^ (RKey & MASK)
		l2 = ror(l2, 0x33, 0x33+0xD) ^ (RKey >> 64)
		r1 = ror(r1, 0x11, 0x2F+0x11) ^ (RKey & MASK)
		r2 = ror(r2, 0x11, 0x2F+0x11) ^ (RKey >> 64)
		l, r = merge([l1, l2], 64), merge([r1, r2], 64)
		print i

	print hex(l), hex(r)

	print '====='

for i in range(42):
	l, r = split(l), split(r)
	l1, l2, r1, r2 = merge(l[:4]), merge(l[4:]), merge(r[:4]), merge(r[4:])
	l1 = rol(l1 ^ (RKey & MASK), 0x33, 0x33+0xD)
	l2 = rol(l2 ^ (RKey >> 64), 0x33, 0x33+0xD)
	r1 = rol(r1 ^ (RKey & MASK), 0x11, 0x2F+0x11)
	r2 = rol(r2 ^ (RKey >> 64), 0x11, 0x2F+0x11)
	print hex(l1)
	l, r = merge([l1, l2], 64), merge([r1, r2], 64)
	print hex(l), hex(r)
	l, r = split(l), split(r)
	print map(hex, l), map(hex, r)
	l = ipermute(l[:4], 0x8d) + ipermute(l[4:], 0xd2)
	r = ipermute(r[:4], 0x39) + ipermute(r[4:], 0x87)
	l, r = r[4:] + l[:4], r[:4] + l[4:]
	print map(hex, l), map(hex, r)
	l, r = merge(l), merge(r)

print hex(l), hex(r)
key = [0x5f,0x38,1]
flag = struct.pack("<4Q", l & (2 ** 64 - 1), l >> 64, r & (2 ** 64 - 1), r >> 64)
flag = bytearray(flag)
print `flag`
flag = bytearray((x - y) & 0xff for x, y in zip(flag, itertools.cycle(key)))
print `flag`