ARPA is a Secure Computation Network Compatible With Blockchains They propose a blockchain-based secure computation network of Multi-party Computation (MPC). ARPA cryptographically enables private smart contract, unprecedented data-at-use privacy protection, as well as scalable computational sharding.
Cloakcoin is a completely secure, fully private and untraceable digital cash with full fungibilty (all coins equivalent). Cloakcoin is able to achieve this privacy through the use of an offchain coin mixing system called “Enigma”. Check out CoinBureau for the complete review on Cloakcoin.