Interview with David Schwartz, Chief Cryptographer

David Schwartz is the Chief Cryptographer for the Ripple protocol. Previously, he spent twelve years as the CTO of WebMaster Incorporated. He can often be found discussing crypto-currencies on and The Ripple Forum as “JoelKatz.”

What is Ripple?

Ripple is a financial matching engine unlike anything that has previously existed. For the first time, individuals, exchanges, payment systems, and merchants can be directly interconnected.

That’s a major shift in the status quo.

Payment systems today are where email was in the early 80s. Every provider built their own system for their customers and if people used different systems, they couldn’t easily interact with each other. Ripple is designed to connect different payment systems together.

What will be the result of this new interconnectivity?

What makes Ripple so unique and powerful is the way it harnesses the “invisible hand” of market forces.

Can you give an example?

What you see is a payment that “just works” — you have dollars, you want to pay someone in yen, and it just works. You spend dollars, they get yen. But what you don’t see is that under the surface, someone else who was holding yen but wanted to hold dollars gets what they want too.

What are your long-term hopes for Ripple?

I hope Ripple will change the world for the better. I’d like to see big companies lose their control over the flow of other people’s money just as they’ve lost control over the flow of information.

You view it as a liberating technology?

Ripple will make it harder for repressive governments to use their control over their country’s financial systems to repress their people. Just as the Internet has made it impossible for even the world’s most repressive government to keep their people from reading Western media and blogging about conditions in their country, systems like Ripple could make it impossible for repressive governments to force their people to hold currencies those governments can devalue.

What are the advantages of adopting Ripple early?

There’s lots of room for people to innovate around Ripple. Whoever is the first auction site to support Ripple payments or the first gateway in Russia has a chance to hold onto that position as Ripple grows. I hope Ripple makes some new businesses possible and disrupts inefficient financial and payment systems.

How did you get involved with Ripple?

I started contributing to the Bitcoin project and became convinced that payment systems were going to be disrupted soon in a big way. I wanted to be part of that. Then I saw Jed McCaleb‘s anonymous ad for people interested in working on a new crypto-currency project and answered it. I showed up at a coffee shop in Berkeley for an interview having no idea what to expect. In November of 2011, I was the first person hired to work on what would become Ripple.

What was your professional background before Ripple?

At WebMaster Incorporated I developed a line of cryptographically secure storage and messaging systems. A lot of our customers were government and military, including the FBI and NATO. I was the lead developer for their ConferenceRoom and DriveShare product lines.

What previous work are you most proud of?

I would have to say that I’m most proud of the time I spent consulting for the NSA in 2001. It was an amazing experience and played a significant role in my decision to make cryptography my career focus.

What are some of the down-the-road possibilities for Ripple?

I think the social credit aspect is the most exciting. I don’t think the world is quite ready for that yet, but over time as new tools are developed and social rules change, social credit has the potential to completely change how people think about money. It will require social changes, but so did Facebook and texting, and those changes happened. In the long term, I’d like to see finance integrated into social relationships rather than being an awkward secret.

Anything else?

The contract system also has tremendous promise. This system will allow people to commit to a set of rules that will govern future transactions. This will allow people to build in features that we didn’t think of. Stefan [Thomas] came up with a brilliant “agenda” system that permits contracts to be much more complex and scalable, even permitting contracts that implement new cryptographic algorithms.

What parts of Ripple did you build?

I designed the radix tree structure used to store the Ripple ledger and the binary representations used for Ripple structures. I implemented the algorithms used to fetch, synchronize, compare, and modify transaction trees and ledgers, the deterministic wallet system Ripple uses, and the consensus system used to agree on transaction sets.

What are you working on now?

I’m currently working on improving pathfinding to find more complex payment paths involving multiple exchanges and to be smarter in which payment paths to choose when the paths are equal in cost to help improve liquidity in the system. I also spend more time than I’d care to admit tracking down and fixing bugs.

Anything else you think people should know about Ripple?

People should know that there’s a talented group of people who are devoted to making sure Ripple fulfills its promise. People who live in or near the Bay Area who are interested in Ripple can come to a meetup and meet the Ripple team, see a demonstration of what Ripple can already do, and share their ideas and questions.

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