Decrypts your Monster Hunter world save data

extract.py

import sys, errno, io
import struct
import base64

import blowfish

key = base64.b64decode(b'eGllWmpvZSNQMjEzNC0zem1hZ2hncHFvZTB6OCQzYXplcQ==')
cipher = blowfish.Cipher(key, byte_order="little")

if sys.version_info[0] == 3:
	stdin = sys.stdin.buffer
	stdout = sys.stdout.buffer
else:
	stdin = sys.stdin
	stdout = sys.stdout

CHUNK_SIZE = 2048
def iter_chunks():
	while True:
		buf = stdin.read(CHUNK_SIZE)
		if not buf: break
		yield buf

def decrypt_chunks(chunk_iter):
	for chunk in chunk_iter:
		yield b"".join(cipher.decrypt_ecb(chunk))

# just a bit of pretty printing don't kill me for it
def wrap_in_bar(buffer_it):
	# don't print any progress bar if we are not in a tty setting
	if not sys.stderr.isatty():
		return buffer_it
	try:
		from progress.bar import Bar
		from progress.spinner import Spinner
	except ImportError:
		# or if progress is not available
		return buffer_it
	# try to detect the file size. This should be same (~9MiB) but who knows
	# what you are doing with it :)
	if stdin.seekable():
		pos = stdin.tell()
		end = stdin.seek(0, io.SEEK_END)
		if end != pos:
			repos = stdin.seek(0, io.SEEK_SET)
			assert pos == repos, "couldn't seek back to the initial position in the stream"
		bar = Bar("Processing", file=sys.stderr, max = (end - pos + CHUNK_SIZE - 1) // CHUNK_SIZE)
		return bar.iter(buffer_it)
	else:
		return Spinner("Processing", file=sys.stderr).iter(buffer_it)

if __name__ == "__main__":
	if stdin.isatty():
		print("Usage: python3 {} < SAVEDATA1000 > SAVEDATA1000.extracted.bin".format(sys.argv[0]), file=sys.stderr)
		exit(1)
	buffer_it = wrap_in_bar(iter_chunks())
	for buf in decrypt_chunks(buffer_it):
		try:
			stdout.write(buf)
		except IOError as e:
			if e.errno == errno.EPIPE:
				break
	# This suppresses a warning python would print if stdout is attached
	# to a pipe instead of a file.
	# see: https://stackoverflow.com/questions/26692284/
	sys.stderr.close()

optional-requirements.txt

progress

requirements.txt

blowfish