Cheap Zero-Knowledge Magic ... (and a puzzle to solve 👀).

This tutorial shows how to build a zero-knowledge proof that a user knows a password, then verify it on Starknet using Garaga, at a stated cost of about $5 for deployment and under $1 per proof verification. It walks through writing a Circom circuit that checks a password against its Poseidon hash, generating a Groth16 proof, and generating a Starknet verifier contract with Garaga's CLI. The author notes that writing the checker circuit is the difficult part of zk-apps. The article closes with a challenge: submit a zk-proof that a Starknet address factors into up to 32 integers whose product equals the address, with more factors earning a bigger reward.