This challenge is about ECDSA nonce-reuse weakness. See [this post](https://ropnroll.co.uk/2017/05/breaking-ecdsa/) for explanation.
Solver code: [ecdsa_solve.py](https://github.com/CTF-STeam/ctf-writeups/blob/master/2021/TenableCTF/ecdsa_solve.py)
Flag: `flag{cRypt0_c4r3fully}`