[Cryptography] SPDZ, a practical protocol for Multi-Party Computation

Max Kington mkington at webhanger.com
Wed Sep 11 13:14:42 EDT 2013

On 11 Sep 2013 18:01, "Eugen Leitl" <eugen at leitl.org> wrote:
> Breakthrough in cryptography could result in more secure computing
> (9/10/2013)
> Tags: computer science, research, security, cryptography
> Nigel Smart, Professor of Cryptology
> New research to be presented at the 18th European Symposium on Research in
> Computer Security (ESORICS 2013) this week could result in a sea change in
> how to secure computations.
> The collaborative work between the University of Bristol and Aarhus
> University (Denmark) will be presented by Bristol PhD student Peter Scholl
> from the Department of Computer Science.
> The paper, entitled 'Practical covertly secure MPC for dishonest majority
> or: Breaking the SPDZ limits', builds upon earlier joint work between
> and Aarhus and fills in the missing pieces of the jigsaw from the groups
> prior work that was presented at the CRYPTO conference in Santa Barbara
> year.
> The SPDZ protocol (pronounced "Speedz") is a co-development between
> and Aarhus and provides the fastest protocol known to implement a
> idea called "Multi-Party Computation".
> The idea behind Multi-Party Computation is that it should enable two or
> people to compute any function of their choosing on their secret inputs,
> without revealing their inputs to either party. One example is an
> voters want their vote to be counted but they do not want their vote made
> public.
> The protocol developed by the universities turns Multi-Party Computation
> a theoretical tool into a practical reality. Using the SPDZ protocol the
> can now compute complex functions in a secure manner, enabling possible
> applications in the finance, drugs and chemical industries where
> often needs to be performed on secret data.
> Nigel Smart, Professor of Cryptology in the University of Bristol's
> Department of Computer Science and leader on the project, said: "We have
> demonstrated our protocol to various groups and organisations across the
> world, and everyone is impressed by how fast we can actually perform
> computations.
> "Only a few years ago such a theoretical idea becoming reality was
> Alice in Wonderland style over ambitious hope. However, we in Bristol
> realised around five years ago that a number of advances in different
> would enable the pipe dream to be achieved. It is great that we have been
> able to demonstrate our foresight was correct."
> The University of Bristol is now starting to consider commercialising the
> protocol via a company Dyadic Security Limited, co-founded by Professor
> and Professor Yehuda Lindell from Bar-Ilan University in Israel.

A colleague is looking into this venture. I gave him a synopsis of their
additions to SPDZ. There is a white paper describing their technology at
their website which talks about the other two related protocols, Yao and

One interesting use that occurred to me was the ability to split the two
nodes in their implementation across jurisdictions. Especially those who
are unlikely to ever collaborate. That giving you an advantage over a
typical HSM which could live in a jurisdiction that could be seized.

The wp and associated bibliography is available at


> Note: This story has been adapted from a news release issued by the
> University of Bristol
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