Tags: paillier safe_prime 

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## TL;DR
1. Generate a safe prime `q = 2p + 1`
2. Use p * q as public key
3. Send enc(q) as c
4. `x0 = dec(c0) % p`
5. `x1 = dec(c1) % q`

Original writeup (https://sasdf.cf/ctf-tasks-writeup/writeup/2018/HackOver/crypto/oblivious/).