We consider what constitutes identities in cryptography. Typical examples include your name and your social-security number, or your fingerprint/iris-scan, or your address, or your (non-revoked) publickey coming from some trusted public-key infrastructure. In many situations, however, where you are defines your identity. For example, we know the role of a bank-teller behind a bullet-proof bank ...

In this work, we initiate the study of position-based cryptography in the quantum setting. The aim is to use the geographical position of a party as its only credential. This has interesting applications, e.g., it enables two military bases to communicate over insecure channels and without having any pre-shared key, with the guarantee that only parties within the bases learn the content of the ...

We study the problem of constructing secure positioning protocols (Sastry et. al, 2003). Informally, the goal of such protocols is to enable a party P to convince a set of verifiers about P ’s location in space, using information about the time it takes P to respond to queries sent from different points. It has been shown by Chandramn et al (2009) that in general such task is impossible to achi...