ASIS CTF RE/Serial Number

serial.py

asis = [0x41, 0x53, 0x49, 0x53, 0x5f]

flag = [+0x06, -0x24, +0x09, -0x29, -0x2d, -0x2b,
        -0x24, +0x06, +0x08, -0x24, +0x07, +0x06,
        +0x09, -0x25, +0x09, +0x09, -0x26, +0x09,
        -0x25, +0x09, -0x2c, +0x05, -0x26, -0x2d,
        +0x08, +0x07, +0x08, +0x04, +0x07, -0x25,
        -0x29, -0x2a]

for key in range(256):
    a = [f+key&0xff for f in flag]
    b = [chr(i) in '0123456789abcdef' for i in a]
    if False not in b:
        print 'key: ' + str(key)
        print ''.join(map(chr, asis + a))