Non-interactive Proofs of Proof-of-Work (NIPoPoW)
From CryptoWiki
The main problem with sidechains today is their security. There are several attacks where mainchains can be compromised through side chains. The Cardanos team has changed this by introducing a provably secure sidechain technology that fixes all known avenues of attack, opening the way for secure sidechains. They call it Non-interactive Proofs of Proof-of-Work (NIPoPoW). Although the Cardano’s team is far from implementing NIPoPoW sidechains on Cardano, the technology is a significant step forward.
