Script to search offset of the LUKS header on a device file

search-for-luks-header.py

#!/usr/bin/env python3

import threading
import queue
import argparse
import os.path
import sys

NUM_WORKER_THREADS = 16
LUKS_HEADER = b'LUKS\xba\xbe'
BLOCK_SIZE = 1024

# globals
q = queue.Queue()
found = False

def look_for_header(item):
    global found

    f, offset = item
    f.seek(offset)
    b = f.read(BLOCK_SIZE)
    indx = b.find(LUKS_HEADER)
    if indx != -1:
        found = True
        print(f'Found LUKS header at offset {offset+indx} (in bytes)')

def worker():
    global q

    while True:
        item = q.get()
        if not found:
            look_for_header(item)
        q.task_done()

def main(args):
    for i in range(NUM_WORKER_THREADS):
        t = threading.Thread(target=worker)
        t.daemon = True
        t.start()

    for offset in range(0, args.limit*1024*1024, BLOCK_SIZE):
        item = (args.f, offset)
        q.put(item)

    q.join() # block until all tasks are done

if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Look for LUKS header in device file')
    parser.add_argument('-l', '--limit', default=2, type=int, help='limit in MB where to look for the header (default=2)')
    parser.add_argument('device', help='the device where to look for LUKS header')
    args = parser.parse_args()

    if not os.path.isfile(args.device):
        print(f'Error: device {args.device} not found or not readable', file=sys.stderr)
        sys.exit(-1)
        
    try:
        args.f = open(args.device, 'rb')
        main(args)
        args.f.close()
    except KeyboardInterrupt as k:
        print('Aborted by user')
    finally:
        args.f.close()