Securing data transfers with relativity
New way to secure data transfers based on the physical principle of
relativity

Date:
November 3, 2021
Source:
Universite' de Gene`ve
Summary:
The volume of data transferred is constantly increasing, but the
absolute security of these exchanges cannot be guaranteed, as shown
by cases of hacking frequently reported in the news. To counter
hacking, a team has developed a new system based on the concept
of 'zero-knowledge proofs', the security of which is based on the
physical principle of relativity: information cannot travel faster
than the speed of light. Thus, one of the fundamental principles of
modern physics allows for secure data transfer. This system allows
users to identify themselves in complete confidentiality without
disclosing any personal information, promising applications in
the field of cryptocurrencies and blockchain.



FULL STORY ==========================================================================
The volume of data transferred is constantly increasing, but the absolute security of these exchanges cannot be guaranteed, as shown by cases of
hacking frequently reported in the news. To counter hacking, a team from
the University of Geneva (UNIGE), Switzerland, has developed a new system
based on the concept of "zero-knowledge proofs," the security of which
is based on the physical principle of relativity: information cannot
travel faster than the speed of light. Thus, one of the fundamental
principles of modern physics allows for secure data transfer. This
system allows users to identify themselves in complete confidentiality
without disclosing any personal information, promising applications in
the field of cryptocurrencies and blockchain. These results can be read
in the journal Nature.


==========================================================================
When a person -- the so called 'prover' -- wants to confirm their
identity, for example when they want to withdraw money from an ATM, they
must provide their personal data to the verifier, in our example the bank, which processes this information (e.g. the identification number and the
pin code). As long as only the prover and the verifier know this data, confidentiality is guaranteed. If others get hold of this information,
for example by hacking into the bank's server, security is compromised.

Zero-knowledge proof as a solution To counter this problem, the prover
should ideally be able to confirm their identity, without revealing any information at all about their personal data.

But is this even possible? Surprisingly the answer is yes, via the concept
of a zero-knowledge proof. "Imagine I want to prove a mathematical
theorem to a colleague. If I show them the steps of the proof, they
will be convinced, but then have access to all the information and could
easily reproduce the proof," explains Nicolas Brunner, a professor in the Department of Applied Physics at the UNIGE Faculty of Science. "On the contrary, with a zero-knowledge proof, I will be able to convince them
that I know the proof, without giving away any information about it, thus preventing any possible data recovery." The principle of zero-knowledge
proof, invented in the mid-1980s, has been put into practice in recent
years, notably for cryptocurrencies. However, these implementations
suffer from a weakness, as they are based on a mathematical assumption
(that a specific encoding function is difficult to decode). If this
assumption is disproved -- which cannot be ruled out today -- security
is compromised because the data would become accessible. Today, the
Geneva team is demonstrating a radically different system in practice: a relativistic zero- knowledge proof. Security is based here on a physics concept, the principle of relativity, rather than on a mathematical
hypothesis. The principle of relativity -- that information does not
travel faster than light -- is a pillar of modern physics, unlikely to
be ever challenged. The Geneva researchers' protocol therefore offers
perfect security and is guaranteed over the long term.

Dual verification based on a three-colorability problem Implementing
a relativistic zero-knowledge proof involves two distant verifier/
prover pairs and a challenging mathematical problem. "We use a three- colorability problem. This type of problem consists of a graph made up
of a set of nodes connected or not by links," explains Hugo Zbinden,
professor in the Department of Applied Physics at the UNIGE. Each node
is given one out of three possible colours -- green, blue or red -- and
two nodes that are linked together must be of different colours. These three-colouring problems, here featuring 5,000 nodes and 10,000 links,
are in practice impossible to solve, as all possibilities must be
tried. So why do we need two pairs of checker/prover? "To confirm
their identity, the provers will no longer have to provide a code,
but demonstrate to the verifier that they know a way to three-colour a
certain graph," continues Nicolas Brunner. To be sure, the verifiers
will randomly choose a large number of pairs of nodes on the graph
connected by a link, then ask their respective prover what colour the
node is. Since this verification is done almost simultaneously, the
provers cannot communicate with each other during the test, and therefore cannot cheat. Thus, if the two colours announced are always different,
the verifiers are convinced of the identity of the provers, because
they actually know a three-colouring of this graph. "It's like when the
police interrogates two criminals at the same time in separate offices:
it's a matter of checking that their answers match, without allowing them
to communicate with each other," says Hugo Zbinden. In this case, the
questions are almost simultaneous, so the provers cannot communicate with
each other, as this information would have to travel faster than light,
which is of course impossible. Finally, to prevent the verifiers from reproducing the graph, the two provers constantly change the colour code
in a correlated manner: what was green becomes blue, blue becomes red,
etc. "In this way, the proof is made and verified, without revealing
any information about it," says the Geneva-based physicist.

A reliable and ultra-fast system In practice, this verification is
carried out more than three million times, all in less than three
seconds. "The idea would be to assign a graph to each person or client," continues Nicolas Brunner. In the Geneva researchers' experiment,
the two prover/verifier pairs are 60 metres apart, to ensure that they
cannot communicate. "But this system can already be used, for example,
between two branches of a bank and does not require complex or expensive technology," he says. However, the research team believes that in the very
near future this distance can be reduced to one metre. Whenever a data
transfer has to be made, this relativistic zero-knowledge proof system
would guarantee absolute security of data processing and could not be
hacked. "In a few seconds, we would guarantee absolute confidentiality," concludes Hugo Zbinden.

========================================================================== Story Source: Materials provided by Universite'_de_Gene`ve. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Pouriya Alikhani, Nicolas Brunner, Claude Cre'peau, Se'bastien
Designolle, Raphae"l Houlmann, Weixu Shi, Nan Yang, Hugo Zbinden.

Experimental relativistic zero-knowledge proofs. Nature, 2021;
599 (7883): 47 DOI: 10.1038/s41586-021-03998-y ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/11/211103140105.htm

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