Crypto Without Privacy Isn't Crypto

Privacy is the soul of crypto, and without it, nothing else we’re doing really matters.

If you care about financial sovereignty, you need privacy. If you care about coordinating with others to effect social change, or thinking freely, or building a more prosperous society, you need the free exchange of value. Freedom begins with privacy.

As engineers and scientists working on Zcash, we have spent years developing private financial tools that will be embedded into the future of civilization. It is no exaggeration to say that our descendants will either live in a world that rests upon the foundations that we are building today, or else live in a world that we neglected.

Zcash was the first cryptocurrency to ship real, strong privacy with zero-knowledge proofs. Solving the privacy problem with cryptography was only the first step: we needed to quickly iterate and improve our cryptography so that it was practical to run on phones, and invest heavily into research that would make it possible to scale. Today, our innovations sit at the heart of many decentralized protocols.

But while the path forward for scaling the private on-chain payments is now straightforward, no project has addressed the fundamental challenge of scaling private wallets at the same time.

Most users of cryptocurrencies will use wallet software that relies on a remote server to enable sending and receiving payments. This helps address scaling problems by pushing bandwidth and computational burdens away from users’ devices, but comes at the cost of requiring the user to relinquish their privacy to remote services.

To make our privacy-preserving monetary project a reality we need a user experience that is just as convenient as one that has no privacy at all.

The simplest solution is to use exotic cryptography to enable remote servers to assist our local wallet software without revealing any private information. We’ve known that this is theoretically possible, but until recently it seemed to be impractical at scale — at least a decade of new science away, or so we thought.

Enter Project Tachyon. With existing cryptography and some clever protocol adjustments, it is completely practical for Zcash’s wallet software to synchronize with a highly active blockchain full of transactions by outsourcing the expensive parts to untrusted third party servers. The servers don’t learn anything about your wallet and cannot even tell which on-chain transactions correspond with their users.

To be sure, the cryptography needed to make this possible and scalable is still not simple. Fortunately, Zcash has a long track record of building and shipping this exact kind of advanced cryptography. We’ve already set the stage for it in some of our recent upgrades, and with Project Tachyon we plan to make rapid progress deploying the remaining changes over the next year.

I’m excited that we have such strong enthusiasm and alignment in the Zcash community to make it a reality. But I’m also relieved that we can meet the moment and actually build highly scalable, unstoppable digital money. We don’t have time to wait for any more research or scientific advances. Fortunately, with Tachyon, we can build and deliver today.