Coda Protocol: Using zk-SNARKs For A Constant-Size Blockchain

Izaak Meckler gives an approachable overview of Coda: the first cryptocurrency with a constant-sized blockchain. Instead of persisting the entire blockchain, Coda uses recursive composition of zk-SNARKs to compress the blockchain into a tiny proof and sends around that proof instead. That means that no matter how big the blockchain gets, or how many transactions are performed, the cost to verify transactions and data remains constant and inexpensive — around 20kbs and 10ms to verify an account's balance.