Upper Bounds for the Security of Quantum Cryptography Using Geometrically Homogeneous Coherent States

The paper investigates the stability of quantum cryptography on geometrically homogeneous coherent states. The technology of using a large number of symmetric states allows us to fight against an error-free discrimination of states (USD-attack) attack, but at the same time, resistance against this attack does not guarantee resistance against any other attacks. Attacks that, under fading conditions, can be effective against a given quantum key distribution system are considered.