404 at the moment, and not in Wayback. Google Cache finds it at:
http://webcache.googleusercontent.com/search?q=cache:https%3...
in turn listing the source as:
http://www.cl.cam.ac.uk/~pes20/nqsbtls-usenix-security15.pdf
http://webcache.googleusercontent.com/search?q=cache:https%3...
in turn listing the source as:
http://www.cl.cam.ac.uk/~pes20/nqsbtls-usenix-security15.pdf
I left another copy of the paper on my homepage at http://anil.recoil.org/papers/2015-usenixsec-nqsb.pdf, but Peter's version or the USENIX site should be fine as well.
In case the information is of any value, this much later, the first link (at nqsb.io) works for me, now. (So does the second link.)