I am David Schwartz, Chief Cryptographer at Ripple. AMA!
I am Chief Cryptographer at Ripple and one of the original architects of the XRP Ledger. Since November 2011, I've been working on developing and improving the underlying technologies behind Ripple's blockchain, currently focused on improving decentralization. I am known as “JoelKatz” in many online communities.
Update: Thanks so much for the great questions. I guess I should go back to work now. Feel free to contact me on Twitter -- I'm pretty much holding an AMA every day.