2017湖湘杯writeup

python
#Embedded file name: rev300.py
__g = globals()
__y = (lambda f: (lambda x: x(x))(lambda y: f(lambda : y(y)())))
string = (__import__('string', __g, __g))
table = (string.printable.strip())
"""
setbit = (lambda p, pos, value: (lambda __l: [ [ [ (lambda __target, __slice, __value: [ (lambda __target, __slice, __value: [ __l['p'] for __target[__slice] in [(lambda __old: (lambda __ret: (__old | __value if __ret is NotImplemented else __ret))(getattr(__old, '__ior__', lambda other: NotImplemented)(__value)))(__target[__slice])] ][0])(__l['p'], __l['cpos'], __l['value'] << __l['bpos']) for __target[__slice] in [(lambda __old: (lambda __ret: (__old & __value if __ret is NotImplemented else __ret))(getattr(__old, '__iand__', lambda other: NotImplemented)(__value)))(__target[__slice])] ][0])(__l['p'], __l['cpos'], ~(1 << __l['bpos'])) for __l['bpos'] in [__l['pos'] % 8] ][0] for __l['cpos'] in [__l['pos'] / 8] ][0] for __l['p'], __l['pos'], __l['value'] in [(p, pos, value)] ][0])({}))
setbit.__name__ = 'setbit'
getbit = (lambda p, pos: (lambda __l: [ [ [ __l['p'][__l['cpos']] >> __l['bpos'] & 1 for __l['bpos'] in [__l['pos'] % 8] ][0] for __l['cpos'] in [__l['pos'] / 8] ][0] for __l['p'], __l['pos'] in [(p, pos)] ][0])({}))
getbit.__name__ = 'getbit'
encode =  (lambda data, buf: (lambda __l: [ [ (lambda __items, __after, __sentinel: __y(lambda __this: lambda : (lambda __i: ([ [ __this() for __l['data'][__l['i']] in [table.index(__l['data'][__l['i']]) + 1] ][0] for __l['i'] in [__i] ][0] if __i is not __sentinel else __after()))(next(__items, __sentinel)))())(iter(xrange(__l['_len'])), lambda : (lambda __items, __after, __sentinel: __y(lambda __this: lambda : (lambda __i: ([ [ [ __this() for __l['buf'] in [setbit(__l['buf'], __l['i'], getbit(__l['data'], __l['j']))] ][0] for __l['j'] in [__l['i'] / 6 * 8 + __l['i'] % 6] ][0] for __l['i'] in [__i] ][0] if __i is not __sentinel else __after()))(next(__items, __sentinel)))())(iter(xrange(__l['_len'] * 6)), lambda : __l['buf'], []), []) for __l['_len'] in [len(__l['data'])] ][0] for __l['data'], __l['buf'] in [(data, buf)] ][0])({}))
encode.__name__ = 'encode'
"""
def setbit(p,pos,value):
    bpos = pos % 8
    cpos = pos / 8
    s = p
    s[cpos] = p[cpos] & (~(1 << bpos))
    s[cpos] = p[cpos] | (value << bpos)
    return s
def getbit(p,pos):
    bpos = pos % 8
    cpos = pos / 8
    return p[cpos] >> bpos & 1
def encode(data, buf):
    indexdata = []
    for i in xrange(len(data)):
        indexdata.append(table.index(data[i]) + 1)
    res = buf
    for i in xrange(len(data)*6):
        j = i / 6 * 8 + i % 6
        setbit(res, i, getbit(indexdata, j))
    return res
def encrypt():
    fin = open('key.txt', 'r')
    s = fin.read().strip()
    fin.close()
    ss = ([])
    sss = ([])
    __items = iter(s)
    __after = (lambda : [ [ (lambda __items, __after, __sentinel: __y(lambda __this: lambda : (lambda __i: ([ (lambda __value: [ __this() for __g['sssss'] in [(lambda __ret: (__g['sssss'] + __value if __ret is NotImplemented else __ret))(getattr(__g['sssss'], '__iadd__', lambda other: NotImplemented)(__value))] ][0])(chr(c)) for __g['c'] in [__i] ][0] if __i is not __sentinel else __after()))(next(__items, __sentinel)))())(iter(ssss), lambda : [ (fout.write(sssss), (fout.close(), None)[1])[1] for __g['fout'] in [open('key1.enc', 'wb+')] ][0], []) for __g['sssss'] in [''] ][0] for __g['ssss'] in [encode(ss, sss)] ][0])
    __sentinel = ([])
    __y(lambda __this: lambda : (lambda __i: ([ (ss.append(c), (sss.append(0), __this())[1])[1] for __g['c'] in [__i] ][0] if __i is not __sentinel else __after()))(next(__items, __sentinel)))()
def decrypt():
    fin = open('key.enc','rb')
    cipher = fin.read()
    plain = ''
    def decode3b(s):
        a = s >> 16
        b = (s >> 8) & 0xFF
        c = s & 0xff
        sa = bin(a)[2:].zfill(8)
        sb = bin(b)[2:].zfill(8)
        sc = bin(c)[2:].zfill(8)
        return table[int(sa[2:], 2)] + table[int(sb[4:] + sa[:2], 2)] + table[int(sc[6:] + sb[:4], 2)] + table[int(sc[:6], 2)]
    for i in xrange(0,len(cipher),3):
        s = int(cipher[i:i+3].encode('hex'),16)
        plain += decode3b(s)
    print plain
    return ''.join(table[(table.index(c) + 63) % 64] for c in plain)
if __name__ == '__main__':
    print decrypt()
    print table[table.index("d")+64]
    #Key:9733c070b2138e5f