# Challenge Description

Bob is hosting a party and invited everyone but me. But all the invitations I can collect are encrypted.

# Solution
The challenge files contain the source code.
We can see this is another RSA challenge that includes some weird custom padding:
```python
def 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<