The much-anticipated replacement protocol for ZCoin’s Zerocoin protocol, Sigma has been released. The team in an official post said:

We are proud to finally release Zcoin 13.8.1 which will activate our Sigma privacy protocol on block 182,030 or approximately 23 July 2019. This release is a culmination of work that began in early 2018 and a testnet launch in early May 2019.

Members of the community have been asked to update their existing wallets and Znodes to the new version before the scheduled hard fork.

As a recap of what Sigma is, the new protocol is meant to introduce a “no trusted” setup, while replacing RSA accumulators with elliptic curves for faster verification time.

In addition to the above upgrades included in the Sigma protocol, the team is developing its GUI to meet up with the new protocol. For a start, the QT wallet has been simplified to allow users mint and spend Sigma easily. Fees for mints and spends are dynamic, changing with the size of the transaction.

The Sigma privacy protocol represents a very important innovation in blockchain privacy as it combines the high privacy of zero-knowledge proof schemes without many of its associated drawbacks. It provides a compelling alternative to zkSNARKs which has very high anonymity and great performance but does this at the cost of trusted setup, exotic cryptography and complicated constructions that are prone to errors.