# Challenge Description
Bob is hosting a party and invited everyone but me. But all the invitations I can collect are encrypted.
# SolutionThe challenge files contain the source code.We can see this is another RSA challenge that includes some weird custom padding:```pythondef MGF(seed, length):    random.seed(seed)    return [random.randint(0,255) for _ in range(length)]
def pad(stream, bitlength, tag = b''):    seed = sha256(stream).digest()    DB = sha256(tag).digest() + b'\x00' * ((bitlength - 16 - 2*hLen) // 8 - len(stream)) + b'\x01' + stream    mask = MGF(seed, len(DB))    maskedDB = [DB[i] ^ mask[i] for i in range(len(DB))]    seedmask = MGF(bytes_to_long(bytes(maskedDB)), hLen // 8)    masked_seed = [seed[i] ^ seedmask[i] for i in range(hLen // 8)]    EM = [0] + masked_seed + maskedDB    return bytes(EM)
key = RSA.generate(N, e = (1<<(1<