[Original writeup](https://imp.ress.me/blog/2022-07-26/mch-2022-crypto/#squaring-off)

tl;dr Solve discrete log modulo prime^2 with combination of Pohlig-Hellman and Paillier decryption.

Original writeup (https://imp.ress.me/blog/2022-07-26/mch-2022-crypto/#squaring-off).