Projective coordinates are leaked through power analysis, which results in nonce bit recovery. Applying a lattice attack on the Hidden Number Problem to recover the private key. [Original version](https://blog.cryptohack.org/ecdsa-side-channel-attack-projective-signatures-donjon-ctf-writeup)

Original writeup (https://blog.cryptohack.org/ecdsa-side-channel-attack-projective-signatures-donjon-ctf-writeup).