Secure positioning and non-local correlations
  Recently, the problem of secure position-verification has been extensively analyzed in a formal notion where distant verifiers send encrypted challenge along with the decryption information to the prover. However, currently it is known that all the existing position-verification scheme are insecure and secure positioning is impossible. We propose here a different notion for position-verification where distant verifiers determine the actions of the prover through non-local correlations generated by local measurements at the provers site. The proposed scheme guarantees secure positioning even if the verifiers do not have any pre-shared data with the prover, position is the only credential of the prover. Our proposed scheme is secure in general and evades known quantum attacks based on instantaneous non-local computations in particular. The scheme enables verifiers to identify dishonest provers with very high probability , where n is the number of entangled pairs used. 
Muhammad Nadeem
quant-ph