On July 13th, Zooko Wilcox, the Founder and CEO of the privacy coin Zcash tweeted about the upcoming network upgrade, named Sapling. The upgrade is reportedly aimed at increasing the speed of transactions on the network.
Sapling will also play an important role in increasing the efficiency of shielded transactions which will further assist in the adoption of Zcash shielded addresses by exchanges and vendors.
According to the Zcash blog, the activation of the Sapling upgrade is planned to take place in October this year. However, a specific block height has not been decided yet.
Sapling is a proof of all the designing and engineering efforts by Zcash in the course of two years, with major cryptographic crackdowns contributing to the functionality and performance of shield transactions.
The computational cost to prove the validity of shielded transactions is high. Therefore, Zcash is currently using transparent addresses that work in the same way as Bitcoin. Sapling is Zcash’s ‘big move’ to promote ubiquity in shielded addresses.
Some of the technical changes made by Zcash in its shielded transactions are:
The given address is known as ‘Sprout z-address’. This is because Zcash introduced it in its original release of Sprout. These addresses always begin with ‘zc’. Sprout series was the codename given to the MainNet launch of Zcash blockchain back in 2016.
A Sapling Z-address begins with ‘zs’ and is much shorter. Post the activation of Sapling, the Sprout Z-addresses will still function but it will not be long before the new address takes over.
Some of its implications are:
The transactions containing the Sapling Z-addresses will take much lesser time [a few seconds] and a memory of about 40 megabytes only. This will enable phone wallets, vendors, and all other parties to support shielded addresses.
This will greatly impact the overall privacy of the entire network by a frequent use of shielded addresses.
Decoupled Spend Authority: Changes and implications
Zcash uses a privacy protocol known as zero-knowledge proof, which will be used by all shielded transactions. The spending key that signs for the transaction must also possess the hardware used to construct the proof. With Sapling, the co-dependency between the two hardwares that construct the proof and authorize the transaction is removed.
With this change, a computer that is not trusted by an enterprise can still construct the proof for it, providing the enterprise with an inexpensive signature procedure in a trusted environment.
Improved keys: Changes and implications
The current state of the shielded addresses is that it only supports an incoming viewing key. This key can be used by the holder to view the values of all the incoming transactions as well as the memo field. However, the feature of viewing the sending addresses and spending the funds is unavailable.
Sapling also enables the holders to view outgoing transactions. Through this, the key holder can view the transaction amount, the memo field and the target address.
These features enable the owners of shielded addresses to view transactions without having to reveal their private information.
The Zcash blog stated:
“Sapling z-addresses come with a feature which allows trillions of addresses to receive payments simultaneously with no additional performance cost on the receiving end. All of these addresses are unlinkable with each other.”
It further explained:
“Currently, exchanges and merchants must pay a computational penalty to receive on large numbers of z-addresses. The new Sapling z-addresses allow these businesses to create large numbers of distinct and unlinkable z-addresses for their clients.”