I'm David Schwartz, known as JoelKatz on many forums. I'm the Chief Cryptographer at Ripple (formerly Ripple Labs) and one of the original architects of what is now called the Ripple Consensus Ledger (RCL).
My identity can be verified by my well-known Bitcoin address:
That can be confirmed to be mine here:
It also appears in the about page on my blog:
I have signed this message:
The signature is:
You can verify the signature with the following bitcoin-cli command (or some other tool):
bitcoin-cli verifymessage \ "1Joe1Katzci1rFcsr9HH7SLuHVnDy2aihZ" \ "HBGKKXVdpkaQu46gu6ZGeMgOHyJLEinAV2JdicAmTRawC1OcimvG3P+40xvBh82M7bnF//HgdKZyj8SEGKAQszw=" \ "07/19/2016-joelkatz-steemit.com"`