We construct a 1-round delegation scheme (i.e., argument-system) for every language computable in time
t
=
t
(
n
), where the running time of the prover is
poly
(
t
) and the running time of the verifier is n ·
polylog
(
t
). In particular, for every language in
P
we obtain a delegation scheme with almost linear time verification. Our construction relies on the existence of a computational sub-exponentially secure private information retrieval (
PIR
) scheme.
The proof exploits a curious connection between the problem of
computation delegation
and the model of
multi-prover interactive proofs that are sound against no-signaling (cheating) strategies
, a model that was studied in the context of multi-prover interactive proofs with provers that share quantum entanglement, and is motivated by the physical principle that information cannot travel faster than light.
For any language computable in time
t
=
t
(
n
), we construct a multi-prover interactive proof (
MIP
), that is, sound against no-signaling strategies, where the running time of the provers is
poly
(
t
), the number of provers is
polylog
(
t
), and the running time of the verifier is
n
·
polylog
(
t
).
In particular, this shows that the class of languages that have polynomial-time
MIP
s that are sound against no-signaling strategies, is exactly
EXP
. Previously, this class was only known to contain
PSPACE
.
To convert our
MIP
into a 1-round delegation scheme, we use the method suggested by Aiello et al. (ICALP, 2000), which makes use of a
PIR
scheme. This method lacked a proof of security. We prove that this method is secure assuming the underlying
MIP
is secure against no-signaling provers.