How well can you know the edge of a quantum pyramid?

Abstract

The methods of quantum cryptography enable one to have perfectly secure communication lines, whereby the laws of quantum physics protect the privacy of the data exchanged. Each quantum-cryptography scheme has its own security criteria that need to be met in a practical implementation. We find, however, that the generally accepted criteria are flawed for a whole class of such schemes.

3 pages, 1 color figure; this is a brief announcement of a recent result, about which a more detailed report is being prepared