  We present an accreditation protocol for the outputs of noisy
intermediate-scale quantum devices. By testing entire circuits rather than
individual gates, our accreditation protocol can provide an upper-bound on the
variation distance between noisy and noiseless probability distribution of the
outputs of the target circuit of interest. Our accreditation protocol requires
implementation of quantum circuits no larger than the target circuit, therefore
it is practical in the near term and scalable in the long term. Inspired by
trap-based protocols for the verification of quantum computations, our
accreditation protocol assumes that noise in single-qubit gates is bounded (but
potentially gate-dependent) in diamond norm. We allow for arbitrary spatial and
temporal correlations in the noise affecting state preparation, measurements
and two-qubit gates. We describe how to implement our protocol on real-world
devices, and we also present a novel cryptographic protocol (which we call
`mesothetic' protocol) inspired by our accreditation protocol.
