ИСТИНА

The Trojan-horse attacks on quantum key distribution (QKD) systems are known to be a threat to secure key sharing between two parties (Alice and Bob). To protect a QKD system against such attacks a variety of passive optical and active optical devices embedded in Alice’s and Bob’s setup are widely used. However, a security analysis against the Trojan-horse attack is required to ensure the unconditional security of a QKD system. We present a security analysis against the Trojan-horse attacks on a practical fiber-based QKD phase-coding system in 400–1700 nm spectral range. The obtained results made it possible to calculate the higher limit of average photon number returned to Eve and the probabilities of Eve’s success of the attack on a particular QKD system.